initial commit.

Change-Id: I5e639061c99b7cc6da3da06ccf19bde683a69e9f
Signed-off-by: Loïc Collignon <loic.collignon@iot.bzh>

1 files changed, 13003 insertions, 0 deletions

diff --git a/3rdparty/json/json.hpp b/3rdparty/json/json.hpp
new file mode 100755
index 00000000..6dfc1831
--- /dev/null
+++ b/3rdparty/json/json.hpp
@@ -0,0 +1,13003 @@
+/*
+    __ _____ _____ _____
+ __|  |   __|     |   | |  JSON for Modern C++
+|  |  |__   |  |  | | | |  version 2.1.1
+|_____|_____|_____|_|___|  https://github.com/nlohmann/json
+
+Licensed under the MIT License <http://opensource.org/licenses/MIT>.
+Copyright (c) 2013-2017 Niels Lohmann <http://nlohmann.me>.
+
+Permission is hereby  granted, free of charge, to any  person obtaining a copy
+of this software and associated  documentation files (the "Software"), to deal
+in the Software  without restriction, including without  limitation the rights
+to  use, copy,  modify, merge,  publish, distribute,  sublicense, and/or  sell
+copies  of  the Software,  and  to  permit persons  to  whom  the Software  is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE  IS PROVIDED "AS  IS", WITHOUT WARRANTY  OF ANY KIND,  EXPRESS OR
+IMPLIED,  INCLUDING BUT  NOT  LIMITED TO  THE  WARRANTIES OF  MERCHANTABILITY,
+FITNESS FOR  A PARTICULAR PURPOSE AND  NONINFRINGEMENT. IN NO EVENT  SHALL THE
+AUTHORS  OR COPYRIGHT  HOLDERS  BE  LIABLE FOR  ANY  CLAIM,  DAMAGES OR  OTHER
+LIABILITY, WHETHER IN AN ACTION OF  CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE  OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+
+#ifndef NLOHMANN_JSON_HPP
+#define NLOHMANN_JSON_HPP
+
+#include <algorithm> // all_of, copy, fill, find, for_each, none_of, remove, reverse, transform
+#include <array> // array
+#include <cassert> // assert
+#include <cctype> // isdigit
+#include <ciso646> // and, not, or
+#include <cmath> // isfinite, labs, ldexp, signbit
+#include <cstddef> // nullptr_t, ptrdiff_t, size_t
+#include <cstdint> // int64_t, uint64_t
+#include <cstdlib> // abort, strtod, strtof, strtold, strtoul, strtoll, strtoull
+#include <cstring> // strlen
+#include <forward_list> // forward_list
+#include <functional> // function, hash, less
+#include <initializer_list> // initializer_list
+#include <iomanip> // setw
+#include <iostream> // istream, ostream
+#include <iterator> // advance, begin, back_inserter, bidirectional_iterator_tag, distance, end, inserter, iterator, iterator_traits, next, random_access_iterator_tag, reverse_iterator
+#include <limits> // numeric_limits
+#include <locale> // locale
+#include <map> // map
+#include <memory> // addressof, allocator, allocator_traits, unique_ptr
+#include <numeric> // accumulate
+#include <sstream> // stringstream
+#include <stdexcept> // domain_error, invalid_argument, out_of_range
+#include <string> // getline, stoi, string, to_string
+#include <type_traits> // add_pointer, conditional, decay, enable_if, false_type, integral_constant, is_arithmetic, is_base_of, is_const, is_constructible, is_convertible, is_default_constructible, is_enum, is_floating_point, is_integral, is_nothrow_move_assignable, is_nothrow_move_constructible, is_pointer, is_reference, is_same, is_scalar, is_signed, remove_const, remove_cv, remove_pointer, remove_reference, true_type, underlying_type
+#include <utility> // declval, forward, make_pair, move, pair, swap
+#include <vector> // vector
+
+// exclude unsupported compilers
+#if defined(__clang__)
+    #if (__clang_major__ * 10000 + __clang_minor__ * 100 + __clang_patchlevel__) < 30400
+        #error "unsupported Clang version - see https://github.com/nlohmann/json#supported-compilers"
+    #endif
+#elif defined(__GNUC__)
+    #if (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) < 40900
+        #error "unsupported GCC version - see https://github.com/nlohmann/json#supported-compilers"
+    #endif
+#endif
+
+// disable float-equal warnings on GCC/clang
+#if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
+    #pragma GCC diagnostic push
+    #pragma GCC diagnostic ignored "-Wfloat-equal"
+#endif
+
+// disable documentation warnings on clang
+#if defined(__clang__)
+    #pragma GCC diagnostic push
+    #pragma GCC diagnostic ignored "-Wdocumentation"
+#endif
+
+// allow for portable deprecation warnings
+#if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
+    #define JSON_DEPRECATED __attribute__((deprecated))
+#elif defined(_MSC_VER)
+    #define JSON_DEPRECATED __declspec(deprecated)
+#else
+    #define JSON_DEPRECATED
+#endif
+
+// allow to disable exceptions
+#if not defined(JSON_NOEXCEPTION) || defined(__EXCEPTIONS)
+    #define JSON_THROW(exception) throw exception
+    #define JSON_TRY try
+    #define JSON_CATCH(exception) catch(exception)
+#else
+    #define JSON_THROW(exception) std::abort()
+    #define JSON_TRY if(true)
+    #define JSON_CATCH(exception) if(false)
+#endif
+
+/*!
+@brief namespace for Niels Lohmann
+@see https://github.com/nlohmann
+@since version 1.0.0
+*/
+namespace nlohmann
+{
+
+/*!
+@brief unnamed namespace with internal helper functions
+
+This namespace collects some functions that could not be defined inside the
+@ref basic_json class.
+
+@since version 2.1.0
+*/
+namespace detail
+{
+///////////////////////////
+// JSON type enumeration //
+///////////////////////////
+
+/*!
+@brief the JSON type enumeration
+
+This enumeration collects the different JSON types. It is internally used to
+distinguish the stored values, and the functions @ref basic_json::is_null(),
+@ref basic_json::is_object(), @ref basic_json::is_array(),
+@ref basic_json::is_string(), @ref basic_json::is_boolean(),
+@ref basic_json::is_number() (with @ref basic_json::is_number_integer(),
+@ref basic_json::is_number_unsigned(), and @ref basic_json::is_number_float()),
+@ref basic_json::is_discarded(), @ref basic_json::is_primitive(), and
+@ref basic_json::is_structured() rely on it.
+
+@note There are three enumeration entries (number_integer, number_unsigned, and
+number_float), because the library distinguishes these three types for numbers:
+@ref basic_json::number_unsigned_t is used for unsigned integers,
+@ref basic_json::number_integer_t is used for signed integers, and
+@ref basic_json::number_float_t is used for floating-point numbers or to
+approximate integers which do not fit in the limits of their respective type.
+
+@sa @ref basic_json::basic_json(const value_t value_type) -- create a JSON
+value with the default value for a given type
+
+@since version 1.0.0
+*/
+enum class value_t : uint8_t
+{
+    null,            ///< null value
+    object,          ///< object (unordered set of name/value pairs)
+    array,           ///< array (ordered collection of values)
+    string,          ///< string value
+    boolean,         ///< boolean value
+    number_integer,  ///< number value (signed integer)
+    number_unsigned, ///< number value (unsigned integer)
+    number_float,    ///< number value (floating-point)
+    discarded        ///< discarded by the the parser callback function
+};
+
+/*!
+@brief comparison operator for JSON types
+
+Returns an ordering that is similar to Python:
+- order: null < boolean < number < object < array < string
+- furthermore, each type is not smaller than itself
+
+@since version 1.0.0
+*/
+inline bool operator<(const value_t lhs, const value_t rhs) noexcept
+{
+    static constexpr std::array<uint8_t, 8> order = {{
+            0, // null
+            3, // object
+            4, // array
+            5, // string
+            1, // boolean
+            2, // integer
+            2, // unsigned
+            2, // float
+        }
+    };
+
+    // discarded values are not comparable
+    if (lhs == value_t::discarded or rhs == value_t::discarded)
+    {
+        return false;
+    }
+
+    return order[static_cast<std::size_t>(lhs)] <
+           order[static_cast<std::size_t>(rhs)];
+}
+
+
+/////////////
+// helpers //
+/////////////
+
+// alias templates to reduce boilerplate
+template<bool B, typename T = void>
+using enable_if_t = typename std::enable_if<B, T>::type;
+
+template<typename T>
+using uncvref_t = typename std::remove_cv<typename std::remove_reference<T>::type>::type;
+
+// taken from http://stackoverflow.com/a/26936864/266378
+template<typename T>
+using is_unscoped_enum =
+    std::integral_constant<bool, std::is_convertible<T, int>::value and
+    std::is_enum<T>::value>;
+
+/*
+Implementation of two C++17 constructs: conjunction, negation. This is needed
+to avoid evaluating all the traits in a condition
+
+For example: not std::is_same<void, T>::value and has_value_type<T>::value
+will not compile when T = void (on MSVC at least). Whereas
+conjunction<negation<std::is_same<void, T>>, has_value_type<T>>::value will
+stop evaluating if negation<...>::value == false
+
+Please note that those constructs must be used with caution, since symbols can
+become very long quickly (which can slow down compilation and cause MSVC
+internal compiler errors). Only use it when you have to (see example ahead).
+*/
+template<class...> struct conjunction : std::true_type {};
+template<class B1> struct conjunction<B1> : B1 {};
+template<class B1, class... Bn>
+struct conjunction<B1, Bn...> : std::conditional<bool(B1::value), conjunction<Bn...>, B1>::type {};
+
+template<class B> struct negation : std::integral_constant < bool, !B::value > {};
+
+// dispatch utility (taken from ranges-v3)
+template<unsigned N> struct priority_tag : priority_tag < N - 1 > {};
+template<> struct priority_tag<0> {};
+
+
+//////////////////
+// constructors //
+//////////////////
+
+template<value_t> struct external_constructor;
+
+template<>
+struct external_constructor<value_t::boolean>
+{
+    template<typename BasicJsonType>
+    static void construct(BasicJsonType& j, typename BasicJsonType::boolean_t b) noexcept
+    {
+        j.m_type = value_t::boolean;
+        j.m_value = b;
+        j.assert_invariant();
+    }
+};
+
+template<>
+struct external_constructor<value_t::string>
+{
+    template<typename BasicJsonType>
+    static void construct(BasicJsonType& j, const typename BasicJsonType::string_t& s)
+    {
+        j.m_type = value_t::string;
+        j.m_value = s;
+        j.assert_invariant();
+    }
+};
+
+template<>
+struct external_constructor<value_t::number_float>
+{
+    template<typename BasicJsonType>
+    static void construct(BasicJsonType& j, typename BasicJsonType::number_float_t val) noexcept
+    {
+        // replace infinity and NAN by null
+        if (not std::isfinite(val))
+        {
+            j = BasicJsonType{};
+        }
+        else
+        {
+            j.m_type = value_t::number_float;
+            j.m_value = val;
+        }
+        j.assert_invariant();
+    }
+};
+
+template<>
+struct external_constructor<value_t::number_unsigned>
+{
+    template<typename BasicJsonType>
+    static void construct(BasicJsonType& j, typename BasicJsonType::number_unsigned_t val) noexcept
+    {
+        j.m_type = value_t::number_unsigned;
+        j.m_value = val;
+        j.assert_invariant();
+    }
+};
+
+template<>
+struct external_constructor<value_t::number_integer>
+{
+    template<typename BasicJsonType>
+    static void construct(BasicJsonType& j, typename BasicJsonType::number_integer_t val) noexcept
+    {
+        j.m_type = value_t::number_integer;
+        j.m_value = val;
+        j.assert_invariant();
+    }
+};
+
+template<>
+struct external_constructor<value_t::array>
+{
+    template<typename BasicJsonType>
+    static void construct(BasicJsonType& j, const typename BasicJsonType::array_t& arr)
+    {
+        j.m_type = value_t::array;
+        j.m_value = arr;
+        j.assert_invariant();
+    }
+
+    template<typename BasicJsonType, typename CompatibleArrayType,
+             enable_if_t<not std::is_same<CompatibleArrayType,
+                                          typename BasicJsonType::array_t>::value,
+                         int> = 0>
+    static void construct(BasicJsonType& j, const CompatibleArrayType& arr)
+    {
+        using std::begin;
+        using std::end;
+        j.m_type = value_t::array;
+        j.m_value.array = j.template create<typename BasicJsonType::array_t>(begin(arr), end(arr));
+        j.assert_invariant();
+    }
+};
+
+template<>
+struct external_constructor<value_t::object>
+{
+    template<typename BasicJsonType>
+    static void construct(BasicJsonType& j, const typename BasicJsonType::object_t& obj)
+    {
+        j.m_type = value_t::object;
+        j.m_value = obj;
+        j.assert_invariant();
+    }
+
+    template<typename BasicJsonType, typename CompatibleObjectType,
+             enable_if_t<not std::is_same<CompatibleObjectType,
+                                          typename BasicJsonType::object_t>::value,
+                         int> = 0>
+    static void construct(BasicJsonType& j, const CompatibleObjectType& obj)
+    {
+        using std::begin;
+        using std::end;
+
+        j.m_type = value_t::object;
+        j.m_value.object = j.template create<typename BasicJsonType::object_t>(begin(obj), end(obj));
+        j.assert_invariant();
+    }
+};
+
+
+////////////////////////
+// has_/is_ functions //
+////////////////////////
+
+/*!
+@brief Helper to determine whether there's a key_type for T.
+
+This helper is used to tell associative containers apart from other containers
+such as sequence containers. For instance, `std::map` passes the test as it
+contains a `mapped_type`, whereas `std::vector` fails the test.
+
+@sa http://stackoverflow.com/a/7728728/266378
+@since version 1.0.0, overworked in version 2.0.6
+*/
+#define NLOHMANN_JSON_HAS_HELPER(type)                                        \
+    template<typename T> struct has_##type {                                  \
+    private:                                                                  \
+        template<typename U, typename = typename U::type>                     \
+        static int detect(U &&);                                              \
+        static void detect(...);                                              \
+    public:                                                                   \
+        static constexpr bool value =                                         \
+                std::is_integral<decltype(detect(std::declval<T>()))>::value; \
+    }
+
+NLOHMANN_JSON_HAS_HELPER(mapped_type);
+NLOHMANN_JSON_HAS_HELPER(key_type);
+NLOHMANN_JSON_HAS_HELPER(value_type);
+NLOHMANN_JSON_HAS_HELPER(iterator);
+
+#undef NLOHMANN_JSON_HAS_HELPER
+
+
+template<bool B, class RealType, class CompatibleObjectType>
+struct is_compatible_object_type_impl : std::false_type {};
+
+template<class RealType, class CompatibleObjectType>
+struct is_compatible_object_type_impl<true, RealType, CompatibleObjectType>
+{
+    static constexpr auto value =
+        std::is_constructible<typename RealType::key_type,
+        typename CompatibleObjectType::key_type>::value and
+        std::is_constructible<typename RealType::mapped_type,
+        typename CompatibleObjectType::mapped_type>::value;
+};
+
+template<class BasicJsonType, class CompatibleObjectType>
+struct is_compatible_object_type
+{
+    static auto constexpr value = is_compatible_object_type_impl <
+                                  conjunction<negation<std::is_same<void, CompatibleObjectType>>,
+                                  has_mapped_type<CompatibleObjectType>,
+                                  has_key_type<CompatibleObjectType>>::value,
+                                  typename BasicJsonType::object_t, CompatibleObjectType >::value;
+};
+
+template<typename BasicJsonType, typename T>
+struct is_basic_json_nested_type
+{
+    static auto constexpr value = std::is_same<T, typename BasicJsonType::iterator>::value or
+                                  std::is_same<T, typename BasicJsonType::const_iterator>::value or
+                                  std::is_same<T, typename BasicJsonType::reverse_iterator>::value or
+                                  std::is_same<T, typename BasicJsonType::const_reverse_iterator>::value or
+                                  std::is_same<T, typename BasicJsonType::json_pointer>::value;
+};
+
+template<class BasicJsonType, class CompatibleArrayType>
+struct is_compatible_array_type
+{
+    static auto constexpr value =
+        conjunction<negation<std::is_same<void, CompatibleArrayType>>,
+        negation<is_compatible_object_type<
+        BasicJsonType, CompatibleArrayType>>,
+        negation<std::is_constructible<typename BasicJsonType::string_t,
+        CompatibleArrayType>>,
+        negation<is_basic_json_nested_type<BasicJsonType, CompatibleArrayType>>,
+        has_value_type<CompatibleArrayType>,
+        has_iterator<CompatibleArrayType>>::value;
+};
+
+template<bool, typename, typename>
+struct is_compatible_integer_type_impl : std::false_type {};
+
+template<typename RealIntegerType, typename CompatibleNumberIntegerType>
+struct is_compatible_integer_type_impl<true, RealIntegerType, CompatibleNumberIntegerType>
+{
+    // is there an assert somewhere on overflows?
+    using RealLimits = std::numeric_limits<RealIntegerType>;
+    using CompatibleLimits = std::numeric_limits<CompatibleNumberIntegerType>;
+
+    static constexpr auto value =
+        std::is_constructible<RealIntegerType,
+        CompatibleNumberIntegerType>::value and
+        CompatibleLimits::is_integer and
+        RealLimits::is_signed == CompatibleLimits::is_signed;
+};
+
+template<typename RealIntegerType, typename CompatibleNumberIntegerType>
+struct is_compatible_integer_type
+{
+    static constexpr auto value =
+        is_compatible_integer_type_impl <
+        std::is_integral<CompatibleNumberIntegerType>::value and
+        not std::is_same<bool, CompatibleNumberIntegerType>::value,
+        RealIntegerType, CompatibleNumberIntegerType > ::value;
+};
+
+
+// trait checking if JSONSerializer<T>::from_json(json const&, udt&) exists
+template<typename BasicJsonType, typename T>
+struct has_from_json
+{
+  private:
+    // also check the return type of from_json
+    template<typename U, typename = enable_if_t<std::is_same<void, decltype(uncvref_t<U>::from_json(
+                 std::declval<BasicJsonType>(), std::declval<T&>()))>::value>>
+    static int detect(U&&);
+    static void detect(...);
+
+  public:
+    static constexpr bool value = std::is_integral<decltype(
+                                      detect(std::declval<typename BasicJsonType::template json_serializer<T, void>>()))>::value;
+};
+
+// This trait checks if JSONSerializer<T>::from_json(json const&) exists
+// this overload is used for non-default-constructible user-defined-types
+template<typename BasicJsonType, typename T>
+struct has_non_default_from_json
+{
+  private:
+    template <
+        typename U,
+        typename = enable_if_t<std::is_same<
+                                   T, decltype(uncvref_t<U>::from_json(std::declval<BasicJsonType>()))>::value >>
+    static int detect(U&&);
+    static void detect(...);
+
+  public:
+    static constexpr bool value = std::is_integral<decltype(detect(
+                                      std::declval<typename BasicJsonType::template json_serializer<T, void>>()))>::value;
+};
+
+// This trait checks if BasicJsonType::json_serializer<T>::to_json exists
+template<typename BasicJsonType, typename T>
+struct has_to_json
+{
+  private:
+    template<typename U, typename = decltype(uncvref_t<U>::to_json(
+                 std::declval<BasicJsonType&>(), std::declval<T>()))>
+    static int detect(U&&);
+    static void detect(...);
+
+  public:
+    static constexpr bool value = std::is_integral<decltype(detect(
+                                      std::declval<typename BasicJsonType::template json_serializer<T, void>>()))>::value;
+};
+
+
+/////////////
+// to_json //
+/////////////
+
+template<typename BasicJsonType, typename T, enable_if_t<
+             std::is_same<T, typename BasicJsonType::boolean_t>::value, int> = 0>
+void to_json(BasicJsonType& j, T b) noexcept
+{
+    external_constructor<value_t::boolean>::construct(j, b);
+}
+
+template<typename BasicJsonType, typename CompatibleString,
+         enable_if_t<std::is_constructible<typename BasicJsonType::string_t,
+                     CompatibleString>::value, int> = 0>
+void to_json(BasicJsonType& j, const CompatibleString& s)
+{
+    external_constructor<value_t::string>::construct(j, s);
+}
+
+template<typename BasicJsonType, typename FloatType,
+         enable_if_t<std::is_floating_point<FloatType>::value, int> = 0>
+void to_json(BasicJsonType& j, FloatType val) noexcept
+{
+    external_constructor<value_t::number_float>::construct(j, static_cast<typename BasicJsonType::number_float_t>(val));
+}
+
+template <
+    typename BasicJsonType, typename CompatibleNumberUnsignedType,
+    enable_if_t<is_compatible_integer_type<typename BasicJsonType::number_unsigned_t,
+                CompatibleNumberUnsignedType>::value, int> = 0 >
+void to_json(BasicJsonType& j, CompatibleNumberUnsignedType val) noexcept
+{
+    external_constructor<value_t::number_unsigned>::construct(j, static_cast<typename BasicJsonType::number_unsigned_t>(val));
+}
+
+template <
+    typename BasicJsonType, typename CompatibleNumberIntegerType,
+    enable_if_t<is_compatible_integer_type<typename BasicJsonType::number_integer_t,
+                CompatibleNumberIntegerType>::value, int> = 0 >
+void to_json(BasicJsonType& j, CompatibleNumberIntegerType val) noexcept
+{
+    external_constructor<value_t::number_integer>::construct(j, static_cast<typename BasicJsonType::number_integer_t>(val));
+}
+
+template<typename BasicJsonType, typename UnscopedEnumType,
+         enable_if_t<is_unscoped_enum<UnscopedEnumType>::value, int> = 0>
+void to_json(BasicJsonType& j, UnscopedEnumType e) noexcept
+{
+    external_constructor<value_t::number_integer>::construct(j, e);
+}
+
+template <
+    typename BasicJsonType, typename CompatibleArrayType,
+    enable_if_t <
+        is_compatible_array_type<BasicJsonType, CompatibleArrayType>::value or
+        std::is_same<typename BasicJsonType::array_t, CompatibleArrayType>::value,
+        int > = 0 >
+void to_json(BasicJsonType& j, const  CompatibleArrayType& arr)
+{
+    external_constructor<value_t::array>::construct(j, arr);
+}
+
+template <
+    typename BasicJsonType, typename CompatibleObjectType,
+    enable_if_t<is_compatible_object_type<BasicJsonType, CompatibleObjectType>::value,
+                int> = 0 >
+void to_json(BasicJsonType& j, const  CompatibleObjectType& arr)
+{
+    external_constructor<value_t::object>::construct(j, arr);
+}
+
+
+///////////////
+// from_json //
+///////////////
+
+// overloads for basic_json template parameters
+template<typename BasicJsonType, typename ArithmeticType,
+         enable_if_t<std::is_arithmetic<ArithmeticType>::value and
+                     not std::is_same<ArithmeticType,
+                                      typename BasicJsonType::boolean_t>::value,
+                     int> = 0>
+void get_arithmetic_value(const BasicJsonType& j, ArithmeticType& val)
+{
+    switch (static_cast<value_t>(j))
+    {
+        case value_t::number_unsigned:
+        {
+            val = static_cast<ArithmeticType>(
+                      *j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>());
+            break;
+        }
+        case value_t::number_integer:
+        {
+            val = static_cast<ArithmeticType>(
+                      *j.template get_ptr<const typename BasicJsonType::number_integer_t*>());
+            break;
+        }
+        case value_t::number_float:
+        {
+            val = static_cast<ArithmeticType>(
+                      *j.template get_ptr<const typename BasicJsonType::number_float_t*>());
+            break;
+        }
+        default:
+        {
+            JSON_THROW(
+                std::domain_error("type must be number, but is " + j.type_name()));
+        }
+    }
+}
+
+template<typename BasicJsonType>
+void from_json(const BasicJsonType& j, typename BasicJsonType::boolean_t& b)
+{
+    if (not j.is_boolean())
+    {
+        JSON_THROW(std::domain_error("type must be boolean, but is " + j.type_name()));
+    }
+    b = *j.template get_ptr<const typename BasicJsonType::boolean_t*>();
+}
+
+template<typename BasicJsonType>
+void from_json(const BasicJsonType& j, typename BasicJsonType::string_t& s)
+{
+    if (not j.is_string())
+    {
+        JSON_THROW(std::domain_error("type must be string, but is " + j.type_name()));
+    }
+    s = *j.template get_ptr<const typename BasicJsonType::string_t*>();
+}
+
+template<typename BasicJsonType>
+void from_json(const BasicJsonType& j, typename BasicJsonType::number_float_t& val)
+{
+    get_arithmetic_value(j, val);
+}
+
+template<typename BasicJsonType>
+void from_json(const BasicJsonType& j, typename BasicJsonType::number_unsigned_t& val)
+{
+    get_arithmetic_value(j, val);
+}
+
+template<typename BasicJsonType>
+void from_json(const BasicJsonType& j, typename BasicJsonType::number_integer_t& val)
+{
+    get_arithmetic_value(j, val);
+}
+
+template<typename BasicJsonType, typename UnscopedEnumType,
+         enable_if_t<is_unscoped_enum<UnscopedEnumType>::value, int> = 0>
+void from_json(const BasicJsonType& j, UnscopedEnumType& e)
+{
+    typename std::underlying_type<UnscopedEnumType>::type val;
+    get_arithmetic_value(j, val);
+    e = static_cast<UnscopedEnumType>(val);
+}
+
+template<typename BasicJsonType>
+void from_json(const BasicJsonType& j, typename BasicJsonType::array_t& arr)
+{
+    if (not j.is_array())
+    {
+        JSON_THROW(std::domain_error("type must be array, but is " + j.type_name()));
+    }
+    arr = *j.template get_ptr<const typename BasicJsonType::array_t*>();
+}
+
+// forward_list doesn't have an insert method
+template<typename BasicJsonType, typename T, typename Allocator>
+void from_json(const BasicJsonType& j, std::forward_list<T, Allocator>& l)
+{
+    // do not perform the check when user wants to retrieve jsons
+    // (except when it's null.. ?)
+    if (j.is_null())
+    {
+        JSON_THROW(std::domain_error("type must be array, but is " + j.type_name()));
+    }
+    if (not std::is_same<T, BasicJsonType>::value)
+    {
+        if (not j.is_array())
+        {
+            JSON_THROW(std::domain_error("type must be array, but is " + j.type_name()));
+        }
+    }
+    for (auto it = j.rbegin(), end = j.rend(); it != end; ++it)
+    {
+        l.push_front(it->template get<T>());
+    }
+}
+
+template<typename BasicJsonType, typename CompatibleArrayType>
+void from_json_array_impl(const BasicJsonType& j, CompatibleArrayType& arr, priority_tag<0>)
+{
+    using std::begin;
+    using std::end;
+
+    std::transform(j.begin(), j.end(),
+                   std::inserter(arr, end(arr)), [](const BasicJsonType & i)
+    {
+        // get<BasicJsonType>() returns *this, this won't call a from_json
+        // method when value_type is BasicJsonType
+        return i.template get<typename CompatibleArrayType::value_type>();
+    });
+}
+
+template<typename BasicJsonType, typename CompatibleArrayType>
+auto from_json_array_impl(const BasicJsonType& j, CompatibleArrayType& arr, priority_tag<1>)
+-> decltype(
+    arr.reserve(std::declval<typename CompatibleArrayType::size_type>()),
+    void())
+{
+    using std::begin;
+    using std::end;
+
+    arr.reserve(j.size());
+    std::transform(
+        j.begin(), j.end(), std::inserter(arr, end(arr)), [](const BasicJsonType & i)
+    {
+        // get<BasicJsonType>() returns *this, this won't call a from_json
+        // method when value_type is BasicJsonType
+        return i.template get<typename CompatibleArrayType::value_type>();
+    });
+}
+
+template<typename BasicJsonType, typename CompatibleArrayType,
+         enable_if_t<is_compatible_array_type<BasicJsonType, CompatibleArrayType>::value and
+                     not std::is_same<typename BasicJsonType::array_t, CompatibleArrayType>::value, int> = 0>
+void from_json(const BasicJsonType& j, CompatibleArrayType& arr)
+{
+    if (j.is_null())
+    {
+        JSON_THROW(std::domain_error("type must be array, but is " + j.type_name()));
+    }
+
+    // when T == BasicJsonType, do not check if value_t is correct
+    if (not std::is_same<typename CompatibleArrayType::value_type, BasicJsonType>::value)
+    {
+        if (not j.is_array())
+        {
+            JSON_THROW(std::domain_error("type must be array, but is " + j.type_name()));
+        }
+    }
+    from_json_array_impl(j, arr, priority_tag<1> {});
+}
+
+template<typename BasicJsonType, typename CompatibleObjectType,
+         enable_if_t<is_compatible_object_type<BasicJsonType, CompatibleObjectType>::value, int> = 0>
+void from_json(const BasicJsonType& j, CompatibleObjectType& obj)
+{
+    if (not j.is_object())
+    {
+        JSON_THROW(std::domain_error("type must be object, but is " + j.type_name()));
+    }
+
+    auto inner_object = j.template get_ptr<const typename BasicJsonType::object_t*>();
+    using std::begin;
+    using std::end;
+    // we could avoid the assignment, but this might require a for loop, which
+    // might be less efficient than the container constructor for some
+    // containers (would it?)
+    obj = CompatibleObjectType(begin(*inner_object), end(*inner_object));
+}
+
+// overload for arithmetic types, not chosen for basic_json template arguments
+// (BooleanType, etc..); note: Is it really necessary to provide explicit
+// overloads for boolean_t etc. in case of a custom BooleanType which is not
+// an arithmetic type?
+template<typename BasicJsonType, typename ArithmeticType,
+         enable_if_t <
+             std::is_arithmetic<ArithmeticType>::value and
+             not std::is_same<ArithmeticType, typename BasicJsonType::number_unsigned_t>::value and
+             not std::is_same<ArithmeticType, typename BasicJsonType::number_integer_t>::value and
+             not std::is_same<ArithmeticType, typename BasicJsonType::number_float_t>::value and
+             not std::is_same<ArithmeticType, typename BasicJsonType::boolean_t>::value,
+             int> = 0>
+void from_json(const BasicJsonType& j, ArithmeticType& val)
+{
+    switch (static_cast<value_t>(j))
+    {
+        case value_t::number_unsigned:
+        {
+            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>());
+            break;
+        }
+        case value_t::number_integer:
+        {
+            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_integer_t*>());
+            break;
+        }
+        case value_t::number_float:
+        {
+            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_float_t*>());
+            break;
+        }
+        case value_t::boolean:
+        {
+            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::boolean_t*>());
+            break;
+        }
+        default:
+        {
+            JSON_THROW(std::domain_error("type must be number, but is " + j.type_name()));
+        }
+    }
+}
+
+struct to_json_fn
+{
+  private:
+    template<typename BasicJsonType, typename T>
+    auto call(BasicJsonType& j, T&& val, priority_tag<1>) const noexcept(noexcept(to_json(j, std::forward<T>(val))))
+    -> decltype(to_json(j, std::forward<T>(val)), void())
+    {
+        return to_json(j, std::forward<T>(val));
+    }
+
+    template<typename BasicJsonType, typename T>
+    void call(BasicJsonType&, T&&, priority_tag<0>) const noexcept
+    {
+        static_assert(sizeof(BasicJsonType) == 0,
+                      "could not find to_json() method in T's namespace");
+    }
+
+  public:
+    template<typename BasicJsonType, typename T>
+    void operator()(BasicJsonType& j, T&& val) const
+    noexcept(noexcept(std::declval<to_json_fn>().call(j, std::forward<T>(val), priority_tag<1> {})))
+    {
+        return call(j, std::forward<T>(val), priority_tag<1> {});
+    }
+};
+
+struct from_json_fn
+{
+  private:
+    template<typename BasicJsonType, typename T>
+    auto call(const BasicJsonType& j, T& val, priority_tag<1>) const
+    noexcept(noexcept(from_json(j, val)))
+    -> decltype(from_json(j, val), void())
+    {
+        return from_json(j, val);
+    }
+
+    template<typename BasicJsonType, typename T>
+    void call(const BasicJsonType&, T&, priority_tag<0>) const noexcept
+    {
+        static_assert(sizeof(BasicJsonType) == 0,
+                      "could not find from_json() method in T's namespace");
+    }
+
+  public:
+    template<typename BasicJsonType, typename T>
+    void operator()(const BasicJsonType& j, T& val) const
+    noexcept(noexcept(std::declval<from_json_fn>().call(j, val, priority_tag<1> {})))
+    {
+        return call(j, val, priority_tag<1> {});
+    }
+};
+
+// taken from ranges-v3
+template<typename T>
+struct static_const
+{
+    static constexpr T value{};
+};
+
+template<typename T>
+constexpr T static_const<T>::value;
+} // namespace detail
+
+
+/// namespace to hold default `to_json` / `from_json` functions
+namespace
+{
+constexpr const auto& to_json = detail::static_const<detail::to_json_fn>::value;
+constexpr const auto& from_json = detail::static_const<detail::from_json_fn>::value;
+}
+
+
+/*!
+@brief default JSONSerializer template argument
+
+This serializer ignores the template arguments and uses ADL
+([argument-dependent lookup](http://en.cppreference.com/w/cpp/language/adl))
+for serialization.
+*/
+template<typename = void, typename = void>
+struct adl_serializer
+{
+    /*!
+    @brief convert a JSON value to any value type
+
+    This function is usually called by the `get()` function of the
+    @ref basic_json class (either explicit or via conversion operators).
+
+    @param[in] j         JSON value to read from
+    @param[in,out] val  value to write to
+    */
+    template<typename BasicJsonType, typename ValueType>
+    static void from_json(BasicJsonType&& j, ValueType& val) noexcept(
+        noexcept(::nlohmann::from_json(std::forward<BasicJsonType>(j), val)))
+    {
+        ::nlohmann::from_json(std::forward<BasicJsonType>(j), val);
+    }
+
+    /*!
+    @brief convert any value type to a JSON value
+
+    This function is usually called by the constructors of the @ref basic_json
+    class.
+
+    @param[in,out] j  JSON value to write to
+    @param[in] val     value to read from
+    */
+    template<typename BasicJsonType, typename ValueType>
+    static void to_json(BasicJsonType& j, ValueType&& val) noexcept(
+        noexcept(::nlohmann::to_json(j, std::forward<ValueType>(val))))
+    {
+        ::nlohmann::to_json(j, std::forward<ValueType>(val));
+    }
+};
+
+
+/*!
+@brief a class to store JSON values
+
+@tparam ObjectType type for JSON objects (`std::map` by default; will be used
+in @ref object_t)
+@tparam ArrayType type for JSON arrays (`std::vector` by default; will be used
+in @ref array_t)
+@tparam StringType type for JSON strings and object keys (`std::string` by
+default; will be used in @ref string_t)
+@tparam BooleanType type for JSON booleans (`bool` by default; will be used
+in @ref boolean_t)
+@tparam NumberIntegerType type for JSON integer numbers (`int64_t` by
+default; will be used in @ref number_integer_t)
+@tparam NumberUnsignedType type for JSON unsigned integer numbers (@c
+`uint64_t` by default; will be used in @ref number_unsigned_t)
+@tparam NumberFloatType type for JSON floating-point numbers (`double` by
+default; will be used in @ref number_float_t)
+@tparam AllocatorType type of the allocator to use (`std::allocator` by
+default)
+@tparam JSONSerializer the serializer to resolve internal calls to `to_json()`
+and `from_json()` (@ref adl_serializer by default)
+
+@requirement The class satisfies the following concept requirements:
+- Basic
+ - [DefaultConstructible](http://en.cppreference.com/w/cpp/concept/DefaultConstructible):
+   JSON values can be default constructed. The result will be a JSON null
+   value.
+ - [MoveConstructible](http://en.cppreference.com/w/cpp/concept/MoveConstructible):
+   A JSON value can be constructed from an rvalue argument.
+ - [CopyConstructible](http://en.cppreference.com/w/cpp/concept/CopyConstructible):
+   A JSON value can be copy-constructed from an lvalue expression.
+ - [MoveAssignable](http://en.cppreference.com/w/cpp/concept/MoveAssignable):
+   A JSON value van be assigned from an rvalue argument.
+ - [CopyAssignable](http://en.cppreference.com/w/cpp/concept/CopyAssignable):
+   A JSON value can be copy-assigned from an lvalue expression.
+ - [Destructible](http://en.cppreference.com/w/cpp/concept/Destructible):
+   JSON values can be destructed.
+- Layout
+ - [StandardLayoutType](http://en.cppreference.com/w/cpp/concept/StandardLayoutType):
+   JSON values have
+   [standard layout](http://en.cppreference.com/w/cpp/language/data_members#Standard_layout):
+   All non-static data members are private and standard layout types, the
+   class has no virtual functions or (virtual) base classes.
+- Library-wide
+ - [EqualityComparable](http://en.cppreference.com/w/cpp/concept/EqualityComparable):
+   JSON values can be compared with `==`, see @ref
+   operator==(const_reference,const_reference).
+ - [LessThanComparable](http://en.cppreference.com/w/cpp/concept/LessThanComparable):
+   JSON values can be compared with `<`, see @ref
+   operator<(const_reference,const_reference).
+ - [Swappable](http://en.cppreference.com/w/cpp/concept/Swappable):
+   Any JSON lvalue or rvalue of can be swapped with any lvalue or rvalue of
+   other compatible types, using unqualified function call @ref swap().
+ - [NullablePointer](http://en.cppreference.com/w/cpp/concept/NullablePointer):
+   JSON values can be compared against `std::nullptr_t` objects which are used
+   to model the `null` value.
+- Container
+ - [Container](http://en.cppreference.com/w/cpp/concept/Container):
+   JSON values can be used like STL containers and provide iterator access.
+ - [ReversibleContainer](http://en.cppreference.com/w/cpp/concept/ReversibleContainer);
+   JSON values can be used like STL containers and provide reverse iterator
+   access.
+
+@invariant The member variables @a m_value and @a m_type have the following
+relationship:
+- If `m_type == value_t::object`, then `m_value.object != nullptr`.
+- If `m_type == value_t::array`, then `m_value.array != nullptr`.
+- If `m_type == value_t::string`, then `m_value.string != nullptr`.
+The invariants are checked by member function assert_invariant().
+
+@internal
+@note ObjectType trick from http://stackoverflow.com/a/9860911
+@endinternal
+
+@see [RFC 7159: The JavaScript Object Notation (JSON) Data Interchange
+Format](http://rfc7159.net/rfc7159)
+
+@since version 1.0.0
+
+@nosubgrouping
+*/
+template <
+    template<typename U, typename V, typename... Args> class ObjectType = std::map,
+    template<typename U, typename... Args> class ArrayType = std::vector,
+    class StringType = std::string,
+    class BooleanType = bool,
+    class NumberIntegerType = std::int64_t,
+    class NumberUnsignedType = std::uint64_t,
+    class NumberFloatType = double,
+    template<typename U> class AllocatorType = std::allocator,
+    template<typename T, typename SFINAE = void> class JSONSerializer = adl_serializer
+    >
+class basic_json
+{
+  private:
+    template<detail::value_t> friend struct detail::external_constructor;
+    /// workaround type for MSVC
+    using basic_json_t = basic_json<ObjectType, ArrayType, StringType,
+          BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType,
+          AllocatorType, JSONSerializer>;
+
+  public:
+    using value_t = detail::value_t;
+    // forward declarations
+    template<typename U> class iter_impl;
+    template<typename Base> class json_reverse_iterator;
+    class json_pointer;
+    template<typename T, typename SFINAE>
+    using json_serializer = JSONSerializer<T, SFINAE>;
+
+    /////////////////////
+    // container types //
+    /////////////////////
+
+    /// @name container types
+    /// The canonic container types to use @ref basic_json like any other STL
+    /// container.
+    /// @{
+
+    /// the type of elements in a basic_json container
+    using value_type = basic_json;
+
+    /// the type of an element reference
+    using reference = value_type&;
+    /// the type of an element const reference
+    using const_reference = const value_type&;
+
+    /// a type to represent differences between iterators
+    using difference_type = std::ptrdiff_t;
+    /// a type to represent container sizes
+    using size_type = std::size_t;
+
+    /// the allocator type
+    using allocator_type = AllocatorType<basic_json>;
+
+    /// the type of an element pointer
+    using pointer = typename std::allocator_traits<allocator_type>::pointer;
+    /// the type of an element const pointer
+    using const_pointer = typename std::allocator_traits<allocator_type>::const_pointer;
+
+    /// an iterator for a basic_json container
+    using iterator = iter_impl<basic_json>;
+    /// a const iterator for a basic_json container
+    using const_iterator = iter_impl<const basic_json>;
+    /// a reverse iterator for a basic_json container
+    using reverse_iterator = json_reverse_iterator<typename basic_json::iterator>;
+    /// a const reverse iterator for a basic_json container
+    using const_reverse_iterator = json_reverse_iterator<typename basic_json::const_iterator>;
+
+    /// @}
+
+
+    /*!
+    @brief returns the allocator associated with the container
+    */
+    static allocator_type get_allocator()
+    {
+        return allocator_type();
+    }
+
+    /*!
+    @brief returns version information on the library
+
+    This function returns a JSON object with information about the library,
+    including the version number and information on the platform and compiler.
+
+    @return JSON object holding version information
+    key         | description
+    ----------- | ---------------
+    `compiler`  | Information on the used compiler. It is an object with the following keys: `c++` (the used C++ standard), `family` (the compiler family; possible values are `clang`, `icc`, `gcc`, `ilecpp`, `msvc`, `pgcpp`, `sunpro`, and `unknown`), and `version` (the compiler version).
+    `copyright` | The copyright line for the library as string.
+    `name`      | The name of the library as string.
+    `platform`  | The used platform as string. Possible values are `win32`, `linux`, `apple`, `unix`, and `unknown`.
+    `url`       | The URL of the project as string.
+    `version`   | The version of the library. It is an object with the following keys: `major`, `minor`, and `patch` as defined by [Semantic Versioning](http://semver.org), and `string` (the version string).
+
+    @liveexample{The following code shows an example output of the `meta()`
+    function.,meta}
+
+    @complexity Constant.
+
+    @since 2.1.0
+    */
+    static basic_json meta()
+    {
+        basic_json result;
+
+        result["copyright"] = "(C) 2013-2017 Niels Lohmann";
+        result["name"] = "JSON for Modern C++";
+        result["url"] = "https://github.com/nlohmann/json";
+        result["version"] =
+        {
+            {"string", "2.1.1"},
+            {"major", 2},
+            {"minor", 1},
+            {"patch", 1}
+        };
+
+#ifdef _WIN32
+        result["platform"] = "win32";
+#elif defined __linux__
+        result["platform"] = "linux";
+#elif defined __APPLE__
+        result["platform"] = "apple";
+#elif defined __unix__
+        result["platform"] = "unix";
+#else
+        result["platform"] = "unknown";
+#endif
+
+#if defined(__clang__)
+        result["compiler"] = {{"family", "clang"}, {"version", __clang_version__}};
+#elif defined(__ICC) || defined(__INTEL_COMPILER)
+        result["compiler"] = {{"family", "icc"}, {"version", __INTEL_COMPILER}};
+#elif defined(__GNUC__) || defined(__GNUG__)
+        result["compiler"] = {{"family", "gcc"}, {"version", std::to_string(__GNUC__) + "." + std::to_string(__GNUC_MINOR__) + "." + std::to_string(__GNUC_PATCHLEVEL__)}};
+#elif defined(__HP_cc) || defined(__HP_aCC)
+        result["compiler"] = "hp"
+#elif defined(__IBMCPP__)
+        result["compiler"] = {{"family", "ilecpp"}, {"version", __IBMCPP__}};
+#elif defined(_MSC_VER)
+        result["compiler"] = {{"family", "msvc"}, {"version", _MSC_VER}};
+#elif defined(__PGI)
+        result["compiler"] = {{"family", "pgcpp"}, {"version", __PGI}};
+#elif defined(__SUNPRO_CC)
+        result["compiler"] = {{"family", "sunpro"}, {"version", __SUNPRO_CC}};
+#else
+        result["compiler"] = {{"family", "unknown"}, {"version", "unknown"}};
+#endif
+
+#ifdef __cplusplus
+        result["compiler"]["c++"] = std::to_string(__cplusplus);
+#else
+        result["compiler"]["c++"] = "unknown";
+#endif
+        return result;
+    }
+
+
+    ///////////////////////////
+    // JSON value data types //
+    ///////////////////////////
+
+    /// @name JSON value data types
+    /// The data types to store a JSON value. These types are derived from
+    /// the template arguments passed to class @ref basic_json.
+    /// @{
+
+    /*!
+    @brief a type for an object
+
+    [RFC 7159](http://rfc7159.net/rfc7159) describes JSON objects as follows:
+    > An object is an unordered collection of zero or more name/value pairs,
+    > where a name is a string and a value is a string, number, boolean, null,
+    > object, or array.
+
+    To store objects in C++, a type is defined by the template parameters
+    described below.
+
+    @tparam ObjectType  the container to store objects (e.g., `std::map` or
+    `std::unordered_map`)
+    @tparam StringType the type of the keys or names (e.g., `std::string`).
+    The comparison function `std::less<StringType>` is used to order elements
+    inside the container.
+    @tparam AllocatorType the allocator to use for objects (e.g.,
+    `std::allocator`)
+
+    #### Default type
+
+    With the default values for @a ObjectType (`std::map`), @a StringType
+    (`std::string`), and @a AllocatorType (`std::allocator`), the default
+    value for @a object_t is:
+
+    @code {.cpp}
+    std::map<
+      std::string, // key_type
+      basic_json, // value_type
+      std::less<std::string>, // key_compare
+      std::allocator<std::pair<const std::string, basic_json>> // allocator_type
+    >
+    @endcode
+
+    #### Behavior
+
+    The choice of @a object_t influences the behavior of the JSON class. With
+    the default type, objects have the following behavior:
+
+    - When all names are unique, objects will be interoperable in the sense
+      that all software implementations receiving that object will agree on
+      the name-value mappings.
+    - When the names within an object are not unique, later stored name/value
+      pairs overwrite previously stored name/value pairs, leaving the used
+      names unique. For instance, `{"key": 1}` and `{"key": 2, "key": 1}` will
+      be treated as equal and both stored as `{"key": 1}`.
+    - Internally, name/value pairs are stored in lexicographical order of the
+      names. Objects will also be serialized (see @ref dump) in this order.
+      For instance, `{"b": 1, "a": 2}` and `{"a": 2, "b": 1}` will be stored
+      and serialized as `{"a": 2, "b": 1}`.
+    - When comparing objects, the order of the name/value pairs is irrelevant.
+      This makes objects interoperable in the sense that they will not be
+      affected by these differences. For instance, `{"b": 1, "a": 2}` and
+      `{"a": 2, "b": 1}` will be treated as equal.
+
+    #### Limits
+
+    [RFC 7159](http://rfc7159.net/rfc7159) specifies:
+    > An implementation may set limits on the maximum depth of nesting.
+
+    In this class, the object's limit of nesting is not constraint explicitly.
+    However, a maximum depth of nesting may be introduced by the compiler or
+    runtime environment. A theoretical limit can be queried by calling the
+    @ref max_size function of a JSON object.
+
+    #### Storage
+
+    Objects are stored as pointers in a @ref basic_json type. That is, for any
+    access to object values, a pointer of type `object_t*` must be
+    dereferenced.
+
+    @sa @ref array_t -- type for an array value
+
+    @since version 1.0.0
+
+    @note The order name/value pairs are added to the object is *not*
+    preserved by the library. Therefore, iterating an object may return
+    name/value pairs in a different order than they were originally stored. In
+    fact, keys will be traversed in alphabetical order as `std::map` with
+    `std::less` is used by default. Please note this behavior conforms to [RFC
+    7159](http://rfc7159.net/rfc7159), because any order implements the
+    specified "unordered" nature of JSON objects.
+    */
+    using object_t = ObjectType<StringType,
+          basic_json,
+          std::less<StringType>,
+          AllocatorType<std::pair<const StringType,
+          basic_json>>>;
+
+    /*!
+    @brief a type for an array
+
+    [RFC 7159](http://rfc7159.net/rfc7159) describes JSON arrays as follows:
+    > An array is an ordered sequence of zero or more values.
+
+    To store objects in C++, a type is defined by the template parameters
+    explained below.
+
+    @tparam ArrayType  container type to store arrays (e.g., `std::vector` or
+    `std::list`)
+    @tparam AllocatorType allocator to use for arrays (e.g., `std::allocator`)
+
+    #### Default type
+
+    With the default values for @a ArrayType (`std::vector`) and @a
+    AllocatorType (`std::allocator`), the default value for @a array_t is:
+
+    @code {.cpp}
+    std::vector<
+      basic_json, // value_type
+      std::allocator<basic_json> // allocator_type
+    >
+    @endcode
+
+    #### Limits
+
+    [RFC 7159](http://rfc7159.net/rfc7159) specifies:
+    > An implementation may set limits on the maximum depth of nesting.
+
+    In this class, the array's limit of nesting is not constraint explicitly.
+    However, a maximum depth of nesting may be introduced by the compiler or
+    runtime environment. A theoretical limit can be queried by calling the
+    @ref max_size function of a JSON array.
+
+    #### Storage
+
+    Arrays are stored as pointers in a @ref basic_json type. That is, for any
+    access to array values, a pointer of type `array_t*` must be dereferenced.
+
+    @sa @ref object_t -- type for an object value
+
+    @since version 1.0.0
+    */
+    using array_t = ArrayType<basic_json, AllocatorType<basic_json>>;
+
+    /*!
+    @brief a type for a string
+
+    [RFC 7159](http://rfc7159.net/rfc7159) describes JSON strings as follows:
+    > A string is a sequence of zero or more Unicode characters.
+
+    To store objects in C++, a type is defined by the template parameter
+    described below. Unicode values are split by the JSON class into
+    byte-sized characters during deserialization.
+
+    @tparam StringType  the container to store strings (e.g., `std::string`).
+    Note this container is used for keys/names in objects, see @ref object_t.
+
+    #### Default type
+
+    With the default values for @a StringType (`std::string`), the default
+    value for @a string_t is:
+
+    @code {.cpp}
+    std::string
+    @endcode
+
+    #### Encoding
+
+    Strings are stored in UTF-8 encoding. Therefore, functions like
+    `std::string::size()` or `std::string::length()` return the number of
+    bytes in the string rather than the number of characters or glyphs.
+
+    #### String comparison
+
+    [RFC 7159](http://rfc7159.net/rfc7159) states:
+    > Software implementations are typically required to test names of object
+    > members for equality. Implementations that transform the textual
+    > representation into sequences of Unicode code units and then perform the
+    > comparison numerically, code unit by code unit, are interoperable in the
+    > sense that implementations will agree in all cases on equality or
+    > inequality of two strings. For example, implementations that compare
+    > strings with escaped characters unconverted may incorrectly find that
+    > `"a\\b"` and `"a\u005Cb"` are not equal.
+
+    This implementation is interoperable as it does compare strings code unit
+    by code unit.
+
+    #### Storage
+
+    String values are stored as pointers in a @ref basic_json type. That is,
+    for any access to string values, a pointer of type `string_t*` must be
+    dereferenced.
+
+    @since version 1.0.0
+    */
+    using string_t = StringType;
+
+    /*!
+    @brief a type for a boolean
+
+    [RFC 7159](http://rfc7159.net/rfc7159) implicitly describes a boolean as a
+    type which differentiates the two literals `true` and `false`.
+
+    To store objects in C++, a type is defined by the template parameter @a
+    BooleanType which chooses the type to use.
+
+    #### Default type
+
+    With the default values for @a BooleanType (`bool`), the default value for
+    @a boolean_t is:
+
+    @code {.cpp}
+    bool
+    @endcode
+
+    #### Storage
+
+    Boolean values are stored directly inside a @ref basic_json type.
+
+    @since version 1.0.0
+    */
+    using boolean_t = BooleanType;
+
+    /*!
+    @brief a type for a number (integer)
+
+    [RFC 7159](http://rfc7159.net/rfc7159) describes numbers as follows:
+    > The representation of numbers is similar to that used in most
+    > programming languages. A number is represented in base 10 using decimal
+    > digits. It contains an integer component that may be prefixed with an
+    > optional minus sign, which may be followed by a fraction part and/or an
+    > exponent part. Leading zeros are not allowed. (...) Numeric values that
+    > cannot be represented in the grammar below (such as Infinity and NaN)
+    > are not permitted.
+
+    This description includes both integer and floating-point numbers.
+    However, C++ allows more precise storage if it is known whether the number
+    is a signed integer, an unsigned integer or a floating-point number.
+    Therefore, three different types, @ref number_integer_t, @ref
+    number_unsigned_t and @ref number_float_t are used.
+
+    To store integer numbers in C++, a type is defined by the template
+    parameter @a NumberIntegerType which chooses the type to use.
+
+    #### Default type
+
+    With the default values for @a NumberIntegerType (`int64_t`), the default
+    value for @a number_integer_t is:
+
+    @code {.cpp}
+    int64_t
+    @endcode
+
+    #### Default behavior
+
+    - The restrictions about leading zeros is not enforced in C++. Instead,
+      leading zeros in integer literals lead to an interpretation as octal
+      number. Internally, the value will be stored as decimal number. For
+      instance, the C++ integer literal `010` will be serialized to `8`.
+      During deserialization, leading zeros yield an error.
+    - Not-a-number (NaN) values will be serialized to `null`.
+
+    #### Limits
+
+    [RFC 7159](http://rfc7159.net/rfc7159) specifies:
+    > An implementation may set limits on the range and precision of numbers.
+
+    When the default type is used, the maximal integer number that can be
+    stored is `9223372036854775807` (INT64_MAX) and the minimal integer number
+    that can be stored is `-9223372036854775808` (INT64_MIN). Integer numbers
+    that are out of range will yield over/underflow when used in a
+    constructor. During deserialization, too large or small integer numbers
+    will be automatically be stored as @ref number_unsigned_t or @ref
+    number_float_t.
+
+    [RFC 7159](http://rfc7159.net/rfc7159) further states:
+    > Note that when such software is used, numbers that are integers and are
+    > in the range \f$[-2^{53}+1, 2^{53}-1]\f$ are interoperable in the sense
+    > that implementations will agree exactly on their numeric values.
+
+    As this range is a subrange of the exactly supported range [INT64_MIN,
+    INT64_MAX], this class's integer type is interoperable.
+
+    #### Storage
+
+    Integer number values are stored directly inside a @ref basic_json type.
+
+    @sa @ref number_float_t -- type for number values (floating-point)
+
+    @sa @ref number_unsigned_t -- type for number values (unsigned integer)
+
+    @since version 1.0.0
+    */
+    using number_integer_t = NumberIntegerType;
+
+    /*!
+    @brief a type for a number (unsigned)
+
+    [RFC 7159](http://rfc7159.net/rfc7159) describes numbers as follows:
+    > The representation of numbers is similar to that used in most
+    > programming languages. A number is represented in base 10 using decimal
+    > digits. It contains an integer component that may be prefixed with an
+    > optional minus sign, which may be followed by a fraction part and/or an
+    > exponent part. Leading zeros are not allowed. (...) Numeric values that
+    > cannot be represented in the grammar below (such as Infinity and NaN)
+    > are not permitted.
+
+    This description includes both integer and floating-point numbers.
+    However, C++ allows more precise storage if it is known whether the number
+    is a signed integer, an unsigned integer or a floating-point number.
+    Therefore, three different types, @ref number_integer_t, @ref
+    number_unsigned_t and @ref number_float_t are used.
+
+    To store unsigned integer numbers in C++, a type is defined by the
+    template parameter @a NumberUnsignedType which chooses the type to use.
+
+    #### Default type
+
+    With the default values for @a NumberUnsignedType (`uint64_t`), the
+    default value for @a number_unsigned_t is:
+
+    @code {.cpp}
+    uint64_t
+    @endcode
+
+    #### Default behavior
+
+    - The restrictions about leading zeros is not enforced in C++. Instead,
+      leading zeros in integer literals lead to an interpretation as octal
+      number. Internally, the value will be stored as decimal number. For
+      instance, the C++ integer literal `010` will be serialized to `8`.
+      During deserialization, leading zeros yield an error.
+    - Not-a-number (NaN) values will be serialized to `null`.
+
+    #### Limits
+
+    [RFC 7159](http://rfc7159.net/rfc7159) specifies:
+    > An implementation may set limits on the range and precision of numbers.
+
+    When the default type is used, the maximal integer number that can be
+    stored is `18446744073709551615` (UINT64_MAX) and the minimal integer
+    number that can be stored is `0`. Integer numbers that are out of range
+    will yield over/underflow when used in a constructor. During
+    deserialization, too large or small integer numbers will be automatically
+    be stored as @ref number_integer_t or @ref number_float_t.
+
+    [RFC 7159](http://rfc7159.net/rfc7159) further states:
+    > Note that when such software is used, numbers that are integers and are
+    > in the range \f$[-2^{53}+1, 2^{53}-1]\f$ are interoperable in the sense
+    > that implementations will agree exactly on their numeric values.
+
+    As this range is a subrange (when considered in conjunction with the
+    number_integer_t type) of the exactly supported range [0, UINT64_MAX],
+    this class's integer type is interoperable.
+
+    #### Storage
+
+    Integer number values are stored directly inside a @ref basic_json type.
+
+    @sa @ref number_float_t -- type for number values (floating-point)
+    @sa @ref number_integer_t -- type for number values (integer)
+
+    @since version 2.0.0
+    */
+    using number_unsigned_t = NumberUnsignedType;
+
+    /*!
+    @brief a type for a number (floating-point)
+
+    [RFC 7159](http://rfc7159.net/rfc7159) describes numbers as follows:
+    > The representation of numbers is similar to that used in most
+    > programming languages. A number is represented in base 10 using decimal
+    > digits. It contains an integer component that may be prefixed with an
+    > optional minus sign, which may be followed by a fraction part and/or an
+    > exponent part. Leading zeros are not allowed. (...) Numeric values that
+    > cannot be represented in the grammar below (such as Infinity and NaN)
+    > are not permitted.
+
+    This description includes both integer and floating-point numbers.
+    However, C++ allows more precise storage if it is known whether the number
+    is a signed integer, an unsigned integer or a floating-point number.
+    Therefore, three different types, @ref number_integer_t, @ref
+    number_unsigned_t and @ref number_float_t are used.
+
+    To store floating-point numbers in C++, a type is defined by the template
+    parameter @a NumberFloatType which chooses the type to use.
+
+    #### Default type
+
+    With the default values for @a NumberFloatType (`double`), the default
+    value for @a number_float_t is:
+
+    @code {.cpp}
+    double
+    @endcode
+
+    #### Default behavior
+
+    - The restrictions about leading zeros is not enforced in C++. Instead,
+      leading zeros in floating-point literals will be ignored. Internally,
+      the value will be stored as decimal number. For instance, the C++
+      floating-point literal `01.2` will be serialized to `1.2`. During
+      deserialization, leading zeros yield an error.
+    - Not-a-number (NaN) values will be serialized to `null`.
+
+    #### Limits
+
+    [RFC 7159](http://rfc7159.net/rfc7159) states:
+    > This specification allows implementations to set limits on the range and
+    > precision of numbers accepted. Since software that implements IEEE
+    > 754-2008 binary64 (double precision) numbers is generally available and
+    > widely used, good interoperability can be achieved by implementations
+    > that expect no more precision or range than these provide, in the sense
+    > that implementations will approximate JSON numbers within the expected
+    > precision.
+
+    This implementation does exactly follow this approach, as it uses double
+    precision floating-point numbers. Note values smaller than
+    `-1.79769313486232e+308` and values greater than `1.79769313486232e+308`
+    will be stored as NaN internally and be serialized to `null`.
+
+    #### Storage
+
+    Floating-point number values are stored directly inside a @ref basic_json
+    type.
+
+    @sa @ref number_integer_t -- type for number values (integer)
+
+    @sa @ref number_unsigned_t -- type for number values (unsigned integer)
+
+    @since version 1.0.0
+    */
+    using number_float_t = NumberFloatType;
+
+    /// @}
+
+  private:
+
+    /// helper for exception-safe object creation
+    template<typename T, typename... Args>
+    static T* create(Args&& ... args)
+    {
+        AllocatorType<T> alloc;
+        auto deleter = [&](T * object)
+        {
+            alloc.deallocate(object, 1);
+        };
+        std::unique_ptr<T, decltype(deleter)> object(alloc.allocate(1), deleter);
+        alloc.construct(object.get(), std::forward<Args>(args)...);
+        assert(object != nullptr);
+        return object.release();
+    }
+
+    ////////////////////////
+    // JSON value storage //
+    ////////////////////////
+
+    /*!
+    @brief a JSON value
+
+    The actual storage for a JSON value of the @ref basic_json class. This
+    union combines the different storage types for the JSON value types
+    defined in @ref value_t.
+
+    JSON type | value_t type    | used type
+    --------- | --------------- | ------------------------
+    object    | object          | pointer to @ref object_t
+    array     | array           | pointer to @ref array_t
+    string    | string          | pointer to @ref string_t
+    boolean   | boolean         | @ref boolean_t
+    number    | number_integer  | @ref number_integer_t
+    number    | number_unsigned | @ref number_unsigned_t
+    number    | number_float    | @ref number_float_t
+    null      | null            | *no value is stored*
+
+    @note Variable-length types (objects, arrays, and strings) are stored as
+    pointers. The size of the union should not exceed 64 bits if the default
+    value types are used.
+
+    @since version 1.0.0
+    */
+    union json_value
+    {
+        /// object (stored with pointer to save storage)
+        object_t* object;
+        /// array (stored with pointer to save storage)
+        array_t* array;
+        /// string (stored with pointer to save storage)
+        string_t* string;
+        /// boolean
+        boolean_t boolean;
+        /// number (integer)
+        number_integer_t number_integer;
+        /// number (unsigned integer)
+        number_unsigned_t number_unsigned;
+        /// number (floating-point)
+        number_float_t number_float;
+
+        /// default constructor (for null values)
+        json_value() = default;
+        /// constructor for booleans
+        json_value(boolean_t v) noexcept : boolean(v) {}
+        /// constructor for numbers (integer)
+        json_value(number_integer_t v) noexcept : number_integer(v) {}
+        /// constructor for numbers (unsigned)
+        json_value(number_unsigned_t v) noexcept : number_unsigned(v) {}
+        /// constructor for numbers (floating-point)
+        json_value(number_float_t v) noexcept : number_float(v) {}
+        /// constructor for empty values of a given type
+        json_value(value_t t)
+        {
+            switch (t)
+            {
+                case value_t::object:
+                {
+                    object = create<object_t>();
+                    break;
+                }
+
+                case value_t::array:
+                {
+                    array = create<array_t>();
+                    break;
+                }
+
+                case value_t::string:
+                {
+                    string = create<string_t>("");
+                    break;
+                }
+
+                case value_t::boolean:
+                {
+                    boolean = boolean_t(false);
+                    break;
+                }
+
+                case value_t::number_integer:
+                {
+                    number_integer = number_integer_t(0);
+                    break;
+                }
+
+                case value_t::number_unsigned:
+                {
+                    number_unsigned = number_unsigned_t(0);
+                    break;
+                }
+
+                case value_t::number_float:
+                {
+                    number_float = number_float_t(0.0);
+                    break;
+                }
+
+                case value_t::null:
+                {
+                    break;
+                }
+
+                default:
+                {
+                    if (t == value_t::null)
+                    {
+                        JSON_THROW(std::domain_error("961c151d2e87f2686a955a9be24d316f1362bf21 2.1.1")); // LCOV_EXCL_LINE
+                    }
+                    break;
+                }
+            }
+        }
+
+        /// constructor for strings
+        json_value(const string_t& value)
+        {
+            string = create<string_t>(value);
+        }
+
+        /// constructor for objects
+        json_value(const object_t& value)
+        {
+            object = create<object_t>(value);
+        }
+
+        /// constructor for arrays
+        json_value(const array_t& value)
+        {
+            array = create<array_t>(value);
+        }
+    };
+
+    /*!
+    @brief checks the class invariants
+
+    This function asserts the class invariants. It needs to be called at the
+    end of every constructor to make sure that created objects respect the
+    invariant. Furthermore, it has to be called each time the type of a JSON
+    value is changed, because the invariant expresses a relationship between
+    @a m_type and @a m_value.
+    */
+    void assert_invariant() const
+    {
+        assert(m_type != value_t::object or m_value.object != nullptr);
+        assert(m_type != value_t::array or m_value.array != nullptr);
+        assert(m_type != value_t::string or m_value.string != nullptr);
+    }
+
+  public:
+    //////////////////////////
+    // JSON parser callback //
+    //////////////////////////
+
+    /*!
+    @brief JSON callback events
+
+    This enumeration lists the parser events that can trigger calling a
+    callback function of type @ref parser_callback_t during parsing.
+
+    @image html callback_events.png "Example when certain parse events are triggered"
+
+    @since version 1.0.0
+    */
+    enum class parse_event_t : uint8_t
+    {
+        /// the parser read `{` and started to process a JSON object
+        object_start,
+        /// the parser read `}` and finished processing a JSON object
+        object_end,
+        /// the parser read `[` and started to process a JSON array
+        array_start,
+        /// the parser read `]` and finished processing a JSON array
+        array_end,
+        /// the parser read a key of a value in an object
+        key,
+        /// the parser finished reading a JSON value
+        value
+    };
+
+    /*!
+    @brief per-element parser callback type
+
+    With a parser callback function, the result of parsing a JSON text can be
+    influenced. When passed to @ref parse(std::istream&, const
+    parser_callback_t) or @ref parse(const CharT, const parser_callback_t),
+    it is called on certain events (passed as @ref parse_event_t via parameter
+    @a event) with a set recursion depth @a depth and context JSON value
+    @a parsed. The return value of the callback function is a boolean
+    indicating whether the element that emitted the callback shall be kept or
+    not.
+
+    We distinguish six scenarios (determined by the event type) in which the
+    callback function can be called. The following table describes the values
+    of the parameters @a depth, @a event, and @a parsed.
+
+    parameter @a event | description | parameter @a depth | parameter @a parsed
+    ------------------ | ----------- | ------------------ | -------------------
+    parse_event_t::object_start | the parser read `{` and started to process a JSON object | depth of the parent of the JSON object | a JSON value with type discarded
+    parse_event_t::key | the parser read a key of a value in an object | depth of the currently parsed JSON object | a JSON string containing the key
+    parse_event_t::object_end | the parser read `}` and finished processing a JSON object | depth of the parent of the JSON object | the parsed JSON object
+    parse_event_t::array_start | the parser read `[` and started to process a JSON array | depth of the parent of the JSON array | a JSON value with type discarded
+    parse_event_t::array_end | the parser read `]` and finished processing a JSON array | depth of the parent of the JSON array | the parsed JSON array
+    parse_event_t::value | the parser finished reading a JSON value | depth of the value | the parsed JSON value
+
+    @image html callback_events.png "Example when certain parse events are triggered"
+
+    Discarding a value (i.e., returning `false`) has different effects
+    depending on the context in which function was called:
+
+    - Discarded values in structured types are skipped. That is, the parser
+      will behave as if the discarded value was never read.
+    - In case a value outside a structured type is skipped, it is replaced
+      with `null`. This case happens if the top-level element is skipped.
+
+    @param[in] depth  the depth of the recursion during parsing
+
+    @param[in] event  an event of type parse_event_t indicating the context in
+    the callback function has been called
+
+    @param[in,out] parsed  the current intermediate parse result; note that
+    writing to this value has no effect for parse_event_t::key events
+
+    @return Whether the JSON value which called the function during parsing
+    should be kept (`true`) or not (`false`). In the latter case, it is either
+    skipped completely or replaced by an empty discarded object.
+
+    @sa @ref parse(std::istream&, parser_callback_t) or
+    @ref parse(const CharT, const parser_callback_t) for examples
+
+    @since version 1.0.0
+    */
+    using parser_callback_t = std::function<bool(int depth,
+                              parse_event_t event,
+                              basic_json& parsed)>;
+
+
+    //////////////////
+    // constructors //
+    //////////////////
+
+    /// @name constructors and destructors
+    /// Constructors of class @ref basic_json, copy/move constructor, copy
+    /// assignment, static functions creating objects, and the destructor.
+    /// @{
+
+    /*!
+    @brief create an empty value with a given type
+
+    Create an empty JSON value with a given type. The value will be default
+    initialized with an empty value which depends on the type:
+
+    Value type  | initial value
+    ----------- | -------------
+    null        | `null`
+    boolean     | `false`
+    string      | `""`
+    number      | `0`
+    object      | `{}`
+    array       | `[]`
+
+    @param[in] value_type  the type of the value to create
+
+    @complexity Constant.
+
+    @throw std::bad_alloc if allocation for object, array, or string value
+    fails
+
+    @liveexample{The following code shows the constructor for different @ref
+    value_t values,basic_json__value_t}
+
+    @since version 1.0.0
+    */
+    basic_json(const value_t value_type)
+        : m_type(value_type), m_value(value_type)
+    {
+        assert_invariant();
+    }
+
+    /*!
+    @brief create a null object
+
+    Create a `null` JSON value. It either takes a null pointer as parameter
+    (explicitly creating `null`) or no parameter (implicitly creating `null`).
+    The passed null pointer itself is not read -- it is only used to choose
+    the right constructor.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this constructor never throws
+    exceptions.
+
+    @liveexample{The following code shows the constructor with and without a
+    null pointer parameter.,basic_json__nullptr_t}
+
+    @since version 1.0.0
+    */
+    basic_json(std::nullptr_t = nullptr) noexcept
+        : basic_json(value_t::null)
+    {
+        assert_invariant();
+    }
+
+    /*!
+    @brief create a JSON value
+
+    This is a "catch all" constructor for all compatible JSON types; that is,
+    types for which a `to_json()` method exsits. The constructor forwards the
+    parameter @a val to that method (to `json_serializer<U>::to_json` method
+    with `U = uncvref_t<CompatibleType>`, to be exact).
+
+    Template type @a CompatibleType includes, but is not limited to, the
+    following types:
+    - **arrays**: @ref array_t and all kinds of compatible containers such as
+      `std::vector`, `std::deque`, `std::list`, `std::forward_list`,
+      `std::array`, `std::set`, `std::unordered_set`, `std::multiset`, and
+      `unordered_multiset` with a `value_type` from which a @ref basic_json
+      value can be constructed.
+    - **objects**: @ref object_t and all kinds of compatible associative
+      containers such as `std::map`, `std::unordered_map`, `std::multimap`,
+      and `std::unordered_multimap` with a `key_type` compatible to
+      @ref string_t and a `value_type` from which a @ref basic_json value can
+      be constructed.
+    - **strings**: @ref string_t, string literals, and all compatible string
+      containers can be used.
+    - **numbers**: @ref number_integer_t, @ref number_unsigned_t,
+      @ref number_float_t, and all convertible number types such as `int`,
+      `size_t`, `int64_t`, `float` or `double` can be used.
+    - **boolean**: @ref boolean_t / `bool` can be used.
+
+    See the examples below.
+
+    @tparam CompatibleType a type such that:
+    - @a CompatibleType is not derived from `std::istream`,
+    - @a CompatibleType is not @ref basic_json (to avoid hijacking copy/move
+         constructors),
+    - @a CompatibleType is not a @ref basic_json nested type (e.g.,
+         @ref json_pointer, @ref iterator, etc ...)
+    - @ref @ref json_serializer<U> has a
+         `to_json(basic_json_t&, CompatibleType&&)` method
+
+    @tparam U = `uncvref_t<CompatibleType>`
+
+    @param[in] val the value to be forwarded
+
+    @complexity Usually linear in the size of the passed @a val, also
+                depending on the implementation of the called `to_json()`
+                method.
+
+    @throw what `json_serializer<U>::to_json()` throws
+
+    @liveexample{The following code shows the constructor with several
+    compatible types.,basic_json__CompatibleType}
+
+    @since version 2.1.0
+    */
+    template<typename CompatibleType, typename U = detail::uncvref_t<CompatibleType>,
+             detail::enable_if_t<not std::is_base_of<std::istream, U>::value and
+                                 not std::is_same<U, basic_json_t>::value and
+                                 not detail::is_basic_json_nested_type<
+                                     basic_json_t, U>::value and
+                                 detail::has_to_json<basic_json, U>::value,
+                                 int> = 0>
+    basic_json(CompatibleType && val) noexcept(noexcept(JSONSerializer<U>::to_json(
+                std::declval<basic_json_t&>(), std::forward<CompatibleType>(val))))
+    {
+        JSONSerializer<U>::to_json(*this, std::forward<CompatibleType>(val));
+        assert_invariant();
+    }
+
+    /*!
+    @brief create a container (array or object) from an initializer list
+
+    Creates a JSON value of type array or object from the passed initializer
+    list @a init. In case @a type_deduction is `true` (default), the type of
+    the JSON value to be created is deducted from the initializer list @a init
+    according to the following rules:
+
+    1. If the list is empty, an empty JSON object value `{}` is created.
+    2. If the list consists of pairs whose first element is a string, a JSON
+       object value is created where the first elements of the pairs are
+       treated as keys and the second elements are as values.
+    3. In all other cases, an array is created.
+
+    The rules aim to create the best fit between a C++ initializer list and
+    JSON values. The rationale is as follows:
+
+    1. The empty initializer list is written as `{}` which is exactly an empty
+       JSON object.
+    2. C++ has now way of describing mapped types other than to list a list of
+       pairs. As JSON requires that keys must be of type string, rule 2 is the
+       weakest constraint one can pose on initializer lists to interpret them
+       as an object.
+    3. In all other cases, the initializer list could not be interpreted as
+       JSON object type, so interpreting it as JSON array type is safe.
+
+    With the rules described above, the following JSON values cannot be
+    expressed by an initializer list:
+
+    - the empty array (`[]`): use @ref array(std::initializer_list<basic_json>)
+      with an empty initializer list in this case
+    - arrays whose elements satisfy rule 2: use @ref
+      array(std::initializer_list<basic_json>) with the same initializer list
+      in this case
+
+    @note When used without parentheses around an empty initializer list, @ref
+    basic_json() is called instead of this function, yielding the JSON null
+    value.
+
+    @param[in] init  initializer list with JSON values
+
+    @param[in] type_deduction internal parameter; when set to `true`, the type
+    of the JSON value is deducted from the initializer list @a init; when set
+    to `false`, the type provided via @a manual_type is forced. This mode is
+    used by the functions @ref array(std::initializer_list<basic_json>) and
+    @ref object(std::initializer_list<basic_json>).
+
+    @param[in] manual_type internal parameter; when @a type_deduction is set
+    to `false`, the created JSON value will use the provided type (only @ref
+    value_t::array and @ref value_t::object are valid); when @a type_deduction
+    is set to `true`, this parameter has no effect
+
+    @throw std::domain_error if @a type_deduction is `false`, @a manual_type
+    is `value_t::object`, but @a init contains an element which is not a pair
+    whose first element is a string; example: `"cannot create object from
+    initializer list"`
+
+    @complexity Linear in the size of the initializer list @a init.
+
+    @liveexample{The example below shows how JSON values are created from
+    initializer lists.,basic_json__list_init_t}
+
+    @sa @ref array(std::initializer_list<basic_json>) -- create a JSON array
+    value from an initializer list
+    @sa @ref object(std::initializer_list<basic_json>) -- create a JSON object
+    value from an initializer list
+
+    @since version 1.0.0
+    */
+    basic_json(std::initializer_list<basic_json> init,
+               bool type_deduction = true,
+               value_t manual_type = value_t::array)
+    {
+        // check if each element is an array with two elements whose first
+        // element is a string
+        bool is_an_object = std::all_of(init.begin(), init.end(),
+                                        [](const basic_json & element)
+        {
+            return element.is_array() and element.size() == 2 and element[0].is_string();
+        });
+
+        // adjust type if type deduction is not wanted
+        if (not type_deduction)
+        {
+            // if array is wanted, do not create an object though possible
+            if (manual_type == value_t::array)
+            {
+                is_an_object = false;
+            }
+
+            // if object is wanted but impossible, throw an exception
+            if (manual_type == value_t::object and not is_an_object)
+            {
+                JSON_THROW(std::domain_error("cannot create object from initializer list"));
+            }
+        }
+
+        if (is_an_object)
+        {
+            // the initializer list is a list of pairs -> create object
+            m_type = value_t::object;
+            m_value = value_t::object;
+
+            std::for_each(init.begin(), init.end(), [this](const basic_json & element)
+            {
+                m_value.object->emplace(*(element[0].m_value.string), element[1]);
+            });
+        }
+        else
+        {
+            // the initializer list describes an array -> create array
+            m_type = value_t::array;
+            m_value.array = create<array_t>(init);
+        }
+
+        assert_invariant();
+    }
+
+    /*!
+    @brief explicitly create an array from an initializer list
+
+    Creates a JSON array value from a given initializer list. That is, given a
+    list of values `a, b, c`, creates the JSON value `[a, b, c]`. If the
+    initializer list is empty, the empty array `[]` is created.
+
+    @note This function is only needed to express two edge cases that cannot
+    be realized with the initializer list constructor (@ref
+    basic_json(std::initializer_list<basic_json>, bool, value_t)). These cases
+    are:
+    1. creating an array whose elements are all pairs whose first element is a
+    string -- in this case, the initializer list constructor would create an
+    object, taking the first elements as keys
+    2. creating an empty array -- passing the empty initializer list to the
+    initializer list constructor yields an empty object
+
+    @param[in] init  initializer list with JSON values to create an array from
+    (optional)
+
+    @return JSON array value
+
+    @complexity Linear in the size of @a init.
+
+    @liveexample{The following code shows an example for the `array`
+    function.,array}
+
+    @sa @ref basic_json(std::initializer_list<basic_json>, bool, value_t) --
+    create a JSON value from an initializer list
+    @sa @ref object(std::initializer_list<basic_json>) -- create a JSON object
+    value from an initializer list
+
+    @since version 1.0.0
+    */
+    static basic_json array(std::initializer_list<basic_json> init =
+                                std::initializer_list<basic_json>())
+    {
+        return basic_json(init, false, value_t::array);
+    }
+
+    /*!
+    @brief explicitly create an object from an initializer list
+
+    Creates a JSON object value from a given initializer list. The initializer
+    lists elements must be pairs, and their first elements must be strings. If
+    the initializer list is empty, the empty object `{}` is created.
+
+    @note This function is only added for symmetry reasons. In contrast to the
+    related function @ref array(std::initializer_list<basic_json>), there are
+    no cases which can only be expressed by this function. That is, any
+    initializer list @a init can also be passed to the initializer list
+    constructor @ref basic_json(std::initializer_list<basic_json>, bool,
+    value_t).
+
+    @param[in] init  initializer list to create an object from (optional)
+
+    @return JSON object value
+
+    @throw std::domain_error if @a init is not a pair whose first elements are
+    strings; thrown by
+    @ref basic_json(std::initializer_list<basic_json>, bool, value_t)
+
+    @complexity Linear in the size of @a init.
+
+    @liveexample{The following code shows an example for the `object`
+    function.,object}
+
+    @sa @ref basic_json(std::initializer_list<basic_json>, bool, value_t) --
+    create a JSON value from an initializer list
+    @sa @ref array(std::initializer_list<basic_json>) -- create a JSON array
+    value from an initializer list
+
+    @since version 1.0.0
+    */
+    static basic_json object(std::initializer_list<basic_json> init =
+                                 std::initializer_list<basic_json>())
+    {
+        return basic_json(init, false, value_t::object);
+    }
+
+    /*!
+    @brief construct an array with count copies of given value
+
+    Constructs a JSON array value by creating @a cnt copies of a passed value.
+    In case @a cnt is `0`, an empty array is created. As postcondition,
+    `std::distance(begin(),end()) == cnt` holds.
+
+    @param[in] cnt  the number of JSON copies of @a val to create
+    @param[in] val  the JSON value to copy
+
+    @complexity Linear in @a cnt.
+
+    @liveexample{The following code shows examples for the @ref
+    basic_json(size_type\, const basic_json&)
+    constructor.,basic_json__size_type_basic_json}
+
+    @since version 1.0.0
+    */
+    basic_json(size_type cnt, const basic_json& val)
+        : m_type(value_t::array)
+    {
+        m_value.array = create<array_t>(cnt, val);
+        assert_invariant();
+    }
+
+    /*!
+    @brief construct a JSON container given an iterator range
+
+    Constructs the JSON value with the contents of the range `[first, last)`.
+    The semantics depends on the different types a JSON value can have:
+    - In case of primitive types (number, boolean, or string), @a first must
+      be `begin()` and @a last must be `end()`. In this case, the value is
+      copied. Otherwise, std::out_of_range is thrown.
+    - In case of structured types (array, object), the constructor behaves as
+      similar versions for `std::vector`.
+    - In case of a null type, std::domain_error is thrown.
+
+    @tparam InputIT an input iterator type (@ref iterator or @ref
+    const_iterator)
+
+    @param[in] first begin of the range to copy from (included)
+    @param[in] last end of the range to copy from (excluded)
+
+    @pre Iterators @a first and @a last must be initialized. **This
+         precondition is enforced with an assertion.**
+
+    @throw std::domain_error if iterators are not compatible; that is, do not
+    belong to the same JSON value; example: `"iterators are not compatible"`
+    @throw std::out_of_range if iterators are for a primitive type (number,
+    boolean, or string) where an out of range error can be detected easily;
+    example: `"iterators out of range"`
+    @throw std::bad_alloc if allocation for object, array, or string fails
+    @throw std::domain_error if called with a null value; example: `"cannot
+    use construct with iterators from null"`
+
+    @complexity Linear in distance between @a first and @a last.
+
+    @liveexample{The example below shows several ways to create JSON values by
+    specifying a subrange with iterators.,basic_json__InputIt_InputIt}
+
+    @since version 1.0.0
+    */
+    template<class InputIT, typename std::enable_if<
+                 std::is_same<InputIT, typename basic_json_t::iterator>::value or
+                 std::is_same<InputIT, typename basic_json_t::const_iterator>::value, int>::type = 0>
+    basic_json(InputIT first, InputIT last)
+    {
+        assert(first.m_object != nullptr);
+        assert(last.m_object != nullptr);
+
+        // make sure iterator fits the current value
+        if (first.m_object != last.m_object)
+        {
+            JSON_THROW(std::domain_error("iterators are not compatible"));
+        }
+
+        // copy type from first iterator
+        m_type = first.m_object->m_type;
+
+        // check if iterator range is complete for primitive values
+        switch (m_type)
+        {
+            case value_t::boolean:
+            case value_t::number_float:
+            case value_t::number_integer:
+            case value_t::number_unsigned:
+            case value_t::string:
+            {
+                if (not first.m_it.primitive_iterator.is_begin() or not last.m_it.primitive_iterator.is_end())
+                {
+                    JSON_THROW(std::out_of_range("iterators out of range"));
+                }
+                break;
+            }
+
+            default:
+            {
+                break;
+            }
+        }
+
+        switch (m_type)
+        {
+            case value_t::number_integer:
+            {
+                m_value.number_integer = first.m_object->m_value.number_integer;
+                break;
+            }
+
+            case value_t::number_unsigned:
+            {
+                m_value.number_unsigned = first.m_object->m_value.number_unsigned;
+                break;
+            }
+
+            case value_t::number_float:
+            {
+                m_value.number_float = first.m_object->m_value.number_float;
+                break;
+            }
+
+            case value_t::boolean:
+            {
+                m_value.boolean = first.m_object->m_value.boolean;
+                break;
+            }
+
+            case value_t::string:
+            {
+                m_value = *first.m_object->m_value.string;
+                break;
+            }
+
+            case value_t::object:
+            {
+                m_value.object = create<object_t>(first.m_it.object_iterator,
+                                                  last.m_it.object_iterator);
+                break;
+            }
+
+            case value_t::array:
+            {
+                m_value.array = create<array_t>(first.m_it.array_iterator,
+                                                last.m_it.array_iterator);
+                break;
+            }
+
+            default:
+            {
+                JSON_THROW(std::domain_error("cannot use construct with iterators from " + first.m_object->type_name()));
+            }
+        }
+
+        assert_invariant();
+    }
+
+    /*!
+    @brief construct a JSON value given an input stream
+
+    @param[in,out] i  stream to read a serialized JSON value from
+    @param[in] cb a parser callback function of type @ref parser_callback_t
+    which is used to control the deserialization by filtering unwanted values
+    (optional)
+
+    @complexity Linear in the length of the input. The parser is a predictive
+    LL(1) parser. The complexity can be higher if the parser callback function
+    @a cb has a super-linear complexity.
+
+    @note A UTF-8 byte order mark is silently ignored.
+
+    @deprecated This constructor is deprecated and will be removed in version
+      3.0.0 to unify the interface of the library. Deserialization will be
+      done by stream operators or by calling one of the `parse` functions,
+      e.g. @ref parse(std::istream&, const parser_callback_t). That is, calls
+      like `json j(i);` for an input stream @a i need to be replaced by
+      `json j = json::parse(i);`. See the example below.
+
+    @liveexample{The example below demonstrates constructing a JSON value from
+    a `std::stringstream` with and without callback
+    function.,basic_json__istream}
+
+    @since version 2.0.0, deprecated in version 2.0.3, to be removed in
+           version 3.0.0
+    */
+    JSON_DEPRECATED
+    explicit basic_json(std::istream& i, const parser_callback_t cb = nullptr)
+    {
+        *this = parser(i, cb).parse();
+        assert_invariant();
+    }
+
+    ///////////////////////////////////////
+    // other constructors and destructor //
+    ///////////////////////////////////////
+
+    /*!
+    @brief copy constructor
+
+    Creates a copy of a given JSON value.
+
+    @param[in] other  the JSON value to copy
+
+    @complexity Linear in the size of @a other.
+
+    @requirement This function helps `basic_json` satisfying the
+    [Container](http://en.cppreference.com/w/cpp/concept/Container)
+    requirements:
+    - The complexity is linear.
+    - As postcondition, it holds: `other == basic_json(other)`.
+
+    @throw std::bad_alloc if allocation for object, array, or string fails.
+
+    @liveexample{The following code shows an example for the copy
+    constructor.,basic_json__basic_json}
+
+    @since version 1.0.0
+    */
+    basic_json(const basic_json& other)
+        : m_type(other.m_type)
+    {
+        // check of passed value is valid
+        other.assert_invariant();
+
+        switch (m_type)
+        {
+            case value_t::object:
+            {
+                m_value = *other.m_value.object;
+                break;
+            }
+
+            case value_t::array:
+            {
+                m_value = *other.m_value.array;
+                break;
+            }
+
+            case value_t::string:
+            {
+                m_value = *other.m_value.string;
+                break;
+            }
+
+            case value_t::boolean:
+            {
+                m_value = other.m_value.boolean;
+                break;
+            }
+
+            case value_t::number_integer:
+            {
+                m_value = other.m_value.number_integer;
+                break;
+            }
+
+            case value_t::number_unsigned:
+            {
+                m_value = other.m_value.number_unsigned;
+                break;
+            }
+
+            case value_t::number_float:
+            {
+                m_value = other.m_value.number_float;
+                break;
+            }
+
+            default:
+            {
+                break;
+            }
+        }
+
+        assert_invariant();
+    }
+
+    /*!
+    @brief move constructor
+
+    Move constructor. Constructs a JSON value with the contents of the given
+    value @a other using move semantics. It "steals" the resources from @a
+    other and leaves it as JSON null value.
+
+    @param[in,out] other  value to move to this object
+
+    @post @a other is a JSON null value
+
+    @complexity Constant.
+
+    @liveexample{The code below shows the move constructor explicitly called
+    via std::move.,basic_json__moveconstructor}
+
+    @since version 1.0.0
+    */
+    basic_json(basic_json&& other) noexcept
+        : m_type(std::move(other.m_type)),
+          m_value(std::move(other.m_value))
+    {
+        // check that passed value is valid
+        other.assert_invariant();
+
+        // invalidate payload
+        other.m_type = value_t::null;
+        other.m_value = {};
+
+        assert_invariant();
+    }
+
+    /*!
+    @brief copy assignment
+
+    Copy assignment operator. Copies a JSON value via the "copy and swap"
+    strategy: It is expressed in terms of the copy constructor, destructor,
+    and the swap() member function.
+
+    @param[in] other  value to copy from
+
+    @complexity Linear.
+
+    @requirement This function helps `basic_json` satisfying the
+    [Container](http://en.cppreference.com/w/cpp/concept/Container)
+    requirements:
+    - The complexity is linear.
+
+    @liveexample{The code below shows and example for the copy assignment. It
+    creates a copy of value `a` which is then swapped with `b`. Finally\, the
+    copy of `a` (which is the null value after the swap) is
+    destroyed.,basic_json__copyassignment}
+
+    @since version 1.0.0
+    */
+    reference& operator=(basic_json other) noexcept (
+        std::is_nothrow_move_constructible<value_t>::value and
+        std::is_nothrow_move_assignable<value_t>::value and
+        std::is_nothrow_move_constructible<json_value>::value and
+        std::is_nothrow_move_assignable<json_value>::value
+    )
+    {
+        // check that passed value is valid
+        other.assert_invariant();
+
+        using std::swap;
+        swap(m_type, other.m_type);
+        swap(m_value, other.m_value);
+
+        assert_invariant();
+        return *this;
+    }
+
+    /*!
+    @brief destructor
+
+    Destroys the JSON value and frees all allocated memory.
+
+    @complexity Linear.
+
+    @requirement This function helps `basic_json` satisfying the
+    [Container](http://en.cppreference.com/w/cpp/concept/Container)
+    requirements:
+    - The complexity is linear.
+    - All stored elements are destroyed and all memory is freed.
+
+    @since version 1.0.0
+    */
+    ~basic_json()
+    {
+        assert_invariant();
+
+        switch (m_type)
+        {
+            case value_t::object:
+            {
+                AllocatorType<object_t> alloc;
+                alloc.destroy(m_value.object);
+                alloc.deallocate(m_value.object, 1);
+                break;
+            }
+
+            case value_t::array:
+            {
+                AllocatorType<array_t> alloc;
+                alloc.destroy(m_value.array);
+                alloc.deallocate(m_value.array, 1);
+                break;
+            }
+
+            case value_t::string:
+            {
+                AllocatorType<string_t> alloc;
+                alloc.destroy(m_value.string);
+                alloc.deallocate(m_value.string, 1);
+                break;
+            }
+
+            default:
+            {
+                // all other types need no specific destructor
+                break;
+            }
+        }
+    }
+
+    /// @}
+
+  public:
+    ///////////////////////
+    // object inspection //
+    ///////////////////////
+
+    /// @name object inspection
+    /// Functions to inspect the type of a JSON value.
+    /// @{
+
+    /*!
+    @brief serialization
+
+    Serialization function for JSON values. The function tries to mimic
+    Python's `json.dumps()` function, and currently supports its @a indent
+    parameter.
+
+    @param[in] indent If indent is nonnegative, then array elements and object
+    members will be pretty-printed with that indent level. An indent level of
+    `0` will only insert newlines. `-1` (the default) selects the most compact
+    representation.
+
+    @return string containing the serialization of the JSON value
+
+    @complexity Linear.
+
+    @liveexample{The following example shows the effect of different @a indent
+    parameters to the result of the serialization.,dump}
+
+    @see https://docs.python.org/2/library/json.html#json.dump
+
+    @since version 1.0.0
+    */
+    string_t dump(const int indent = -1) const
+    {
+        std::stringstream ss;
+
+        if (indent >= 0)
+        {
+            dump(ss, true, static_cast<unsigned int>(indent));
+        }
+        else
+        {
+            dump(ss, false, 0);
+        }
+
+        return ss.str();
+    }
+
+    /*!
+    @brief return the type of the JSON value (explicit)
+
+    Return the type of the JSON value as a value from the @ref value_t
+    enumeration.
+
+    @return the type of the JSON value
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `type()` for all JSON
+    types.,type}
+
+    @since version 1.0.0
+    */
+    constexpr value_t type() const noexcept
+    {
+        return m_type;
+    }
+
+    /*!
+    @brief return whether type is primitive
+
+    This function returns true iff the JSON type is primitive (string, number,
+    boolean, or null).
+
+    @return `true` if type is primitive (string, number, boolean, or null),
+    `false` otherwise.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_primitive()` for all JSON
+    types.,is_primitive}
+
+    @sa @ref is_structured() -- returns whether JSON value is structured
+    @sa @ref is_null() -- returns whether JSON value is `null`
+    @sa @ref is_string() -- returns whether JSON value is a string
+    @sa @ref is_boolean() -- returns whether JSON value is a boolean
+    @sa @ref is_number() -- returns whether JSON value is a number
+
+    @since version 1.0.0
+    */
+    constexpr bool is_primitive() const noexcept
+    {
+        return is_null() or is_string() or is_boolean() or is_number();
+    }
+
+    /*!
+    @brief return whether type is structured
+
+    This function returns true iff the JSON type is structured (array or
+    object).
+
+    @return `true` if type is structured (array or object), `false` otherwise.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_structured()` for all JSON
+    types.,is_structured}
+
+    @sa @ref is_primitive() -- returns whether value is primitive
+    @sa @ref is_array() -- returns whether value is an array
+    @sa @ref is_object() -- returns whether value is an object
+
+    @since version 1.0.0
+    */
+    constexpr bool is_structured() const noexcept
+    {
+        return is_array() or is_object();
+    }
+
+    /*!
+    @brief return whether value is null
+
+    This function returns true iff the JSON value is null.
+
+    @return `true` if type is null, `false` otherwise.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_null()` for all JSON
+    types.,is_null}
+
+    @since version 1.0.0
+    */
+    constexpr bool is_null() const noexcept
+    {
+        return m_type == value_t::null;
+    }
+
+    /*!
+    @brief return whether value is a boolean
+
+    This function returns true iff the JSON value is a boolean.
+
+    @return `true` if type is boolean, `false` otherwise.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_boolean()` for all JSON
+    types.,is_boolean}
+
+    @since version 1.0.0
+    */
+    constexpr bool is_boolean() const noexcept
+    {
+        return m_type == value_t::boolean;
+    }
+
+    /*!
+    @brief return whether value is a number
+
+    This function returns true iff the JSON value is a number. This includes
+    both integer and floating-point values.
+
+    @return `true` if type is number (regardless whether integer, unsigned
+    integer or floating-type), `false` otherwise.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_number()` for all JSON
+    types.,is_number}
+
+    @sa @ref is_number_integer() -- check if value is an integer or unsigned
+    integer number
+    @sa @ref is_number_unsigned() -- check if value is an unsigned integer
+    number
+    @sa @ref is_number_float() -- check if value is a floating-point number
+
+    @since version 1.0.0
+    */
+    constexpr bool is_number() const noexcept
+    {
+        return is_number_integer() or is_number_float();
+    }
+
+    /*!
+    @brief return whether value is an integer number
+
+    This function returns true iff the JSON value is an integer or unsigned
+    integer number. This excludes floating-point values.
+
+    @return `true` if type is an integer or unsigned integer number, `false`
+    otherwise.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_number_integer()` for all
+    JSON types.,is_number_integer}
+
+    @sa @ref is_number() -- check if value is a number
+    @sa @ref is_number_unsigned() -- check if value is an unsigned integer
+    number
+    @sa @ref is_number_float() -- check if value is a floating-point number
+
+    @since version 1.0.0
+    */
+    constexpr bool is_number_integer() const noexcept
+    {
+        return m_type == value_t::number_integer or m_type == value_t::number_unsigned;
+    }
+
+    /*!
+    @brief return whether value is an unsigned integer number
+
+    This function returns true iff the JSON value is an unsigned integer
+    number. This excludes floating-point and (signed) integer values.
+
+    @return `true` if type is an unsigned integer number, `false` otherwise.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_number_unsigned()` for all
+    JSON types.,is_number_unsigned}
+
+    @sa @ref is_number() -- check if value is a number
+    @sa @ref is_number_integer() -- check if value is an integer or unsigned
+    integer number
+    @sa @ref is_number_float() -- check if value is a floating-point number
+
+    @since version 2.0.0
+    */
+    constexpr bool is_number_unsigned() const noexcept
+    {
+        return m_type == value_t::number_unsigned;
+    }
+
+    /*!
+    @brief return whether value is a floating-point number
+
+    This function returns true iff the JSON value is a floating-point number.
+    This excludes integer and unsigned integer values.
+
+    @return `true` if type is a floating-point number, `false` otherwise.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_number_float()` for all
+    JSON types.,is_number_float}
+
+    @sa @ref is_number() -- check if value is number
+    @sa @ref is_number_integer() -- check if value is an integer number
+    @sa @ref is_number_unsigned() -- check if value is an unsigned integer
+    number
+
+    @since version 1.0.0
+    */
+    constexpr bool is_number_float() const noexcept
+    {
+        return m_type == value_t::number_float;
+    }
+
+    /*!
+    @brief return whether value is an object
+
+    This function returns true iff the JSON value is an object.
+
+    @return `true` if type is object, `false` otherwise.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_object()` for all JSON
+    types.,is_object}
+
+    @since version 1.0.0
+    */
+    constexpr bool is_object() const noexcept
+    {
+        return m_type == value_t::object;
+    }
+
+    /*!
+    @brief return whether value is an array
+
+    This function returns true iff the JSON value is an array.
+
+    @return `true` if type is array, `false` otherwise.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_array()` for all JSON
+    types.,is_array}
+
+    @since version 1.0.0
+    */
+    constexpr bool is_array() const noexcept
+    {
+        return m_type == value_t::array;
+    }
+
+    /*!
+    @brief return whether value is a string
+
+    This function returns true iff the JSON value is a string.
+
+    @return `true` if type is string, `false` otherwise.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_string()` for all JSON
+    types.,is_string}
+
+    @since version 1.0.0
+    */
+    constexpr bool is_string() const noexcept
+    {
+        return m_type == value_t::string;
+    }
+
+    /*!
+    @brief return whether value is discarded
+
+    This function returns true iff the JSON value was discarded during parsing
+    with a callback function (see @ref parser_callback_t).
+
+    @note This function will always be `false` for JSON values after parsing.
+    That is, discarded values can only occur during parsing, but will be
+    removed when inside a structured value or replaced by null in other cases.
+
+    @return `true` if type is discarded, `false` otherwise.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_discarded()` for all JSON
+    types.,is_discarded}
+
+    @since version 1.0.0
+    */
+    constexpr bool is_discarded() const noexcept
+    {
+        return m_type == value_t::discarded;
+    }
+
+    /*!
+    @brief return the type of the JSON value (implicit)
+
+    Implicitly return the type of the JSON value as a value from the @ref
+    value_t enumeration.
+
+    @return the type of the JSON value
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies the @ref value_t operator for
+    all JSON types.,operator__value_t}
+
+    @since version 1.0.0
+    */
+    constexpr operator value_t() const noexcept
+    {
+        return m_type;
+    }
+
+    /// @}
+
+  private:
+    //////////////////
+    // value access //
+    //////////////////
+
+    /// get a boolean (explicit)
+    boolean_t get_impl(boolean_t* /*unused*/) const
+    {
+        if (is_boolean())
+        {
+            return m_value.boolean;
+        }
+
+        JSON_THROW(std::domain_error("type must be boolean, but is " + type_name()));
+    }
+
+    /// get a pointer to the value (object)
+    object_t* get_impl_ptr(object_t* /*unused*/) noexcept
+    {
+        return is_object() ? m_value.object : nullptr;
+    }
+
+    /// get a pointer to the value (object)
+    constexpr const object_t* get_impl_ptr(const object_t* /*unused*/) const noexcept
+    {
+        return is_object() ? m_value.object : nullptr;
+    }
+
+    /// get a pointer to the value (array)
+    array_t* get_impl_ptr(array_t* /*unused*/) noexcept
+    {
+        return is_array() ? m_value.array : nullptr;
+    }
+
+    /// get a pointer to the value (array)
+    constexpr const array_t* get_impl_ptr(const array_t* /*unused*/) const noexcept
+    {
+        return is_array() ? m_value.array : nullptr;
+    }
+
+    /// get a pointer to the value (string)
+    string_t* get_impl_ptr(string_t* /*unused*/) noexcept
+    {
+        return is_string() ? m_value.string : nullptr;
+    }
+
+    /// get a pointer to the value (string)
+    constexpr const string_t* get_impl_ptr(const string_t* /*unused*/) const noexcept
+    {
+        return is_string() ? m_value.string : nullptr;
+    }
+
+    /// get a pointer to the value (boolean)
+    boolean_t* get_impl_ptr(boolean_t* /*unused*/) noexcept
+    {
+        return is_boolean() ? &m_value.boolean : nullptr;
+    }
+
+    /// get a pointer to the value (boolean)
+    constexpr const boolean_t* get_impl_ptr(const boolean_t* /*unused*/) const noexcept
+    {
+        return is_boolean() ? &m_value.boolean : nullptr;
+    }
+
+    /// get a pointer to the value (integer number)
+    number_integer_t* get_impl_ptr(number_integer_t* /*unused*/) noexcept
+    {
+        return is_number_integer() ? &m_value.number_integer : nullptr;
+    }
+
+    /// get a pointer to the value (integer number)
+    constexpr const number_integer_t* get_impl_ptr(const number_integer_t* /*unused*/) const noexcept
+    {
+        return is_number_integer() ? &m_value.number_integer : nullptr;
+    }
+
+    /// get a pointer to the value (unsigned number)
+    number_unsigned_t* get_impl_ptr(number_unsigned_t* /*unused*/) noexcept
+    {
+        return is_number_unsigned() ? &m_value.number_unsigned : nullptr;
+    }
+
+    /// get a pointer to the value (unsigned number)
+    constexpr const number_unsigned_t* get_impl_ptr(const number_unsigned_t* /*unused*/) const noexcept
+    {
+        return is_number_unsigned() ? &m_value.number_unsigned : nullptr;
+    }
+
+    /// get a pointer to the value (floating-point number)
+    number_float_t* get_impl_ptr(number_float_t* /*unused*/) noexcept
+    {
+        return is_number_float() ? &m_value.number_float : nullptr;
+    }
+
+    /// get a pointer to the value (floating-point number)
+    constexpr const number_float_t* get_impl_ptr(const number_float_t* /*unused*/) const noexcept
+    {
+        return is_number_float() ? &m_value.number_float : nullptr;
+    }
+
+    /*!
+    @brief helper function to implement get_ref()
+
+    This funcion helps to implement get_ref() without code duplication for
+    const and non-const overloads
+
+    @tparam ThisType will be deduced as `basic_json` or `const basic_json`
+
+    @throw std::domain_error if ReferenceType does not match underlying value
+    type of the current JSON
+    */
+    template<typename ReferenceType, typename ThisType>
+    static ReferenceType get_ref_impl(ThisType& obj)
+    {
+        // helper type
+        using PointerType = typename std::add_pointer<ReferenceType>::type;
+
+        // delegate the call to get_ptr<>()
+        auto ptr = obj.template get_ptr<PointerType>();
+
+        if (ptr != nullptr)
+        {
+            return *ptr;
+        }
+
+        JSON_THROW(std::domain_error("incompatible ReferenceType for get_ref, actual type is " +
+                                     obj.type_name()));
+    }
+
+  public:
+    /// @name value access
+    /// Direct access to the stored value of a JSON value.
+    /// @{
+
+    /*!
+    @brief get special-case overload
+
+    This overloads avoids a lot of template boilerplate, it can be seen as the
+    identity method
+
+    @tparam BasicJsonType == @ref basic_json
+
+    @return a copy of *this
+
+    @complexity Constant.
+
+    @since version 2.1.0
+    */
+    template <
+        typename BasicJsonType,
+        detail::enable_if_t<std::is_same<typename std::remove_const<BasicJsonType>::type,
+                                         basic_json_t>::value,
+                            int> = 0 >
+    basic_json get() const
+    {
+        return *this;
+    }
+
+    /*!
+    @brief get a value (explicit)
+
+    Explicit type conversion between the JSON value and a compatible value
+    which is [CopyConstructible](http://en.cppreference.com/w/cpp/concept/CopyConstructible)
+    and [DefaultConstructible](http://en.cppreference.com/w/cpp/concept/DefaultConstructible).
+    The value is converted by calling the @ref json_serializer<ValueType>
+    `from_json()` method.
+
+    The function is equivalent to executing
+    @code {.cpp}
+    ValueType ret;
+    JSONSerializer<ValueType>::from_json(*this, ret);
+    return ret;
+    @endcode
+
+    This overloads is chosen if:
+    - @a ValueType is not @ref basic_json,
+    - @ref json_serializer<ValueType> has a `from_json()` method of the form
+      `void from_json(const @ref basic_json&, ValueType&)`, and
+    - @ref json_serializer<ValueType> does not have a `from_json()` method of
+      the form `ValueType from_json(const @ref basic_json&)`
+
+    @tparam ValueTypeCV the provided value type
+    @tparam ValueType the returned value type
+
+    @return copy of the JSON value, converted to @a ValueType
+
+    @throw what @ref json_serializer<ValueType> `from_json()` method throws
+
+    @liveexample{The example below shows several conversions from JSON values
+    to other types. There a few things to note: (1) Floating-point numbers can
+    be converted to integers\, (2) A JSON array can be converted to a standard
+    `std::vector<short>`\, (3) A JSON object can be converted to C++
+    associative containers such as `std::unordered_map<std::string\,
+    json>`.,get__ValueType_const}
+
+    @since version 2.1.0
+    */
+    template <
+        typename ValueTypeCV,
+        typename ValueType = detail::uncvref_t<ValueTypeCV>,
+        detail::enable_if_t <
+            not std::is_same<basic_json_t, ValueType>::value and
+            detail::has_from_json<basic_json_t, ValueType>::value and
+            not detail::has_non_default_from_json<basic_json_t, ValueType>::value,
+            int > = 0 >
+    ValueType get() const noexcept(noexcept(
+                                       JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>(), std::declval<ValueType&>())))
+    {
+        // we cannot static_assert on ValueTypeCV being non-const, because
+        // there is support for get<const basic_json_t>(), which is why we
+        // still need the uncvref
+        static_assert(not std::is_reference<ValueTypeCV>::value,
+                      "get() cannot be used with reference types, you might want to use get_ref()");
+        static_assert(std::is_default_constructible<ValueType>::value,
+                      "types must be DefaultConstructible when used with get()");
+
+        ValueType ret;
+        JSONSerializer<ValueType>::from_json(*this, ret);
+        return ret;
+    }
+
+    /*!
+    @brief get a value (explicit); special case
+
+    Explicit type conversion between the JSON value and a compatible value
+    which is **not** [CopyConstructible](http://en.cppreference.com/w/cpp/concept/CopyConstructible)
+    and **not** [DefaultConstructible](http://en.cppreference.com/w/cpp/concept/DefaultConstructible).
+    The value is converted by calling the @ref json_serializer<ValueType>
+    `from_json()` method.
+
+    The function is equivalent to executing
+    @code {.cpp}
+    return JSONSerializer<ValueTypeCV>::from_json(*this);
+    @endcode
+
+    This overloads is chosen if:
+    - @a ValueType is not @ref basic_json and
+    - @ref json_serializer<ValueType> has a `from_json()` method of the form
+      `ValueType from_json(const @ref basic_json&)`
+
+    @note If @ref json_serializer<ValueType> has both overloads of
+    `from_json()`, this one is chosen.
+
+    @tparam ValueTypeCV the provided value type
+    @tparam ValueType the returned value type
+
+    @return copy of the JSON value, converted to @a ValueType
+
+    @throw what @ref json_serializer<ValueType> `from_json()` method throws
+
+    @since version 2.1.0
+    */
+    template <
+        typename ValueTypeCV,
+        typename ValueType = detail::uncvref_t<ValueTypeCV>,
+        detail::enable_if_t<not std::is_same<basic_json_t, ValueType>::value and
+                            detail::has_non_default_from_json<basic_json_t,
+                                    ValueType>::value, int> = 0 >
+    ValueType get() const noexcept(noexcept(
+                                       JSONSerializer<ValueTypeCV>::from_json(std::declval<const basic_json_t&>())))
+    {
+        static_assert(not std::is_reference<ValueTypeCV>::value,
+                      "get() cannot be used with reference types, you might want to use get_ref()");
+        return JSONSerializer<ValueTypeCV>::from_json(*this);
+    }
+
+    /*!
+    @brief get a pointer value (explicit)
+
+    Explicit pointer access to the internally stored JSON value. No copies are
+    made.
+
+    @warning The pointer becomes invalid if the underlying JSON object
+    changes.
+
+    @tparam PointerType pointer type; must be a pointer to @ref array_t, @ref
+    object_t, @ref string_t, @ref boolean_t, @ref number_integer_t,
+    @ref number_unsigned_t, or @ref number_float_t.
+
+    @return pointer to the internally stored JSON value if the requested
+    pointer type @a PointerType fits to the JSON value; `nullptr` otherwise
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how pointers to internal values of a
+    JSON value can be requested. Note that no type conversions are made and a
+    `nullptr` is returned if the value and the requested pointer type does not
+    match.,get__PointerType}
+
+    @sa @ref get_ptr() for explicit pointer-member access
+
+    @since version 1.0.0
+    */
+    template<typename PointerType, typename std::enable_if<
+                 std::is_pointer<PointerType>::value, int>::type = 0>
+    PointerType get() noexcept
+    {
+        // delegate the call to get_ptr
+        return get_ptr<PointerType>();
+    }
+
+    /*!
+    @brief get a pointer value (explicit)
+    @copydoc get()
+    */
+    template<typename PointerType, typename std::enable_if<
+                 std::is_pointer<PointerType>::value, int>::type = 0>
+    constexpr const PointerType get() const noexcept
+    {
+        // delegate the call to get_ptr
+        return get_ptr<PointerType>();
+    }
+
+    /*!
+    @brief get a pointer value (implicit)
+
+    Implicit pointer access to the internally stored JSON value. No copies are
+    made.
+
+    @warning Writing data to the pointee of the result yields an undefined
+    state.
+
+    @tparam PointerType pointer type; must be a pointer to @ref array_t, @ref
+    object_t, @ref string_t, @ref boolean_t, @ref number_integer_t,
+    @ref number_unsigned_t, or @ref number_float_t. Enforced by a static
+    assertion.
+
+    @return pointer to the internally stored JSON value if the requested
+    pointer type @a PointerType fits to the JSON value; `nullptr` otherwise
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how pointers to internal values of a
+    JSON value can be requested. Note that no type conversions are made and a
+    `nullptr` is returned if the value and the requested pointer type does not
+    match.,get_ptr}
+
+    @since version 1.0.0
+    */
+    template<typename PointerType, typename std::enable_if<
+                 std::is_pointer<PointerType>::value, int>::type = 0>
+    PointerType get_ptr() noexcept
+    {
+        // get the type of the PointerType (remove pointer and const)
+        using pointee_t = typename std::remove_const<typename
+                          std::remove_pointer<typename
+                          std::remove_const<PointerType>::type>::type>::type;
+        // make sure the type matches the allowed types
+        static_assert(
+            std::is_same<object_t, pointee_t>::value
+            or std::is_same<array_t, pointee_t>::value
+            or std::is_same<string_t, pointee_t>::value
+            or std::is_same<boolean_t, pointee_t>::value
+            or std::is_same<number_integer_t, pointee_t>::value
+            or std::is_same<number_unsigned_t, pointee_t>::value
+            or std::is_same<number_float_t, pointee_t>::value
+            , "incompatible pointer type");
+
+        // delegate the call to get_impl_ptr<>()
+        return get_impl_ptr(static_cast<PointerType>(nullptr));
+    }
+
+    /*!
+    @brief get a pointer value (implicit)
+    @copydoc get_ptr()
+    */
+    template<typename PointerType, typename std::enable_if<
+                 std::is_pointer<PointerType>::value and
+                 std::is_const<typename std::remove_pointer<PointerType>::type>::value, int>::type = 0>
+    constexpr const PointerType get_ptr() const noexcept
+    {
+        // get the type of the PointerType (remove pointer and const)
+        using pointee_t = typename std::remove_const<typename
+                          std::remove_pointer<typename
+                          std::remove_const<PointerType>::type>::type>::type;
+        // make sure the type matches the allowed types
+        static_assert(
+            std::is_same<object_t, pointee_t>::value
+            or std::is_same<array_t, pointee_t>::value
+            or std::is_same<string_t, pointee_t>::value
+            or std::is_same<boolean_t, pointee_t>::value
+            or std::is_same<number_integer_t, pointee_t>::value
+            or std::is_same<number_unsigned_t, pointee_t>::value
+            or std::is_same<number_float_t, pointee_t>::value
+            , "incompatible pointer type");
+
+        // delegate the call to get_impl_ptr<>() const
+        return get_impl_ptr(static_cast<const PointerType>(nullptr));
+    }
+
+    /*!
+    @brief get a reference value (implicit)
+
+    Implicit reference access to the internally stored JSON value. No copies
+    are made.
+
+    @warning Writing data to the referee of the result yields an undefined
+    state.
+
+    @tparam ReferenceType reference type; must be a reference to @ref array_t,
+    @ref object_t, @ref string_t, @ref boolean_t, @ref number_integer_t, or
+    @ref number_float_t. Enforced by static assertion.
+
+    @return reference to the internally stored JSON value if the requested
+    reference type @a ReferenceType fits to the JSON value; throws
+    std::domain_error otherwise
+
+    @throw std::domain_error in case passed type @a ReferenceType is
+    incompatible with the stored JSON value
+
+    @complexity Constant.
+
+    @liveexample{The example shows several calls to `get_ref()`.,get_ref}
+
+    @since version 1.1.0
+    */
+    template<typename ReferenceType, typename std::enable_if<
+                 std::is_reference<ReferenceType>::value, int>::type = 0>
+    ReferenceType get_ref()
+    {
+        // delegate call to get_ref_impl
+        return get_ref_impl<ReferenceType>(*this);
+    }
+
+    /*!
+    @brief get a reference value (implicit)
+    @copydoc get_ref()
+    */
+    template<typename ReferenceType, typename std::enable_if<
+                 std::is_reference<ReferenceType>::value and
+                 std::is_const<typename std::remove_reference<ReferenceType>::type>::value, int>::type = 0>
+    ReferenceType get_ref() const
+    {
+        // delegate call to get_ref_impl
+        return get_ref_impl<ReferenceType>(*this);
+    }
+
+    /*!
+    @brief get a value (implicit)
+
+    Implicit type conversion between the JSON value and a compatible value.
+    The call is realized by calling @ref get() const.
+
+    @tparam ValueType non-pointer type compatible to the JSON value, for
+    instance `int` for JSON integer numbers, `bool` for JSON booleans, or
+    `std::vector` types for JSON arrays. The character type of @ref string_t
+    as well as an initializer list of this type is excluded to avoid
+    ambiguities as these types implicitly convert to `std::string`.
+
+    @return copy of the JSON value, converted to type @a ValueType
+
+    @throw std::domain_error in case passed type @a ValueType is incompatible
+    to JSON, thrown by @ref get() const
+
+    @complexity Linear in the size of the JSON value.
+
+    @liveexample{The example below shows several conversions from JSON values
+    to other types. There a few things to note: (1) Floating-point numbers can
+    be converted to integers\, (2) A JSON array can be converted to a standard
+    `std::vector<short>`\, (3) A JSON object can be converted to C++
+    associative containers such as `std::unordered_map<std::string\,
+    json>`.,operator__ValueType}
+
+    @since version 1.0.0
+    */
+    template < typename ValueType, typename std::enable_if <
+                   not std::is_pointer<ValueType>::value and
+                   not std::is_same<ValueType, typename string_t::value_type>::value
+#ifndef _MSC_VER  // fix for issue #167 operator<< ambiguity under VS2015
+                   and not std::is_same<ValueType, std::initializer_list<typename string_t::value_type>>::value
+#endif
+                   , int >::type = 0 >
+    operator ValueType() const
+    {
+        // delegate the call to get<>() const
+        return get<ValueType>();
+    }
+
+    /// @}
+
+
+    ////////////////////
+    // element access //
+    ////////////////////
+
+    /// @name element access
+    /// Access to the JSON value.
+    /// @{
+
+    /*!
+    @brief access specified array element with bounds checking
+
+    Returns a reference to the element at specified location @a idx, with
+    bounds checking.
+
+    @param[in] idx  index of the element to access
+
+    @return reference to the element at index @a idx
+
+    @throw std::domain_error if the JSON value is not an array; example:
+    `"cannot use at() with string"`
+    @throw std::out_of_range if the index @a idx is out of range of the array;
+    that is, `idx >= size()`; example: `"array index 7 is out of range"`
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how array elements can be read and
+    written using `at()`.,at__size_type}
+
+    @since version 1.0.0
+    */
+    reference at(size_type idx)
+    {
+        // at only works for arrays
+        if (is_array())
+        {
+            JSON_TRY
+            {
+                return m_value.array->at(idx);
+            }
+            JSON_CATCH (std::out_of_range&)
+            {
+                // create better exception explanation
+                JSON_THROW(std::out_of_range("array index " + std::to_string(idx) + " is out of range"));
+            }
+        }
+        else
+        {
+            JSON_THROW(std::domain_error("cannot use at() with " + type_name()));
+        }
+    }
+
+    /*!
+    @brief access specified array element with bounds checking
+
+    Returns a const reference to the element at specified location @a idx,
+    with bounds checking.
+
+    @param[in] idx  index of the element to access
+
+    @return const reference to the element at index @a idx
+
+    @throw std::domain_error if the JSON value is not an array; example:
+    `"cannot use at() with string"`
+    @throw std::out_of_range if the index @a idx is out of range of the array;
+    that is, `idx >= size()`; example: `"array index 7 is out of range"`
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how array elements can be read using
+    `at()`.,at__size_type_const}
+
+    @since version 1.0.0
+    */
+    const_reference at(size_type idx) const
+    {
+        // at only works for arrays
+        if (is_array())
+        {
+            JSON_TRY
+            {
+                return m_value.array->at(idx);
+            }
+            JSON_CATCH (std::out_of_range&)
+            {
+                // create better exception explanation
+                JSON_THROW(std::out_of_range("array index " + std::to_string(idx) + " is out of range"));
+            }
+        }
+        else
+        {
+            JSON_THROW(std::domain_error("cannot use at() with " + type_name()));
+        }
+    }
+
+    /*!
+    @brief access specified object element with bounds checking
+
+    Returns a reference to the element at with specified key @a key, with
+    bounds checking.
+
+    @param[in] key  key of the element to access
+
+    @return reference to the element at key @a key
+
+    @throw std::domain_error if the JSON value is not an object; example:
+    `"cannot use at() with boolean"`
+    @throw std::out_of_range if the key @a key is is not stored in the object;
+    that is, `find(key) == end()`; example: `"key "the fast" not found"`
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be read and
+    written using `at()`.,at__object_t_key_type}
+
+    @sa @ref operator[](const typename object_t::key_type&) for unchecked
+    access by reference
+    @sa @ref value() for access by value with a default value
+
+    @since version 1.0.0
+    */
+    reference at(const typename object_t::key_type& key)
+    {
+        // at only works for objects
+        if (is_object())
+        {
+            JSON_TRY
+            {
+                return m_value.object->at(key);
+            }
+            JSON_CATCH (std::out_of_range&)
+            {
+                // create better exception explanation
+                JSON_THROW(std::out_of_range("key '" + key + "' not found"));
+            }
+        }
+        else
+        {
+            JSON_THROW(std::domain_error("cannot use at() with " + type_name()));
+        }
+    }
+
+    /*!
+    @brief access specified object element with bounds checking
+
+    Returns a const reference to the element at with specified key @a key,
+    with bounds checking.
+
+    @param[in] key  key of the element to access
+
+    @return const reference to the element at key @a key
+
+    @throw std::domain_error if the JSON value is not an object; example:
+    `"cannot use at() with boolean"`
+    @throw std::out_of_range if the key @a key is is not stored in the object;
+    that is, `find(key) == end()`; example: `"key "the fast" not found"`
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be read using
+    `at()`.,at__object_t_key_type_const}
+
+    @sa @ref operator[](const typename object_t::key_type&) for unchecked
+    access by reference
+    @sa @ref value() for access by value with a default value
+
+    @since version 1.0.0
+    */
+    const_reference at(const typename object_t::key_type& key) const
+    {
+        // at only works for objects
+        if (is_object())
+        {
+            JSON_TRY
+            {
+                return m_value.object->at(key);
+            }
+            JSON_CATCH (std::out_of_range&)
+            {
+                // create better exception explanation
+                JSON_THROW(std::out_of_range("key '" + key + "' not found"));
+            }
+        }
+        else
+        {
+            JSON_THROW(std::domain_error("cannot use at() with " + type_name()));
+        }
+    }
+
+    /*!
+    @brief access specified array element
+
+    Returns a reference to the element at specified location @a idx.
+
+    @note If @a idx is beyond the range of the array (i.e., `idx >= size()`),
+    then the array is silently filled up with `null` values to make `idx` a
+    valid reference to the last stored element.
+
+    @param[in] idx  index of the element to access
+
+    @return reference to the element at index @a idx
+
+    @throw std::domain_error if JSON is not an array or null; example:
+    `"cannot use operator[] with string"`
+
+    @complexity Constant if @a idx is in the range of the array. Otherwise
+    linear in `idx - size()`.
+
+    @liveexample{The example below shows how array elements can be read and
+    written using `[]` operator. Note the addition of `null`
+    values.,operatorarray__size_type}
+
+    @since version 1.0.0
+    */
+    reference operator[](size_type idx)
+    {
+        // implicitly convert null value to an empty array
+        if (is_null())
+        {
+            m_type = value_t::array;
+            m_value.array = create<array_t>();
+            assert_invariant();
+        }
+
+        // operator[] only works for arrays
+        if (is_array())
+        {
+            // fill up array with null values if given idx is outside range
+            if (idx >= m_value.array->size())
+            {
+                m_value.array->insert(m_value.array->end(),
+                                      idx - m_value.array->size() + 1,
+                                      basic_json());
+            }
+
+            return m_value.array->operator[](idx);
+        }
+
+        JSON_THROW(std::domain_error("cannot use operator[] with " + type_name()));
+    }
+
+    /*!
+    @brief access specified array element
+
+    Returns a const reference to the element at specified location @a idx.
+
+    @param[in] idx  index of the element to access
+
+    @return const reference to the element at index @a idx
+
+    @throw std::domain_error if JSON is not an array; example: `"cannot use
+    operator[] with null"`
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how array elements can be read using
+    the `[]` operator.,operatorarray__size_type_const}
+
+    @since version 1.0.0
+    */
+    const_reference operator[](size_type idx) const
+    {
+        // const operator[] only works for arrays
+        if (is_array())
+        {
+            return m_value.array->operator[](idx);
+        }
+
+        JSON_THROW(std::domain_error("cannot use operator[] with " + type_name()));
+    }
+
+    /*!
+    @brief access specified object element
+
+    Returns a reference to the element at with specified key @a key.
+
+    @note If @a key is not found in the object, then it is silently added to
+    the object and filled with a `null` value to make `key` a valid reference.
+    In case the value was `null` before, it is converted to an object.
+
+    @param[in] key  key of the element to access
+
+    @return reference to the element at key @a key
+
+    @throw std::domain_error if JSON is not an object or null; example:
+    `"cannot use operator[] with string"`
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be read and
+    written using the `[]` operator.,operatorarray__key_type}
+
+    @sa @ref at(const typename object_t::key_type&) for access by reference
+    with range checking
+    @sa @ref value() for access by value with a default value
+
+    @since version 1.0.0
+    */
+    reference operator[](const typename object_t::key_type& key)
+    {
+        // implicitly convert null value to an empty object
+        if (is_null())
+        {
+            m_type = value_t::object;
+            m_value.object = create<object_t>();
+            assert_invariant();
+        }
+
+        // operator[] only works for objects
+        if (is_object())
+        {
+            return m_value.object->operator[](key);
+        }
+
+        JSON_THROW(std::domain_error("cannot use operator[] with " + type_name()));
+    }
+
+    /*!
+    @brief read-only access specified object element
+
+    Returns a const reference to the element at with specified key @a key. No
+    bounds checking is performed.
+
+    @warning If the element with key @a key does not exist, the behavior is
+    undefined.
+
+    @param[in] key  key of the element to access
+
+    @return const reference to the element at key @a key
+
+    @pre The element with key @a key must exist. **This precondition is
+         enforced with an assertion.**
+
+    @throw std::domain_error if JSON is not an object; example: `"cannot use
+    operator[] with null"`
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be read using
+    the `[]` operator.,operatorarray__key_type_const}
+
+    @sa @ref at(const typename object_t::key_type&) for access by reference
+    with range checking
+    @sa @ref value() for access by value with a default value
+
+    @since version 1.0.0
+    */
+    const_reference operator[](const typename object_t::key_type& key) const
+    {
+        // const operator[] only works for objects
+        if (is_object())
+        {
+            assert(m_value.object->find(key) != m_value.object->end());
+            return m_value.object->find(key)->second;
+        }
+
+        JSON_THROW(std::domain_error("cannot use operator[] with " + type_name()));
+    }
+
+    /*!
+    @brief access specified object element
+
+    Returns a reference to the element at with specified key @a key.
+
+    @note If @a key is not found in the object, then it is silently added to
+    the object and filled with a `null` value to make `key` a valid reference.
+    In case the value was `null` before, it is converted to an object.
+
+    @param[in] key  key of the element to access
+
+    @return reference to the element at key @a key
+
+    @throw std::domain_error if JSON is not an object or null; example:
+    `"cannot use operator[] with string"`
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be read and
+    written using the `[]` operator.,operatorarray__key_type}
+
+    @sa @ref at(const typename object_t::key_type&) for access by reference
+    with range checking
+    @sa @ref value() for access by value with a default value
+
+    @since version 1.0.0
+    */
+    template<typename T, std::size_t n>
+    reference operator[](T * (&key)[n])
+    {
+        return operator[](static_cast<const T>(key));
+    }
+
+    /*!
+    @brief read-only access specified object element
+
+    Returns a const reference to the element at with specified key @a key. No
+    bounds checking is performed.
+
+    @warning If the element with key @a key does not exist, the behavior is
+    undefined.
+
+    @note This function is required for compatibility reasons with Clang.
+
+    @param[in] key  key of the element to access
+
+    @return const reference to the element at key @a key
+
+    @throw std::domain_error if JSON is not an object; example: `"cannot use
+    operator[] with null"`
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be read using
+    the `[]` operator.,operatorarray__key_type_const}
+
+    @sa @ref at(const typename object_t::key_type&) for access by reference
+    with range checking
+    @sa @ref value() for access by value with a default value
+
+    @since version 1.0.0
+    */
+    template<typename T, std::size_t n>
+    const_reference operator[](T * (&key)[n]) const
+    {
+        return operator[](static_cast<const T>(key));
+    }
+
+    /*!
+    @brief access specified object element
+
+    Returns a reference to the element at with specified key @a key.
+
+    @note If @a key is not found in the object, then it is silently added to
+    the object and filled with a `null` value to make `key` a valid reference.
+    In case the value was `null` before, it is converted to an object.
+
+    @param[in] key  key of the element to access
+
+    @return reference to the element at key @a key
+
+    @throw std::domain_error if JSON is not an object or null; example:
+    `"cannot use operator[] with string"`
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be read and
+    written using the `[]` operator.,operatorarray__key_type}
+
+    @sa @ref at(const typename object_t::key_type&) for access by reference
+    with range checking
+    @sa @ref value() for access by value with a default value
+
+    @since version 1.1.0
+    */
+    template<typename T>
+    reference operator[](T* key)
+    {
+        // implicitly convert null to object
+        if (is_null())
+        {
+            m_type = value_t::object;
+            m_value = value_t::object;
+            assert_invariant();
+        }
+
+        // at only works for objects
+        if (is_object())
+        {
+            return m_value.object->operator[](key);
+        }
+
+        JSON_THROW(std::domain_error("cannot use operator[] with " + type_name()));
+    }
+
+    /*!
+    @brief read-only access specified object element
+
+    Returns a const reference to the element at with specified key @a key. No
+    bounds checking is performed.
+
+    @warning If the element with key @a key does not exist, the behavior is
+    undefined.
+
+    @param[in] key  key of the element to access
+
+    @return const reference to the element at key @a key
+
+    @pre The element with key @a key must exist. **This precondition is
+         enforced with an assertion.**
+
+    @throw std::domain_error if JSON is not an object; example: `"cannot use
+    operator[] with null"`
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be read using
+    the `[]` operator.,operatorarray__key_type_const}
+
+    @sa @ref at(const typename object_t::key_type&) for access by reference
+    with range checking
+    @sa @ref value() for access by value with a default value
+
+    @since version 1.1.0
+    */
+    template<typename T>
+    const_reference operator[](T* key) const
+    {
+        // at only works for objects
+        if (is_object())
+        {
+            assert(m_value.object->find(key) != m_value.object->end());
+            return m_value.object->find(key)->second;
+        }
+
+        JSON_THROW(std::domain_error("cannot use operator[] with " + type_name()));
+    }
+
+    /*!
+    @brief access specified object element with default value
+
+    Returns either a copy of an object's element at the specified key @a key
+    or a given default value if no element with key @a key exists.
+
+    The function is basically equivalent to executing
+    @code {.cpp}
+    try {
+        return at(key);
+    } catch(std::out_of_range) {
+        return default_value;
+    }
+    @endcode
+
+    @note Unlike @ref at(const typename object_t::key_type&), this function
+    does not throw if the given key @a key was not found.
+
+    @note Unlike @ref operator[](const typename object_t::key_type& key), this
+    function does not implicitly add an element to the position defined by @a
+    key. This function is furthermore also applicable to const objects.
+
+    @param[in] key  key of the element to access
+    @param[in] default_value  the value to return if @a key is not found
+
+    @tparam ValueType type compatible to JSON values, for instance `int` for
+    JSON integer numbers, `bool` for JSON booleans, or `std::vector` types for
+    JSON arrays. Note the type of the expected value at @a key and the default
+    value @a default_value must be compatible.
+
+    @return copy of the element at key @a key or @a default_value if @a key
+    is not found
+
+    @throw std::domain_error if JSON is not an object; example: `"cannot use
+    value() with null"`
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be queried
+    with a default value.,basic_json__value}
+
+    @sa @ref at(const typename object_t::key_type&) for access by reference
+    with range checking
+    @sa @ref operator[](const typename object_t::key_type&) for unchecked
+    access by reference
+
+    @since version 1.0.0
+    */
+    template<class ValueType, typename std::enable_if<
+                 std::is_convertible<basic_json_t, ValueType>::value, int>::type = 0>
+    ValueType value(const typename object_t::key_type& key, ValueType default_value) const
+    {
+        // at only works for objects
+        if (is_object())
+        {
+            // if key is found, return value and given default value otherwise
+            const auto it = find(key);
+            if (it != end())
+            {
+                return *it;
+            }
+
+            return default_value;
+        }
+        else
+        {
+            JSON_THROW(std::domain_error("cannot use value() with " + type_name()));
+        }
+    }
+
+    /*!
+    @brief overload for a default value of type const char*
+    @copydoc basic_json::value(const typename object_t::key_type&, ValueType) const
+    */
+    string_t value(const typename object_t::key_type& key, const char* default_value) const
+    {
+        return value(key, string_t(default_value));
+    }
+
+    /*!
+    @brief access specified object element via JSON Pointer with default value
+
+    Returns either a copy of an object's element at the specified key @a key
+    or a given default value if no element with key @a key exists.
+
+    The function is basically equivalent to executing
+    @code {.cpp}
+    try {
+        return at(ptr);
+    } catch(std::out_of_range) {
+        return default_value;
+    }
+    @endcode
+
+    @note Unlike @ref at(const json_pointer&), this function does not throw
+    if the given key @a key was not found.
+
+    @param[in] ptr  a JSON pointer to the element to access
+    @param[in] default_value  the value to return if @a ptr found no value
+
+    @tparam ValueType type compatible to JSON values, for instance `int` for
+    JSON integer numbers, `bool` for JSON booleans, or `std::vector` types for
+    JSON arrays. Note the type of the expected value at @a key and the default
+    value @a default_value must be compatible.
+
+    @return copy of the element at key @a key or @a default_value if @a key
+    is not found
+
+    @throw std::domain_error if JSON is not an object; example: `"cannot use
+    value() with null"`
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be queried
+    with a default value.,basic_json__value_ptr}
+
+    @sa @ref operator[](const json_pointer&) for unchecked access by reference
+
+    @since version 2.0.2
+    */
+    template<class ValueType, typename std::enable_if<
+                 std::is_convertible<basic_json_t, ValueType>::value, int>::type = 0>
+    ValueType value(const json_pointer& ptr, ValueType default_value) const
+    {
+        // at only works for objects
+        if (is_object())
+        {
+            // if pointer resolves a value, return it or use default value
+            JSON_TRY
+            {
+                return ptr.get_checked(this);
+            }
+            JSON_CATCH (std::out_of_range&)
+            {
+                return default_value;
+            }
+        }
+
+        JSON_THROW(std::domain_error("cannot use value() with " + type_name()));
+    }
+
+    /*!
+    @brief overload for a default value of type const char*
+    @copydoc basic_json::value(const json_pointer&, ValueType) const
+    */
+    string_t value(const json_pointer& ptr, const char* default_value) const
+    {
+        return value(ptr, string_t(default_value));
+    }
+
+    /*!
+    @brief access the first element
+
+    Returns a reference to the first element in the container. For a JSON
+    container `c`, the expression `c.front()` is equivalent to `*c.begin()`.
+
+    @return In case of a structured type (array or object), a reference to the
+    first element is returned. In case of number, string, or boolean values, a
+    reference to the value is returned.
+
+    @complexity Constant.
+
+    @pre The JSON value must not be `null` (would throw `std::out_of_range`)
+    or an empty array or object (undefined behavior, **guarded by
+    assertions**).
+    @post The JSON value remains unchanged.
+
+    @throw std::out_of_range when called on `null` value
+
+    @liveexample{The following code shows an example for `front()`.,front}
+
+    @sa @ref back() -- access the last element
+
+    @since version 1.0.0
+    */
+    reference front()
+    {
+        return *begin();
+    }
+
+    /*!
+    @copydoc basic_json::front()
+    */
+    const_reference front() const
+    {
+        return *cbegin();
+    }
+
+    /*!
+    @brief access the last element
+
+    Returns a reference to the last element in the container. For a JSON
+    container `c`, the expression `c.back()` is equivalent to
+    @code {.cpp}
+    auto tmp = c.end();
+    --tmp;
+    return *tmp;
+    @endcode
+
+    @return In case of a structured type (array or object), a reference to the
+    last element is returned. In case of number, string, or boolean values, a
+    reference to the value is returned.
+
+    @complexity Constant.
+
+    @pre The JSON value must not be `null` (would throw `std::out_of_range`)
+    or an empty array or object (undefined behavior, **guarded by
+    assertions**).
+    @post The JSON value remains unchanged.
+
+    @throw std::out_of_range when called on `null` value.
+
+    @liveexample{The following code shows an example for `back()`.,back}
+
+    @sa @ref front() -- access the first element
+
+    @since version 1.0.0
+    */
+    reference back()
+    {
+        auto tmp = end();
+        --tmp;
+        return *tmp;
+    }
+
+    /*!
+    @copydoc basic_json::back()
+    */
+    const_reference back() const
+    {
+        auto tmp = cend();
+        --tmp;
+        return *tmp;
+    }
+
+    /*!
+    @brief remove element given an iterator
+
+    Removes the element specified by iterator @a pos. The iterator @a pos must
+    be valid and dereferenceable. Thus the `end()` iterator (which is valid,
+    but is not dereferenceable) cannot be used as a value for @a pos.
+
+    If called on a primitive type other than `null`, the resulting JSON value
+    will be `null`.
+
+    @param[in] pos iterator to the element to remove
+    @return Iterator following the last removed element. If the iterator @a
+    pos refers to the last element, the `end()` iterator is returned.
+
+    @tparam IteratorType an @ref iterator or @ref const_iterator
+
+    @post Invalidates iterators and references at or after the point of the
+    erase, including the `end()` iterator.
+
+    @throw std::domain_error if called on a `null` value; example: `"cannot
+    use erase() with null"`
+    @throw std::domain_error if called on an iterator which does not belong to
+    the current JSON value; example: `"iterator does not fit current value"`
+    @throw std::out_of_range if called on a primitive type with invalid
+    iterator (i.e., any iterator which is not `begin()`); example: `"iterator
+    out of range"`
+
+    @complexity The complexity depends on the type:
+    - objects: amortized constant
+    - arrays: linear in distance between @a pos and the end of the container
+    - strings: linear in the length of the string
+    - other types: constant
+
+    @liveexample{The example shows the result of `erase()` for different JSON
+    types.,erase__IteratorType}
+
+    @sa @ref erase(IteratorType, IteratorType) -- removes the elements in
+    the given range
+    @sa @ref erase(const typename object_t::key_type&) -- removes the element
+    from an object at the given key
+    @sa @ref erase(const size_type) -- removes the element from an array at
+    the given index
+
+    @since version 1.0.0
+    */
+    template<class IteratorType, typename std::enable_if<
+                 std::is_same<IteratorType, typename basic_json_t::iterator>::value or
+                 std::is_same<IteratorType, typename basic_json_t::const_iterator>::value, int>::type
+             = 0>
+    IteratorType erase(IteratorType pos)
+    {
+        // make sure iterator fits the current value
+        if (this != pos.m_object)
+        {
+            JSON_THROW(std::domain_error("iterator does not fit current value"));
+        }
+
+        IteratorType result = end();
+
+        switch (m_type)
+        {
+            case value_t::boolean:
+            case value_t::number_float:
+            case value_t::number_integer:
+            case value_t::number_unsigned:
+            case value_t::string:
+            {
+                if (not pos.m_it.primitive_iterator.is_begin())
+                {
+                    JSON_THROW(std::out_of_range("iterator out of range"));
+                }
+
+                if (is_string())
+                {
+                    AllocatorType<string_t> alloc;
+                    alloc.destroy(m_value.string);
+                    alloc.deallocate(m_value.string, 1);
+                    m_value.string = nullptr;
+                }
+
+                m_type = value_t::null;
+                assert_invariant();
+                break;
+            }
+
+            case value_t::object:
+            {
+                result.m_it.object_iterator = m_value.object->erase(pos.m_it.object_iterator);
+                break;
+            }
+
+            case value_t::array:
+            {
+                result.m_it.array_iterator = m_value.array->erase(pos.m_it.array_iterator);
+                break;
+            }
+
+            default:
+            {
+                JSON_THROW(std::domain_error("cannot use erase() with " + type_name()));
+            }
+        }
+
+        return result;
+    }
+
+    /*!
+    @brief remove elements given an iterator range
+
+    Removes the element specified by the range `[first; last)`. The iterator
+    @a first does not need to be dereferenceable if `first == last`: erasing
+    an empty range is a no-op.
+
+    If called on a primitive type other than `null`, the resulting JSON value
+    will be `null`.
+
+    @param[in] first iterator to the beginning of the range to remove
+    @param[in] last iterator past the end of the range to remove
+    @return Iterator following the last removed element. If the iterator @a
+    second refers to the last element, the `end()` iterator is returned.
+
+    @tparam IteratorType an @ref iterator or @ref const_iterator
+
+    @post Invalidates iterators and references at or after the point of the
+    erase, including the `end()` iterator.
+
+    @throw std::domain_error if called on a `null` value; example: `"cannot
+    use erase() with null"`
+    @throw std::domain_error if called on iterators which does not belong to
+    the current JSON value; example: `"iterators do not fit current value"`
+    @throw std::out_of_range if called on a primitive type with invalid
+    iterators (i.e., if `first != begin()` and `last != end()`); example:
+    `"iterators out of range"`
+
+    @complexity The complexity depends on the type:
+    - objects: `log(size()) + std::distance(first, last)`
+    - arrays: linear in the distance between @a first and @a last, plus linear
+      in the distance between @a last and end of the container
+    - strings: linear in the length of the string
+    - other types: constant
+
+    @liveexample{The example shows the result of `erase()` for different JSON
+    types.,erase__IteratorType_IteratorType}
+
+    @sa @ref erase(IteratorType) -- removes the element at a given position
+    @sa @ref erase(const typename object_t::key_type&) -- removes the element
+    from an object at the given key
+    @sa @ref erase(const size_type) -- removes the element from an array at
+    the given index
+
+    @since version 1.0.0
+    */
+    template<class IteratorType, typename std::enable_if<
+                 std::is_same<IteratorType, typename basic_json_t::iterator>::value or
+                 std::is_same<IteratorType, typename basic_json_t::const_iterator>::value, int>::type
+             = 0>
+    IteratorType erase(IteratorType first, IteratorType last)
+    {
+        // make sure iterator fits the current value
+        if (this != first.m_object or this != last.m_object)
+        {
+            JSON_THROW(std::domain_error("iterators do not fit current value"));
+        }
+
+        IteratorType result = end();
+
+        switch (m_type)
+        {
+            case value_t::boolean:
+            case value_t::number_float:
+            case value_t::number_integer:
+            case value_t::number_unsigned:
+            case value_t::string:
+            {
+                if (not first.m_it.primitive_iterator.is_begin() or not last.m_it.primitive_iterator.is_end())
+                {
+                    JSON_THROW(std::out_of_range("iterators out of range"));
+                }
+
+                if (is_string())
+                {
+                    AllocatorType<string_t> alloc;
+                    alloc.destroy(m_value.string);
+                    alloc.deallocate(m_value.string, 1);
+                    m_value.string = nullptr;
+                }
+
+                m_type = value_t::null;
+                assert_invariant();
+                break;
+            }
+
+            case value_t::object:
+            {
+                result.m_it.object_iterator = m_value.object->erase(first.m_it.object_iterator,
+                                              last.m_it.object_iterator);
+                break;
+            }
+
+            case value_t::array:
+            {
+                result.m_it.array_iterator = m_value.array->erase(first.m_it.array_iterator,
+                                             last.m_it.array_iterator);
+                break;
+            }
+
+            default:
+            {
+                JSON_THROW(std::domain_error("cannot use erase() with " + type_name()));
+            }
+        }
+
+        return result;
+    }
+
+    /*!
+    @brief remove element from a JSON object given a key
+
+    Removes elements from a JSON object with the key value @a key.
+
+    @param[in] key value of the elements to remove
+
+    @return Number of elements removed. If @a ObjectType is the default
+    `std::map` type, the return value will always be `0` (@a key was not
+    found) or `1` (@a key was found).
+
+    @post References and iterators to the erased elements are invalidated.
+    Other references and iterators are not affected.
+
+    @throw std::domain_error when called on a type other than JSON object;
+    example: `"cannot use erase() with null"`
+
+    @complexity `log(size()) + count(key)`
+
+    @liveexample{The example shows the effect of `erase()`.,erase__key_type}
+
+    @sa @ref erase(IteratorType) -- removes the element at a given position
+    @sa @ref erase(IteratorType, IteratorType) -- removes the elements in
+    the given range
+    @sa @ref erase(const size_type) -- removes the element from an array at
+    the given index
+
+    @since version 1.0.0
+    */
+    size_type erase(const typename object_t::key_type& key)
+    {
+        // this erase only works for objects
+        if (is_object())
+        {
+            return m_value.object->erase(key);
+        }
+
+        JSON_THROW(std::domain_error("cannot use erase() with " + type_name()));
+    }
+
+    /*!
+    @brief remove element from a JSON array given an index
+
+    Removes element from a JSON array at the index @a idx.
+
+    @param[in] idx index of the element to remove
+
+    @throw std::domain_error when called on a type other than JSON array;
+    example: `"cannot use erase() with null"`
+    @throw std::out_of_range when `idx >= size()`; example: `"array index 17
+    is out of range"`
+
+    @complexity Linear in distance between @a idx and the end of the container.
+
+    @liveexample{The example shows the effect of `erase()`.,erase__size_type}
+
+    @sa @ref erase(IteratorType) -- removes the element at a given position
+    @sa @ref erase(IteratorType, IteratorType) -- removes the elements in
+    the given range
+    @sa @ref erase(const typename object_t::key_type&) -- removes the element
+    from an object at the given key
+
+    @since version 1.0.0
+    */
+    void erase(const size_type idx)
+    {
+        // this erase only works for arrays
+        if (is_array())
+        {
+            if (idx >= size())
+            {
+                JSON_THROW(std::out_of_range("array index " + std::to_string(idx) + " is out of range"));
+            }
+
+            m_value.array->erase(m_value.array->begin() + static_cast<difference_type>(idx));
+        }
+        else
+        {
+            JSON_THROW(std::domain_error("cannot use erase() with " + type_name()));
+        }
+    }
+
+    /// @}
+
+
+    ////////////
+    // lookup //
+    ////////////
+
+    /// @name lookup
+    /// @{
+
+    /*!
+    @brief find an element in a JSON object
+
+    Finds an element in a JSON object with key equivalent to @a key. If the
+    element is not found or the JSON value is not an object, end() is
+    returned.
+
+    @note This method always returns @ref end() when executed on a JSON type
+          that is not an object.
+
+    @param[in] key key value of the element to search for
+
+    @return Iterator to an element with key equivalent to @a key. If no such
+    element is found or the JSON value is not an object, past-the-end (see
+    @ref end()) iterator is returned.
+
+    @complexity Logarithmic in the size of the JSON object.
+
+    @liveexample{The example shows how `find()` is used.,find__key_type}
+
+    @since version 1.0.0
+    */
+    iterator find(typename object_t::key_type key)
+    {
+        auto result = end();
+
+        if (is_object())
+        {
+            result.m_it.object_iterator = m_value.object->find(key);
+        }
+
+        return result;
+    }
+
+    /*!
+    @brief find an element in a JSON object
+    @copydoc find(typename object_t::key_type)
+    */
+    const_iterator find(typename object_t::key_type key) const
+    {
+        auto result = cend();
+
+        if (is_object())
+        {
+            result.m_it.object_iterator = m_value.object->find(key);
+        }
+
+        return result;
+    }
+
+    /*!
+    @brief returns the number of occurrences of a key in a JSON object
+
+    Returns the number of elements with key @a key. If ObjectType is the
+    default `std::map` type, the return value will always be `0` (@a key was
+    not found) or `1` (@a key was found).
+
+    @note This method always returns `0` when executed on a JSON type that is
+          not an object.
+
+    @param[in] key key value of the element to count
+
+    @return Number of elements with key @a key. If the JSON value is not an
+    object, the return value will be `0`.
+
+    @complexity Logarithmic in the size of the JSON object.
+
+    @liveexample{The example shows how `count()` is used.,count}
+
+    @since version 1.0.0
+    */
+    size_type count(typename object_t::key_type key) const
+    {
+        // return 0 for all nonobject types
+        return is_object() ? m_value.object->count(key) : 0;
+    }
+
+    /// @}
+
+
+    ///////////////
+    // iterators //
+    ///////////////
+
+    /// @name iterators
+    /// @{
+
+    /*!
+    @brief returns an iterator to the first element
+
+    Returns an iterator to the first element.
+
+    @image html range-begin-end.svg "Illustration from cppreference.com"
+
+    @return iterator to the first element
+
+    @complexity Constant.
+
+    @requirement This function helps `basic_json` satisfying the
+    [Container](http://en.cppreference.com/w/cpp/concept/Container)
+    requirements:
+    - The complexity is constant.
+
+    @liveexample{The following code shows an example for `begin()`.,begin}
+
+    @sa @ref cbegin() -- returns a const iterator to the beginning
+    @sa @ref end() -- returns an iterator to the end
+    @sa @ref cend() -- returns a const iterator to the end
+
+    @since version 1.0.0
+    */
+    iterator begin() noexcept
+    {
+        iterator result(this);
+        result.set_begin();
+        return result;
+    }
+
+    /*!
+    @copydoc basic_json::cbegin()
+    */
+    const_iterator begin() const noexcept
+    {
+        return cbegin();
+    }
+
+    /*!
+    @brief returns a const iterator to the first element
+
+    Returns a const iterator to the first element.
+
+    @image html range-begin-end.svg "Illustration from cppreference.com"
+
+    @return const iterator to the first element
+
+    @complexity Constant.
+
+    @requirement This function helps `basic_json` satisfying the
+    [Container](http://en.cppreference.com/w/cpp/concept/Container)
+    requirements:
+    - The complexity is constant.
+    - Has the semantics of `const_cast<const basic_json&>(*this).begin()`.
+
+    @liveexample{The following code shows an example for `cbegin()`.,cbegin}
+
+    @sa @ref begin() -- returns an iterator to the beginning
+    @sa @ref end() -- returns an iterator to the end
+    @sa @ref cend() -- returns a const iterator to the end
+
+    @since version 1.0.0
+    */
+    const_iterator cbegin() const noexcept
+    {
+        const_iterator result(this);
+        result.set_begin();
+        return result;
+    }
+
+    /*!
+    @brief returns an iterator to one past the last element
+
+    Returns an iterator to one past the last element.
+
+    @image html range-begin-end.svg "Illustration from cppreference.com"
+
+    @return iterator one past the last element
+
+    @complexity Constant.
+
+    @requirement This function helps `basic_json` satisfying the
+    [Container](http://en.cppreference.com/w/cpp/concept/Container)
+    requirements:
+    - The complexity is constant.
+
+    @liveexample{The following code shows an example for `end()`.,end}
+
+    @sa @ref cend() -- returns a const iterator to the end
+    @sa @ref begin() -- returns an iterator to the beginning
+    @sa @ref cbegin() -- returns a const iterator to the beginning
+
+    @since version 1.0.0
+    */
+    iterator end() noexcept
+    {
+        iterator result(this);
+        result.set_end();
+        return result;
+    }
+
+    /*!
+    @copydoc basic_json::cend()
+    */
+    const_iterator end() const noexcept
+    {
+        return cend();
+    }
+
+    /*!
+    @brief returns a const iterator to one past the last element
+
+    Returns a const iterator to one past the last element.
+
+    @image html range-begin-end.svg "Illustration from cppreference.com"
+
+    @return const iterator one past the last element
+
+    @complexity Constant.
+
+    @requirement This function helps `basic_json` satisfying the
+    [Container](http://en.cppreference.com/w/cpp/concept/Container)
+    requirements:
+    - The complexity is constant.
+    - Has the semantics of `const_cast<const basic_json&>(*this).end()`.
+
+    @liveexample{The following code shows an example for `cend()`.,cend}
+
+    @sa @ref end() -- returns an iterator to the end
+    @sa @ref begin() -- returns an iterator to the beginning
+    @sa @ref cbegin() -- returns a const iterator to the beginning
+
+    @since version 1.0.0
+    */
+    const_iterator cend() const noexcept
+    {
+        const_iterator result(this);
+        result.set_end();
+        return result;
+    }
+
+    /*!
+    @brief returns an iterator to the reverse-beginning
+
+    Returns an iterator to the reverse-beginning; that is, the last element.
+
+    @image html range-rbegin-rend.svg "Illustration from cppreference.com"
+
+    @complexity Constant.
+
+    @requirement This function helps `basic_json` satisfying the
+    [ReversibleContainer](http://en.cppreference.com/w/cpp/concept/ReversibleContainer)
+    requirements:
+    - The complexity is constant.
+    - Has the semantics of `reverse_iterator(end())`.
+
+    @liveexample{The following code shows an example for `rbegin()`.,rbegin}
+
+    @sa @ref crbegin() -- returns a const reverse iterator to the beginning
+    @sa @ref rend() -- returns a reverse iterator to the end
+    @sa @ref crend() -- returns a const reverse iterator to the end
+
+    @since version 1.0.0
+    */
+    reverse_iterator rbegin() noexcept
+    {
+        return reverse_iterator(end());
+    }
+
+    /*!
+    @copydoc basic_json::crbegin()
+    */
+    const_reverse_iterator rbegin() const noexcept
+    {
+        return crbegin();
+    }
+
+    /*!
+    @brief returns an iterator to the reverse-end
+
+    Returns an iterator to the reverse-end; that is, one before the first
+    element.
+
+    @image html range-rbegin-rend.svg "Illustration from cppreference.com"
+
+    @complexity Constant.
+
+    @requirement This function helps `basic_json` satisfying the
+    [ReversibleContainer](http://en.cppreference.com/w/cpp/concept/ReversibleContainer)
+    requirements:
+    - The complexity is constant.
+    - Has the semantics of `reverse_iterator(begin())`.
+
+    @liveexample{The following code shows an example for `rend()`.,rend}
+
+    @sa @ref crend() -- returns a const reverse iterator to the end
+    @sa @ref rbegin() -- returns a reverse iterator to the beginning
+    @sa @ref crbegin() -- returns a const reverse iterator to the beginning
+
+    @since version 1.0.0
+    */
+    reverse_iterator rend() noexcept
+    {
+        return reverse_iterator(begin());
+    }
+
+    /*!
+    @copydoc basic_json::crend()
+    */
+    const_reverse_iterator rend() const noexcept
+    {
+        return crend();
+    }
+
+    /*!
+    @brief returns a const reverse iterator to the last element
+
+    Returns a const iterator to the reverse-beginning; that is, the last
+    element.
+
+    @image html range-rbegin-rend.svg "Illustration from cppreference.com"
+
+    @complexity Constant.
+
+    @requirement This function helps `basic_json` satisfying the
+    [ReversibleContainer](http://en.cppreference.com/w/cpp/concept/ReversibleContainer)
+    requirements:
+    - The complexity is constant.
+    - Has the semantics of `const_cast<const basic_json&>(*this).rbegin()`.
+
+    @liveexample{The following code shows an example for `crbegin()`.,crbegin}
+
+    @sa @ref rbegin() -- returns a reverse iterator to the beginning
+    @sa @ref rend() -- returns a reverse iterator to the end
+    @sa @ref crend() -- returns a const reverse iterator to the end
+
+    @since version 1.0.0
+    */
+    const_reverse_iterator crbegin() const noexcept
+    {
+        return const_reverse_iterator(cend());
+    }
+
+    /*!
+    @brief returns a const reverse iterator to one before the first
+
+    Returns a const reverse iterator to the reverse-end; that is, one before
+    the first element.
+
+    @image html range-rbegin-rend.svg "Illustration from cppreference.com"
+
+    @complexity Constant.
+
+    @requirement This function helps `basic_json` satisfying the
+    [ReversibleContainer](http://en.cppreference.com/w/cpp/concept/ReversibleContainer)
+    requirements:
+    - The complexity is constant.
+    - Has the semantics of `const_cast<const basic_json&>(*this).rend()`.
+
+    @liveexample{The following code shows an example for `crend()`.,crend}
+
+    @sa @ref rend() -- returns a reverse iterator to the end
+    @sa @ref rbegin() -- returns a reverse iterator to the beginning
+    @sa @ref crbegin() -- returns a const reverse iterator to the beginning
+
+    @since version 1.0.0
+    */
+    const_reverse_iterator crend() const noexcept
+    {
+        return const_reverse_iterator(cbegin());
+    }
+
+  private:
+    // forward declaration
+    template<typename IteratorType> class iteration_proxy;
+
+  public:
+    /*!
+    @brief wrapper to access iterator member functions in range-based for
+
+    This function allows to access @ref iterator::key() and @ref
+    iterator::value() during range-based for loops. In these loops, a
+    reference to the JSON values is returned, so there is no access to the
+    underlying iterator.
+
+    @note The name of this function is not yet final and may change in the
+    future.
+    */
+    static iteration_proxy<iterator> iterator_wrapper(reference cont)
+    {
+        return iteration_proxy<iterator>(cont);
+    }
+
+    /*!
+    @copydoc iterator_wrapper(reference)
+    */
+    static iteration_proxy<const_iterator> iterator_wrapper(const_reference cont)
+    {
+        return iteration_proxy<const_iterator>(cont);
+    }
+
+    /// @}
+
+
+    //////////////
+    // capacity //
+    //////////////
+
+    /// @name capacity
+    /// @{
+
+    /*!
+    @brief checks whether the container is empty
+
+    Checks if a JSON value has no elements.
+
+    @return The return value depends on the different types and is
+            defined as follows:
+            Value type  | return value
+            ----------- | -------------
+            null        | `true`
+            boolean     | `false`
+            string      | `false`
+            number      | `false`
+            object      | result of function `object_t::empty()`
+            array       | result of function `array_t::empty()`
+
+    @note This function does not return whether a string stored as JSON value
+    is empty - it returns whether the JSON container itself is empty which is
+    false in the case of a string.
+
+    @complexity Constant, as long as @ref array_t and @ref object_t satisfy
+    the Container concept; that is, their `empty()` functions have constant
+    complexity.
+
+    @requirement This function helps `basic_json` satisfying the
+    [Container](http://en.cppreference.com/w/cpp/concept/Container)
+    requirements:
+    - The complexity is constant.
+    - Has the semantics of `begin() == end()`.
+
+    @liveexample{The following code uses `empty()` to check if a JSON
+    object contains any elements.,empty}
+
+    @sa @ref size() -- returns the number of elements
+
+    @since version 1.0.0
+    */
+    bool empty() const noexcept
+    {
+        switch (m_type)
+        {
+            case value_t::null:
+            {
+                // null values are empty
+                return true;
+            }
+
+            case value_t::array:
+            {
+                // delegate call to array_t::empty()
+                return m_value.array->empty();
+            }
+
+            case value_t::object:
+            {
+                // delegate call to object_t::empty()
+                return m_value.object->empty();
+            }
+
+            default:
+            {
+                // all other types are nonempty
+                return false;
+            }
+        }
+    }
+
+    /*!
+    @brief returns the number of elements
+
+    Returns the number of elements in a JSON value.
+
+    @return The return value depends on the different types and is
+            defined as follows:
+            Value type  | return value
+            ----------- | -------------
+            null        | `0`
+            boolean     | `1`
+            string      | `1`
+            number      | `1`
+            object      | result of function object_t::size()
+            array       | result of function array_t::size()
+
+    @note This function does not return the length of a string stored as JSON
+    value - it returns the number of elements in the JSON value which is 1 in
+    the case of a string.
+
+    @complexity Constant, as long as @ref array_t and @ref object_t satisfy
+    the Container concept; that is, their size() functions have constant
+    complexity.
+
+    @requirement This function helps `basic_json` satisfying the
+    [Container](http://en.cppreference.com/w/cpp/concept/Container)
+    requirements:
+    - The complexity is constant.
+    - Has the semantics of `std::distance(begin(), end())`.
+
+    @liveexample{The following code calls `size()` on the different value
+    types.,size}
+
+    @sa @ref empty() -- checks whether the container is empty
+    @sa @ref max_size() -- returns the maximal number of elements
+
+    @since version 1.0.0
+    */
+    size_type size() const noexcept
+    {
+        switch (m_type)
+        {
+            case value_t::null:
+            {
+                // null values are empty
+                return 0;
+            }
+
+            case value_t::array:
+            {
+                // delegate call to array_t::size()
+                return m_value.array->size();
+            }
+
+            case value_t::object:
+            {
+                // delegate call to object_t::size()
+                return m_value.object->size();
+            }
+
+            default:
+            {
+                // all other types have size 1
+                return 1;
+            }
+        }
+    }
+
+    /*!
+    @brief returns the maximum possible number of elements
+
+    Returns the maximum number of elements a JSON value is able to hold due to
+    system or library implementation limitations, i.e. `std::distance(begin(),
+    end())` for the JSON value.
+
+    @return The return value depends on the different types and is
+            defined as follows:
+            Value type  | return value
+            ----------- | -------------
+            null        | `0` (same as `size()`)
+            boolean     | `1` (same as `size()`)
+            string      | `1` (same as `size()`)
+            number      | `1` (same as `size()`)
+            object      | result of function `object_t::max_size()`
+            array       | result of function `array_t::max_size()`
+
+    @complexity Constant, as long as @ref array_t and @ref object_t satisfy
+    the Container concept; that is, their `max_size()` functions have constant
+    complexity.
+
+    @requirement This function helps `basic_json` satisfying the
+    [Container](http://en.cppreference.com/w/cpp/concept/Container)
+    requirements:
+    - The complexity is constant.
+    - Has the semantics of returning `b.size()` where `b` is the largest
+      possible JSON value.
+
+    @liveexample{The following code calls `max_size()` on the different value
+    types. Note the output is implementation specific.,max_size}
+
+    @sa @ref size() -- returns the number of elements
+
+    @since version 1.0.0
+    */
+    size_type max_size() const noexcept
+    {
+        switch (m_type)
+        {
+            case value_t::array:
+            {
+                // delegate call to array_t::max_size()
+                return m_value.array->max_size();
+            }
+
+            case value_t::object:
+            {
+                // delegate call to object_t::max_size()
+                return m_value.object->max_size();
+            }
+
+            default:
+            {
+                // all other types have max_size() == size()
+                return size();
+            }
+        }
+    }
+
+    /// @}
+
+
+    ///////////////
+    // modifiers //
+    ///////////////
+
+    /// @name modifiers
+    /// @{
+
+    /*!
+    @brief clears the contents
+
+    Clears the content of a JSON value and resets it to the default value as
+    if @ref basic_json(value_t) would have been called:
+
+    Value type  | initial value
+    ----------- | -------------
+    null        | `null`
+    boolean     | `false`
+    string      | `""`
+    number      | `0`
+    object      | `{}`
+    array       | `[]`
+
+    @complexity Linear in the size of the JSON value.
+
+    @liveexample{The example below shows the effect of `clear()` to different
+    JSON types.,clear}
+
+    @since version 1.0.0
+    */
+    void clear() noexcept
+    {
+        switch (m_type)
+        {
+            case value_t::number_integer:
+            {
+                m_value.number_integer = 0;
+                break;
+            }
+
+            case value_t::number_unsigned:
+            {
+                m_value.number_unsigned = 0;
+                break;
+            }
+
+            case value_t::number_float:
+            {
+                m_value.number_float = 0.0;
+                break;
+            }
+
+            case value_t::boolean:
+            {
+                m_value.boolean = false;
+                break;
+            }
+
+            case value_t::string:
+            {
+                m_value.string->clear();
+                break;
+            }
+
+            case value_t::array:
+            {
+                m_value.array->clear();
+                break;
+            }
+
+            case value_t::object:
+            {
+                m_value.object->clear();
+                break;
+            }
+
+            default:
+            {
+                break;
+            }
+        }
+    }
+
+    /*!
+    @brief add an object to an array
+
+    Appends the given element @a val to the end of the JSON value. If the
+    function is called on a JSON null value, an empty array is created before
+    appending @a val.
+
+    @param[in] val the value to add to the JSON array
+
+    @throw std::domain_error when called on a type other than JSON array or
+    null; example: `"cannot use push_back() with number"`
+
+    @complexity Amortized constant.
+
+    @liveexample{The example shows how `push_back()` and `+=` can be used to
+    add elements to a JSON array. Note how the `null` value was silently
+    converted to a JSON array.,push_back}
+
+    @since version 1.0.0
+    */
+    void push_back(basic_json&& val)
+    {
+        // push_back only works for null objects or arrays
+        if (not(is_null() or is_array()))
+        {
+            JSON_THROW(std::domain_error("cannot use push_back() with " + type_name()));
+        }
+
+        // transform null object into an array
+        if (is_null())
+        {
+            m_type = value_t::array;
+            m_value = value_t::array;
+            assert_invariant();
+        }
+
+        // add element to array (move semantics)
+        m_value.array->push_back(std::move(val));
+        // invalidate object
+        val.m_type = value_t::null;
+    }
+
+    /*!
+    @brief add an object to an array
+    @copydoc push_back(basic_json&&)
+    */
+    reference operator+=(basic_json&& val)
+    {
+        push_back(std::move(val));
+        return *this;
+    }
+
+    /*!
+    @brief add an object to an array
+    @copydoc push_back(basic_json&&)
+    */
+    void push_back(const basic_json& val)
+    {
+        // push_back only works for null objects or arrays
+        if (not(is_null() or is_array()))
+        {
+            JSON_THROW(std::domain_error("cannot use push_back() with " + type_name()));
+        }
+
+        // transform null object into an array
+        if (is_null())
+        {
+            m_type = value_t::array;
+            m_value = value_t::array;
+            assert_invariant();
+        }
+
+        // add element to array
+        m_value.array->push_back(val);
+    }
+
+    /*!
+    @brief add an object to an array
+    @copydoc push_back(basic_json&&)
+    */
+    reference operator+=(const basic_json& val)
+    {
+        push_back(val);
+        return *this;
+    }
+
+    /*!
+    @brief add an object to an object
+
+    Inserts the given element @a val to the JSON object. If the function is
+    called on a JSON null value, an empty object is created before inserting
+    @a val.
+
+    @param[in] val the value to add to the JSON object
+
+    @throw std::domain_error when called on a type other than JSON object or
+    null; example: `"cannot use push_back() with number"`
+
+    @complexity Logarithmic in the size of the container, O(log(`size()`)).
+
+    @liveexample{The example shows how `push_back()` and `+=` can be used to
+    add elements to a JSON object. Note how the `null` value was silently
+    converted to a JSON object.,push_back__object_t__value}
+
+    @since version 1.0.0
+    */
+    void push_back(const typename object_t::value_type& val)
+    {
+        // push_back only works for null objects or objects
+        if (not(is_null() or is_object()))
+        {
+            JSON_THROW(std::domain_error("cannot use push_back() with " + type_name()));
+        }
+
+        // transform null object into an object
+        if (is_null())
+        {
+            m_type = value_t::object;
+            m_value = value_t::object;
+            assert_invariant();
+        }
+
+        // add element to array
+        m_value.object->insert(val);
+    }
+
+    /*!
+    @brief add an object to an object
+    @copydoc push_back(const typename object_t::value_type&)
+    */
+    reference operator+=(const typename object_t::value_type& val)
+    {
+        push_back(val);
+        return *this;
+    }
+
+    /*!
+    @brief add an object to an object
+
+    This function allows to use `push_back` with an initializer list. In case
+
+    1. the current value is an object,
+    2. the initializer list @a init contains only two elements, and
+    3. the first element of @a init is a string,
+
+    @a init is converted into an object element and added using
+    @ref push_back(const typename object_t::value_type&). Otherwise, @a init
+    is converted to a JSON value and added using @ref push_back(basic_json&&).
+
+    @param init  an initializer list
+
+    @complexity Linear in the size of the initializer list @a init.
+
+    @note This function is required to resolve an ambiguous overload error,
+          because pairs like `{"key", "value"}` can be both interpreted as
+          `object_t::value_type` or `std::initializer_list<basic_json>`, see
+          https://github.com/nlohmann/json/issues/235 for more information.
+
+    @liveexample{The example shows how initializer lists are treated as
+    objects when possible.,push_back__initializer_list}
+    */
+    void push_back(std::initializer_list<basic_json> init)
+    {
+        if (is_object() and init.size() == 2 and init.begin()->is_string())
+        {
+            const string_t key = *init.begin();
+            push_back(typename object_t::value_type(key, *(init.begin() + 1)));
+        }
+        else
+        {
+            push_back(basic_json(init));
+        }
+    }
+
+    /*!
+    @brief add an object to an object
+    @copydoc push_back(std::initializer_list<basic_json>)
+    */
+    reference operator+=(std::initializer_list<basic_json> init)
+    {
+        push_back(init);
+        return *this;
+    }
+
+    /*!
+    @brief add an object to an array
+
+    Creates a JSON value from the passed parameters @a args to the end of the
+    JSON value. If the function is called on a JSON null value, an empty array
+    is created before appending the value created from @a args.
+
+    @param[in] args arguments to forward to a constructor of @ref basic_json
+    @tparam Args compatible types to create a @ref basic_json object
+
+    @throw std::domain_error when called on a type other than JSON array or
+    null; example: `"cannot use emplace_back() with number"`
+
+    @complexity Amortized constant.
+
+    @liveexample{The example shows how `push_back()` can be used to add
+    elements to a JSON array. Note how the `null` value was silently converted
+    to a JSON array.,emplace_back}
+
+    @since version 2.0.8
+    */
+    template<class... Args>
+    void emplace_back(Args&& ... args)
+    {
+        // emplace_back only works for null objects or arrays
+        if (not(is_null() or is_array()))
+        {
+            JSON_THROW(std::domain_error("cannot use emplace_back() with " + type_name()));
+        }
+
+        // transform null object into an array
+        if (is_null())
+        {
+            m_type = value_t::array;
+            m_value = value_t::array;
+            assert_invariant();
+        }
+
+        // add element to array (perfect forwarding)
+        m_value.array->emplace_back(std::forward<Args>(args)...);
+    }
+
+    /*!
+    @brief add an object to an object if key does not exist
+
+    Inserts a new element into a JSON object constructed in-place with the
+    given @a args if there is no element with the key in the container. If the
+    function is called on a JSON null value, an empty object is created before
+    appending the value created from @a args.
+
+    @param[in] args arguments to forward to a constructor of @ref basic_json
+    @tparam Args compatible types to create a @ref basic_json object
+
+    @return a pair consisting of an iterator to the inserted element, or the
+            already-existing element if no insertion happened, and a bool
+            denoting whether the insertion took place.
+
+    @throw std::domain_error when called on a type other than JSON object or
+    null; example: `"cannot use emplace() with number"`
+
+    @complexity Logarithmic in the size of the container, O(log(`size()`)).
+
+    @liveexample{The example shows how `emplace()` can be used to add elements
+    to a JSON object. Note how the `null` value was silently converted to a
+    JSON object. Further note how no value is added if there was already one
+    value stored with the same key.,emplace}
+
+    @since version 2.0.8
+    */
+    template<class... Args>
+    std::pair<iterator, bool> emplace(Args&& ... args)
+    {
+        // emplace only works for null objects or arrays
+        if (not(is_null() or is_object()))
+        {
+            JSON_THROW(std::domain_error("cannot use emplace() with " + type_name()));
+        }
+
+        // transform null object into an object
+        if (is_null())
+        {
+            m_type = value_t::object;
+            m_value = value_t::object;
+            assert_invariant();
+        }
+
+        // add element to array (perfect forwarding)
+        auto res = m_value.object->emplace(std::forward<Args>(args)...);
+        // create result iterator and set iterator to the result of emplace
+        auto it = begin();
+        it.m_it.object_iterator = res.first;
+
+        // return pair of iterator and boolean
+        return {it, res.second};
+    }
+
+    /*!
+    @brief inserts element
+
+    Inserts element @a val before iterator @a pos.
+
+    @param[in] pos iterator before which the content will be inserted; may be
+    the end() iterator
+    @param[in] val element to insert
+    @return iterator pointing to the inserted @a val.
+
+    @throw std::domain_error if called on JSON values other than arrays;
+    example: `"cannot use insert() with string"`
+    @throw std::domain_error if @a pos is not an iterator of *this; example:
+    `"iterator does not fit current value"`
+
+    @complexity Constant plus linear in the distance between @a pos and end of
+    the container.
+
+    @liveexample{The example shows how `insert()` is used.,insert}
+
+    @since version 1.0.0
+    */
+    iterator insert(const_iterator pos, const basic_json& val)
+    {
+        // insert only works for arrays
+        if (is_array())
+        {
+            // check if iterator pos fits to this JSON value
+            if (pos.m_object != this)
+            {
+                JSON_THROW(std::domain_error("iterator does not fit current value"));
+            }
+
+            // insert to array and return iterator
+            iterator result(this);
+            result.m_it.array_iterator = m_value.array->insert(pos.m_it.array_iterator, val);
+            return result;
+        }
+
+        JSON_THROW(std::domain_error("cannot use insert() with " + type_name()));
+    }
+
+    /*!
+    @brief inserts element
+    @copydoc insert(const_iterator, const basic_json&)
+    */
+    iterator insert(const_iterator pos, basic_json&& val)
+    {
+        return insert(pos, val);
+    }
+
+    /*!
+    @brief inserts elements
+
+    Inserts @a cnt copies of @a val before iterator @a pos.
+
+    @param[in] pos iterator before which the content will be inserted; may be
+    the end() iterator
+    @param[in] cnt number of copies of @a val to insert
+    @param[in] val element to insert
+    @return iterator pointing to the first element inserted, or @a pos if
+    `cnt==0`
+
+    @throw std::domain_error if called on JSON values other than arrays;
+    example: `"cannot use insert() with string"`
+    @throw std::domain_error if @a pos is not an iterator of *this; example:
+    `"iterator does not fit current value"`
+
+    @complexity Linear in @a cnt plus linear in the distance between @a pos
+    and end of the container.
+
+    @liveexample{The example shows how `insert()` is used.,insert__count}
+
+    @since version 1.0.0
+    */
+    iterator insert(const_iterator pos, size_type cnt, const basic_json& val)
+    {
+        // insert only works for arrays
+        if (is_array())
+        {
+            // check if iterator pos fits to this JSON value
+            if (pos.m_object != this)
+            {
+                JSON_THROW(std::domain_error("iterator does not fit current value"));
+            }
+
+            // insert to array and return iterator
+            iterator result(this);
+            result.m_it.array_iterator = m_value.array->insert(pos.m_it.array_iterator, cnt, val);
+            return result;
+        }
+
+        JSON_THROW(std::domain_error("cannot use insert() with " + type_name()));
+    }
+
+    /*!
+    @brief inserts elements
+
+    Inserts elements from range `[first, last)` before iterator @a pos.
+
+    @param[in] pos iterator before which the content will be inserted; may be
+    the end() iterator
+    @param[in] first begin of the range of elements to insert
+    @param[in] last end of the range of elements to insert
+
+    @throw std::domain_error if called on JSON values other than arrays;
+    example: `"cannot use insert() with string"`
+    @throw std::domain_error if @a pos is not an iterator of *this; example:
+    `"iterator does not fit current value"`
+    @throw std::domain_error if @a first and @a last do not belong to the same
+    JSON value; example: `"iterators do not fit"`
+    @throw std::domain_error if @a first or @a last are iterators into
+    container for which insert is called; example: `"passed iterators may not
+    belong to container"`
+
+    @return iterator pointing to the first element inserted, or @a pos if
+    `first==last`
+
+    @complexity Linear in `std::distance(first, last)` plus linear in the
+    distance between @a pos and end of the container.
+
+    @liveexample{The example shows how `insert()` is used.,insert__range}
+
+    @since version 1.0.0
+    */
+    iterator insert(const_iterator pos, const_iterator first, const_iterator last)
+    {
+        // insert only works for arrays
+        if (not is_array())
+        {
+            JSON_THROW(std::domain_error("cannot use insert() with " + type_name()));
+        }
+
+        // check if iterator pos fits to this JSON value
+        if (pos.m_object != this)
+        {
+            JSON_THROW(std::domain_error("iterator does not fit current value"));
+        }
+
+        // check if range iterators belong to the same JSON object
+        if (first.m_object != last.m_object)
+        {
+            JSON_THROW(std::domain_error("iterators do not fit"));
+        }
+
+        if (first.m_object == this or last.m_object == this)
+        {
+            JSON_THROW(std::domain_error("passed iterators may not belong to container"));
+        }
+
+        // insert to array and return iterator
+        iterator result(this);
+        result.m_it.array_iterator = m_value.array->insert(
+                                         pos.m_it.array_iterator,
+                                         first.m_it.array_iterator,
+                                         last.m_it.array_iterator);
+        return result;
+    }
+
+    /*!
+    @brief inserts elements
+
+    Inserts elements from initializer list @a ilist before iterator @a pos.
+
+    @param[in] pos iterator before which the content will be inserted; may be
+    the end() iterator
+    @param[in] ilist initializer list to insert the values from
+
+    @throw std::domain_error if called on JSON values other than arrays;
+    example: `"cannot use insert() with string"`
+    @throw std::domain_error if @a pos is not an iterator of *this; example:
+    `"iterator does not fit current value"`
+
+    @return iterator pointing to the first element inserted, or @a pos if
+    `ilist` is empty
+
+    @complexity Linear in `ilist.size()` plus linear in the distance between
+    @a pos and end of the container.
+
+    @liveexample{The example shows how `insert()` is used.,insert__ilist}
+
+    @since version 1.0.0
+    */
+    iterator insert(const_iterator pos, std::initializer_list<basic_json> ilist)
+    {
+        // insert only works for arrays
+        if (not is_array())
+        {
+            JSON_THROW(std::domain_error("cannot use insert() with " + type_name()));
+        }
+
+        // check if iterator pos fits to this JSON value
+        if (pos.m_object != this)
+        {
+            JSON_THROW(std::domain_error("iterator does not fit current value"));
+        }
+
+        // insert to array and return iterator
+        iterator result(this);
+        result.m_it.array_iterator = m_value.array->insert(pos.m_it.array_iterator, ilist);
+        return result;
+    }
+
+    /*!
+    @brief exchanges the values
+
+    Exchanges the contents of the JSON value with those of @a other. Does not
+    invoke any move, copy, or swap operations on individual elements. All
+    iterators and references remain valid. The past-the-end iterator is
+    invalidated.
+
+    @param[in,out] other JSON value to exchange the contents with
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how JSON values can be swapped with
+    `swap()`.,swap__reference}
+
+    @since version 1.0.0
+    */
+    void swap(reference other) noexcept (
+        std::is_nothrow_move_constructible<value_t>::value and
+        std::is_nothrow_move_assignable<value_t>::value and
+        std::is_nothrow_move_constructible<json_value>::value and
+        std::is_nothrow_move_assignable<json_value>::value
+    )
+    {
+        std::swap(m_type, other.m_type);
+        std::swap(m_value, other.m_value);
+        assert_invariant();
+    }
+
+    /*!
+    @brief exchanges the values
+
+    Exchanges the contents of a JSON array with those of @a other. Does not
+    invoke any move, copy, or swap operations on individual elements. All
+    iterators and references remain valid. The past-the-end iterator is
+    invalidated.
+
+    @param[in,out] other array to exchange the contents with
+
+    @throw std::domain_error when JSON value is not an array; example:
+    `"cannot use swap() with string"`
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how arrays can be swapped with
+    `swap()`.,swap__array_t}
+
+    @since version 1.0.0
+    */
+    void swap(array_t& other)
+    {
+        // swap only works for arrays
+        if (is_array())
+        {
+            std::swap(*(m_value.array), other);
+        }
+        else
+        {
+            JSON_THROW(std::domain_error("cannot use swap() with " + type_name()));
+        }
+    }
+
+    /*!
+    @brief exchanges the values
+
+    Exchanges the contents of a JSON object with those of @a other. Does not
+    invoke any move, copy, or swap operations on individual elements. All
+    iterators and references remain valid. The past-the-end iterator is
+    invalidated.
+
+    @param[in,out] other object to exchange the contents with
+
+    @throw std::domain_error when JSON value is not an object; example:
+    `"cannot use swap() with string"`
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how objects can be swapped with
+    `swap()`.,swap__object_t}
+
+    @since version 1.0.0
+    */
+    void swap(object_t& other)
+    {
+        // swap only works for objects
+        if (is_object())
+        {
+            std::swap(*(m_value.object), other);
+        }
+        else
+        {
+            JSON_THROW(std::domain_error("cannot use swap() with " + type_name()));
+        }
+    }
+
+    /*!
+    @brief exchanges the values
+
+    Exchanges the contents of a JSON string with those of @a other. Does not
+    invoke any move, copy, or swap operations on individual elements. All
+    iterators and references remain valid. The past-the-end iterator is
+    invalidated.
+
+    @param[in,out] other string to exchange the contents with
+
+    @throw std::domain_error when JSON value is not a string; example: `"cannot
+    use swap() with boolean"`
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how strings can be swapped with
+    `swap()`.,swap__string_t}
+
+    @since version 1.0.0
+    */
+    void swap(string_t& other)
+    {
+        // swap only works for strings
+        if (is_string())
+        {
+            std::swap(*(m_value.string), other);
+        }
+        else
+        {
+            JSON_THROW(std::domain_error("cannot use swap() with " + type_name()));
+        }
+    }
+
+    /// @}
+
+  public:
+    //////////////////////////////////////////
+    // lexicographical comparison operators //
+    //////////////////////////////////////////
+
+    /// @name lexicographical comparison operators
+    /// @{
+
+    /*!
+    @brief comparison: equal
+
+    Compares two JSON values for equality according to the following rules:
+    - Two JSON values are equal if (1) they are from the same type and (2)
+      their stored values are the same.
+    - Integer and floating-point numbers are automatically converted before
+      comparison. Floating-point numbers are compared indirectly: two
+      floating-point numbers `f1` and `f2` are considered equal if neither
+      `f1 > f2` nor `f2 > f1` holds.
+    - Two JSON null values are equal.
+
+    @param[in] lhs  first JSON value to consider
+    @param[in] rhs  second JSON value to consider
+    @return whether the values @a lhs and @a rhs are equal
+
+    @complexity Linear.
+
+    @liveexample{The example demonstrates comparing several JSON
+    types.,operator__equal}
+
+    @since version 1.0.0
+    */
+    friend bool operator==(const_reference lhs, const_reference rhs) noexcept
+    {
+        const auto lhs_type = lhs.type();
+        const auto rhs_type = rhs.type();
+
+        if (lhs_type == rhs_type)
+        {
+            switch (lhs_type)
+            {
+                case value_t::array:
+                {
+                    return *lhs.m_value.array == *rhs.m_value.array;
+                }
+                case value_t::object:
+                {
+                    return *lhs.m_value.object == *rhs.m_value.object;
+                }
+                case value_t::null:
+                {
+                    return true;
+                }
+                case value_t::string:
+                {
+                    return *lhs.m_value.string == *rhs.m_value.string;
+                }
+                case value_t::boolean:
+                {
+                    return lhs.m_value.boolean == rhs.m_value.boolean;
+                }
+                case value_t::number_integer:
+                {
+                    return lhs.m_value.number_integer == rhs.m_value.number_integer;
+                }
+                case value_t::number_unsigned:
+                {
+                    return lhs.m_value.number_unsigned == rhs.m_value.number_unsigned;
+                }
+                case value_t::number_float:
+                {
+                    return lhs.m_value.number_float == rhs.m_value.number_float;
+                }
+                default:
+                {
+                    return false;
+                }
+            }
+        }
+        else if (lhs_type == value_t::number_integer and rhs_type == value_t::number_float)
+        {
+            return static_cast<number_float_t>(lhs.m_value.number_integer) == rhs.m_value.number_float;
+        }
+        else if (lhs_type == value_t::number_float and rhs_type == value_t::number_integer)
+        {
+            return lhs.m_value.number_float == static_cast<number_float_t>(rhs.m_value.number_integer);
+        }
+        else if (lhs_type == value_t::number_unsigned and rhs_type == value_t::number_float)
+        {
+            return static_cast<number_float_t>(lhs.m_value.number_unsigned) == rhs.m_value.number_float;
+        }
+        else if (lhs_type == value_t::number_float and rhs_type == value_t::number_unsigned)
+        {
+            return lhs.m_value.number_float == static_cast<number_float_t>(rhs.m_value.number_unsigned);
+        }
+        else if (lhs_type == value_t::number_unsigned and rhs_type == value_t::number_integer)
+        {
+            return static_cast<number_integer_t>(lhs.m_value.number_unsigned) == rhs.m_value.number_integer;
+        }
+        else if (lhs_type == value_t::number_integer and rhs_type == value_t::number_unsigned)
+        {
+            return lhs.m_value.number_integer == static_cast<number_integer_t>(rhs.m_value.number_unsigned);
+        }
+
+        return false;
+    }
+
+    /*!
+    @brief comparison: equal
+    @copydoc operator==(const_reference, const_reference)
+    */
+    template<typename ScalarType, typename std::enable_if<
+                 std::is_scalar<ScalarType>::value, int>::type = 0>
+    friend bool operator==(const_reference lhs, const ScalarType rhs) noexcept
+    {
+        return (lhs == basic_json(rhs));
+    }
+
+    /*!
+    @brief comparison: equal
+    @copydoc operator==(const_reference, const_reference)
+    */
+    template<typename ScalarType, typename std::enable_if<
+                 std::is_scalar<ScalarType>::value, int>::type = 0>
+    friend bool operator==(const ScalarType lhs, const_reference rhs) noexcept
+    {
+        return (basic_json(lhs) == rhs);
+    }
+
+    /*!
+    @brief comparison: not equal
+
+    Compares two JSON values for inequality by calculating `not (lhs == rhs)`.
+
+    @param[in] lhs  first JSON value to consider
+    @param[in] rhs  second JSON value to consider
+    @return whether the values @a lhs and @a rhs are not equal
+
+    @complexity Linear.
+
+    @liveexample{The example demonstrates comparing several JSON
+    types.,operator__notequal}
+
+    @since version 1.0.0
+    */
+    friend bool operator!=(const_reference lhs, const_reference rhs) noexcept
+    {
+        return not (lhs == rhs);
+    }
+
+    /*!
+    @brief comparison: not equal
+    @copydoc operator!=(const_reference, const_reference)
+    */
+    template<typename ScalarType, typename std::enable_if<
+                 std::is_scalar<ScalarType>::value, int>::type = 0>
+    friend bool operator!=(const_reference lhs, const ScalarType rhs) noexcept
+    {
+        return (lhs != basic_json(rhs));
+    }
+
+    /*!
+    @brief comparison: not equal
+    @copydoc operator!=(const_reference, const_reference)
+    */
+    template<typename ScalarType, typename std::enable_if<
+                 std::is_scalar<ScalarType>::value, int>::type = 0>
+    friend bool operator!=(const ScalarType lhs, const_reference rhs) noexcept
+    {
+        return (basic_json(lhs) != rhs);
+    }
+
+    /*!
+    @brief comparison: less than
+
+    Compares whether one JSON value @a lhs is less than another JSON value @a
+    rhs according to the following rules:
+    - If @a lhs and @a rhs have the same type, the values are compared using
+      the default `<` operator.
+    - Integer and floating-point numbers are automatically converted before
+      comparison
+    - In case @a lhs and @a rhs have different types, the values are ignored
+      and the order of the types is considered, see
+      @ref operator<(const value_t, const value_t).
+
+    @param[in] lhs  first JSON value to consider
+    @param[in] rhs  second JSON value to consider
+    @return whether @a lhs is less than @a rhs
+
+    @complexity Linear.
+
+    @liveexample{The example demonstrates comparing several JSON
+    types.,operator__less}
+
+    @since version 1.0.0
+    */
+    friend bool operator<(const_reference lhs, const_reference rhs) noexcept
+    {
+        const auto lhs_type = lhs.type();
+        const auto rhs_type = rhs.type();
+
+        if (lhs_type == rhs_type)
+        {
+            switch (lhs_type)
+            {
+                case value_t::array:
+                {
+                    return *lhs.m_value.array < *rhs.m_value.array;
+                }
+                case value_t::object:
+                {
+                    return *lhs.m_value.object < *rhs.m_value.object;
+                }
+                case value_t::null:
+                {
+                    return false;
+                }
+                case value_t::string:
+                {
+                    return *lhs.m_value.string < *rhs.m_value.string;
+                }
+                case value_t::boolean:
+                {
+                    return lhs.m_value.boolean < rhs.m_value.boolean;
+                }
+                case value_t::number_integer:
+                {
+                    return lhs.m_value.number_integer < rhs.m_value.number_integer;
+                }
+                case value_t::number_unsigned:
+                {
+                    return lhs.m_value.number_unsigned < rhs.m_value.number_unsigned;
+                }
+                case value_t::number_float:
+                {
+                    return lhs.m_value.number_float < rhs.m_value.number_float;
+                }
+                default:
+                {
+                    return false;
+                }
+            }
+        }
+        else if (lhs_type == value_t::number_integer and rhs_type == value_t::number_float)
+        {
+            return static_cast<number_float_t>(lhs.m_value.number_integer) < rhs.m_value.number_float;
+        }
+        else if (lhs_type == value_t::number_float and rhs_type == value_t::number_integer)
+        {
+            return lhs.m_value.number_float < static_cast<number_float_t>(rhs.m_value.number_integer);
+        }
+        else if (lhs_type == value_t::number_unsigned and rhs_type == value_t::number_float)
+        {
+            return static_cast<number_float_t>(lhs.m_value.number_unsigned) < rhs.m_value.number_float;
+        }
+        else if (lhs_type == value_t::number_float and rhs_type == value_t::number_unsigned)
+        {
+            return lhs.m_value.number_float < static_cast<number_float_t>(rhs.m_value.number_unsigned);
+        }
+        else if (lhs_type == value_t::number_integer and rhs_type == value_t::number_unsigned)
+        {
+            return lhs.m_value.number_integer < static_cast<number_integer_t>(rhs.m_value.number_unsigned);
+        }
+        else if (lhs_type == value_t::number_unsigned and rhs_type == value_t::number_integer)
+        {
+            return static_cast<number_integer_t>(lhs.m_value.number_unsigned) < rhs.m_value.number_integer;
+        }
+
+        // We only reach this line if we cannot compare values. In that case,
+        // we compare types. Note we have to call the operator explicitly,
+        // because MSVC has problems otherwise.
+        return operator<(lhs_type, rhs_type);
+    }
+
+    /*!
+    @brief comparison: less than or equal
+
+    Compares whether one JSON value @a lhs is less than or equal to another
+    JSON value by calculating `not (rhs < lhs)`.
+
+    @param[in] lhs  first JSON value to consider
+    @param[in] rhs  second JSON value to consider
+    @return whether @a lhs is less than or equal to @a rhs
+
+    @complexity Linear.
+
+    @liveexample{The example demonstrates comparing several JSON
+    types.,operator__greater}
+
+    @since version 1.0.0
+    */
+    friend bool operator<=(const_reference lhs, const_reference rhs) noexcept
+    {
+        return not (rhs < lhs);
+    }
+
+    /*!
+    @brief comparison: greater than
+
+    Compares whether one JSON value @a lhs is greater than another
+    JSON value by calculating `not (lhs <= rhs)`.
+
+    @param[in] lhs  first JSON value to consider
+    @param[in] rhs  second JSON value to consider
+    @return whether @a lhs is greater than to @a rhs
+
+    @complexity Linear.
+
+    @liveexample{The example demonstrates comparing several JSON
+    types.,operator__lessequal}
+
+    @since version 1.0.0
+    */
+    friend bool operator>(const_reference lhs, const_reference rhs) noexcept
+    {
+        return not (lhs <= rhs);
+    }
+
+    /*!
+    @brief comparison: greater than or equal
+
+    Compares whether one JSON value @a lhs is greater than or equal to another
+    JSON value by calculating `not (lhs < rhs)`.
+
+    @param[in] lhs  first JSON value to consider
+    @param[in] rhs  second JSON value to consider
+    @return whether @a lhs is greater than or equal to @a rhs
+
+    @complexity Linear.
+
+    @liveexample{The example demonstrates comparing several JSON
+    types.,operator__greaterequal}
+
+    @since version 1.0.0
+    */
+    friend bool operator>=(const_reference lhs, const_reference rhs) noexcept
+    {
+        return not (lhs < rhs);
+    }
+
+    /// @}
+
+
+    ///////////////////
+    // serialization //
+    ///////////////////
+
+    /// @name serialization
+    /// @{
+
+    /*!
+    @brief serialize to stream
+
+    Serialize the given JSON value @a j to the output stream @a o. The JSON
+    value will be serialized using the @ref dump member function. The
+    indentation of the output can be controlled with the member variable
+    `width` of the output stream @a o. For instance, using the manipulator
+    `std::setw(4)` on @a o sets the indentation level to `4` and the
+    serialization result is the same as calling `dump(4)`.
+
+    @param[in,out] o  stream to serialize to
+    @param[in] j  JSON value to serialize
+
+    @return the stream @a o
+
+    @complexity Linear.
+
+    @liveexample{The example below shows the serialization with different
+    parameters to `width` to adjust the indentation level.,operator_serialize}
+
+    @since version 1.0.0
+    */
+    friend std::ostream& operator<<(std::ostream& o, const basic_json& j)
+    {
+        // read width member and use it as indentation parameter if nonzero
+        const bool pretty_print = (o.width() > 0);
+        const auto indentation = (pretty_print ? o.width() : 0);
+
+        // reset width to 0 for subsequent calls to this stream
+        o.width(0);
+
+        // do the actual serialization
+        j.dump(o, pretty_print, static_cast<unsigned int>(indentation));
+
+        return o;
+    }
+
+    /*!
+    @brief serialize to stream
+    @copydoc operator<<(std::ostream&, const basic_json&)
+    */
+    friend std::ostream& operator>>(const basic_json& j, std::ostream& o)
+    {
+        return o << j;
+    }
+
+    /// @}
+
+
+    /////////////////////
+    // deserialization //
+    /////////////////////
+
+    /// @name deserialization
+    /// @{
+
+    /*!
+    @brief deserialize from an array
+
+    This function reads from an array of 1-byte values.
+
+    @pre Each element of the container has a size of 1 byte. Violating this
+    precondition yields undefined behavior. **This precondition is enforced
+    with a static assertion.**
+
+    @param[in] array  array to read from
+    @param[in] cb  a parser callback function of type @ref parser_callback_t
+    which is used to control the deserialization by filtering unwanted values
+    (optional)
+
+    @return result of the deserialization
+
+    @complexity Linear in the length of the input. The parser is a predictive
+    LL(1) parser. The complexity can be higher if the parser callback function
+    @a cb has a super-linear complexity.
+
+    @note A UTF-8 byte order mark is silently ignored.
+
+    @liveexample{The example below demonstrates the `parse()` function reading
+    from an array.,parse__array__parser_callback_t}
+
+    @since version 2.0.3
+    */
+    template<class T, std::size_t N>
+    static basic_json parse(T (&array)[N],
+                            const parser_callback_t cb = nullptr)
+    {
+        // delegate the call to the iterator-range parse overload
+        return parse(std::begin(array), std::end(array), cb);
+    }
+
+    /*!
+    @brief deserialize from string literal
+
+    @tparam CharT character/literal type with size of 1 byte
+    @param[in] s  string literal to read a serialized JSON value from
+    @param[in] cb a parser callback function of type @ref parser_callback_t
+    which is used to control the deserialization by filtering unwanted values
+    (optional)
+
+    @return result of the deserialization
+
+    @complexity Linear in the length of the input. The parser is a predictive
+    LL(1) parser. The complexity can be higher if the parser callback function
+    @a cb has a super-linear complexity.
+
+    @note A UTF-8 byte order mark is silently ignored.
+    @note String containers like `std::string` or @ref string_t can be parsed
+          with @ref parse(const ContiguousContainer&, const parser_callback_t)
+
+    @liveexample{The example below demonstrates the `parse()` function with
+    and without callback function.,parse__string__parser_callback_t}
+
+    @sa @ref parse(std::istream&, const parser_callback_t) for a version that
+    reads from an input stream
+
+    @since version 1.0.0 (originally for @ref string_t)
+    */
+    template<typename CharT, typename std::enable_if<
+                 std::is_pointer<CharT>::value and
+                 std::is_integral<typename std::remove_pointer<CharT>::type>::value and
+                 sizeof(typename std::remove_pointer<CharT>::type) == 1, int>::type = 0>
+    static basic_json parse(const CharT s,
+                            const parser_callback_t cb = nullptr)
+    {
+        return parser(reinterpret_cast<const char*>(s), cb).parse();
+    }
+
+    /*!
+    @brief deserialize from stream
+
+    @param[in,out] i  stream to read a serialized JSON value from
+    @param[in] cb a parser callback function of type @ref parser_callback_t
+    which is used to control the deserialization by filtering unwanted values
+    (optional)
+
+    @return result of the deserialization
+
+    @complexity Linear in the length of the input. The parser is a predictive
+    LL(1) parser. The complexity can be higher if the parser callback function
+    @a cb has a super-linear complexity.
+
+    @note A UTF-8 byte order mark is silently ignored.
+
+    @liveexample{The example below demonstrates the `parse()` function with
+    and without callback function.,parse__istream__parser_callback_t}
+
+    @sa @ref parse(const CharT, const parser_callback_t) for a version
+    that reads from a string
+
+    @since version 1.0.0
+    */
+    static basic_json parse(std::istream& i,
+                            const parser_callback_t cb = nullptr)
+    {
+        return parser(i, cb).parse();
+    }
+
+    /*!
+    @copydoc parse(std::istream&, const parser_callback_t)
+    */
+    static basic_json parse(std::istream&& i,
+                            const parser_callback_t cb = nullptr)
+    {
+        return parser(i, cb).parse();
+    }
+
+    /*!
+    @brief deserialize from an iterator range with contiguous storage
+
+    This function reads from an iterator range of a container with contiguous
+    storage of 1-byte values. Compatible container types include
+    `std::vector`, `std::string`, `std::array`, `std::valarray`, and
+    `std::initializer_list`. Furthermore, C-style arrays can be used with
+    `std::begin()`/`std::end()`. User-defined containers can be used as long
+    as they implement random-access iterators and a contiguous storage.
+
+    @pre The iterator range is contiguous. Violating this precondition yields
+    undefined behavior. **This precondition is enforced with an assertion.**
+    @pre Each element in the range has a size of 1 byte. Violating this
+    precondition yields undefined behavior. **This precondition is enforced
+    with a static assertion.**
+
+    @warning There is no way to enforce all preconditions at compile-time. If
+             the function is called with noncompliant iterators and with
+             assertions switched off, the behavior is undefined and will most
+             likely yield segmentation violation.
+
+    @tparam IteratorType iterator of container with contiguous storage
+    @param[in] first  begin of the range to parse (included)
+    @param[in] last  end of the range to parse (excluded)
+    @param[in] cb  a parser callback function of type @ref parser_callback_t
+    which is used to control the deserialization by filtering unwanted values
+    (optional)
+
+    @return result of the deserialization
+
+    @complexity Linear in the length of the input. The parser is a predictive
+    LL(1) parser. The complexity can be higher if the parser callback function
+    @a cb has a super-linear complexity.
+
+    @note A UTF-8 byte order mark is silently ignored.
+
+    @liveexample{The example below demonstrates the `parse()` function reading
+    from an iterator range.,parse__iteratortype__parser_callback_t}
+
+    @since version 2.0.3
+    */
+    template<class IteratorType, typename std::enable_if<
+                 std::is_base_of<
+                     std::random_access_iterator_tag,
+                     typename std::iterator_traits<IteratorType>::iterator_category>::value, int>::type = 0>
+    static basic_json parse(IteratorType first, IteratorType last,
+                            const parser_callback_t cb = nullptr)
+    {
+        // assertion to check that the iterator range is indeed contiguous,
+        // see http://stackoverflow.com/a/35008842/266378 for more discussion
+        assert(std::accumulate(first, last, std::pair<bool, int>(true, 0),
+                               [&first](std::pair<bool, int> res, decltype(*first) val)
+        {
+            res.first &= (val == *(std::next(std::addressof(*first), res.second++)));
+            return res;
+        }).first);
+
+        // assertion to check that each element is 1 byte long
+        static_assert(sizeof(typename std::iterator_traits<IteratorType>::value_type) == 1,
+                      "each element in the iterator range must have the size of 1 byte");
+
+        // if iterator range is empty, create a parser with an empty string
+        // to generate "unexpected EOF" error message
+        if (std::distance(first, last) <= 0)
+        {
+            return parser("").parse();
+        }
+
+        return parser(first, last, cb).parse();
+    }
+
+    /*!
+    @brief deserialize from a container with contiguous storage
+
+    This function reads from a container with contiguous storage of 1-byte
+    values. Compatible container types include `std::vector`, `std::string`,
+    `std::array`, and `std::initializer_list`. User-defined containers can be
+    used as long as they implement random-access iterators and a contiguous
+    storage.
+
+    @pre The container storage is contiguous. Violating this precondition
+    yields undefined behavior. **This precondition is enforced with an
+    assertion.**
+    @pre Each element of the container has a size of 1 byte. Violating this
+    precondition yields undefined behavior. **This precondition is enforced
+    with a static assertion.**
+
+    @warning There is no way to enforce all preconditions at compile-time. If
+             the function is called with a noncompliant container and with
+             assertions switched off, the behavior is undefined and will most
+             likely yield segmentation violation.
+
+    @tparam ContiguousContainer container type with contiguous storage
+    @param[in] c  container to read from
+    @param[in] cb  a parser callback function of type @ref parser_callback_t
+    which is used to control the deserialization by filtering unwanted values
+    (optional)
+
+    @return result of the deserialization
+
+    @complexity Linear in the length of the input. The parser is a predictive
+    LL(1) parser. The complexity can be higher if the parser callback function
+    @a cb has a super-linear complexity.
+
+    @note A UTF-8 byte order mark is silently ignored.
+
+    @liveexample{The example below demonstrates the `parse()` function reading
+    from a contiguous container.,parse__contiguouscontainer__parser_callback_t}
+
+    @since version 2.0.3
+    */
+    template<class ContiguousContainer, typename std::enable_if<
+                 not std::is_pointer<ContiguousContainer>::value and
+                 std::is_base_of<
+                     std::random_access_iterator_tag,
+                     typename std::iterator_traits<decltype(std::begin(std::declval<ContiguousContainer const>()))>::iterator_category>::value
+                 , int>::type = 0>
+    static basic_json parse(const ContiguousContainer& c,
+                            const parser_callback_t cb = nullptr)
+    {
+        // delegate the call to the iterator-range parse overload
+        return parse(std::begin(c), std::end(c), cb);
+    }
+
+    /*!
+    @brief deserialize from stream
+
+    Deserializes an input stream to a JSON value.
+
+    @param[in,out] i  input stream to read a serialized JSON value from
+    @param[in,out] j  JSON value to write the deserialized input to
+
+    @throw std::invalid_argument in case of parse errors
+
+    @complexity Linear in the length of the input. The parser is a predictive
+    LL(1) parser.
+
+    @note A UTF-8 byte order mark is silently ignored.
+
+    @liveexample{The example below shows how a JSON value is constructed by
+    reading a serialization from a stream.,operator_deserialize}
+
+    @sa parse(std::istream&, const parser_callback_t) for a variant with a
+    parser callback function to filter values while parsing
+
+    @since version 1.0.0
+    */
+    friend std::istream& operator<<(basic_json& j, std::istream& i)
+    {
+        j = parser(i).parse();
+        return i;
+    }
+
+    /*!
+    @brief deserialize from stream
+    @copydoc operator<<(basic_json&, std::istream&)
+    */
+    friend std::istream& operator>>(std::istream& i, basic_json& j)
+    {
+        j = parser(i).parse();
+        return i;
+    }
+
+    /// @}
+
+    //////////////////////////////////////////
+    // binary serialization/deserialization //
+    //////////////////////////////////////////
+
+    /// @name binary serialization/deserialization support
+    /// @{
+
+  private:
+    /*!
+    @note Some code in the switch cases has been copied, because otherwise
+          copilers would complain about implicit fallthrough and there is no
+          portable attribute to mute such warnings.
+    */
+    template<typename T>
+    static void add_to_vector(std::vector<uint8_t>& vec, size_t bytes, const T number)
+    {
+        assert(bytes == 1 or bytes == 2 or bytes == 4 or bytes == 8);
+
+        switch (bytes)
+        {
+            case 8:
+            {
+                vec.push_back(static_cast<uint8_t>((static_cast<uint64_t>(number) >> 070) & 0xff));
+                vec.push_back(static_cast<uint8_t>((static_cast<uint64_t>(number) >> 060) & 0xff));
+                vec.push_back(static_cast<uint8_t>((static_cast<uint64_t>(number) >> 050) & 0xff));
+                vec.push_back(static_cast<uint8_t>((static_cast<uint64_t>(number) >> 040) & 0xff));
+                vec.push_back(static_cast<uint8_t>((number >> 030) & 0xff));
+                vec.push_back(static_cast<uint8_t>((number >> 020) & 0xff));
+                vec.push_back(static_cast<uint8_t>((number >> 010) & 0xff));
+                vec.push_back(static_cast<uint8_t>(number & 0xff));
+                break;
+            }
+
+            case 4:
+            {
+                vec.push_back(static_cast<uint8_t>((number >> 030) & 0xff));
+                vec.push_back(static_cast<uint8_t>((number >> 020) & 0xff));
+                vec.push_back(static_cast<uint8_t>((number >> 010) & 0xff));
+                vec.push_back(static_cast<uint8_t>(number & 0xff));
+                break;
+            }
+
+            case 2:
+            {
+                vec.push_back(static_cast<uint8_t>((number >> 010) & 0xff));
+                vec.push_back(static_cast<uint8_t>(number & 0xff));
+                break;
+            }
+
+            case 1:
+            {
+                vec.push_back(static_cast<uint8_t>(number & 0xff));
+                break;
+            }
+        }
+    }
+
+    /*!
+    @brief take sufficient bytes from a vector to fill an integer variable
+
+    In the context of binary serialization formats, we need to read several
+    bytes from a byte vector and combine them to multi-byte integral data
+    types.
+
+    @param[in] vec  byte vector to read from
+    @param[in] current_index  the position in the vector after which to read
+
+    @return the next sizeof(T) bytes from @a vec, in reverse order as T
+
+    @tparam T the integral return type
+
+    @throw std::out_of_range if there are less than sizeof(T)+1 bytes in the
+           vector @a vec to read
+
+    In the for loop, the bytes from the vector are copied in reverse order into
+    the return value. In the figures below, let sizeof(T)=4 and `i` be the loop
+    variable.
+
+    Precondition:
+
+    vec:   |   |   | a | b | c | d |      T: |   |   |   |   |
+                 ^               ^             ^                ^
+           current_index         i            ptr        sizeof(T)
+
+    Postcondition:
+
+    vec:   |   |   | a | b | c | d |      T: | d | c | b | a |
+                 ^   ^                                     ^
+                 |   i                                    ptr
+           current_index
+
+    @sa Code adapted from <http://stackoverflow.com/a/41031865/266378>.
+    */
+    template<typename T>
+    static T get_from_vector(const std::vector<uint8_t>& vec, const size_t current_index)
+    {
+        if (current_index + sizeof(T) + 1 > vec.size())
+        {
+            JSON_THROW(std::out_of_range("cannot read " + std::to_string(sizeof(T)) + " bytes from vector"));
+        }
+
+        T result;
+        auto* ptr = reinterpret_cast<uint8_t*>(&result);
+        for (size_t i = 0; i < sizeof(T); ++i)
+        {
+            *ptr++ = vec[current_index + sizeof(T) - i];
+        }
+        return result;
+    }
+
+    /*!
+    @brief create a MessagePack serialization of a given JSON value
+
+    This is a straightforward implementation of the MessagePack specification.
+
+    @param[in] j  JSON value to serialize
+    @param[in,out] v  byte vector to write the serialization to
+
+    @sa https://github.com/msgpack/msgpack/blob/master/spec.md
+    */
+    static void to_msgpack_internal(const basic_json& j, std::vector<uint8_t>& v)
+    {
+        switch (j.type())
+        {
+            case value_t::null:
+            {
+                // nil
+                v.push_back(0xc0);
+                break;
+            }
+
+            case value_t::boolean:
+            {
+                // true and false
+                v.push_back(j.m_value.boolean ? 0xc3 : 0xc2);
+                break;
+            }
+
+            case value_t::number_integer:
+            {
+                if (j.m_value.number_integer >= 0)
+                {
+                    // MessagePack does not differentiate between positive
+                    // signed integers and unsigned integers. Therefore, we
+                    // used the code from the value_t::number_unsigned case
+                    // here.
+                    if (j.m_value.number_unsigned < 128)
+                    {
+                        // positive fixnum
+                        add_to_vector(v, 1, j.m_value.number_unsigned);
+                    }
+                    else if (j.m_value.number_unsigned <= std::numeric_limits<uint8_t>::max())
+                    {
+                        // uint 8
+                        v.push_back(0xcc);
+                        add_to_vector(v, 1, j.m_value.number_unsigned);
+                    }
+                    else if (j.m_value.number_unsigned <= std::numeric_limits<uint16_t>::max())
+                    {
+                        // uint 16
+                        v.push_back(0xcd);
+                        add_to_vector(v, 2, j.m_value.number_unsigned);
+                    }
+                    else if (j.m_value.number_unsigned <= std::numeric_limits<uint32_t>::max())
+                    {
+                        // uint 32
+                        v.push_back(0xce);
+                        add_to_vector(v, 4, j.m_value.number_unsigned);
+                    }
+                    else if (j.m_value.number_unsigned <= std::numeric_limits<uint64_t>::max())
+                    {
+                        // uint 64
+                        v.push_back(0xcf);
+                        add_to_vector(v, 8, j.m_value.number_unsigned);
+                    }
+                }
+                else
+                {
+                    if (j.m_value.number_integer >= -32)
+                    {
+                        // negative fixnum
+                        add_to_vector(v, 1, j.m_value.number_integer);
+                    }
+                    else if (j.m_value.number_integer >= std::numeric_limits<int8_t>::min() and j.m_value.number_integer <= std::numeric_limits<int8_t>::max())
+                    {
+                        // int 8
+                        v.push_back(0xd0);
+                        add_to_vector(v, 1, j.m_value.number_integer);
+                    }
+                    else if (j.m_value.number_integer >= std::numeric_limits<int16_t>::min() and j.m_value.number_integer <= std::numeric_limits<int16_t>::max())
+                    {
+                        // int 16
+                        v.push_back(0xd1);
+                        add_to_vector(v, 2, j.m_value.number_integer);
+                    }
+                    else if (j.m_value.number_integer >= std::numeric_limits<int32_t>::min() and j.m_value.number_integer <= std::numeric_limits<int32_t>::max())
+                    {
+                        // int 32
+                        v.push_back(0xd2);
+                        add_to_vector(v, 4, j.m_value.number_integer);
+                    }
+                    else if (j.m_value.number_integer >= std::numeric_limits<int64_t>::min() and j.m_value.number_integer <= std::numeric_limits<int64_t>::max())
+                    {
+                        // int 64
+                        v.push_back(0xd3);
+                        add_to_vector(v, 8, j.m_value.number_integer);
+                    }
+                }
+                break;
+            }
+
+            case value_t::number_unsigned:
+            {
+                if (j.m_value.number_unsigned < 128)
+                {
+                    // positive fixnum
+                    add_to_vector(v, 1, j.m_value.number_unsigned);
+                }
+                else if (j.m_value.number_unsigned <= std::numeric_limits<uint8_t>::max())
+                {
+                    // uint 8
+                    v.push_back(0xcc);
+                    add_to_vector(v, 1, j.m_value.number_unsigned);
+                }
+                else if (j.m_value.number_unsigned <= std::numeric_limits<uint16_t>::max())
+                {
+                    // uint 16
+                    v.push_back(0xcd);
+                    add_to_vector(v, 2, j.m_value.number_unsigned);
+                }
+                else if (j.m_value.number_unsigned <= std::numeric_limits<uint32_t>::max())
+                {
+                    // uint 32
+                    v.push_back(0xce);
+                    add_to_vector(v, 4, j.m_value.number_unsigned);
+                }
+                else if (j.m_value.number_unsigned <= std::numeric_limits<uint64_t>::max())
+                {
+                    // uint 64
+                    v.push_back(0xcf);
+                    add_to_vector(v, 8, j.m_value.number_unsigned);
+                }
+                break;
+            }
+
+            case value_t::number_float:
+            {
+                // float 64
+                v.push_back(0xcb);
+                const auto* helper = reinterpret_cast<const uint8_t*>(&(j.m_value.number_float));
+                for (size_t i = 0; i < 8; ++i)
+                {
+                    v.push_back(helper[7 - i]);
+                }
+                break;
+            }
+
+            case value_t::string:
+            {
+                const auto N = j.m_value.string->size();
+                if (N <= 31)
+                {
+                    // fixstr
+                    v.push_back(static_cast<uint8_t>(0xa0 | N));
+                }
+                else if (N <= 255)
+                {
+                    // str 8
+                    v.push_back(0xd9);
+                    add_to_vector(v, 1, N);
+                }
+                else if (N <= 65535)
+                {
+                    // str 16
+                    v.push_back(0xda);
+                    add_to_vector(v, 2, N);
+                }
+                else if (N <= 4294967295)
+                {
+                    // str 32
+                    v.push_back(0xdb);
+                    add_to_vector(v, 4, N);
+                }
+
+                // append string
+                std::copy(j.m_value.string->begin(), j.m_value.string->end(),
+                          std::back_inserter(v));
+                break;
+            }
+
+            case value_t::array:
+            {
+                const auto N = j.m_value.array->size();
+                if (N <= 15)
+                {
+                    // fixarray
+                    v.push_back(static_cast<uint8_t>(0x90 | N));
+                }
+                else if (N <= 0xffff)
+                {
+                    // array 16
+                    v.push_back(0xdc);
+                    add_to_vector(v, 2, N);
+                }
+                else if (N <= 0xffffffff)
+                {
+                    // array 32
+                    v.push_back(0xdd);
+                    add_to_vector(v, 4, N);
+                }
+
+                // append each element
+                for (const auto& el : *j.m_value.array)
+                {
+                    to_msgpack_internal(el, v);
+                }
+                break;
+            }
+
+            case value_t::object:
+            {
+                const auto N = j.m_value.object->size();
+                if (N <= 15)
+                {
+                    // fixmap
+                    v.push_back(static_cast<uint8_t>(0x80 | (N & 0xf)));
+                }
+                else if (N <= 65535)
+                {
+                    // map 16
+                    v.push_back(0xde);
+                    add_to_vector(v, 2, N);
+                }
+                else if (N <= 4294967295)
+                {
+                    // map 32
+                    v.push_back(0xdf);
+                    add_to_vector(v, 4, N);
+                }
+
+                // append each element
+                for (const auto& el : *j.m_value.object)
+                {
+                    to_msgpack_internal(el.first, v);
+                    to_msgpack_internal(el.second, v);
+                }
+                break;
+            }
+
+            default:
+            {
+                break;
+            }
+        }
+    }
+
+    /*!
+    @brief create a CBOR serialization of a given JSON value
+
+    This is a straightforward implementation of the CBOR specification.
+
+    @param[in] j  JSON value to serialize
+    @param[in,out] v  byte vector to write the serialization to
+
+    @sa https://tools.ietf.org/html/rfc7049
+    */
+    static void to_cbor_internal(const basic_json& j, std::vector<uint8_t>& v)
+    {
+        switch (j.type())
+        {
+            case value_t::null:
+            {
+                v.push_back(0xf6);
+                break;
+            }
+
+            case value_t::boolean:
+            {
+                v.push_back(j.m_value.boolean ? 0xf5 : 0xf4);
+                break;
+            }
+
+            case value_t::number_integer:
+            {
+                if (j.m_value.number_integer >= 0)
+                {
+                    // CBOR does not differentiate between positive signed
+                    // integers and unsigned integers. Therefore, we used the
+                    // code from the value_t::number_unsigned case here.
+                    if (j.m_value.number_integer <= 0x17)
+                    {
+                        add_to_vector(v, 1, j.m_value.number_integer);
+                    }
+                    else if (j.m_value.number_integer <= std::numeric_limits<uint8_t>::max())
+                    {
+                        v.push_back(0x18);
+                        // one-byte uint8_t
+                        add_to_vector(v, 1, j.m_value.number_integer);
+                    }
+                    else if (j.m_value.number_integer <= std::numeric_limits<uint16_t>::max())
+                    {
+                        v.push_back(0x19);
+                        // two-byte uint16_t
+                        add_to_vector(v, 2, j.m_value.number_integer);
+                    }
+                    else if (j.m_value.number_integer <= std::numeric_limits<uint32_t>::max())
+                    {
+                        v.push_back(0x1a);
+                        // four-byte uint32_t
+                        add_to_vector(v, 4, j.m_value.number_integer);
+                    }
+                    else
+                    {
+                        v.push_back(0x1b);
+                        // eight-byte uint64_t
+                        add_to_vector(v, 8, j.m_value.number_integer);
+                    }
+                }
+                else
+                {
+                    // The conversions below encode the sign in the first
+                    // byte, and the value is converted to a positive number.
+                    const auto positive_number = -1 - j.m_value.number_integer;
+                    if (j.m_value.number_integer >= -24)
+                    {
+                        v.push_back(static_cast<uint8_t>(0x20 + positive_number));
+                    }
+                    else if (positive_number <= std::numeric_limits<uint8_t>::max())
+                    {
+                        // int 8
+                        v.push_back(0x38);
+                        add_to_vector(v, 1, positive_number);
+                    }
+                    else if (positive_number <= std::numeric_limits<uint16_t>::max())
+                    {
+                        // int 16
+                        v.push_back(0x39);
+                        add_to_vector(v, 2, positive_number);
+                    }
+                    else if (positive_number <= std::numeric_limits<uint32_t>::max())
+                    {
+                        // int 32
+                        v.push_back(0x3a);
+                        add_to_vector(v, 4, positive_number);
+                    }
+                    else
+                    {
+                        // int 64
+                        v.push_back(0x3b);
+                        add_to_vector(v, 8, positive_number);
+                    }
+                }
+                break;
+            }
+
+            case value_t::number_unsigned:
+            {
+                if (j.m_value.number_unsigned <= 0x17)
+                {
+                    v.push_back(static_cast<uint8_t>(j.m_value.number_unsigned));
+                }
+                else if (j.m_value.number_unsigned <= 0xff)
+                {
+                    v.push_back(0x18);
+                    // one-byte uint8_t
+                    add_to_vector(v, 1, j.m_value.number_unsigned);
+                }
+                else if (j.m_value.number_unsigned <= 0xffff)
+                {
+                    v.push_back(0x19);
+                    // two-byte uint16_t
+                    add_to_vector(v, 2, j.m_value.number_unsigned);
+                }
+                else if (j.m_value.number_unsigned <= 0xffffffff)
+                {
+                    v.push_back(0x1a);
+                    // four-byte uint32_t
+                    add_to_vector(v, 4, j.m_value.number_unsigned);
+                }
+                else if (j.m_value.number_unsigned <= 0xffffffffffffffff)
+                {
+                    v.push_back(0x1b);
+                    // eight-byte uint64_t
+                    add_to_vector(v, 8, j.m_value.number_unsigned);
+                }
+                break;
+            }
+
+            case value_t::number_float:
+            {
+                // Double-Precision Float
+                v.push_back(0xfb);
+                const auto* helper = reinterpret_cast<const uint8_t*>(&(j.m_value.number_float));
+                for (size_t i = 0; i < 8; ++i)
+                {
+                    v.push_back(helper[7 - i]);
+                }
+                break;
+            }
+
+            case value_t::string:
+            {
+                const auto N = j.m_value.string->size();
+                if (N <= 0x17)
+                {
+                    v.push_back(0x60 + static_cast<uint8_t>(N));  // 1 byte for string + size
+                }
+                else if (N <= 0xff)
+                {
+                    v.push_back(0x78);  // one-byte uint8_t for N
+                    add_to_vector(v, 1, N);
+                }
+                else if (N <= 0xffff)
+                {
+                    v.push_back(0x79);  // two-byte uint16_t for N
+                    add_to_vector(v, 2, N);
+                }
+                else if (N <= 0xffffffff)
+                {
+                    v.push_back(0x7a); // four-byte uint32_t for N
+                    add_to_vector(v, 4, N);
+                }
+                // LCOV_EXCL_START
+                else if (N <= 0xffffffffffffffff)
+                {
+                    v.push_back(0x7b);  // eight-byte uint64_t for N
+                    add_to_vector(v, 8, N);
+                }
+                // LCOV_EXCL_STOP
+
+                // append string
+                std::copy(j.m_value.string->begin(), j.m_value.string->end(),
+                          std::back_inserter(v));
+                break;
+            }
+
+            case value_t::array:
+            {
+                const auto N = j.m_value.array->size();
+                if (N <= 0x17)
+                {
+                    v.push_back(0x80 + static_cast<uint8_t>(N));  // 1 byte for array + size
+                }
+                else if (N <= 0xff)
+                {
+                    v.push_back(0x98);  // one-byte uint8_t for N
+                    add_to_vector(v, 1, N);
+                }
+                else if (N <= 0xffff)
+                {
+                    v.push_back(0x99);  // two-byte uint16_t for N
+                    add_to_vector(v, 2, N);
+                }
+                else if (N <= 0xffffffff)
+                {
+                    v.push_back(0x9a);  // four-byte uint32_t for N
+                    add_to_vector(v, 4, N);
+                }
+                // LCOV_EXCL_START
+                else if (N <= 0xffffffffffffffff)
+                {
+                    v.push_back(0x9b);  // eight-byte uint64_t for N
+                    add_to_vector(v, 8, N);
+                }
+                // LCOV_EXCL_STOP
+
+                // append each element
+                for (const auto& el : *j.m_value.array)
+                {
+                    to_cbor_internal(el, v);
+                }
+                break;
+            }
+
+            case value_t::object:
+            {
+                const auto N = j.m_value.object->size();
+                if (N <= 0x17)
+                {
+                    v.push_back(0xa0 + static_cast<uint8_t>(N));  // 1 byte for object + size
+                }
+                else if (N <= 0xff)
+                {
+                    v.push_back(0xb8);
+                    add_to_vector(v, 1, N);  // one-byte uint8_t for N
+                }
+                else if (N <= 0xffff)
+                {
+                    v.push_back(0xb9);
+                    add_to_vector(v, 2, N);  // two-byte uint16_t for N
+                }
+                else if (N <= 0xffffffff)
+                {
+                    v.push_back(0xba);
+                    add_to_vector(v, 4, N);  // four-byte uint32_t for N
+                }
+                // LCOV_EXCL_START
+                else if (N <= 0xffffffffffffffff)
+                {
+                    v.push_back(0xbb);
+                    add_to_vector(v, 8, N);  // eight-byte uint64_t for N
+                }
+                // LCOV_EXCL_STOP
+
+                // append each element
+                for (const auto& el : *j.m_value.object)
+                {
+                    to_cbor_internal(el.first, v);
+                    to_cbor_internal(el.second, v);
+                }
+                break;
+            }
+
+            default:
+            {
+                break;
+            }
+        }
+    }
+
+
+    /*
+    @brief checks if given lengths do not exceed the size of a given vector
+
+    To secure the access to the byte vector during CBOR/MessagePack
+    deserialization, bytes are copied from the vector into buffers. This
+    function checks if the number of bytes to copy (@a len) does not exceed
+    the size @s size of the vector. Additionally, an @a offset is given from
+    where to start reading the bytes.
+
+    This function checks whether reading the bytes is safe; that is, offset is
+    a valid index in the vector, offset+len
+
+    @param[in] size    size of the byte vector
+    @param[in] len     number of bytes to read
+    @param[in] offset  offset where to start reading
+
+    vec:  x x x x x X X X X X
+          ^         ^         ^
+          0         offset    len
+
+    @throws out_of_range if `len > v.size()`
+    */
+    static void check_length(const size_t size, const size_t len, const size_t offset)
+    {
+        // simple case: requested length is greater than the vector's length
+        if (len > size or offset > size)
+        {
+            JSON_THROW(std::out_of_range("len out of range"));
+        }
+
+        // second case: adding offset would result in overflow
+        if ((size > (std::numeric_limits<size_t>::max() - offset)))
+        {
+            JSON_THROW(std::out_of_range("len+offset out of range"));
+        }
+
+        // last case: reading past the end of the vector
+        if (len + offset > size)
+        {
+            JSON_THROW(std::out_of_range("len+offset out of range"));
+        }
+    }
+
+    /*!
+    @brief create a JSON value from a given MessagePack vector
+
+    @param[in] v  MessagePack serialization
+    @param[in] idx  byte index to start reading from @a v
+
+    @return deserialized JSON value
+
+    @throw std::invalid_argument if unsupported features from MessagePack were
+    used in the given vector @a v or if the input is not valid MessagePack
+    @throw std::out_of_range if the given vector ends prematurely
+
+    @sa https://github.com/msgpack/msgpack/blob/master/spec.md
+    */
+    static basic_json from_msgpack_internal(const std::vector<uint8_t>& v, size_t& idx)
+    {
+        // make sure reading 1 byte is safe
+        check_length(v.size(), 1, idx);
+
+        // store and increment index
+        const size_t current_idx = idx++;
+
+        if (v[current_idx] <= 0xbf)
+        {
+            if (v[current_idx] <= 0x7f) // positive fixint
+            {
+                return v[current_idx];
+            }
+            if (v[current_idx] <= 0x8f) // fixmap
+            {
+                basic_json result = value_t::object;
+                const size_t len = v[current_idx] & 0x0f;
+                for (size_t i = 0; i < len; ++i)
+                {
+                    std::string key = from_msgpack_internal(v, idx);
+                    result[key] = from_msgpack_internal(v, idx);
+                }
+                return result;
+            }
+            else if (v[current_idx] <= 0x9f) // fixarray
+            {
+                basic_json result = value_t::array;
+                const size_t len = v[current_idx] & 0x0f;
+                for (size_t i = 0; i < len; ++i)
+                {
+                    result.push_back(from_msgpack_internal(v, idx));
+                }
+                return result;
+            }
+            else // fixstr
+            {
+                const size_t len = v[current_idx] & 0x1f;
+                const size_t offset = current_idx + 1;
+                idx += len; // skip content bytes
+                check_length(v.size(), len, offset);
+                return std::string(reinterpret_cast<const char*>(v.data()) + offset, len);
+            }
+        }
+        else if (v[current_idx] >= 0xe0) // negative fixint
+        {
+            return static_cast<int8_t>(v[current_idx]);
+        }
+        else
+        {
+            switch (v[current_idx])
+            {
+                case 0xc0: // nil
+                {
+                    return value_t::null;
+                }
+
+                case 0xc2: // false
+                {
+                    return false;
+                }
+
+                case 0xc3: // true
+                {
+                    return true;
+                }
+
+                case 0xca: // float 32
+                {
+                    // copy bytes in reverse order into the double variable
+                    float res;
+                    for (size_t byte = 0; byte < sizeof(float); ++byte)
+                    {
+                        reinterpret_cast<uint8_t*>(&res)[sizeof(float) - byte - 1] = v.at(current_idx + 1 + byte);
+                    }
+                    idx += sizeof(float); // skip content bytes
+                    return res;
+                }
+
+                case 0xcb: // float 64
+                {
+                    // copy bytes in reverse order into the double variable
+                    double res;
+                    for (size_t byte = 0; byte < sizeof(double); ++byte)
+                    {
+                        reinterpret_cast<uint8_t*>(&res)[sizeof(double) - byte - 1] = v.at(current_idx + 1 + byte);
+                    }
+                    idx += sizeof(double); // skip content bytes
+                    return res;
+                }
+
+                case 0xcc: // uint 8
+                {
+                    idx += 1; // skip content byte
+                    return get_from_vector<uint8_t>(v, current_idx);
+                }
+
+                case 0xcd: // uint 16
+                {
+                    idx += 2; // skip 2 content bytes
+                    return get_from_vector<uint16_t>(v, current_idx);
+                }
+
+                case 0xce: // uint 32
+                {
+                    idx += 4; // skip 4 content bytes
+                    return get_from_vector<uint32_t>(v, current_idx);
+                }
+
+                case 0xcf: // uint 64
+                {
+                    idx += 8; // skip 8 content bytes
+                    return get_from_vector<uint64_t>(v, current_idx);
+                }
+
+                case 0xd0: // int 8
+                {
+                    idx += 1; // skip content byte
+                    return get_from_vector<int8_t>(v, current_idx);
+                }
+
+                case 0xd1: // int 16
+                {
+                    idx += 2; // skip 2 content bytes
+                    return get_from_vector<int16_t>(v, current_idx);
+                }
+
+                case 0xd2: // int 32
+                {
+                    idx += 4; // skip 4 content bytes
+                    return get_from_vector<int32_t>(v, current_idx);
+                }
+
+                case 0xd3: // int 64
+                {
+                    idx += 8; // skip 8 content bytes
+                    return get_from_vector<int64_t>(v, current_idx);
+                }
+
+                case 0xd9: // str 8
+                {
+                    const auto len = static_cast<size_t>(get_from_vector<uint8_t>(v, current_idx));
+                    const size_t offset = current_idx + 2;
+                    idx += len + 1; // skip size byte + content bytes
+                    check_length(v.size(), len, offset);
+                    return std::string(reinterpret_cast<const char*>(v.data()) + offset, len);
+                }
+
+                case 0xda: // str 16
+                {
+                    const auto len = static_cast<size_t>(get_from_vector<uint16_t>(v, current_idx));
+                    const size_t offset = current_idx + 3;
+                    idx += len + 2; // skip 2 size bytes + content bytes
+                    check_length(v.size(), len, offset);
+                    return std::string(reinterpret_cast<const char*>(v.data()) + offset, len);
+                }
+
+                case 0xdb: // str 32
+                {
+                    const auto len = static_cast<size_t>(get_from_vector<uint32_t>(v, current_idx));
+                    const size_t offset = current_idx + 5;
+                    idx += len + 4; // skip 4 size bytes + content bytes
+                    check_length(v.size(), len, offset);
+                    return std::string(reinterpret_cast<const char*>(v.data()) + offset, len);
+                }
+
+                case 0xdc: // array 16
+                {
+                    basic_json result = value_t::array;
+                    const auto len = static_cast<size_t>(get_from_vector<uint16_t>(v, current_idx));
+                    idx += 2; // skip 2 size bytes
+                    for (size_t i = 0; i < len; ++i)
+                    {
+                        result.push_back(from_msgpack_internal(v, idx));
+                    }
+                    return result;
+                }
+
+                case 0xdd: // array 32
+                {
+                    basic_json result = value_t::array;
+                    const auto len = static_cast<size_t>(get_from_vector<uint32_t>(v, current_idx));
+                    idx += 4; // skip 4 size bytes
+                    for (size_t i = 0; i < len; ++i)
+                    {
+                        result.push_back(from_msgpack_internal(v, idx));
+                    }
+                    return result;
+                }
+
+                case 0xde: // map 16
+                {
+                    basic_json result = value_t::object;
+                    const auto len = static_cast<size_t>(get_from_vector<uint16_t>(v, current_idx));
+                    idx += 2; // skip 2 size bytes
+                    for (size_t i = 0; i < len; ++i)
+                    {
+                        std::string key = from_msgpack_internal(v, idx);
+                        result[key] = from_msgpack_internal(v, idx);
+                    }
+                    return result;
+                }
+
+                case 0xdf: // map 32
+                {
+                    basic_json result = value_t::object;
+                    const auto len = static_cast<size_t>(get_from_vector<uint32_t>(v, current_idx));
+                    idx += 4; // skip 4 size bytes
+                    for (size_t i = 0; i < len; ++i)
+                    {
+                        std::string key = from_msgpack_internal(v, idx);
+                        result[key] = from_msgpack_internal(v, idx);
+                    }
+                    return result;
+                }
+
+                default:
+                {
+                    JSON_THROW(std::invalid_argument("error parsing a msgpack @ " + std::to_string(current_idx) + ": " + std::to_string(static_cast<int>(v[current_idx]))));
+                }
+            }
+        }
+    }
+
+    /*!
+    @brief create a JSON value from a given CBOR vector
+
+    @param[in] v  CBOR serialization
+    @param[in] idx  byte index to start reading from @a v
+
+    @return deserialized JSON value
+
+    @throw std::invalid_argument if unsupported features from CBOR were used in
+    the given vector @a v or if the input is not valid CBOR
+    @throw std::out_of_range if the given vector ends prematurely
+
+    @sa https://tools.ietf.org/html/rfc7049
+    */
+    static basic_json from_cbor_internal(const std::vector<uint8_t>& v, size_t& idx)
+    {
+        // store and increment index
+        const size_t current_idx = idx++;
+
+        switch (v.at(current_idx))
+        {
+            // Integer 0x00..0x17 (0..23)
+            case 0x00:
+            case 0x01:
+            case 0x02:
+            case 0x03:
+            case 0x04:
+            case 0x05:
+            case 0x06:
+            case 0x07:
+            case 0x08:
+            case 0x09:
+            case 0x0a:
+            case 0x0b:
+            case 0x0c:
+            case 0x0d:
+            case 0x0e:
+            case 0x0f:
+            case 0x10:
+            case 0x11:
+            case 0x12:
+            case 0x13:
+            case 0x14:
+            case 0x15:
+            case 0x16:
+            case 0x17:
+            {
+                return v[current_idx];
+            }
+
+            case 0x18: // Unsigned integer (one-byte uint8_t follows)
+            {
+                idx += 1; // skip content byte
+                return get_from_vector<uint8_t>(v, current_idx);
+            }
+
+            case 0x19: // Unsigned integer (two-byte uint16_t follows)
+            {
+                idx += 2; // skip 2 content bytes
+                return get_from_vector<uint16_t>(v, current_idx);
+            }
+
+            case 0x1a: // Unsigned integer (four-byte uint32_t follows)
+            {
+                idx += 4; // skip 4 content bytes
+                return get_from_vector<uint32_t>(v, current_idx);
+            }
+
+            case 0x1b: // Unsigned integer (eight-byte uint64_t follows)
+            {
+                idx += 8; // skip 8 content bytes
+                return get_from_vector<uint64_t>(v, current_idx);
+            }
+
+            // Negative integer -1-0x00..-1-0x17 (-1..-24)
+            case 0x20:
+            case 0x21:
+            case 0x22:
+            case 0x23:
+            case 0x24:
+            case 0x25:
+            case 0x26:
+            case 0x27:
+            case 0x28:
+            case 0x29:
+            case 0x2a:
+            case 0x2b:
+            case 0x2c:
+            case 0x2d:
+            case 0x2e:
+            case 0x2f:
+            case 0x30:
+            case 0x31:
+            case 0x32:
+            case 0x33:
+            case 0x34:
+            case 0x35:
+            case 0x36:
+            case 0x37:
+            {
+                return static_cast<int8_t>(0x20 - 1 - v[current_idx]);
+            }
+
+            case 0x38: // Negative integer (one-byte uint8_t follows)
+            {
+                idx += 1; // skip content byte
+                // must be uint8_t !
+                return static_cast<number_integer_t>(-1) - get_from_vector<uint8_t>(v, current_idx);
+            }
+
+            case 0x39: // Negative integer -1-n (two-byte uint16_t follows)
+            {
+                idx += 2; // skip 2 content bytes
+                return static_cast<number_integer_t>(-1) - get_from_vector<uint16_t>(v, current_idx);
+            }
+
+            case 0x3a: // Negative integer -1-n (four-byte uint32_t follows)
+            {
+                idx += 4; // skip 4 content bytes
+                return static_cast<number_integer_t>(-1) - get_from_vector<uint32_t>(v, current_idx);
+            }
+
+            case 0x3b: // Negative integer -1-n (eight-byte uint64_t follows)
+            {
+                idx += 8; // skip 8 content bytes
+                return static_cast<number_integer_t>(-1) - static_cast<number_integer_t>(get_from_vector<uint64_t>(v, current_idx));
+            }
+
+            // UTF-8 string (0x00..0x17 bytes follow)
+            case 0x60:
+            case 0x61:
+            case 0x62:
+            case 0x63:
+            case 0x64:
+            case 0x65:
+            case 0x66:
+            case 0x67:
+            case 0x68:
+            case 0x69:
+            case 0x6a:
+            case 0x6b:
+            case 0x6c:
+            case 0x6d:
+            case 0x6e:
+            case 0x6f:
+            case 0x70:
+            case 0x71:
+            case 0x72:
+            case 0x73:
+            case 0x74:
+            case 0x75:
+            case 0x76:
+            case 0x77:
+            {
+                const auto len = static_cast<size_t>(v[current_idx] - 0x60);
+                const size_t offset = current_idx + 1;
+                idx += len; // skip content bytes
+                check_length(v.size(), len, offset);
+                return std::string(reinterpret_cast<const char*>(v.data()) + offset, len);
+            }
+
+            case 0x78: // UTF-8 string (one-byte uint8_t for n follows)
+            {
+                const auto len = static_cast<size_t>(get_from_vector<uint8_t>(v, current_idx));
+                const size_t offset = current_idx + 2;
+                idx += len + 1; // skip size byte + content bytes
+                check_length(v.size(), len, offset);
+                return std::string(reinterpret_cast<const char*>(v.data()) + offset, len);
+            }
+
+            case 0x79: // UTF-8 string (two-byte uint16_t for n follow)
+            {
+                const auto len = static_cast<size_t>(get_from_vector<uint16_t>(v, current_idx));
+                const size_t offset = current_idx + 3;
+                idx += len + 2; // skip 2 size bytes + content bytes
+                check_length(v.size(), len, offset);
+                return std::string(reinterpret_cast<const char*>(v.data()) + offset, len);
+            }
+
+            case 0x7a: // UTF-8 string (four-byte uint32_t for n follow)
+            {
+                const auto len = static_cast<size_t>(get_from_vector<uint32_t>(v, current_idx));
+                const size_t offset = current_idx + 5;
+                idx += len + 4; // skip 4 size bytes + content bytes
+                check_length(v.size(), len, offset);
+                return std::string(reinterpret_cast<const char*>(v.data()) + offset, len);
+            }
+
+            case 0x7b: // UTF-8 string (eight-byte uint64_t for n follow)
+            {
+                const auto len = static_cast<size_t>(get_from_vector<uint64_t>(v, current_idx));
+                const size_t offset = current_idx + 9;
+                idx += len + 8; // skip 8 size bytes + content bytes
+                check_length(v.size(), len, offset);
+                return std::string(reinterpret_cast<const char*>(v.data()) + offset, len);
+            }
+
+            case 0x7f: // UTF-8 string (indefinite length)
+            {
+                std::string result;
+                while (v.at(idx) != 0xff)
+                {
+                    string_t s = from_cbor_internal(v, idx);
+                    result += s;
+                }
+                // skip break byte (0xFF)
+                idx += 1;
+                return result;
+            }
+
+            // array (0x00..0x17 data items follow)
+            case 0x80:
+            case 0x81:
+            case 0x82:
+            case 0x83:
+            case 0x84:
+            case 0x85:
+            case 0x86:
+            case 0x87:
+            case 0x88:
+            case 0x89:
+            case 0x8a:
+            case 0x8b:
+            case 0x8c:
+            case 0x8d:
+            case 0x8e:
+            case 0x8f:
+            case 0x90:
+            case 0x91:
+            case 0x92:
+            case 0x93:
+            case 0x94:
+            case 0x95:
+            case 0x96:
+            case 0x97:
+            {
+                basic_json result = value_t::array;
+                const auto len = static_cast<size_t>(v[current_idx] - 0x80);
+                for (size_t i = 0; i < len; ++i)
+                {
+                    result.push_back(from_cbor_internal(v, idx));
+                }
+                return result;
+            }
+
+            case 0x98: // array (one-byte uint8_t for n follows)
+            {
+                basic_json result = value_t::array;
+                const auto len = static_cast<size_t>(get_from_vector<uint8_t>(v, current_idx));
+                idx += 1; // skip 1 size byte
+                for (size_t i = 0; i < len; ++i)
+                {
+                    result.push_back(from_cbor_internal(v, idx));
+                }
+                return result;
+            }
+
+            case 0x99: // array (two-byte uint16_t for n follow)
+            {
+                basic_json result = value_t::array;
+                const auto len = static_cast<size_t>(get_from_vector<uint16_t>(v, current_idx));
+                idx += 2; // skip 4 size bytes
+                for (size_t i = 0; i < len; ++i)
+                {
+                    result.push_back(from_cbor_internal(v, idx));
+                }
+                return result;
+            }
+
+            case 0x9a: // array (four-byte uint32_t for n follow)
+            {
+                basic_json result = value_t::array;
+                const auto len = static_cast<size_t>(get_from_vector<uint32_t>(v, current_idx));
+                idx += 4; // skip 4 size bytes
+                for (size_t i = 0; i < len; ++i)
+                {
+                    result.push_back(from_cbor_internal(v, idx));
+                }
+                return result;
+            }
+
+            case 0x9b: // array (eight-byte uint64_t for n follow)
+            {
+                basic_json result = value_t::array;
+                const auto len = static_cast<size_t>(get_from_vector<uint64_t>(v, current_idx));
+                idx += 8; // skip 8 size bytes
+                for (size_t i = 0; i < len; ++i)
+                {
+                    result.push_back(from_cbor_internal(v, idx));
+                }
+                return result;
+            }
+
+            case 0x9f: // array (indefinite length)
+            {
+                basic_json result = value_t::array;
+                while (v.at(idx) != 0xff)
+                {
+                    result.push_back(from_cbor_internal(v, idx));
+                }
+                // skip break byte (0xFF)
+                idx += 1;
+                return result;
+            }
+
+            // map (0x00..0x17 pairs of data items follow)
+            case 0xa0:
+            case 0xa1:
+            case 0xa2:
+            case 0xa3:
+            case 0xa4:
+            case 0xa5:
+            case 0xa6:
+            case 0xa7:
+            case 0xa8:
+            case 0xa9:
+            case 0xaa:
+            case 0xab:
+            case 0xac:
+            case 0xad:
+            case 0xae:
+            case 0xaf:
+            case 0xb0:
+            case 0xb1:
+            case 0xb2:
+            case 0xb3:
+            case 0xb4:
+            case 0xb5:
+            case 0xb6:
+            case 0xb7:
+            {
+                basic_json result = value_t::object;
+                const auto len = static_cast<size_t>(v[current_idx] - 0xa0);
+                for (size_t i = 0; i < len; ++i)
+                {
+                    std::string key = from_cbor_internal(v, idx);
+                    result[key] = from_cbor_internal(v, idx);
+                }
+                return result;
+            }
+
+            case 0xb8: // map (one-byte uint8_t for n follows)
+            {
+                basic_json result = value_t::object;
+                const auto len = static_cast<size_t>(get_from_vector<uint8_t>(v, current_idx));
+                idx += 1; // skip 1 size byte
+                for (size_t i = 0; i < len; ++i)
+                {
+                    std::string key = from_cbor_internal(v, idx);
+                    result[key] = from_cbor_internal(v, idx);
+                }
+                return result;
+            }
+
+            case 0xb9: // map (two-byte uint16_t for n follow)
+            {
+                basic_json result = value_t::object;
+                const auto len = static_cast<size_t>(get_from_vector<uint16_t>(v, current_idx));
+                idx += 2; // skip 2 size bytes
+                for (size_t i = 0; i < len; ++i)
+                {
+                    std::string key = from_cbor_internal(v, idx);
+                    result[key] = from_cbor_internal(v, idx);
+                }
+                return result;
+            }
+
+            case 0xba: // map (four-byte uint32_t for n follow)
+            {
+                basic_json result = value_t::object;
+                const auto len = static_cast<size_t>(get_from_vector<uint32_t>(v, current_idx));
+                idx += 4; // skip 4 size bytes
+                for (size_t i = 0; i < len; ++i)
+                {
+                    std::string key = from_cbor_internal(v, idx);
+                    result[key] = from_cbor_internal(v, idx);
+                }
+                return result;
+            }
+
+            case 0xbb: // map (eight-byte uint64_t for n follow)
+            {
+                basic_json result = value_t::object;
+                const auto len = static_cast<size_t>(get_from_vector<uint64_t>(v, current_idx));
+                idx += 8; // skip 8 size bytes
+                for (size_t i = 0; i < len; ++i)
+                {
+                    std::string key = from_cbor_internal(v, idx);
+                    result[key] = from_cbor_internal(v, idx);
+                }
+                return result;
+            }
+
+            case 0xbf: // map (indefinite length)
+            {
+                basic_json result = value_t::object;
+                while (v.at(idx) != 0xff)
+                {
+                    std::string key = from_cbor_internal(v, idx);
+                    result[key] = from_cbor_internal(v, idx);
+                }
+                // skip break byte (0xFF)
+                idx += 1;
+                return result;
+            }
+
+            case 0xf4: // false
+            {
+                return false;
+            }
+
+            case 0xf5: // true
+            {
+                return true;
+            }
+
+            case 0xf6: // null
+            {
+                return value_t::null;
+            }
+
+            case 0xf9: // Half-Precision Float (two-byte IEEE 754)
+            {
+                idx += 2; // skip two content bytes
+
+                // code from RFC 7049, Appendix D, Figure 3:
+                // As half-precision floating-point numbers were only added to
+                // IEEE 754 in 2008, today's programming platforms often still
+                // only have limited support for them. It is very easy to
+                // include at least decoding support for them even without such
+                // support. An example of a small decoder for half-precision
+                // floating-point numbers in the C language is shown in Fig. 3.
+                const int half = (v.at(current_idx + 1) << 8) + v.at(current_idx + 2);
+                const int exp = (half >> 10) & 0x1f;
+                const int mant = half & 0x3ff;
+                double val;
+                if (exp == 0)
+                {
+                    val = std::ldexp(mant, -24);
+                }
+                else if (exp != 31)
+                {
+                    val = std::ldexp(mant + 1024, exp - 25);
+                }
+                else
+                {
+                    val = mant == 0
+                          ? std::numeric_limits<double>::infinity()
+                          : std::numeric_limits<double>::quiet_NaN();
+                }
+                return (half & 0x8000) != 0 ? -val : val;
+            }
+
+            case 0xfa: // Single-Precision Float (four-byte IEEE 754)
+            {
+                // copy bytes in reverse order into the float variable
+                float res;
+                for (size_t byte = 0; byte < sizeof(float); ++byte)
+                {
+                    reinterpret_cast<uint8_t*>(&res)[sizeof(float) - byte - 1] = v.at(current_idx + 1 + byte);
+                }
+                idx += sizeof(float); // skip content bytes
+                return res;
+            }
+
+            case 0xfb: // Double-Precision Float (eight-byte IEEE 754)
+            {
+                // copy bytes in reverse order into the double variable
+                double res;
+                for (size_t byte = 0; byte < sizeof(double); ++byte)
+                {
+                    reinterpret_cast<uint8_t*>(&res)[sizeof(double) - byte - 1] = v.at(current_idx + 1 + byte);
+                }
+                idx += sizeof(double); // skip content bytes
+                return res;
+            }
+
+            default: // anything else (0xFF is handled inside the other types)
+            {
+                JSON_THROW(std::invalid_argument("error parsing a CBOR @ " + std::to_string(current_idx) + ": " + std::to_string(static_cast<int>(v[current_idx]))));
+            }
+        }
+    }
+
+  public:
+    /*!
+    @brief create a MessagePack serialization of a given JSON value
+
+    Serializes a given JSON value @a j to a byte vector using the MessagePack
+    serialization format. MessagePack is a binary serialization format which
+    aims to be more compact than JSON itself, yet more efficient to parse.
+
+    @param[in] j  JSON value to serialize
+    @return MessagePack serialization as byte vector
+
+    @complexity Linear in the size of the JSON value @a j.
+
+    @liveexample{The example shows the serialization of a JSON value to a byte
+    vector in MessagePack format.,to_msgpack}
+
+    @sa http://msgpack.org
+    @sa @ref from_msgpack(const std::vector<uint8_t>&, const size_t) for the
+        analogous deserialization
+    @sa @ref to_cbor(const basic_json& for the related CBOR format
+
+    @since version 2.0.9
+    */
+    static std::vector<uint8_t> to_msgpack(const basic_json& j)
+    {
+        std::vector<uint8_t> result;
+        to_msgpack_internal(j, result);
+        return result;
+    }
+
+    /*!
+    @brief create a JSON value from a byte vector in MessagePack format
+
+    Deserializes a given byte vector @a v to a JSON value using the MessagePack
+    serialization format.
+
+    @param[in] v  a byte vector in MessagePack format
+    @param[in] start_index the index to start reading from @a v (0 by default)
+    @return deserialized JSON value
+
+    @throw std::invalid_argument if unsupported features from MessagePack were
+    used in the given vector @a v or if the input is not valid MessagePack
+    @throw std::out_of_range if the given vector ends prematurely
+
+    @complexity Linear in the size of the byte vector @a v.
+
+    @liveexample{The example shows the deserialization of a byte vector in
+    MessagePack format to a JSON value.,from_msgpack}
+
+    @sa http://msgpack.org
+    @sa @ref to_msgpack(const basic_json&) for the analogous serialization
+    @sa @ref from_cbor(const std::vector<uint8_t>&, const size_t) for the
+        related CBOR format
+
+    @since version 2.0.9, parameter @a start_index since 2.1.1
+    */
+    static basic_json from_msgpack(const std::vector<uint8_t>& v,
+                                   const size_t start_index = 0)
+    {
+        size_t i = start_index;
+        return from_msgpack_internal(v, i);
+    }
+
+    /*!
+    @brief create a MessagePack serialization of a given JSON value
+
+    Serializes a given JSON value @a j to a byte vector using the CBOR (Concise
+    Binary Object Representation) serialization format. CBOR is a binary
+    serialization format which aims to be more compact than JSON itself, yet
+    more efficient to parse.
+
+    @param[in] j  JSON value to serialize
+    @return MessagePack serialization as byte vector
+
+    @complexity Linear in the size of the JSON value @a j.
+
+    @liveexample{The example shows the serialization of a JSON value to a byte
+    vector in CBOR format.,to_cbor}
+
+    @sa http://cbor.io
+    @sa @ref from_cbor(const std::vector<uint8_t>&, const size_t) for the
+        analogous deserialization
+    @sa @ref to_msgpack(const basic_json& for the related MessagePack format
+
+    @since version 2.0.9
+    */
+    static std::vector<uint8_t> to_cbor(const basic_json& j)
+    {
+        std::vector<uint8_t> result;
+        to_cbor_internal(j, result);
+        return result;
+    }
+
+    /*!
+    @brief create a JSON value from a byte vector in CBOR format
+
+    Deserializes a given byte vector @a v to a JSON value using the CBOR
+    (Concise Binary Object Representation) serialization format.
+
+    @param[in] v  a byte vector in CBOR format
+    @param[in] start_index the index to start reading from @a v (0 by default)
+    @return deserialized JSON value
+
+    @throw std::invalid_argument if unsupported features from CBOR were used in
+    the given vector @a v or if the input is not valid MessagePack
+    @throw std::out_of_range if the given vector ends prematurely
+
+    @complexity Linear in the size of the byte vector @a v.
+
+    @liveexample{The example shows the deserialization of a byte vector in CBOR
+    format to a JSON value.,from_cbor}
+
+    @sa http://cbor.io
+    @sa @ref to_cbor(const basic_json&) for the analogous serialization
+    @sa @ref from_msgpack(const std::vector<uint8_t>&, const size_t) for the
+        related MessagePack format
+
+    @since version 2.0.9, parameter @a start_index since 2.1.1
+    */
+    static basic_json from_cbor(const std::vector<uint8_t>& v,
+                                const size_t start_index = 0)
+    {
+        size_t i = start_index;
+        return from_cbor_internal(v, i);
+    }
+
+    /// @}
+
+    ///////////////////////////
+    // convenience functions //
+    ///////////////////////////
+
+    /*!
+    @brief return the type as string
+
+    Returns the type name as string to be used in error messages - usually to
+    indicate that a function was called on a wrong JSON type.
+
+    @return basically a string representation of a the @a m_type member
+
+    @complexity Constant.
+
+    @liveexample{The following code exemplifies `type_name()` for all JSON
+    types.,type_name}
+
+    @since version 1.0.0, public since 2.1.0
+    */
+    std::string type_name() const
+    {
+        {
+            switch (m_type)
+            {
+                case value_t::null:
+                    return "null";
+                case value_t::object:
+                    return "object";
+                case value_t::array:
+                    return "array";
+                case value_t::string:
+                    return "string";
+                case value_t::boolean:
+                    return "boolean";
+                case value_t::discarded:
+                    return "discarded";
+                default:
+                    return "number";
+            }
+        }
+    }
+
+  private:
+    /*!
+    @brief calculates the extra space to escape a JSON string
+
+    @param[in] s  the string to escape
+    @return the number of characters required to escape string @a s
+
+    @complexity Linear in the length of string @a s.
+    */
+    static std::size_t extra_space(const string_t& s) noexcept
+    {
+        return std::accumulate(s.begin(), s.end(), size_t{},
+                               [](size_t res, typename string_t::value_type c)
+        {
+            switch (c)
+            {
+                case '"':
+                case '\\':
+                case '\b':
+                case '\f':
+                case '\n':
+                case '\r':
+                case '\t':
+                {
+                    // from c (1 byte) to \x (2 bytes)
+                    return res + 1;
+                }
+
+                default:
+                {
+                    if (c >= 0x00 and c <= 0x1f)
+                    {
+                        // from c (1 byte) to \uxxxx (6 bytes)
+                        return res + 5;
+                    }
+
+                    return res;
+                }
+            }
+        });
+    }
+
+    /*!
+    @brief escape a string
+
+    Escape a string by replacing certain special characters by a sequence of
+    an escape character (backslash) and another character and other control
+    characters by a sequence of "\u" followed by a four-digit hex
+    representation.
+
+    @param[in] s  the string to escape
+    @return  the escaped string
+
+    @complexity Linear in the length of string @a s.
+    */
+    static string_t escape_string(const string_t& s)
+    {
+        const auto space = extra_space(s);
+        if (space == 0)
+        {
+            return s;
+        }
+
+        // create a result string of necessary size
+        string_t result(s.size() + space, '\\');
+        std::size_t pos = 0;
+
+        for (const auto& c : s)
+        {
+            switch (c)
+            {
+                // quotation mark (0x22)
+                case '"':
+                {
+                    result[pos + 1] = '"';
+                    pos += 2;
+                    break;
+                }
+
+                // reverse solidus (0x5c)
+                case '\\':
+                {
+                    // nothing to change
+                    pos += 2;
+                    break;
+                }
+
+                // backspace (0x08)
+                case '\b':
+                {
+                    result[pos + 1] = 'b';
+                    pos += 2;
+                    break;
+                }
+
+                // formfeed (0x0c)
+                case '\f':
+                {
+                    result[pos + 1] = 'f';
+                    pos += 2;
+                    break;
+                }
+
+                // newline (0x0a)
+                case '\n':
+                {
+                    result[pos + 1] = 'n';
+                    pos += 2;
+                    break;
+                }
+
+                // carriage return (0x0d)
+                case '\r':
+                {
+                    result[pos + 1] = 'r';
+                    pos += 2;
+                    break;
+                }
+
+                // horizontal tab (0x09)
+                case '\t':
+                {
+                    result[pos + 1] = 't';
+                    pos += 2;
+                    break;
+                }
+
+                default:
+                {
+                    if (c >= 0x00 and c <= 0x1f)
+                    {
+                        // convert a number 0..15 to its hex representation
+                        // (0..f)
+                        static const char hexify[16] =
+                        {
+                            '0', '1', '2', '3', '4', '5', '6', '7',
+                            '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
+                        };
+
+                        // print character c as \uxxxx
+                        for (const char m :
+                    { 'u', '0', '0', hexify[c >> 4], hexify[c & 0x0f]
+                        })
+                        {
+                            result[++pos] = m;
+                        }
+
+                        ++pos;
+                    }
+                    else
+                    {
+                        // all other characters are added as-is
+                        result[pos++] = c;
+                    }
+                    break;
+                }
+            }
+        }
+
+        return result;
+    }
+
+
+    /*!
+    @brief locale-independent serialization for built-in arithmetic types
+    */
+    struct numtostr
+    {
+      public:
+        template<typename NumberType>
+        numtostr(NumberType value)
+        {
+            x_write(value, std::is_integral<NumberType>());
+        }
+
+        const char* c_str() const
+        {
+            return m_buf.data();
+        }
+
+      private:
+        /// a (hopefully) large enough character buffer
+        std::array < char, 64 > m_buf{{}};
+
+        template<typename NumberType>
+        void x_write(NumberType x, /*is_integral=*/std::true_type)
+        {
+            // special case for "0"
+            if (x == 0)
+            {
+                m_buf[0] = '0';
+                return;
+            }
+
+            const bool is_negative = x < 0;
+            size_t i = 0;
+
+            // spare 1 byte for '\0'
+            while (x != 0 and i < m_buf.size() - 1)
+            {
+                const auto digit = std::labs(static_cast<long>(x % 10));
+                m_buf[i++] = static_cast<char>('0' + digit);
+                x /= 10;
+            }
+
+            // make sure the number has been processed completely
+            assert(x == 0);
+
+            if (is_negative)
+            {
+                // make sure there is capacity for the '-'
+                assert(i < m_buf.size() - 2);
+                m_buf[i++] = '-';
+            }
+
+            std::reverse(m_buf.begin(), m_buf.begin() + i);
+        }
+
+        template<typename NumberType>
+        void x_write(NumberType x, /*is_integral=*/std::false_type)
+        {
+            // special case for 0.0 and -0.0
+            if (x == 0)
+            {
+                size_t i = 0;
+                if (std::signbit(x))
+                {
+                    m_buf[i++] = '-';
+                }
+                m_buf[i++] = '0';
+                m_buf[i++] = '.';
+                m_buf[i] = '0';
+                return;
+            }
+
+            // get number of digits for a text -> float -> text round-trip
+            static constexpr auto d = std::numeric_limits<NumberType>::digits10;
+
+            // the actual conversion
+            const auto written_bytes = snprintf(m_buf.data(), m_buf.size(), "%.*g", d, x);
+
+            // negative value indicates an error
+            assert(written_bytes > 0);
+            // check if buffer was large enough
+            assert(static_cast<size_t>(written_bytes) < m_buf.size());
+
+            // read information from locale
+            const auto loc = localeconv();
+            assert(loc != nullptr);
+            const char thousands_sep = !loc->thousands_sep ? '\0'
+                                       : loc->thousands_sep[0];
+
+            const char decimal_point = !loc->decimal_point ? '\0'
+                                       : loc->decimal_point[0];
+
+            // erase thousands separator
+            if (thousands_sep != '\0')
+            {
+                const auto end = std::remove(m_buf.begin(), m_buf.begin() + written_bytes, thousands_sep);
+                std::fill(end, m_buf.end(), '\0');
+            }
+
+            // convert decimal point to '.'
+            if (decimal_point != '\0' and decimal_point != '.')
+            {
+                for (auto& c : m_buf)
+                {
+                    if (c == decimal_point)
+                    {
+                        c = '.';
+                        break;
+                    }
+                }
+            }
+
+            // determine if need to append ".0"
+            size_t i = 0;
+            bool value_is_int_like = true;
+            for (i = 0; i < m_buf.size(); ++i)
+            {
+                // break when end of number is reached
+                if (m_buf[i] == '\0')
+                {
+                    break;
+                }
+
+                // check if we find non-int character
+                value_is_int_like = value_is_int_like and m_buf[i] != '.' and
+                                    m_buf[i] != 'e' and m_buf[i] != 'E';
+            }
+
+            if (value_is_int_like)
+            {
+                // there must be 2 bytes left for ".0"
+                assert((i + 2) < m_buf.size());
+                // we write to the end of the number
+                assert(m_buf[i] == '\0');
+                assert(m_buf[i - 1] != '\0');
+
+                // add ".0"
+                m_buf[i] = '.';
+                m_buf[i + 1] = '0';
+
+                // the resulting string is properly terminated
+                assert(m_buf[i + 2] == '\0');
+            }
+        }
+    };
+
+
+    /*!
+    @brief internal implementation of the serialization function
+
+    This function is called by the public member function dump and organizes
+    the serialization internally. The indentation level is propagated as
+    additional parameter. In case of arrays and objects, the function is
+    called recursively. Note that
+
+    - strings and object keys are escaped using `escape_string()`
+    - integer numbers are converted implicitly via `operator<<`
+    - floating-point numbers are converted to a string using `"%g"` format
+
+    @param[out] o              stream to write to
+    @param[in] pretty_print    whether the output shall be pretty-printed
+    @param[in] indent_step     the indent level
+    @param[in] current_indent  the current indent level (only used internally)
+    */
+    void dump(std::ostream& o,
+              const bool pretty_print,
+              const unsigned int indent_step,
+              const unsigned int current_indent = 0) const
+    {
+        // variable to hold indentation for recursive calls
+        unsigned int new_indent = current_indent;
+
+        switch (m_type)
+        {
+            case value_t::object:
+            {
+                if (m_value.object->empty())
+                {
+                    o << "{}";
+                    return;
+                }
+
+                o << "{";
+
+                // increase indentation
+                if (pretty_print)
+                {
+                    new_indent += indent_step;
+                    o << "\n";
+                }
+
+                for (auto i = m_value.object->cbegin(); i != m_value.object->cend(); ++i)
+                {
+                    if (i != m_value.object->cbegin())
+                    {
+                        o << (pretty_print ? ",\n" : ",");
+                    }
+                    o << string_t(new_indent, ' ') << "\""
+                      << escape_string(i->first) << "\":"
+                      << (pretty_print ? " " : "");
+                    i->second.dump(o, pretty_print, indent_step, new_indent);
+                }
+
+                // decrease indentation
+                if (pretty_print)
+                {
+                    new_indent -= indent_step;
+                    o << "\n";
+                }
+
+                o << string_t(new_indent, ' ') + "}";
+                return;
+            }
+
+            case value_t::array:
+            {
+                if (m_value.array->empty())
+                {
+                    o << "[]";
+                    return;
+                }
+
+                o << "[";
+
+                // increase indentation
+                if (pretty_print)
+                {
+                    new_indent += indent_step;
+                    o << "\n";
+                }
+
+                for (auto i = m_value.array->cbegin(); i != m_value.array->cend(); ++i)
+                {
+                    if (i != m_value.array->cbegin())
+                    {
+                        o << (pretty_print ? ",\n" : ",");
+                    }
+                    o << string_t(new_indent, ' ');
+                    i->dump(o, pretty_print, indent_step, new_indent);
+                }
+
+                // decrease indentation
+                if (pretty_print)
+                {
+                    new_indent -= indent_step;
+                    o << "\n";
+                }
+
+                o << string_t(new_indent, ' ') << "]";
+                return;
+            }
+
+            case value_t::string:
+            {
+                o << string_t("\"") << escape_string(*m_value.string) << "\"";
+                return;
+            }
+
+            case value_t::boolean:
+            {
+                o << (m_value.boolean ? "true" : "false");
+                return;
+            }
+
+            case value_t::number_integer:
+            {
+                o << numtostr(m_value.number_integer).c_str();
+                return;
+            }
+
+            case value_t::number_unsigned:
+            {
+                o << numtostr(m_value.number_unsigned).c_str();
+                return;
+            }
+
+            case value_t::number_float:
+            {
+                o << numtostr(m_value.number_float).c_str();
+                return;
+            }
+
+            case value_t::discarded:
+            {
+                o << "<discarded>";
+                return;
+            }
+
+            case value_t::null:
+            {
+                o << "null";
+                return;
+            }
+        }
+    }
+
+  private:
+    //////////////////////
+    // member variables //
+    //////////////////////
+
+    /// the type of the current element
+    value_t m_type = value_t::null;
+
+    /// the value of the current element
+    json_value m_value = {};
+
+
+  private:
+    ///////////////
+    // iterators //
+    ///////////////
+
+    /*!
+    @brief an iterator for primitive JSON types
+
+    This class models an iterator for primitive JSON types (boolean, number,
+    string). It's only purpose is to allow the iterator/const_iterator classes
+    to "iterate" over primitive values. Internally, the iterator is modeled by
+    a `difference_type` variable. Value begin_value (`0`) models the begin,
+    end_value (`1`) models past the end.
+    */
+    class primitive_iterator_t
+    {
+      public:
+
+        difference_type get_value() const noexcept
+        {
+            return m_it;
+        }
+        /// set iterator to a defined beginning
+        void set_begin() noexcept
+        {
+            m_it = begin_value;
+        }
+
+        /// set iterator to a defined past the end
+        void set_end() noexcept
+        {
+            m_it = end_value;
+        }
+
+        /// return whether the iterator can be dereferenced
+        constexpr bool is_begin() const noexcept
+        {
+            return (m_it == begin_value);
+        }
+
+        /// return whether the iterator is at end
+        constexpr bool is_end() const noexcept
+        {
+            return (m_it == end_value);
+        }
+
+        friend constexpr bool operator==(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
+        {
+            return lhs.m_it == rhs.m_it;
+        }
+
+        friend constexpr bool operator!=(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
+        {
+            return !(lhs == rhs);
+        }
+
+        friend constexpr bool operator<(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
+        {
+            return lhs.m_it < rhs.m_it;
+        }
+
+        friend constexpr bool operator<=(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
+        {
+            return lhs.m_it <= rhs.m_it;
+        }
+
+        friend constexpr bool operator>(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
+        {
+            return lhs.m_it > rhs.m_it;
+        }
+
+        friend constexpr bool operator>=(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
+        {
+            return lhs.m_it >= rhs.m_it;
+        }
+
+        primitive_iterator_t operator+(difference_type i)
+        {
+            auto result = *this;
+            result += i;
+            return result;
+        }
+
+        friend constexpr difference_type operator-(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
+        {
+            return lhs.m_it - rhs.m_it;
+        }
+
+        friend std::ostream& operator<<(std::ostream& os, primitive_iterator_t it)
+        {
+            return os << it.m_it;
+        }
+
+        primitive_iterator_t& operator++()
+        {
+            ++m_it;
+            return *this;
+        }
+
+        primitive_iterator_t operator++(int)
+        {
+            auto result = *this;
+            m_it++;
+            return result;
+        }
+
+        primitive_iterator_t& operator--()
+        {
+            --m_it;
+            return *this;
+        }
+
+        primitive_iterator_t operator--(int)
+        {
+            auto result = *this;
+            m_it--;
+            return result;
+        }
+
+        primitive_iterator_t& operator+=(difference_type n)
+        {
+            m_it += n;
+            return *this;
+        }
+
+        primitive_iterator_t& operator-=(difference_type n)
+        {
+            m_it -= n;
+            return *this;
+        }
+
+      private:
+        static constexpr difference_type begin_value = 0;
+        static constexpr difference_type end_value = begin_value + 1;
+
+        /// iterator as signed integer type
+        difference_type m_it = std::numeric_limits<std::ptrdiff_t>::denorm_min();
+    };
+
+    /*!
+    @brief an iterator value
+
+    @note This structure could easily be a union, but MSVC currently does not
+    allow unions members with complex constructors, see
+    https://github.com/nlohmann/json/pull/105.
+    */
+    struct internal_iterator
+    {
+        /// iterator for JSON objects
+        typename object_t::iterator object_iterator;
+        /// iterator for JSON arrays
+        typename array_t::iterator array_iterator;
+        /// generic iterator for all other types
+        primitive_iterator_t primitive_iterator;
+
+        /// create an uninitialized internal_iterator
+        internal_iterator() noexcept
+            : object_iterator(), array_iterator(), primitive_iterator()
+        {}
+    };
+
+    /// proxy class for the iterator_wrapper functions
+    template<typename IteratorType>
+    class iteration_proxy
+    {
+      private:
+        /// helper class for iteration
+        class iteration_proxy_internal
+        {
+          private:
+            /// the iterator
+            IteratorType anchor;
+            /// an index for arrays (used to create key names)
+            size_t array_index = 0;
+
+          public:
+            explicit iteration_proxy_internal(IteratorType it) noexcept
+                : anchor(it)
+            {}
+
+            /// dereference operator (needed for range-based for)
+            iteration_proxy_internal& operator*()
+            {
+                return *this;
+            }
+
+            /// increment operator (needed for range-based for)
+            iteration_proxy_internal& operator++()
+            {
+                ++anchor;
+                ++array_index;
+
+                return *this;
+            }
+
+            /// inequality operator (needed for range-based for)
+            bool operator!= (const iteration_proxy_internal& o) const
+            {
+                return anchor != o.anchor;
+            }
+
+            /// return key of the iterator
+            typename basic_json::string_t key() const
+            {
+                assert(anchor.m_object != nullptr);
+
+                switch (anchor.m_object->type())
+                {
+                    // use integer array index as key
+                    case value_t::array:
+                    {
+                        return std::to_string(array_index);
+                    }
+
+                    // use key from the object
+                    case value_t::object:
+                    {
+                        return anchor.key();
+                    }
+
+                    // use an empty key for all primitive types
+                    default:
+                    {
+                        return "";
+                    }
+                }
+            }
+
+            /// return value of the iterator
+            typename IteratorType::reference value() const
+            {
+                return anchor.value();
+            }
+        };
+
+        /// the container to iterate
+        typename IteratorType::reference container;
+
+      public:
+        /// construct iteration proxy from a container
+        explicit iteration_proxy(typename IteratorType::reference cont)
+            : container(cont)
+        {}
+
+        /// return iterator begin (needed for range-based for)
+        iteration_proxy_internal begin() noexcept
+        {
+            return iteration_proxy_internal(container.begin());
+        }
+
+        /// return iterator end (needed for range-based for)
+        iteration_proxy_internal end() noexcept
+        {
+            return iteration_proxy_internal(container.end());
+        }
+    };
+
+  public:
+    /*!
+    @brief a template for a random access iterator for the @ref basic_json class
+
+    This class implements a both iterators (iterator and const_iterator) for the
+    @ref basic_json class.
+
+    @note An iterator is called *initialized* when a pointer to a JSON value
+          has been set (e.g., by a constructor or a copy assignment). If the
+          iterator is default-constructed, it is *uninitialized* and most
+          methods are undefined. **The library uses assertions to detect calls
+          on uninitialized iterators.**
+
+    @requirement The class satisfies the following concept requirements:
+    - [RandomAccessIterator](http://en.cppreference.com/w/cpp/concept/RandomAccessIterator):
+      The iterator that can be moved to point (forward and backward) to any
+      element in constant time.
+
+    @since version 1.0.0, simplified in version 2.0.9
+    */
+    template<typename U>
+    class iter_impl : public std::iterator<std::random_access_iterator_tag, U>
+    {
+        /// allow basic_json to access private members
+        friend class basic_json;
+
+        // make sure U is basic_json or const basic_json
+        static_assert(std::is_same<U, basic_json>::value
+                      or std::is_same<U, const basic_json>::value,
+                      "iter_impl only accepts (const) basic_json");
+
+      public:
+        /// the type of the values when the iterator is dereferenced
+        using value_type = typename basic_json::value_type;
+        /// a type to represent differences between iterators
+        using difference_type = typename basic_json::difference_type;
+        /// defines a pointer to the type iterated over (value_type)
+        using pointer = typename std::conditional<std::is_const<U>::value,
+              typename basic_json::const_pointer,
+              typename basic_json::pointer>::type;
+        /// defines a reference to the type iterated over (value_type)
+        using reference = typename std::conditional<std::is_const<U>::value,
+              typename basic_json::const_reference,
+              typename basic_json::reference>::type;
+        /// the category of the iterator
+        using iterator_category = std::bidirectional_iterator_tag;
+
+        /// default constructor
+        iter_impl() = default;
+
+        /*!
+        @brief constructor for a given JSON instance
+        @param[in] object  pointer to a JSON object for this iterator
+        @pre object != nullptr
+        @post The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        explicit iter_impl(pointer object) noexcept
+            : m_object(object)
+        {
+            assert(m_object != nullptr);
+
+            switch (m_object->m_type)
+            {
+                case basic_json::value_t::object:
+                {
+                    m_it.object_iterator = typename object_t::iterator();
+                    break;
+                }
+
+                case basic_json::value_t::array:
+                {
+                    m_it.array_iterator = typename array_t::iterator();
+                    break;
+                }
+
+                default:
+                {
+                    m_it.primitive_iterator = primitive_iterator_t();
+                    break;
+                }
+            }
+        }
+
+        /*
+        Use operator `const_iterator` instead of `const_iterator(const iterator&
+        other) noexcept` to avoid two class definitions for @ref iterator and
+        @ref const_iterator.
+
+        This function is only called if this class is an @ref iterator. If this
+        class is a @ref const_iterator this function is not called.
+        */
+        operator const_iterator() const
+        {
+            const_iterator ret;
+
+            if (m_object)
+            {
+                ret.m_object = m_object;
+                ret.m_it = m_it;
+            }
+
+            return ret;
+        }
+
+        /*!
+        @brief copy constructor
+        @param[in] other  iterator to copy from
+        @note It is not checked whether @a other is initialized.
+        */
+        iter_impl(const iter_impl& other) noexcept
+            : m_object(other.m_object), m_it(other.m_it)
+        {}
+
+        /*!
+        @brief copy assignment
+        @param[in,out] other  iterator to copy from
+        @note It is not checked whether @a other is initialized.
+        */
+        iter_impl& operator=(iter_impl other) noexcept(
+            std::is_nothrow_move_constructible<pointer>::value and
+            std::is_nothrow_move_assignable<pointer>::value and
+            std::is_nothrow_move_constructible<internal_iterator>::value and
+            std::is_nothrow_move_assignable<internal_iterator>::value
+        )
+        {
+            std::swap(m_object, other.m_object);
+            std::swap(m_it, other.m_it);
+            return *this;
+        }
+
+      private:
+        /*!
+        @brief set the iterator to the first value
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        void set_begin() noexcept
+        {
+            assert(m_object != nullptr);
+
+            switch (m_object->m_type)
+            {
+                case basic_json::value_t::object:
+                {
+                    m_it.object_iterator = m_object->m_value.object->begin();
+                    break;
+                }
+
+                case basic_json::value_t::array:
+                {
+                    m_it.array_iterator = m_object->m_value.array->begin();
+                    break;
+                }
+
+                case basic_json::value_t::null:
+                {
+                    // set to end so begin()==end() is true: null is empty
+                    m_it.primitive_iterator.set_end();
+                    break;
+                }
+
+                default:
+                {
+                    m_it.primitive_iterator.set_begin();
+                    break;
+                }
+            }
+        }
+
+        /*!
+        @brief set the iterator past the last value
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        void set_end() noexcept
+        {
+            assert(m_object != nullptr);
+
+            switch (m_object->m_type)
+            {
+                case basic_json::value_t::object:
+                {
+                    m_it.object_iterator = m_object->m_value.object->end();
+                    break;
+                }
+
+                case basic_json::value_t::array:
+                {
+                    m_it.array_iterator = m_object->m_value.array->end();
+                    break;
+                }
+
+                default:
+                {
+                    m_it.primitive_iterator.set_end();
+                    break;
+                }
+            }
+        }
+
+      public:
+        /*!
+        @brief return a reference to the value pointed to by the iterator
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        reference operator*() const
+        {
+            assert(m_object != nullptr);
+
+            switch (m_object->m_type)
+            {
+                case basic_json::value_t::object:
+                {
+                    assert(m_it.object_iterator != m_object->m_value.object->end());
+                    return m_it.object_iterator->second;
+                }
+
+                case basic_json::value_t::array:
+                {
+                    assert(m_it.array_iterator != m_object->m_value.array->end());
+                    return *m_it.array_iterator;
+                }
+
+                case basic_json::value_t::null:
+                {
+                    JSON_THROW(std::out_of_range("cannot get value"));
+                }
+
+                default:
+                {
+                    if (m_it.primitive_iterator.is_begin())
+                    {
+                        return *m_object;
+                    }
+
+                    JSON_THROW(std::out_of_range("cannot get value"));
+                }
+            }
+        }
+
+        /*!
+        @brief dereference the iterator
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        pointer operator->() const
+        {
+            assert(m_object != nullptr);
+
+            switch (m_object->m_type)
+            {
+                case basic_json::value_t::object:
+                {
+                    assert(m_it.object_iterator != m_object->m_value.object->end());
+                    return &(m_it.object_iterator->second);
+                }
+
+                case basic_json::value_t::array:
+                {
+                    assert(m_it.array_iterator != m_object->m_value.array->end());
+                    return &*m_it.array_iterator;
+                }
+
+                default:
+                {
+                    if (m_it.primitive_iterator.is_begin())
+                    {
+                        return m_object;
+                    }
+
+                    JSON_THROW(std::out_of_range("cannot get value"));
+                }
+            }
+        }
+
+        /*!
+        @brief post-increment (it++)
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        iter_impl operator++(int)
+        {
+            auto result = *this;
+            ++(*this);
+            return result;
+        }
+
+        /*!
+        @brief pre-increment (++it)
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        iter_impl& operator++()
+        {
+            assert(m_object != nullptr);
+
+            switch (m_object->m_type)
+            {
+                case basic_json::value_t::object:
+                {
+                    std::advance(m_it.object_iterator, 1);
+                    break;
+                }
+
+                case basic_json::value_t::array:
+                {
+                    std::advance(m_it.array_iterator, 1);
+                    break;
+                }
+
+                default:
+                {
+                    ++m_it.primitive_iterator;
+                    break;
+                }
+            }
+
+            return *this;
+        }
+
+        /*!
+        @brief post-decrement (it--)
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        iter_impl operator--(int)
+        {
+            auto result = *this;
+            --(*this);
+            return result;
+        }
+
+        /*!
+        @brief pre-decrement (--it)
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        iter_impl& operator--()
+        {
+            assert(m_object != nullptr);
+
+            switch (m_object->m_type)
+            {
+                case basic_json::value_t::object:
+                {
+                    std::advance(m_it.object_iterator, -1);
+                    break;
+                }
+
+                case basic_json::value_t::array:
+                {
+                    std::advance(m_it.array_iterator, -1);
+                    break;
+                }
+
+                default:
+                {
+                    --m_it.primitive_iterator;
+                    break;
+                }
+            }
+
+            return *this;
+        }
+
+        /*!
+        @brief  comparison: equal
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        bool operator==(const iter_impl& other) const
+        {
+            // if objects are not the same, the comparison is undefined
+            if (m_object != other.m_object)
+            {
+                JSON_THROW(std::domain_error("cannot compare iterators of different containers"));
+            }
+
+            assert(m_object != nullptr);
+
+            switch (m_object->m_type)
+            {
+                case basic_json::value_t::object:
+                {
+                    return (m_it.object_iterator == other.m_it.object_iterator);
+                }
+
+                case basic_json::value_t::array:
+                {
+                    return (m_it.array_iterator == other.m_it.array_iterator);
+                }
+
+                default:
+                {
+                    return (m_it.primitive_iterator == other.m_it.primitive_iterator);
+                }
+            }
+        }
+
+        /*!
+        @brief  comparison: not equal
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        bool operator!=(const iter_impl& other) const
+        {
+            return not operator==(other);
+        }
+
+        /*!
+        @brief  comparison: smaller
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        bool operator<(const iter_impl& other) const
+        {
+            // if objects are not the same, the comparison is undefined
+            if (m_object != other.m_object)
+            {
+                JSON_THROW(std::domain_error("cannot compare iterators of different containers"));
+            }
+
+            assert(m_object != nullptr);
+
+            switch (m_object->m_type)
+            {
+                case basic_json::value_t::object:
+                {
+                    JSON_THROW(std::domain_error("cannot compare order of object iterators"));
+                }
+
+                case basic_json::value_t::array:
+                {
+                    return (m_it.array_iterator < other.m_it.array_iterator);
+                }
+
+                default:
+                {
+                    return (m_it.primitive_iterator < other.m_it.primitive_iterator);
+                }
+            }
+        }
+
+        /*!
+        @brief  comparison: less than or equal
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        bool operator<=(const iter_impl& other) const
+        {
+            return not other.operator < (*this);
+        }
+
+        /*!
+        @brief  comparison: greater than
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        bool operator>(const iter_impl& other) const
+        {
+            return not operator<=(other);
+        }
+
+        /*!
+        @brief  comparison: greater than or equal
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        bool operator>=(const iter_impl& other) const
+        {
+            return not operator<(other);
+        }
+
+        /*!
+        @brief  add to iterator
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        iter_impl& operator+=(difference_type i)
+        {
+            assert(m_object != nullptr);
+
+            switch (m_object->m_type)
+            {
+                case basic_json::value_t::object:
+                {
+                    JSON_THROW(std::domain_error("cannot use offsets with object iterators"));
+                }
+
+                case basic_json::value_t::array:
+                {
+                    std::advance(m_it.array_iterator, i);
+                    break;
+                }
+
+                default:
+                {
+                    m_it.primitive_iterator += i;
+                    break;
+                }
+            }
+
+            return *this;
+        }
+
+        /*!
+        @brief  subtract from iterator
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        iter_impl& operator-=(difference_type i)
+        {
+            return operator+=(-i);
+        }
+
+        /*!
+        @brief  add to iterator
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        iter_impl operator+(difference_type i)
+        {
+            auto result = *this;
+            result += i;
+            return result;
+        }
+
+        /*!
+        @brief  subtract from iterator
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        iter_impl operator-(difference_type i)
+        {
+            auto result = *this;
+            result -= i;
+            return result;
+        }
+
+        /*!
+        @brief  return difference
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        difference_type operator-(const iter_impl& other) const
+        {
+            assert(m_object != nullptr);
+
+            switch (m_object->m_type)
+            {
+                case basic_json::value_t::object:
+                {
+                    JSON_THROW(std::domain_error("cannot use offsets with object iterators"));
+                }
+
+                case basic_json::value_t::array:
+                {
+                    return m_it.array_iterator - other.m_it.array_iterator;
+                }
+
+                default:
+                {
+                    return m_it.primitive_iterator - other.m_it.primitive_iterator;
+                }
+            }
+        }
+
+        /*!
+        @brief  access to successor
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        reference operator[](difference_type n) const
+        {
+            assert(m_object != nullptr);
+
+            switch (m_object->m_type)
+            {
+                case basic_json::value_t::object:
+                {
+                    JSON_THROW(std::domain_error("cannot use operator[] for object iterators"));
+                }
+
+                case basic_json::value_t::array:
+                {
+                    return *std::next(m_it.array_iterator, n);
+                }
+
+                case basic_json::value_t::null:
+                {
+                    JSON_THROW(std::out_of_range("cannot get value"));
+                }
+
+                default:
+                {
+                    if (m_it.primitive_iterator.get_value() == -n)
+                    {
+                        return *m_object;
+                    }
+
+                    JSON_THROW(std::out_of_range("cannot get value"));
+                }
+            }
+        }
+
+        /*!
+        @brief  return the key of an object iterator
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        typename object_t::key_type key() const
+        {
+            assert(m_object != nullptr);
+
+            if (m_object->is_object())
+            {
+                return m_it.object_iterator->first;
+            }
+
+            JSON_THROW(std::domain_error("cannot use key() for non-object iterators"));
+        }
+
+        /*!
+        @brief  return the value of an iterator
+        @pre The iterator is initialized; i.e. `m_object != nullptr`.
+        */
+        reference value() const
+        {
+            return operator*();
+        }
+
+      private:
+        /// associated JSON instance
+        pointer m_object = nullptr;
+        /// the actual iterator of the associated instance
+        internal_iterator m_it = internal_iterator();
+    };
+
+    /*!
+    @brief a template for a reverse iterator class
+
+    @tparam Base the base iterator type to reverse. Valid types are @ref
+    iterator (to create @ref reverse_iterator) and @ref const_iterator (to
+    create @ref const_reverse_iterator).
+
+    @requirement The class satisfies the following concept requirements:
+    - [RandomAccessIterator](http://en.cppreference.com/w/cpp/concept/RandomAccessIterator):
+      The iterator that can be moved to point (forward and backward) to any
+      element in constant time.
+    - [OutputIterator](http://en.cppreference.com/w/cpp/concept/OutputIterator):
+      It is possible to write to the pointed-to element (only if @a Base is
+      @ref iterator).
+
+    @since version 1.0.0
+    */
+    template<typename Base>
+    class json_reverse_iterator : public std::reverse_iterator<Base>
+    {
+      public:
+        /// shortcut to the reverse iterator adaptor
+        using base_iterator = std::reverse_iterator<Base>;
+        /// the reference type for the pointed-to element
+        using reference = typename Base::reference;
+
+        /// create reverse iterator from iterator
+        json_reverse_iterator(const typename base_iterator::iterator_type& it) noexcept
+            : base_iterator(it)
+        {}
+
+        /// create reverse iterator from base class
+        json_reverse_iterator(const base_iterator& it) noexcept
+            : base_iterator(it)
+        {}
+
+        /// post-increment (it++)
+        json_reverse_iterator operator++(int)
+        {
+            return base_iterator::operator++(1);
+        }
+
+        /// pre-increment (++it)
+        json_reverse_iterator& operator++()
+        {
+            base_iterator::operator++();
+            return *this;
+        }
+
+        /// post-decrement (it--)
+        json_reverse_iterator operator--(int)
+        {
+            return base_iterator::operator--(1);
+        }
+
+        /// pre-decrement (--it)
+        json_reverse_iterator& operator--()
+        {
+            base_iterator::operator--();
+            return *this;
+        }
+
+        /// add to iterator
+        json_reverse_iterator& operator+=(difference_type i)
+        {
+            base_iterator::operator+=(i);
+            return *this;
+        }
+
+        /// add to iterator
+        json_reverse_iterator operator+(difference_type i) const
+        {
+            auto result = *this;
+            result += i;
+            return result;
+        }
+
+        /// subtract from iterator
+        json_reverse_iterator operator-(difference_type i) const
+        {
+            auto result = *this;
+            result -= i;
+            return result;
+        }
+
+        /// return difference
+        difference_type operator-(const json_reverse_iterator& other) const
+        {
+            return this->base() - other.base();
+        }
+
+        /// access to successor
+        reference operator[](difference_type n) const
+        {
+            return *(this->operator+(n));
+        }
+
+        /// return the key of an object iterator
+        typename object_t::key_type key() const
+        {
+            auto it = --this->base();
+            return it.key();
+        }
+
+        /// return the value of an iterator
+        reference value() const
+        {
+            auto it = --this->base();
+            return it.operator * ();
+        }
+    };
+
+
+  private:
+    //////////////////////
+    // lexer and parser //
+    //////////////////////
+
+    /*!
+    @brief lexical analysis
+
+    This class organizes the lexical analysis during JSON deserialization. The
+    core of it is a scanner generated by [re2c](http://re2c.org) that
+    processes a buffer and recognizes tokens according to RFC 7159.
+    */
+    class lexer
+    {
+      public:
+        /// token types for the parser
+        enum class token_type
+        {
+            uninitialized,   ///< indicating the scanner is uninitialized
+            literal_true,    ///< the `true` literal
+            literal_false,   ///< the `false` literal
+            literal_null,    ///< the `null` literal
+            value_string,    ///< a string -- use get_string() for actual value
+            value_unsigned,  ///< an unsigned integer -- use get_number() for actual value
+            value_integer,   ///< a signed integer -- use get_number() for actual value
+            value_float,     ///< an floating point number -- use get_number() for actual value
+            begin_array,     ///< the character for array begin `[`
+            begin_object,    ///< the character for object begin `{`
+            end_array,       ///< the character for array end `]`
+            end_object,      ///< the character for object end `}`
+            name_separator,  ///< the name separator `:`
+            value_separator, ///< the value separator `,`
+            parse_error,     ///< indicating a parse error
+            end_of_input     ///< indicating the end of the input buffer
+        };
+
+        /// the char type to use in the lexer
+        using lexer_char_t = unsigned char;
+
+        /// a lexer from a buffer with given length
+        lexer(const lexer_char_t* buff, const size_t len) noexcept
+            : m_content(buff)
+        {
+            assert(m_content != nullptr);
+            m_start = m_cursor = m_content;
+            m_limit = m_content + len;
+        }
+
+        /// a lexer from an input stream
+        explicit lexer(std::istream& s)
+            : m_stream(&s), m_line_buffer()
+        {
+            // immediately abort if stream is erroneous
+            if (s.fail())
+            {
+                JSON_THROW(std::invalid_argument("stream error"));
+            }
+
+            // fill buffer
+            fill_line_buffer();
+
+            // skip UTF-8 byte-order mark
+            if (m_line_buffer.size() >= 3 and m_line_buffer.substr(0, 3) == "\xEF\xBB\xBF")
+            {
+                m_line_buffer[0] = ' ';
+                m_line_buffer[1] = ' ';
+                m_line_buffer[2] = ' ';
+            }
+        }
+
+        // switch off unwanted functions (due to pointer members)
+        lexer() = delete;
+        lexer(const lexer&) = delete;
+        lexer operator=(const lexer&) = delete;
+
+        /*!
+        @brief create a string from one or two Unicode code points
+
+        There are two cases: (1) @a codepoint1 is in the Basic Multilingual
+        Plane (U+0000 through U+FFFF) and @a codepoint2 is 0, or (2)
+        @a codepoint1 and @a codepoint2 are a UTF-16 surrogate pair to
+        represent a code point above U+FFFF.
+
+        @param[in] codepoint1  the code point (can be high surrogate)
+        @param[in] codepoint2  the code point (can be low surrogate or 0)
+
+        @return string representation of the code point; the length of the
+        result string is between 1 and 4 characters.
+
+        @throw std::out_of_range if code point is > 0x10ffff; example: `"code
+        points above 0x10FFFF are invalid"`
+        @throw std::invalid_argument if the low surrogate is invalid; example:
+        `""missing or wrong low surrogate""`
+
+        @complexity Constant.
+
+        @see <http://en.wikipedia.org/wiki/UTF-8#Sample_code>
+        */
+        static string_t to_unicode(const std::size_t codepoint1,
+                                   const std::size_t codepoint2 = 0)
+        {
+            // calculate the code point from the given code points
+            std::size_t codepoint = codepoint1;
+
+            // check if codepoint1 is a high surrogate
+            if (codepoint1 >= 0xD800 and codepoint1 <= 0xDBFF)
+            {
+                // check if codepoint2 is a low surrogate
+                if (codepoint2 >= 0xDC00 and codepoint2 <= 0xDFFF)
+                {
+                    codepoint =
+                        // high surrogate occupies the most significant 22 bits
+                        (codepoint1 << 10)
+                        // low surrogate occupies the least significant 15 bits
+                        + codepoint2
+                        // there is still the 0xD800, 0xDC00 and 0x10000 noise
+                        // in the result so we have to subtract with:
+                        // (0xD800 << 10) + DC00 - 0x10000 = 0x35FDC00
+                        - 0x35FDC00;
+                }
+                else
+                {
+                    JSON_THROW(std::invalid_argument("missing or wrong low surrogate"));
+                }
+            }
+
+            string_t result;
+
+            if (codepoint < 0x80)
+            {
+                // 1-byte characters: 0xxxxxxx (ASCII)
+                result.append(1, static_cast<typename string_t::value_type>(codepoint));
+            }
+            else if (codepoint <= 0x7ff)
+            {
+                // 2-byte characters: 110xxxxx 10xxxxxx
+                result.append(1, static_cast<typename string_t::value_type>(0xC0 | ((codepoint >> 6) & 0x1F)));
+                result.append(1, static_cast<typename string_t::value_type>(0x80 | (codepoint & 0x3F)));
+            }
+            else if (codepoint <= 0xffff)
+            {
+                // 3-byte characters: 1110xxxx 10xxxxxx 10xxxxxx
+                result.append(1, static_cast<typename string_t::value_type>(0xE0 | ((codepoint >> 12) & 0x0F)));
+                result.append(1, static_cast<typename string_t::value_type>(0x80 | ((codepoint >> 6) & 0x3F)));
+                result.append(1, static_cast<typename string_t::value_type>(0x80 | (codepoint & 0x3F)));
+            }
+            else if (codepoint <= 0x10ffff)
+            {
+                // 4-byte characters: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
+                result.append(1, static_cast<typename string_t::value_type>(0xF0 | ((codepoint >> 18) & 0x07)));
+                result.append(1, static_cast<typename string_t::value_type>(0x80 | ((codepoint >> 12) & 0x3F)));
+                result.append(1, static_cast<typename string_t::value_type>(0x80 | ((codepoint >> 6) & 0x3F)));
+                result.append(1, static_cast<typename string_t::value_type>(0x80 | (codepoint & 0x3F)));
+            }
+            else
+            {
+                JSON_THROW(std::out_of_range("code points above 0x10FFFF are invalid"));
+            }
+
+            return result;
+        }
+
+        /// return name of values of type token_type (only used for errors)
+        static std::string token_type_name(const token_type t)
+        {
+            switch (t)
+            {
+                case token_type::uninitialized:
+                    return "<uninitialized>";
+                case token_type::literal_true:
+                    return "true literal";
+                case token_type::literal_false:
+                    return "false literal";
+                case token_type::literal_null:
+                    return "null literal";
+                case token_type::value_string:
+                    return "string literal";
+                case lexer::token_type::value_unsigned:
+                case lexer::token_type::value_integer:
+                case lexer::token_type::value_float:
+                    return "number literal";
+                case token_type::begin_array:
+                    return "'['";
+                case token_type::begin_object:
+                    return "'{'";
+                case token_type::end_array:
+                    return "']'";
+                case token_type::end_object:
+                    return "'}'";
+                case token_type::name_separator:
+                    return "':'";
+                case token_type::value_separator:
+                    return "','";
+                case token_type::parse_error:
+                    return "<parse error>";
+                case token_type::end_of_input:
+                    return "end of input";
+                default:
+                {
+                    // catch non-enum values
+                    return "unknown token"; // LCOV_EXCL_LINE
+                }
+            }
+        }
+
+        /*!
+        This function implements a scanner for JSON. It is specified using
+        regular expressions that try to follow RFC 7159 as close as possible.
+        These regular expressions are then translated into a minimized
+        deterministic finite automaton (DFA) by the tool
+        [re2c](http://re2c.org). As a result, the translated code for this
+        function consists of a large block of code with `goto` jumps.
+
+        @return the class of the next token read from the buffer
+
+        @complexity Linear in the length of the input.\n
+
+        Proposition: The loop below will always terminate for finite input.\n
+
+        Proof (by contradiction): Assume a finite input. To loop forever, the
+        loop must never hit code with a `break` statement. The only code
+        snippets without a `break` statement are the continue statements for
+        whitespace and byte-order-marks. To loop forever, the input must be an
+        infinite sequence of whitespace or byte-order-marks. This contradicts
+        the assumption of finite input, q.e.d.
+        */
+        token_type scan()
+        {
+            while (true)
+            {
+                // pointer for backtracking information
+                m_marker = nullptr;
+
+                // remember the begin of the token
+                m_start = m_cursor;
+                assert(m_start != nullptr);
+
+
+                {
+                    lexer_char_t yych;
+                    unsigned int yyaccept = 0;
+                    static const unsigned char yybm[] =
+                    {
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        0,  32,  32,   0,   0,  32,   0,   0,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        160, 128,   0, 128, 128, 128, 128, 128,
+                        128, 128, 128, 128, 128, 128, 128, 128,
+                        192, 192, 192, 192, 192, 192, 192, 192,
+                        192, 192, 128, 128, 128, 128, 128, 128,
+                        128, 128, 128, 128, 128, 128, 128, 128,
+                        128, 128, 128, 128, 128, 128, 128, 128,
+                        128, 128, 128, 128, 128, 128, 128, 128,
+                        128, 128, 128, 128,   0, 128, 128, 128,
+                        128, 128, 128, 128, 128, 128, 128, 128,
+                        128, 128, 128, 128, 128, 128, 128, 128,
+                        128, 128, 128, 128, 128, 128, 128, 128,
+                        128, 128, 128, 128, 128, 128, 128, 128,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                        0,   0,   0,   0,   0,   0,   0,   0,
+                    };
+                    if ((m_limit - m_cursor) < 5)
+                    {
+                        fill_line_buffer(5);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yybm[0 + yych] & 32)
+                    {
+                        goto basic_json_parser_6;
+                    }
+                    if (yych <= '[')
+                    {
+                        if (yych <= '-')
+                        {
+                            if (yych <= '"')
+                            {
+                                if (yych <= 0x00)
+                                {
+                                    goto basic_json_parser_2;
+                                }
+                                if (yych <= '!')
+                                {
+                                    goto basic_json_parser_4;
+                                }
+                                goto basic_json_parser_9;
+                            }
+                            else
+                            {
+                                if (yych <= '+')
+                                {
+                                    goto basic_json_parser_4;
+                                }
+                                if (yych <= ',')
+                                {
+                                    goto basic_json_parser_10;
+                                }
+                                goto basic_json_parser_12;
+                            }
+                        }
+                        else
+                        {
+                            if (yych <= '9')
+                            {
+                                if (yych <= '/')
+                                {
+                                    goto basic_json_parser_4;
+                                }
+                                if (yych <= '0')
+                                {
+                                    goto basic_json_parser_13;
+                                }
+                                goto basic_json_parser_15;
+                            }
+                            else
+                            {
+                                if (yych <= ':')
+                                {
+                                    goto basic_json_parser_17;
+                                }
+                                if (yych <= 'Z')
+                                {
+                                    goto basic_json_parser_4;
+                                }
+                                goto basic_json_parser_19;
+                            }
+                        }
+                    }
+                    else
+                    {
+                        if (yych <= 'n')
+                        {
+                            if (yych <= 'e')
+                            {
+                                if (yych == ']')
+                                {
+                                    goto basic_json_parser_21;
+                                }
+                                goto basic_json_parser_4;
+                            }
+                            else
+                            {
+                                if (yych <= 'f')
+                                {
+                                    goto basic_json_parser_23;
+                                }
+                                if (yych <= 'm')
+                                {
+                                    goto basic_json_parser_4;
+                                }
+                                goto basic_json_parser_24;
+                            }
+                        }
+                        else
+                        {
+                            if (yych <= 'z')
+                            {
+                                if (yych == 't')
+                                {
+                                    goto basic_json_parser_25;
+                                }
+                                goto basic_json_parser_4;
+                            }
+                            else
+                            {
+                                if (yych <= '{')
+                                {
+                                    goto basic_json_parser_26;
+                                }
+                                if (yych == '}')
+                                {
+                                    goto basic_json_parser_28;
+                                }
+                                goto basic_json_parser_4;
+                            }
+                        }
+                    }
+basic_json_parser_2:
+                    ++m_cursor;
+                    {
+                        last_token_type = token_type::end_of_input;
+                        break;
+                    }
+basic_json_parser_4:
+                    ++m_cursor;
+basic_json_parser_5:
+                    {
+                        last_token_type = token_type::parse_error;
+                        break;
+                    }
+basic_json_parser_6:
+                    ++m_cursor;
+                    if (m_limit <= m_cursor)
+                    {
+                        fill_line_buffer(1);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yybm[0 + yych] & 32)
+                    {
+                        goto basic_json_parser_6;
+                    }
+                    {
+                        continue;
+                    }
+basic_json_parser_9:
+                    yyaccept = 0;
+                    yych = *(m_marker = ++m_cursor);
+                    if (yych <= 0x1F)
+                    {
+                        goto basic_json_parser_5;
+                    }
+                    if (yych <= 0x7F)
+                    {
+                        goto basic_json_parser_31;
+                    }
+                    if (yych <= 0xC1)
+                    {
+                        goto basic_json_parser_5;
+                    }
+                    if (yych <= 0xF4)
+                    {
+                        goto basic_json_parser_31;
+                    }
+                    goto basic_json_parser_5;
+basic_json_parser_10:
+                    ++m_cursor;
+                    {
+                        last_token_type = token_type::value_separator;
+                        break;
+                    }
+basic_json_parser_12:
+                    yych = *++m_cursor;
+                    if (yych <= '/')
+                    {
+                        goto basic_json_parser_5;
+                    }
+                    if (yych <= '0')
+                    {
+                        goto basic_json_parser_43;
+                    }
+                    if (yych <= '9')
+                    {
+                        goto basic_json_parser_45;
+                    }
+                    goto basic_json_parser_5;
+basic_json_parser_13:
+                    yyaccept = 1;
+                    yych = *(m_marker = ++m_cursor);
+                    if (yych <= '9')
+                    {
+                        if (yych == '.')
+                        {
+                            goto basic_json_parser_47;
+                        }
+                        if (yych >= '0')
+                        {
+                            goto basic_json_parser_48;
+                        }
+                    }
+                    else
+                    {
+                        if (yych <= 'E')
+                        {
+                            if (yych >= 'E')
+                            {
+                                goto basic_json_parser_51;
+                            }
+                        }
+                        else
+                        {
+                            if (yych == 'e')
+                            {
+                                goto basic_json_parser_51;
+                            }
+                        }
+                    }
+basic_json_parser_14:
+                    {
+                        last_token_type = token_type::value_unsigned;
+                        break;
+                    }
+basic_json_parser_15:
+                    yyaccept = 1;
+                    m_marker = ++m_cursor;
+                    if ((m_limit - m_cursor) < 3)
+                    {
+                        fill_line_buffer(3);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yybm[0 + yych] & 64)
+                    {
+                        goto basic_json_parser_15;
+                    }
+                    if (yych <= 'D')
+                    {
+                        if (yych == '.')
+                        {
+                            goto basic_json_parser_47;
+                        }
+                        goto basic_json_parser_14;
+                    }
+                    else
+                    {
+                        if (yych <= 'E')
+                        {
+                            goto basic_json_parser_51;
+                        }
+                        if (yych == 'e')
+                        {
+                            goto basic_json_parser_51;
+                        }
+                        goto basic_json_parser_14;
+                    }
+basic_json_parser_17:
+                    ++m_cursor;
+                    {
+                        last_token_type = token_type::name_separator;
+                        break;
+                    }
+basic_json_parser_19:
+                    ++m_cursor;
+                    {
+                        last_token_type = token_type::begin_array;
+                        break;
+                    }
+basic_json_parser_21:
+                    ++m_cursor;
+                    {
+                        last_token_type = token_type::end_array;
+                        break;
+                    }
+basic_json_parser_23:
+                    yyaccept = 0;
+                    yych = *(m_marker = ++m_cursor);
+                    if (yych == 'a')
+                    {
+                        goto basic_json_parser_52;
+                    }
+                    goto basic_json_parser_5;
+basic_json_parser_24:
+                    yyaccept = 0;
+                    yych = *(m_marker = ++m_cursor);
+                    if (yych == 'u')
+                    {
+                        goto basic_json_parser_53;
+                    }
+                    goto basic_json_parser_5;
+basic_json_parser_25:
+                    yyaccept = 0;
+                    yych = *(m_marker = ++m_cursor);
+                    if (yych == 'r')
+                    {
+                        goto basic_json_parser_54;
+                    }
+                    goto basic_json_parser_5;
+basic_json_parser_26:
+                    ++m_cursor;
+                    {
+                        last_token_type = token_type::begin_object;
+                        break;
+                    }
+basic_json_parser_28:
+                    ++m_cursor;
+                    {
+                        last_token_type = token_type::end_object;
+                        break;
+                    }
+basic_json_parser_30:
+                    ++m_cursor;
+                    if (m_limit <= m_cursor)
+                    {
+                        fill_line_buffer(1);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+basic_json_parser_31:
+                    if (yybm[0 + yych] & 128)
+                    {
+                        goto basic_json_parser_30;
+                    }
+                    if (yych <= 0xE0)
+                    {
+                        if (yych <= '\\')
+                        {
+                            if (yych <= 0x1F)
+                            {
+                                goto basic_json_parser_32;
+                            }
+                            if (yych <= '"')
+                            {
+                                goto basic_json_parser_33;
+                            }
+                            goto basic_json_parser_35;
+                        }
+                        else
+                        {
+                            if (yych <= 0xC1)
+                            {
+                                goto basic_json_parser_32;
+                            }
+                            if (yych <= 0xDF)
+                            {
+                                goto basic_json_parser_36;
+                            }
+                            goto basic_json_parser_37;
+                        }
+                    }
+                    else
+                    {
+                        if (yych <= 0xEF)
+                        {
+                            if (yych == 0xED)
+                            {
+                                goto basic_json_parser_39;
+                            }
+                            goto basic_json_parser_38;
+                        }
+                        else
+                        {
+                            if (yych <= 0xF0)
+                            {
+                                goto basic_json_parser_40;
+                            }
+                            if (yych <= 0xF3)
+                            {
+                                goto basic_json_parser_41;
+                            }
+                            if (yych <= 0xF4)
+                            {
+                                goto basic_json_parser_42;
+                            }
+                        }
+                    }
+basic_json_parser_32:
+                    m_cursor = m_marker;
+                    if (yyaccept <= 1)
+                    {
+                        if (yyaccept == 0)
+                        {
+                            goto basic_json_parser_5;
+                        }
+                        else
+                        {
+                            goto basic_json_parser_14;
+                        }
+                    }
+                    else
+                    {
+                        if (yyaccept == 2)
+                        {
+                            goto basic_json_parser_44;
+                        }
+                        else
+                        {
+                            goto basic_json_parser_58;
+                        }
+                    }
+basic_json_parser_33:
+                    ++m_cursor;
+                    {
+                        last_token_type = token_type::value_string;
+                        break;
+                    }
+basic_json_parser_35:
+                    ++m_cursor;
+                    if (m_limit <= m_cursor)
+                    {
+                        fill_line_buffer(1);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yych <= 'e')
+                    {
+                        if (yych <= '/')
+                        {
+                            if (yych == '"')
+                            {
+                                goto basic_json_parser_30;
+                            }
+                            if (yych <= '.')
+                            {
+                                goto basic_json_parser_32;
+                            }
+                            goto basic_json_parser_30;
+                        }
+                        else
+                        {
+                            if (yych <= '\\')
+                            {
+                                if (yych <= '[')
+                                {
+                                    goto basic_json_parser_32;
+                                }
+                                goto basic_json_parser_30;
+                            }
+                            else
+                            {
+                                if (yych == 'b')
+                                {
+                                    goto basic_json_parser_30;
+                                }
+                                goto basic_json_parser_32;
+                            }
+                        }
+                    }
+                    else
+                    {
+                        if (yych <= 'q')
+                        {
+                            if (yych <= 'f')
+                            {
+                                goto basic_json_parser_30;
+                            }
+                            if (yych == 'n')
+                            {
+                                goto basic_json_parser_30;
+                            }
+                            goto basic_json_parser_32;
+                        }
+                        else
+                        {
+                            if (yych <= 's')
+                            {
+                                if (yych <= 'r')
+                                {
+                                    goto basic_json_parser_30;
+                                }
+                                goto basic_json_parser_32;
+                            }
+                            else
+                            {
+                                if (yych <= 't')
+                                {
+                                    goto basic_json_parser_30;
+                                }
+                                if (yych <= 'u')
+                                {
+                                    goto basic_json_parser_55;
+                                }
+                                goto basic_json_parser_32;
+                            }
+                        }
+                    }
+basic_json_parser_36:
+                    ++m_cursor;
+                    if (m_limit <= m_cursor)
+                    {
+                        fill_line_buffer(1);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yych <= 0x7F)
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych <= 0xBF)
+                    {
+                        goto basic_json_parser_30;
+                    }
+                    goto basic_json_parser_32;
+basic_json_parser_37:
+                    ++m_cursor;
+                    if (m_limit <= m_cursor)
+                    {
+                        fill_line_buffer(1);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yych <= 0x9F)
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych <= 0xBF)
+                    {
+                        goto basic_json_parser_36;
+                    }
+                    goto basic_json_parser_32;
+basic_json_parser_38:
+                    ++m_cursor;
+                    if (m_limit <= m_cursor)
+                    {
+                        fill_line_buffer(1);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yych <= 0x7F)
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych <= 0xBF)
+                    {
+                        goto basic_json_parser_36;
+                    }
+                    goto basic_json_parser_32;
+basic_json_parser_39:
+                    ++m_cursor;
+                    if (m_limit <= m_cursor)
+                    {
+                        fill_line_buffer(1);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yych <= 0x7F)
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych <= 0x9F)
+                    {
+                        goto basic_json_parser_36;
+                    }
+                    goto basic_json_parser_32;
+basic_json_parser_40:
+                    ++m_cursor;
+                    if (m_limit <= m_cursor)
+                    {
+                        fill_line_buffer(1);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yych <= 0x8F)
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych <= 0xBF)
+                    {
+                        goto basic_json_parser_38;
+                    }
+                    goto basic_json_parser_32;
+basic_json_parser_41:
+                    ++m_cursor;
+                    if (m_limit <= m_cursor)
+                    {
+                        fill_line_buffer(1);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yych <= 0x7F)
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych <= 0xBF)
+                    {
+                        goto basic_json_parser_38;
+                    }
+                    goto basic_json_parser_32;
+basic_json_parser_42:
+                    ++m_cursor;
+                    if (m_limit <= m_cursor)
+                    {
+                        fill_line_buffer(1);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yych <= 0x7F)
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych <= 0x8F)
+                    {
+                        goto basic_json_parser_38;
+                    }
+                    goto basic_json_parser_32;
+basic_json_parser_43:
+                    yyaccept = 2;
+                    yych = *(m_marker = ++m_cursor);
+                    if (yych <= '9')
+                    {
+                        if (yych == '.')
+                        {
+                            goto basic_json_parser_47;
+                        }
+                        if (yych >= '0')
+                        {
+                            goto basic_json_parser_48;
+                        }
+                    }
+                    else
+                    {
+                        if (yych <= 'E')
+                        {
+                            if (yych >= 'E')
+                            {
+                                goto basic_json_parser_51;
+                            }
+                        }
+                        else
+                        {
+                            if (yych == 'e')
+                            {
+                                goto basic_json_parser_51;
+                            }
+                        }
+                    }
+basic_json_parser_44:
+                    {
+                        last_token_type = token_type::value_integer;
+                        break;
+                    }
+basic_json_parser_45:
+                    yyaccept = 2;
+                    m_marker = ++m_cursor;
+                    if ((m_limit - m_cursor) < 3)
+                    {
+                        fill_line_buffer(3);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yych <= '9')
+                    {
+                        if (yych == '.')
+                        {
+                            goto basic_json_parser_47;
+                        }
+                        if (yych <= '/')
+                        {
+                            goto basic_json_parser_44;
+                        }
+                        goto basic_json_parser_45;
+                    }
+                    else
+                    {
+                        if (yych <= 'E')
+                        {
+                            if (yych <= 'D')
+                            {
+                                goto basic_json_parser_44;
+                            }
+                            goto basic_json_parser_51;
+                        }
+                        else
+                        {
+                            if (yych == 'e')
+                            {
+                                goto basic_json_parser_51;
+                            }
+                            goto basic_json_parser_44;
+                        }
+                    }
+basic_json_parser_47:
+                    yych = *++m_cursor;
+                    if (yych <= '/')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych <= '9')
+                    {
+                        goto basic_json_parser_56;
+                    }
+                    goto basic_json_parser_32;
+basic_json_parser_48:
+                    ++m_cursor;
+                    if (m_limit <= m_cursor)
+                    {
+                        fill_line_buffer(1);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yych <= '/')
+                    {
+                        goto basic_json_parser_50;
+                    }
+                    if (yych <= '9')
+                    {
+                        goto basic_json_parser_48;
+                    }
+basic_json_parser_50:
+                    {
+                        last_token_type = token_type::parse_error;
+                        break;
+                    }
+basic_json_parser_51:
+                    yych = *++m_cursor;
+                    if (yych <= ',')
+                    {
+                        if (yych == '+')
+                        {
+                            goto basic_json_parser_59;
+                        }
+                        goto basic_json_parser_32;
+                    }
+                    else
+                    {
+                        if (yych <= '-')
+                        {
+                            goto basic_json_parser_59;
+                        }
+                        if (yych <= '/')
+                        {
+                            goto basic_json_parser_32;
+                        }
+                        if (yych <= '9')
+                        {
+                            goto basic_json_parser_60;
+                        }
+                        goto basic_json_parser_32;
+                    }
+basic_json_parser_52:
+                    yych = *++m_cursor;
+                    if (yych == 'l')
+                    {
+                        goto basic_json_parser_62;
+                    }
+                    goto basic_json_parser_32;
+basic_json_parser_53:
+                    yych = *++m_cursor;
+                    if (yych == 'l')
+                    {
+                        goto basic_json_parser_63;
+                    }
+                    goto basic_json_parser_32;
+basic_json_parser_54:
+                    yych = *++m_cursor;
+                    if (yych == 'u')
+                    {
+                        goto basic_json_parser_64;
+                    }
+                    goto basic_json_parser_32;
+basic_json_parser_55:
+                    ++m_cursor;
+                    if (m_limit <= m_cursor)
+                    {
+                        fill_line_buffer(1);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yych <= '@')
+                    {
+                        if (yych <= '/')
+                        {
+                            goto basic_json_parser_32;
+                        }
+                        if (yych <= '9')
+                        {
+                            goto basic_json_parser_65;
+                        }
+                        goto basic_json_parser_32;
+                    }
+                    else
+                    {
+                        if (yych <= 'F')
+                        {
+                            goto basic_json_parser_65;
+                        }
+                        if (yych <= '`')
+                        {
+                            goto basic_json_parser_32;
+                        }
+                        if (yych <= 'f')
+                        {
+                            goto basic_json_parser_65;
+                        }
+                        goto basic_json_parser_32;
+                    }
+basic_json_parser_56:
+                    yyaccept = 3;
+                    m_marker = ++m_cursor;
+                    if ((m_limit - m_cursor) < 3)
+                    {
+                        fill_line_buffer(3);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yych <= 'D')
+                    {
+                        if (yych <= '/')
+                        {
+                            goto basic_json_parser_58;
+                        }
+                        if (yych <= '9')
+                        {
+                            goto basic_json_parser_56;
+                        }
+                    }
+                    else
+                    {
+                        if (yych <= 'E')
+                        {
+                            goto basic_json_parser_51;
+                        }
+                        if (yych == 'e')
+                        {
+                            goto basic_json_parser_51;
+                        }
+                    }
+basic_json_parser_58:
+                    {
+                        last_token_type = token_type::value_float;
+                        break;
+                    }
+basic_json_parser_59:
+                    yych = *++m_cursor;
+                    if (yych <= '/')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych >= ':')
+                    {
+                        goto basic_json_parser_32;
+                    }
+basic_json_parser_60:
+                    ++m_cursor;
+                    if (m_limit <= m_cursor)
+                    {
+                        fill_line_buffer(1);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yych <= '/')
+                    {
+                        goto basic_json_parser_58;
+                    }
+                    if (yych <= '9')
+                    {
+                        goto basic_json_parser_60;
+                    }
+                    goto basic_json_parser_58;
+basic_json_parser_62:
+                    yych = *++m_cursor;
+                    if (yych == 's')
+                    {
+                        goto basic_json_parser_66;
+                    }
+                    goto basic_json_parser_32;
+basic_json_parser_63:
+                    yych = *++m_cursor;
+                    if (yych == 'l')
+                    {
+                        goto basic_json_parser_67;
+                    }
+                    goto basic_json_parser_32;
+basic_json_parser_64:
+                    yych = *++m_cursor;
+                    if (yych == 'e')
+                    {
+                        goto basic_json_parser_69;
+                    }
+                    goto basic_json_parser_32;
+basic_json_parser_65:
+                    ++m_cursor;
+                    if (m_limit <= m_cursor)
+                    {
+                        fill_line_buffer(1);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yych <= '@')
+                    {
+                        if (yych <= '/')
+                        {
+                            goto basic_json_parser_32;
+                        }
+                        if (yych <= '9')
+                        {
+                            goto basic_json_parser_71;
+                        }
+                        goto basic_json_parser_32;
+                    }
+                    else
+                    {
+                        if (yych <= 'F')
+                        {
+                            goto basic_json_parser_71;
+                        }
+                        if (yych <= '`')
+                        {
+                            goto basic_json_parser_32;
+                        }
+                        if (yych <= 'f')
+                        {
+                            goto basic_json_parser_71;
+                        }
+                        goto basic_json_parser_32;
+                    }
+basic_json_parser_66:
+                    yych = *++m_cursor;
+                    if (yych == 'e')
+                    {
+                        goto basic_json_parser_72;
+                    }
+                    goto basic_json_parser_32;
+basic_json_parser_67:
+                    ++m_cursor;
+                    {
+                        last_token_type = token_type::literal_null;
+                        break;
+                    }
+basic_json_parser_69:
+                    ++m_cursor;
+                    {
+                        last_token_type = token_type::literal_true;
+                        break;
+                    }
+basic_json_parser_71:
+                    ++m_cursor;
+                    if (m_limit <= m_cursor)
+                    {
+                        fill_line_buffer(1);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yych <= '@')
+                    {
+                        if (yych <= '/')
+                        {
+                            goto basic_json_parser_32;
+                        }
+                        if (yych <= '9')
+                        {
+                            goto basic_json_parser_74;
+                        }
+                        goto basic_json_parser_32;
+                    }
+                    else
+                    {
+                        if (yych <= 'F')
+                        {
+                            goto basic_json_parser_74;
+                        }
+                        if (yych <= '`')
+                        {
+                            goto basic_json_parser_32;
+                        }
+                        if (yych <= 'f')
+                        {
+                            goto basic_json_parser_74;
+                        }
+                        goto basic_json_parser_32;
+                    }
+basic_json_parser_72:
+                    ++m_cursor;
+                    {
+                        last_token_type = token_type::literal_false;
+                        break;
+                    }
+basic_json_parser_74:
+                    ++m_cursor;
+                    if (m_limit <= m_cursor)
+                    {
+                        fill_line_buffer(1);    // LCOV_EXCL_LINE
+                    }
+                    yych = *m_cursor;
+                    if (yych <= '@')
+                    {
+                        if (yych <= '/')
+                        {
+                            goto basic_json_parser_32;
+                        }
+                        if (yych <= '9')
+                        {
+                            goto basic_json_parser_30;
+                        }
+                        goto basic_json_parser_32;
+                    }
+                    else
+                    {
+                        if (yych <= 'F')
+                        {
+                            goto basic_json_parser_30;
+                        }
+                        if (yych <= '`')
+                        {
+                            goto basic_json_parser_32;
+                        }
+                        if (yych <= 'f')
+                        {
+                            goto basic_json_parser_30;
+                        }
+                        goto basic_json_parser_32;
+                    }
+                }
+
+            }
+
+            return last_token_type;
+        }
+
+        /*!
+        @brief append data from the stream to the line buffer
+
+        This function is called by the scan() function when the end of the
+        buffer (`m_limit`) is reached and the `m_cursor` pointer cannot be
+        incremented without leaving the limits of the line buffer. Note re2c
+        decides when to call this function.
+
+        If the lexer reads from contiguous storage, there is no trailing null
+        byte. Therefore, this function must make sure to add these padding
+        null bytes.
+
+        If the lexer reads from an input stream, this function reads the next
+        line of the input.
+
+        @pre
+            p p p p p p u u u u u x . . . . . .
+            ^           ^       ^   ^
+            m_content   m_start |   m_limit
+                                m_cursor
+
+        @post
+            u u u u u x x x x x x x . . . . . .
+            ^       ^               ^
+            |       m_cursor        m_limit
+            m_start
+            m_content
+        */
+        void fill_line_buffer(size_t n = 0)
+        {
+            // if line buffer is used, m_content points to its data
+            assert(m_line_buffer.empty()
+                   or m_content == reinterpret_cast<const lexer_char_t*>(m_line_buffer.data()));
+
+            // if line buffer is used, m_limit is set past the end of its data
+            assert(m_line_buffer.empty()
+                   or m_limit == m_content + m_line_buffer.size());
+
+            // pointer relationships
+            assert(m_content <= m_start);
+            assert(m_start <= m_cursor);
+            assert(m_cursor <= m_limit);
+            assert(m_marker == nullptr or m_marker  <= m_limit);
+
+            // number of processed characters (p)
+            const auto num_processed_chars = static_cast<size_t>(m_start - m_content);
+            // offset for m_marker wrt. to m_start
+            const auto offset_marker = (m_marker == nullptr) ? 0 : m_marker - m_start;
+            // number of unprocessed characters (u)
+            const auto offset_cursor = m_cursor - m_start;
+
+            // no stream is used or end of file is reached
+            if (m_stream == nullptr or m_stream->eof())
+            {
+                // m_start may or may not be pointing into m_line_buffer at
+                // this point. We trust the standard library to do the right
+                // thing. See http://stackoverflow.com/q/28142011/266378
+                m_line_buffer.assign(m_start, m_limit);
+
+                // append n characters to make sure that there is sufficient
+                // space between m_cursor and m_limit
+                m_line_buffer.append(1, '\x00');
+                if (n > 0)
+                {
+                    m_line_buffer.append(n - 1, '\x01');
+                }
+            }
+            else
+            {
+                // delete processed characters from line buffer
+                m_line_buffer.erase(0, num_processed_chars);
+                // read next line from input stream
+                m_line_buffer_tmp.clear();
+                std::getline(*m_stream, m_line_buffer_tmp, '\n');
+
+                // add line with newline symbol to the line buffer
+                m_line_buffer += m_line_buffer_tmp;
+                m_line_buffer.push_back('\n');
+            }
+
+            // set pointers
+            m_content = reinterpret_cast<const lexer_char_t*>(m_line_buffer.data());
+            assert(m_content != nullptr);
+            m_start  = m_content;
+            m_marker = m_start + offset_marker;
+            m_cursor = m_start + offset_cursor;
+            m_limit  = m_start + m_line_buffer.size();
+        }
+
+        /// return string representation of last read token
+        string_t get_token_string() const
+        {
+            assert(m_start != nullptr);
+            return string_t(reinterpret_cast<typename string_t::const_pointer>(m_start),
+                            static_cast<size_t>(m_cursor - m_start));
+        }
+
+        /*!
+        @brief return string value for string tokens
+
+        The function iterates the characters between the opening and closing
+        quotes of the string value. The complete string is the range
+        [m_start,m_cursor). Consequently, we iterate from m_start+1 to
+        m_cursor-1.
+
+        We differentiate two cases:
+
+        1. Escaped characters. In this case, a new character is constructed
+           according to the nature of the escape. Some escapes create new
+           characters (e.g., `"\\n"` is replaced by `"\n"`), some are copied
+           as is (e.g., `"\\\\"`). Furthermore, Unicode escapes of the shape
+           `"\\uxxxx"` need special care. In this case, to_unicode takes care
+           of the construction of the values.
+        2. Unescaped characters are copied as is.
+
+        @pre `m_cursor - m_start >= 2`, meaning the length of the last token
+        is at least 2 bytes which is trivially true for any string (which
+        consists of at least two quotes).
+
+            " c1 c2 c3 ... "
+            ^                ^
+            m_start          m_cursor
+
+        @complexity Linear in the length of the string.\n
+
+        Lemma: The loop body will always terminate.\n
+
+        Proof (by contradiction): Assume the loop body does not terminate. As
+        the loop body does not contain another loop, one of the called
+        functions must never return. The called functions are `std::strtoul`
+        and to_unicode. Neither function can loop forever, so the loop body
+        will never loop forever which contradicts the assumption that the loop
+        body does not terminate, q.e.d.\n
+
+        Lemma: The loop condition for the for loop is eventually false.\n
+
+        Proof (by contradiction): Assume the loop does not terminate. Due to
+        the above lemma, this can only be due to a tautological loop
+        condition; that is, the loop condition i < m_cursor - 1 must always be
+        true. Let x be the change of i for any loop iteration. Then
+        m_start + 1 + x < m_cursor - 1 must hold to loop indefinitely. This
+        can be rephrased to m_cursor - m_start - 2 > x. With the
+        precondition, we x <= 0, meaning that the loop condition holds
+        indefinitely if i is always decreased. However, observe that the value
+        of i is strictly increasing with each iteration, as it is incremented
+        by 1 in the iteration expression and never decremented inside the loop
+        body. Hence, the loop condition will eventually be false which
+        contradicts the assumption that the loop condition is a tautology,
+        q.e.d.
+
+        @return string value of current token without opening and closing
+        quotes
+        @throw std::out_of_range if to_unicode fails
+        */
+        string_t get_string() const
+        {
+            assert(m_cursor - m_start >= 2);
+
+            string_t result;
+            result.reserve(static_cast<size_t>(m_cursor - m_start - 2));
+
+            // iterate the result between the quotes
+            for (const lexer_char_t* i = m_start + 1; i < m_cursor - 1; ++i)
+            {
+                // find next escape character
+                auto e = std::find(i, m_cursor - 1, '\\');
+                if (e != i)
+                {
+                    // see https://github.com/nlohmann/json/issues/365#issuecomment-262874705
+                    for (auto k = i; k < e; k++)
+                    {
+                        result.push_back(static_cast<typename string_t::value_type>(*k));
+                    }
+                    i = e - 1; // -1 because of ++i
+                }
+                else
+                {
+                    // processing escaped character
+                    // read next character
+                    ++i;
+
+                    switch (*i)
+                    {
+                        // the default escapes
+                        case 't':
+                        {
+                            result += "\t";
+                            break;
+                        }
+                        case 'b':
+                        {
+                            result += "\b";
+                            break;
+                        }
+                        case 'f':
+                        {
+                            result += "\f";
+                            break;
+                        }
+                        case 'n':
+                        {
+                            result += "\n";
+                            break;
+                        }
+                        case 'r':
+                        {
+                            result += "\r";
+                            break;
+                        }
+                        case '\\':
+                        {
+                            result += "\\";
+                            break;
+                        }
+                        case '/':
+                        {
+                            result += "/";
+                            break;
+                        }
+                        case '"':
+                        {
+                            result += "\"";
+                            break;
+                        }
+
+                        // unicode
+                        case 'u':
+                        {
+                            // get code xxxx from uxxxx
+                            auto codepoint = std::strtoul(std::string(reinterpret_cast<typename string_t::const_pointer>(i + 1),
+                                                          4).c_str(), nullptr, 16);
+
+                            // check if codepoint is a high surrogate
+                            if (codepoint >= 0xD800 and codepoint <= 0xDBFF)
+                            {
+                                // make sure there is a subsequent unicode
+                                if ((i + 6 >= m_limit) or * (i + 5) != '\\' or * (i + 6) != 'u')
+                                {
+                                    JSON_THROW(std::invalid_argument("missing low surrogate"));
+                                }
+
+                                // get code yyyy from uxxxx\uyyyy
+                                auto codepoint2 = std::strtoul(std::string(reinterpret_cast<typename string_t::const_pointer>
+                                                               (i + 7), 4).c_str(), nullptr, 16);
+                                result += to_unicode(codepoint, codepoint2);
+                                // skip the next 10 characters (xxxx\uyyyy)
+                                i += 10;
+                            }
+                            else if (codepoint >= 0xDC00 and codepoint <= 0xDFFF)
+                            {
+                                // we found a lone low surrogate
+                                JSON_THROW(std::invalid_argument("missing high surrogate"));
+                            }
+                            else
+                            {
+                                // add unicode character(s)
+                                result += to_unicode(codepoint);
+                                // skip the next four characters (xxxx)
+                                i += 4;
+                            }
+                            break;
+                        }
+                    }
+                }
+            }
+
+            return result;
+        }
+
+
+        /*!
+        @brief parse string into a built-in arithmetic type as if the current
+               locale is POSIX.
+
+        @note in floating-point case strtod may parse past the token's end -
+              this is not an error
+
+        @note any leading blanks are not handled
+        */
+        struct strtonum
+        {
+          public:
+            strtonum(const char* start, const char* end)
+                : m_start(start), m_end(end)
+            {}
+
+            /*!
+            @return true iff parsed successfully as number of type T
+
+            @param[in,out] val shall contain parsed value, or undefined value
+            if could not parse
+            */
+            template<typename T, typename = typename std::enable_if<std::is_arithmetic<T>::value>::type>
+            bool to(T& val) const
+            {
+                return parse(val, std::is_integral<T>());
+            }
+
+          private:
+            const char* const m_start = nullptr;
+            const char* const m_end = nullptr;
+
+            // floating-point conversion
+
+            // overloaded wrappers for strtod/strtof/strtold
+            // that will be called from parse<floating_point_t>
+            static void strtof(float& f, const char* str, char** endptr)
+            {
+                f = std::strtof(str, endptr);
+            }
+
+            static void strtof(double& f, const char* str, char** endptr)
+            {
+                f = std::strtod(str, endptr);
+            }
+
+            static void strtof(long double& f, const char* str, char** endptr)
+            {
+                f = std::strtold(str, endptr);
+            }
+
+            template<typename T>
+            bool parse(T& value, /*is_integral=*/std::false_type) const
+            {
+                // replace decimal separator with locale-specific version,
+                // when necessary; data will point to either the original
+                // string, or buf, or tempstr containing the fixed string.
+                std::string tempstr;
+                std::array<char, 64> buf;
+                const size_t len = static_cast<size_t>(m_end - m_start);
+
+                // lexer will reject empty numbers
+                assert(len > 0);
+
+                // since dealing with strtod family of functions, we're
+                // getting the decimal point char from the C locale facilities
+                // instead of C++'s numpunct facet of the current std::locale
+                const auto loc = localeconv();
+                assert(loc != nullptr);
+                const char decimal_point_char = (loc->decimal_point == nullptr) ? '.' : loc->decimal_point[0];
+
+                const char* data = m_start;
+
+                if (decimal_point_char != '.')
+                {
+                    const size_t ds_pos = static_cast<size_t>(std::find(m_start, m_end, '.') - m_start);
+
+                    if (ds_pos != len)
+                    {
+                        // copy the data into the local buffer or tempstr, if
+                        // buffer is too small; replace decimal separator, and
+                        // update data to point to the modified bytes
+                        if ((len + 1) < buf.size())
+                        {
+                            std::copy(m_start, m_end, buf.begin());
+                            buf[len] = 0;
+                            buf[ds_pos] = decimal_point_char;
+                            data = buf.data();
+                        }
+                        else
+                        {
+                            tempstr.assign(m_start, m_end);
+                            tempstr[ds_pos] = decimal_point_char;
+                            data = tempstr.c_str();
+                        }
+                    }
+                }
+
+                char* endptr = nullptr;
+                value = 0;
+                // this calls appropriate overload depending on T
+                strtof(value, data, &endptr);
+
+                // parsing was successful iff strtof parsed exactly the number
+                // of characters determined by the lexer (len)
+                const bool ok = (endptr == (data + len));
+
+                if (ok and (value == static_cast<T>(0.0)) and (*data == '-'))
+                {
+                    // some implementations forget to negate the zero
+                    value = -0.0;
+                }
+
+                return ok;
+            }
+
+            // integral conversion
+
+            signed long long parse_integral(char** endptr, /*is_signed*/std::true_type) const
+            {
+                return std::strtoll(m_start, endptr, 10);
+            }
+
+            unsigned long long parse_integral(char** endptr, /*is_signed*/std::false_type) const
+            {
+                return std::strtoull(m_start, endptr, 10);
+            }
+
+            template<typename T>
+            bool parse(T& value, /*is_integral=*/std::true_type) const
+            {
+                char* endptr = nullptr;
+                errno = 0; // these are thread-local
+                const auto x = parse_integral(&endptr, std::is_signed<T>());
+
+                // called right overload?
+                static_assert(std::is_signed<T>() == std::is_signed<decltype(x)>(), "");
+
+                value = static_cast<T>(x);
+
+                return (x == static_cast<decltype(x)>(value)) // x fits into destination T
+                       and (x < 0) == (value < 0)             // preserved sign
+                       //and ((x != 0) or is_integral())        // strto[u]ll did nto fail
+                       and (errno == 0)                       // strto[u]ll did not overflow
+                       and (m_start < m_end)                  // token was not empty
+                       and (endptr == m_end);                 // parsed entire token exactly
+            }
+        };
+
+        /*!
+        @brief return number value for number tokens
+
+        This function translates the last token into the most appropriate
+        number type (either integer, unsigned integer or floating point),
+        which is passed back to the caller via the result parameter.
+
+        integral numbers that don't fit into the the range of the respective
+        type are parsed as number_float_t
+
+        floating-point values do not satisfy std::isfinite predicate
+        are converted to value_t::null
+
+        throws if the entire string [m_start .. m_cursor) cannot be
+        interpreted as a number
+
+        @param[out] result  @ref basic_json object to receive the number.
+        @param[in]  token   the type of the number token
+        */
+        bool get_number(basic_json& result, const token_type token) const
+        {
+            assert(m_start != nullptr);
+            assert(m_start < m_cursor);
+            assert((token == token_type::value_unsigned) or
+                   (token == token_type::value_integer) or
+                   (token == token_type::value_float));
+
+            strtonum num_converter(reinterpret_cast<const char*>(m_start),
+                                   reinterpret_cast<const char*>(m_cursor));
+
+            switch (token)
+            {
+                case lexer::token_type::value_unsigned:
+                {
+                    number_unsigned_t val;
+                    if (num_converter.to(val))
+                    {
+                        // parsing successful
+                        result.m_type = value_t::number_unsigned;
+                        result.m_value = val;
+                        return true;
+                    }
+                    break;
+                }
+
+                case lexer::token_type::value_integer:
+                {
+                    number_integer_t val;
+                    if (num_converter.to(val))
+                    {
+                        // parsing successful
+                        result.m_type = value_t::number_integer;
+                        result.m_value = val;
+                        return true;
+                    }
+                    break;
+                }
+
+                default:
+                {
+                    break;
+                }
+            }
+
+            // parse float (either explicitly or because a previous conversion
+            // failed)
+            number_float_t val;
+            if (num_converter.to(val))
+            {
+                // parsing successful
+                result.m_type = value_t::number_float;
+                result.m_value = val;
+
+                // replace infinity and NAN by null
+                if (not std::isfinite(result.m_value.number_float))
+                {
+                    result.m_type  = value_t::null;
+                    result.m_value = basic_json::json_value();
+                }
+
+                return true;
+            }
+
+            // couldn't parse number in any format
+            return false;
+        }
+
+      private:
+        /// optional input stream
+        std::istream* m_stream = nullptr;
+        /// line buffer buffer for m_stream
+        string_t m_line_buffer {};
+        /// used for filling m_line_buffer
+        string_t m_line_buffer_tmp {};
+        /// the buffer pointer
+        const lexer_char_t* m_content = nullptr;
+        /// pointer to the beginning of the current symbol
+        const lexer_char_t* m_start = nullptr;
+        /// pointer for backtracking information
+        const lexer_char_t* m_marker = nullptr;
+        /// pointer to the current symbol
+        const lexer_char_t* m_cursor = nullptr;
+        /// pointer to the end of the buffer
+        const lexer_char_t* m_limit = nullptr;
+        /// the last token type
+        token_type last_token_type = token_type::end_of_input;
+    };
+
+    /*!
+    @brief syntax analysis
+
+    This class implements a recursive decent parser.
+    */
+    class parser
+    {
+      public:
+        /// a parser reading from a string literal
+        parser(const char* buff, const parser_callback_t cb = nullptr)
+            : callback(cb),
+              m_lexer(reinterpret_cast<const typename lexer::lexer_char_t*>(buff), std::strlen(buff))
+        {}
+
+        /// a parser reading from an input stream
+        parser(std::istream& is, const parser_callback_t cb = nullptr)
+            : callback(cb), m_lexer(is)
+        {}
+
+        /// a parser reading from an iterator range with contiguous storage
+        template<class IteratorType, typename std::enable_if<
+                     std::is_same<typename std::iterator_traits<IteratorType>::iterator_category, std::random_access_iterator_tag>::value
+                     , int>::type
+                 = 0>
+        parser(IteratorType first, IteratorType last, const parser_callback_t cb = nullptr)
+            : callback(cb),
+              m_lexer(reinterpret_cast<const typename lexer::lexer_char_t*>(&(*first)),
+                      static_cast<size_t>(std::distance(first, last)))
+        {}
+
+        /// public parser interface
+        basic_json parse()
+        {
+            // read first token
+            get_token();
+
+            basic_json result = parse_internal(true);
+            result.assert_invariant();
+
+            expect(lexer::token_type::end_of_input);
+
+            // return parser result and replace it with null in case the
+            // top-level value was discarded by the callback function
+            return result.is_discarded() ? basic_json() : std::move(result);
+        }
+
+      private:
+        /// the actual parser
+        basic_json parse_internal(bool keep)
+        {
+            auto result = basic_json(value_t::discarded);
+
+            switch (last_token)
+            {
+                case lexer::token_type::begin_object:
+                {
+                    if (keep and (not callback
+                                  or ((keep = callback(depth++, parse_event_t::object_start, result)) != 0)))
+                    {
+                        // explicitly set result to object to cope with {}
+                        result.m_type = value_t::object;
+                        result.m_value = value_t::object;
+                    }
+
+                    // read next token
+                    get_token();
+
+                    // closing } -> we are done
+                    if (last_token == lexer::token_type::end_object)
+                    {
+                        get_token();
+                        if (keep and callback and not callback(--depth, parse_event_t::object_end, result))
+                        {
+                            result = basic_json(value_t::discarded);
+                        }
+                        return result;
+                    }
+
+                    // no comma is expected here
+                    unexpect(lexer::token_type::value_separator);
+
+                    // otherwise: parse key-value pairs
+                    do
+                    {
+                        // ugly, but could be fixed with loop reorganization
+                        if (last_token == lexer::token_type::value_separator)
+                        {
+                            get_token();
+                        }
+
+                        // store key
+                        expect(lexer::token_type::value_string);
+                        const auto key = m_lexer.get_string();
+
+                        bool keep_tag = false;
+                        if (keep)
+                        {
+                            if (callback)
+                            {
+                                basic_json k(key);
+                                keep_tag = callback(depth, parse_event_t::key, k);
+                            }
+                            else
+                            {
+                                keep_tag = true;
+                            }
+                        }
+
+                        // parse separator (:)
+                        get_token();
+                        expect(lexer::token_type::name_separator);
+
+                        // parse and add value
+                        get_token();
+                        auto value = parse_internal(keep);
+                        if (keep and keep_tag and not value.is_discarded())
+                        {
+                            result[key] = std::move(value);
+                        }
+                    }
+                    while (last_token == lexer::token_type::value_separator);
+
+                    // closing }
+                    expect(lexer::token_type::end_object);
+                    get_token();
+                    if (keep and callback and not callback(--depth, parse_event_t::object_end, result))
+                    {
+                        result = basic_json(value_t::discarded);
+                    }
+
+                    return result;
+                }
+
+                case lexer::token_type::begin_array:
+                {
+                    if (keep and (not callback
+                                  or ((keep = callback(depth++, parse_event_t::array_start, result)) != 0)))
+                    {
+                        // explicitly set result to object to cope with []
+                        result.m_type = value_t::array;
+                        result.m_value = value_t::array;
+                    }
+
+                    // read next token
+                    get_token();
+
+                    // closing ] -> we are done
+                    if (last_token == lexer::token_type::end_array)
+                    {
+                        get_token();
+                        if (callback and not callback(--depth, parse_event_t::array_end, result))
+                        {
+                            result = basic_json(value_t::discarded);
+                        }
+                        return result;
+                    }
+
+                    // no comma is expected here
+                    unexpect(lexer::token_type::value_separator);
+
+                    // otherwise: parse values
+                    do
+                    {
+                        // ugly, but could be fixed with loop reorganization
+                        if (last_token == lexer::token_type::value_separator)
+                        {
+                            get_token();
+                        }
+
+                        // parse value
+                        auto value = parse_internal(keep);
+                        if (keep and not value.is_discarded())
+                        {
+                            result.push_back(std::move(value));
+                        }
+                    }
+                    while (last_token == lexer::token_type::value_separator);
+
+                    // closing ]
+                    expect(lexer::token_type::end_array);
+                    get_token();
+                    if (keep and callback and not callback(--depth, parse_event_t::array_end, result))
+                    {
+                        result = basic_json(value_t::discarded);
+                    }
+
+                    return result;
+                }
+
+                case lexer::token_type::literal_null:
+                {
+                    get_token();
+                    result.m_type = value_t::null;
+                    break;
+                }
+
+                case lexer::token_type::value_string:
+                {
+                    const auto s = m_lexer.get_string();
+                    get_token();
+                    result = basic_json(s);
+                    break;
+                }
+
+                case lexer::token_type::literal_true:
+                {
+                    get_token();
+                    result.m_type = value_t::boolean;
+                    result.m_value = true;
+                    break;
+                }
+
+                case lexer::token_type::literal_false:
+                {
+                    get_token();
+                    result.m_type = value_t::boolean;
+                    result.m_value = false;
+                    break;
+                }
+
+                case lexer::token_type::value_unsigned:
+                case lexer::token_type::value_integer:
+                case lexer::token_type::value_float:
+                {
+                    m_lexer.get_number(result, last_token);
+                    get_token();
+                    break;
+                }
+
+                default:
+                {
+                    // the last token was unexpected
+                    unexpect(last_token);
+                }
+            }
+
+            if (keep and callback and not callback(depth, parse_event_t::value, result))
+            {
+                result = basic_json(value_t::discarded);
+            }
+            return result;
+        }
+
+        /// get next token from lexer
+        typename lexer::token_type get_token()
+        {
+            last_token = m_lexer.scan();
+            return last_token;
+        }
+
+        void expect(typename lexer::token_type t) const
+        {
+            if (t != last_token)
+            {
+                std::string error_msg = "parse error - unexpected ";
+                error_msg += (last_token == lexer::token_type::parse_error ? ("'" +  m_lexer.get_token_string() +
+                              "'") :
+                              lexer::token_type_name(last_token));
+                error_msg += "; expected " + lexer::token_type_name(t);
+                JSON_THROW(std::invalid_argument(error_msg));
+            }
+        }
+
+        void unexpect(typename lexer::token_type t) const
+        {
+            if (t == last_token)
+            {
+                std::string error_msg = "parse error - unexpected ";
+                error_msg += (last_token == lexer::token_type::parse_error ? ("'" +  m_lexer.get_token_string() +
+                              "'") :
+                              lexer::token_type_name(last_token));
+                JSON_THROW(std::invalid_argument(error_msg));
+            }
+        }
+
+      private:
+        /// current level of recursion
+        int depth = 0;
+        /// callback function
+        const parser_callback_t callback = nullptr;
+        /// the type of the last read token
+        typename lexer::token_type last_token = lexer::token_type::uninitialized;
+        /// the lexer
+        lexer m_lexer;
+    };
+
+  public:
+    /*!
+    @brief JSON Pointer
+
+    A JSON pointer defines a string syntax for identifying a specific value
+    within a JSON document. It can be used with functions `at` and
+    `operator[]`. Furthermore, JSON pointers are the base for JSON patches.
+
+    @sa [RFC 6901](https://tools.ietf.org/html/rfc6901)
+
+    @since version 2.0.0
+    */
+    class json_pointer
+    {
+        /// allow basic_json to access private members
+        friend class basic_json;
+
+      public:
+        /*!
+        @brief create JSON pointer
+
+        Create a JSON pointer according to the syntax described in
+        [Section 3 of RFC6901](https://tools.ietf.org/html/rfc6901#section-3).
+
+        @param[in] s  string representing the JSON pointer; if omitted, the
+                      empty string is assumed which references the whole JSON
+                      value
+
+        @throw std::domain_error if reference token is nonempty and does not
+        begin with a slash (`/`); example: `"JSON pointer must be empty or
+        begin with /"`
+        @throw std::domain_error if a tilde (`~`) is not followed by `0`
+        (representing `~`) or `1` (representing `/`); example: `"escape error:
+        ~ must be followed with 0 or 1"`
+
+        @liveexample{The example shows the construction several valid JSON
+        pointers as well as the exceptional behavior.,json_pointer}
+
+        @since version 2.0.0
+        */
+        explicit json_pointer(const std::string& s = "")
+            : reference_tokens(split(s))
+        {}
+
+        /*!
+        @brief return a string representation of the JSON pointer
+
+        @invariant For each JSON pointer `ptr`, it holds:
+        @code {.cpp}
+        ptr == json_pointer(ptr.to_string());
+        @endcode
+
+        @return a string representation of the JSON pointer
+
+        @liveexample{The example shows the result of `to_string`.,
+        json_pointer__to_string}
+
+        @since version 2.0.0
+        */
+        std::string to_string() const noexcept
+        {
+            return std::accumulate(reference_tokens.begin(),
+                                   reference_tokens.end(), std::string{},
+                                   [](const std::string & a, const std::string & b)
+            {
+                return a + "/" + escape(b);
+            });
+        }
+
+        /// @copydoc to_string()
+        operator std::string() const
+        {
+            return to_string();
+        }
+
+      private:
+        /// remove and return last reference pointer
+        std::string pop_back()
+        {
+            if (is_root())
+            {
+                JSON_THROW(std::domain_error("JSON pointer has no parent"));
+            }
+
+            auto last = reference_tokens.back();
+            reference_tokens.pop_back();
+            return last;
+        }
+
+        /// return whether pointer points to the root document
+        bool is_root() const
+        {
+            return reference_tokens.empty();
+        }
+
+        json_pointer top() const
+        {
+            if (is_root())
+            {
+                JSON_THROW(std::domain_error("JSON pointer has no parent"));
+            }
+
+            json_pointer result = *this;
+            result.reference_tokens = {reference_tokens[0]};
+            return result;
+        }
+
+        /*!
+        @brief create and return a reference to the pointed to value
+
+        @complexity Linear in the number of reference tokens.
+        */
+        reference get_and_create(reference j) const
+        {
+            pointer result = &j;
+
+            // in case no reference tokens exist, return a reference to the
+            // JSON value j which will be overwritten by a primitive value
+            for (const auto& reference_token : reference_tokens)
+            {
+                switch (result->m_type)
+                {
+                    case value_t::null:
+                    {
+                        if (reference_token == "0")
+                        {
+                            // start a new array if reference token is 0
+                            result = &result->operator[](0);
+                        }
+                        else
+                        {
+                            // start a new object otherwise
+                            result = &result->operator[](reference_token);
+                        }
+                        break;
+                    }
+
+                    case value_t::object:
+                    {
+                        // create an entry in the object
+                        result = &result->operator[](reference_token);
+                        break;
+                    }
+
+                    case value_t::array:
+                    {
+                        // create an entry in the array
+                        result = &result->operator[](static_cast<size_type>(std::stoi(reference_token)));
+                        break;
+                    }
+
+                    /*
+                    The following code is only reached if there exists a
+                    reference token _and_ the current value is primitive. In
+                    this case, we have an error situation, because primitive
+                    values may only occur as single value; that is, with an
+                    empty list of reference tokens.
+                    */
+                    default:
+                    {
+                        JSON_THROW(std::domain_error("invalid value to unflatten"));
+                    }
+                }
+            }
+
+            return *result;
+        }
+
+        /*!
+        @brief return a reference to the pointed to value
+
+        @note This version does not throw if a value is not present, but tries
+        to create nested values instead. For instance, calling this function
+        with pointer `"/this/that"` on a null value is equivalent to calling
+        `operator[]("this").operator[]("that")` on that value, effectively
+        changing the null value to an object.
+
+        @param[in] ptr  a JSON value
+
+        @return reference to the JSON value pointed to by the JSON pointer
+
+        @complexity Linear in the length of the JSON pointer.
+
+        @throw std::out_of_range      if the JSON pointer can not be resolved
+        @throw std::domain_error      if an array index begins with '0'
+        @throw std::invalid_argument  if an array index was not a number
+        */
+        reference get_unchecked(pointer ptr) const
+        {
+            for (const auto& reference_token : reference_tokens)
+            {
+                // convert null values to arrays or objects before continuing
+                if (ptr->m_type == value_t::null)
+                {
+                    // check if reference token is a number
+                    const bool nums = std::all_of(reference_token.begin(),
+                                                  reference_token.end(),
+                                                  [](const char x)
+                    {
+                        return std::isdigit(x);
+                    });
+
+                    // change value to array for numbers or "-" or to object
+                    // otherwise
+                    if (nums or reference_token == "-")
+                    {
+                        *ptr = value_t::array;
+                    }
+                    else
+                    {
+                        *ptr = value_t::object;
+                    }
+                }
+
+                switch (ptr->m_type)
+                {
+                    case value_t::object:
+                    {
+                        // use unchecked object access
+                        ptr = &ptr->operator[](reference_token);
+                        break;
+                    }
+
+                    case value_t::array:
+                    {
+                        // error condition (cf. RFC 6901, Sect. 4)
+                        if (reference_token.size() > 1 and reference_token[0] == '0')
+                        {
+                            JSON_THROW(std::domain_error("array index must not begin with '0'"));
+                        }
+
+                        if (reference_token == "-")
+                        {
+                            // explicitly treat "-" as index beyond the end
+                            ptr = &ptr->operator[](ptr->m_value.array->size());
+                        }
+                        else
+                        {
+                            // convert array index to number; unchecked access
+                            ptr = &ptr->operator[](static_cast<size_type>(std::stoi(reference_token)));
+                        }
+                        break;
+                    }
+
+                    default:
+                    {
+                        JSON_THROW(std::out_of_range("unresolved reference token '" + reference_token + "'"));
+                    }
+                }
+            }
+
+            return *ptr;
+        }
+
+        reference get_checked(pointer ptr) const
+        {
+            for (const auto& reference_token : reference_tokens)
+            {
+                switch (ptr->m_type)
+                {
+                    case value_t::object:
+                    {
+                        // note: at performs range check
+                        ptr = &ptr->at(reference_token);
+                        break;
+                    }
+
+                    case value_t::array:
+                    {
+                        if (reference_token == "-")
+                        {
+                            // "-" always fails the range check
+                            JSON_THROW(std::out_of_range("array index '-' (" +
+                                                         std::to_string(ptr->m_value.array->size()) +
+                                                         ") is out of range"));
+                        }
+
+                        // error condition (cf. RFC 6901, Sect. 4)
+                        if (reference_token.size() > 1 and reference_token[0] == '0')
+                        {
+                            JSON_THROW(std::domain_error("array index must not begin with '0'"));
+                        }
+
+                        // note: at performs range check
+                        ptr = &ptr->at(static_cast<size_type>(std::stoi(reference_token)));
+                        break;
+                    }
+
+                    default:
+                    {
+                        JSON_THROW(std::out_of_range("unresolved reference token '" + reference_token + "'"));
+                    }
+                }
+            }
+
+            return *ptr;
+        }
+
+        /*!
+        @brief return a const reference to the pointed to value
+
+        @param[in] ptr  a JSON value
+
+        @return const reference to the JSON value pointed to by the JSON
+                pointer
+        */
+        const_reference get_unchecked(const_pointer ptr) const
+        {
+            for (const auto& reference_token : reference_tokens)
+            {
+                switch (ptr->m_type)
+                {
+                    case value_t::object:
+                    {
+                        // use unchecked object access
+                        ptr = &ptr->operator[](reference_token);
+                        break;
+                    }
+
+                    case value_t::array:
+                    {
+                        if (reference_token == "-")
+                        {
+                            // "-" cannot be used for const access
+                            JSON_THROW(std::out_of_range("array index '-' (" +
+                                                         std::to_string(ptr->m_value.array->size()) +
+                                                         ") is out of range"));
+                        }
+
+                        // error condition (cf. RFC 6901, Sect. 4)
+                        if (reference_token.size() > 1 and reference_token[0] == '0')
+                        {
+                            JSON_THROW(std::domain_error("array index must not begin with '0'"));
+                        }
+
+                        // use unchecked array access
+                        ptr = &ptr->operator[](static_cast<size_type>(std::stoi(reference_token)));
+                        break;
+                    }
+
+                    default:
+                    {
+                        JSON_THROW(std::out_of_range("unresolved reference token '" + reference_token + "'"));
+                    }
+                }
+            }
+
+            return *ptr;
+        }
+
+        const_reference get_checked(const_pointer ptr) const
+        {
+            for (const auto& reference_token : reference_tokens)
+            {
+                switch (ptr->m_type)
+                {
+                    case value_t::object:
+                    {
+                        // note: at performs range check
+                        ptr = &ptr->at(reference_token);
+                        break;
+                    }
+
+                    case value_t::array:
+                    {
+                        if (reference_token == "-")
+                        {
+                            // "-" always fails the range check
+                            JSON_THROW(std::out_of_range("array index '-' (" +
+                                                         std::to_string(ptr->m_value.array->size()) +
+                                                         ") is out of range"));
+                        }
+
+                        // error condition (cf. RFC 6901, Sect. 4)
+                        if (reference_token.size() > 1 and reference_token[0] == '0')
+                        {
+                            JSON_THROW(std::domain_error("array index must not begin with '0'"));
+                        }
+
+                        // note: at performs range check
+                        ptr = &ptr->at(static_cast<size_type>(std::stoi(reference_token)));
+                        break;
+                    }
+
+                    default:
+                    {
+                        JSON_THROW(std::out_of_range("unresolved reference token '" + reference_token + "'"));
+                    }
+                }
+            }
+
+            return *ptr;
+        }
+
+        /// split the string input to reference tokens
+        static std::vector<std::string> split(const std::string& reference_string)
+        {
+            std::vector<std::string> result;
+
+            // special case: empty reference string -> no reference tokens
+            if (reference_string.empty())
+            {
+                return result;
+            }
+
+            // check if nonempty reference string begins with slash
+            if (reference_string[0] != '/')
+            {
+                JSON_THROW(std::domain_error("JSON pointer must be empty or begin with '/'"));
+            }
+
+            // extract the reference tokens:
+            // - slash: position of the last read slash (or end of string)
+            // - start: position after the previous slash
+            for (
+                // search for the first slash after the first character
+                size_t slash = reference_string.find_first_of('/', 1),
+                // set the beginning of the first reference token
+                start = 1;
+                // we can stop if start == string::npos+1 = 0
+                start != 0;
+                // set the beginning of the next reference token
+                // (will eventually be 0 if slash == std::string::npos)
+                start = slash + 1,
+                // find next slash
+                slash = reference_string.find_first_of('/', start))
+            {
+                // use the text between the beginning of the reference token
+                // (start) and the last slash (slash).
+                auto reference_token = reference_string.substr(start, slash - start);
+
+                // check reference tokens are properly escaped
+                for (size_t pos = reference_token.find_first_of('~');
+                        pos != std::string::npos;
+                        pos = reference_token.find_first_of('~', pos + 1))
+                {
+                    assert(reference_token[pos] == '~');
+
+                    // ~ must be followed by 0 or 1
+                    if (pos == reference_token.size() - 1 or
+                            (reference_token[pos + 1] != '0' and
+                             reference_token[pos + 1] != '1'))
+                    {
+                        JSON_THROW(std::domain_error("escape error: '~' must be followed with '0' or '1'"));
+                    }
+                }
+
+                // finally, store the reference token
+                unescape(reference_token);
+                result.push_back(reference_token);
+            }
+
+            return result;
+        }
+
+      private:
+        /*!
+        @brief replace all occurrences of a substring by another string
+
+        @param[in,out] s  the string to manipulate; changed so that all
+                          occurrences of @a f are replaced with @a t
+        @param[in]     f  the substring to replace with @a t
+        @param[in]     t  the string to replace @a f
+
+        @pre The search string @a f must not be empty.
+
+        @since version 2.0.0
+        */
+        static void replace_substring(std::string& s,
+                                      const std::string& f,
+                                      const std::string& t)
+        {
+            assert(not f.empty());
+
+            for (
+                size_t pos = s.find(f);         // find first occurrence of f
+                pos != std::string::npos;       // make sure f was found
+                s.replace(pos, f.size(), t),    // replace with t
+                pos = s.find(f, pos + t.size()) // find next occurrence of f
+            );
+        }
+
+        /// escape tilde and slash
+        static std::string escape(std::string s)
+        {
+            // escape "~"" to "~0" and "/" to "~1"
+            replace_substring(s, "~", "~0");
+            replace_substring(s, "/", "~1");
+            return s;
+        }
+
+        /// unescape tilde and slash
+        static void unescape(std::string& s)
+        {
+            // first transform any occurrence of the sequence '~1' to '/'
+            replace_substring(s, "~1", "/");
+            // then transform any occurrence of the sequence '~0' to '~'
+            replace_substring(s, "~0", "~");
+        }
+
+        /*!
+        @param[in] reference_string  the reference string to the current value
+        @param[in] value             the value to consider
+        @param[in,out] result        the result object to insert values to
+
+        @note Empty objects or arrays are flattened to `null`.
+        */
+        static void flatten(const std::string& reference_string,
+                            const basic_json& value,
+                            basic_json& result)
+        {
+            switch (value.m_type)
+            {
+                case value_t::array:
+                {
+                    if (value.m_value.array->empty())
+                    {
+                        // flatten empty array as null
+                        result[reference_string] = nullptr;
+                    }
+                    else
+                    {
+                        // iterate array and use index as reference string
+                        for (size_t i = 0; i < value.m_value.array->size(); ++i)
+                        {
+                            flatten(reference_string + "/" + std::to_string(i),
+                                    value.m_value.array->operator[](i), result);
+                        }
+                    }
+                    break;
+                }
+
+                case value_t::object:
+                {
+                    if (value.m_value.object->empty())
+                    {
+                        // flatten empty object as null
+                        result[reference_string] = nullptr;
+                    }
+                    else
+                    {
+                        // iterate object and use keys as reference string
+                        for (const auto& element : *value.m_value.object)
+                        {
+                            flatten(reference_string + "/" + escape(element.first),
+                                    element.second, result);
+                        }
+                    }
+                    break;
+                }
+
+                default:
+                {
+                    // add primitive value with its reference string
+                    result[reference_string] = value;
+                    break;
+                }
+            }
+        }
+
+        /*!
+        @param[in] value  flattened JSON
+
+        @return unflattened JSON
+        */
+        static basic_json unflatten(const basic_json& value)
+        {
+            if (not value.is_object())
+            {
+                JSON_THROW(std::domain_error("only objects can be unflattened"));
+            }
+
+            basic_json result;
+
+            // iterate the JSON object values
+            for (const auto& element : *value.m_value.object)
+            {
+                if (not element.second.is_primitive())
+                {
+                    JSON_THROW(std::domain_error("values in object must be primitive"));
+                }
+
+                // assign value to reference pointed to by JSON pointer; Note
+                // that if the JSON pointer is "" (i.e., points to the whole
+                // value), function get_and_create returns a reference to
+                // result itself. An assignment will then create a primitive
+                // value.
+                json_pointer(element.first).get_and_create(result) = element.second;
+            }
+
+            return result;
+        }
+
+      private:
+        friend bool operator==(json_pointer const& lhs,
+                               json_pointer const& rhs) noexcept
+        {
+            return lhs.reference_tokens == rhs.reference_tokens;
+        }
+
+        friend bool operator!=(json_pointer const& lhs,
+                               json_pointer const& rhs) noexcept
+        {
+            return !(lhs == rhs);
+        }
+
+        /// the reference tokens
+        std::vector<std::string> reference_tokens {};
+    };
+
+    //////////////////////////
+    // JSON Pointer support //
+    //////////////////////////
+
+    /// @name JSON Pointer functions
+    /// @{
+
+    /*!
+    @brief access specified element via JSON Pointer
+
+    Uses a JSON pointer to retrieve a reference to the respective JSON value.
+    No bound checking is performed. Similar to @ref operator[](const typename
+    object_t::key_type&), `null` values are created in arrays and objects if
+    necessary.
+
+    In particular:
+    - If the JSON pointer points to an object key that does not exist, it
+      is created an filled with a `null` value before a reference to it
+      is returned.
+    - If the JSON pointer points to an array index that does not exist, it
+      is created an filled with a `null` value before a reference to it
+      is returned. All indices between the current maximum and the given
+      index are also filled with `null`.
+    - The special value `-` is treated as a synonym for the index past the
+      end.
+
+    @param[in] ptr  a JSON pointer
+
+    @return reference to the element pointed to by @a ptr
+
+    @complexity Constant.
+
+    @throw std::out_of_range      if the JSON pointer can not be resolved
+    @throw std::domain_error      if an array index begins with '0'
+    @throw std::invalid_argument  if an array index was not a number
+
+    @liveexample{The behavior is shown in the example.,operatorjson_pointer}
+
+    @since version 2.0.0
+    */
+    reference operator[](const json_pointer& ptr)
+    {
+        return ptr.get_unchecked(this);
+    }
+
+    /*!
+    @brief access specified element via JSON Pointer
+
+    Uses a JSON pointer to retrieve a reference to the respective JSON value.
+    No bound checking is performed. The function does not change the JSON
+    value; no `null` values are created. In particular, the the special value
+    `-` yields an exception.
+
+    @param[in] ptr  JSON pointer to the desired element
+
+    @return const reference to the element pointed to by @a ptr
+
+    @complexity Constant.
+
+    @throw std::out_of_range      if the JSON pointer can not be resolved
+    @throw std::domain_error      if an array index begins with '0'
+    @throw std::invalid_argument  if an array index was not a number
+
+    @liveexample{The behavior is shown in the example.,operatorjson_pointer_const}
+
+    @since version 2.0.0
+    */
+    const_reference operator[](const json_pointer& ptr) const
+    {
+        return ptr.get_unchecked(this);
+    }
+
+    /*!
+    @brief access specified element via JSON Pointer
+
+    Returns a reference to the element at with specified JSON pointer @a ptr,
+    with bounds checking.
+
+    @param[in] ptr  JSON pointer to the desired element
+
+    @return reference to the element pointed to by @a ptr
+
+    @complexity Constant.
+
+    @throw std::out_of_range      if the JSON pointer can not be resolved
+    @throw std::domain_error      if an array index begins with '0'
+    @throw std::invalid_argument  if an array index was not a number
+
+    @liveexample{The behavior is shown in the example.,at_json_pointer}
+
+    @since version 2.0.0
+    */
+    reference at(const json_pointer& ptr)
+    {
+        return ptr.get_checked(this);
+    }
+
+    /*!
+    @brief access specified element via JSON Pointer
+
+    Returns a const reference to the element at with specified JSON pointer @a
+    ptr, with bounds checking.
+
+    @param[in] ptr  JSON pointer to the desired element
+
+    @return reference to the element pointed to by @a ptr
+
+    @complexity Constant.
+
+    @throw std::out_of_range      if the JSON pointer can not be resolved
+    @throw std::domain_error      if an array index begins with '0'
+    @throw std::invalid_argument  if an array index was not a number
+
+    @liveexample{The behavior is shown in the example.,at_json_pointer_const}
+
+    @since version 2.0.0
+    */
+    const_reference at(const json_pointer& ptr) const
+    {
+        return ptr.get_checked(this);
+    }
+
+    /*!
+    @brief return flattened JSON value
+
+    The function creates a JSON object whose keys are JSON pointers (see [RFC
+    6901](https://tools.ietf.org/html/rfc6901)) and whose values are all
+    primitive. The original JSON value can be restored using the @ref
+    unflatten() function.
+
+    @return an object that maps JSON pointers to primitive values
+
+    @note Empty objects and arrays are flattened to `null` and will not be
+          reconstructed correctly by the @ref unflatten() function.
+
+    @complexity Linear in the size the JSON value.
+
+    @liveexample{The following code shows how a JSON object is flattened to an
+    object whose keys consist of JSON pointers.,flatten}
+
+    @sa @ref unflatten() for the reverse function
+
+    @since version 2.0.0
+    */
+    basic_json flatten() const
+    {
+        basic_json result(value_t::object);
+        json_pointer::flatten("", *this, result);
+        return result;
+    }
+
+    /*!
+    @brief unflatten a previously flattened JSON value
+
+    The function restores the arbitrary nesting of a JSON value that has been
+    flattened before using the @ref flatten() function. The JSON value must
+    meet certain constraints:
+    1. The value must be an object.
+    2. The keys must be JSON pointers (see
+       [RFC 6901](https://tools.ietf.org/html/rfc6901))
+    3. The mapped values must be primitive JSON types.
+
+    @return the original JSON from a flattened version
+
+    @note Empty objects and arrays are flattened by @ref flatten() to `null`
+          values and can not unflattened to their original type. Apart from
+          this example, for a JSON value `j`, the following is always true:
+          `j == j.flatten().unflatten()`.
+
+    @complexity Linear in the size the JSON value.
+
+    @liveexample{The following code shows how a flattened JSON object is
+    unflattened into the original nested JSON object.,unflatten}
+
+    @sa @ref flatten() for the reverse function
+
+    @since version 2.0.0
+    */
+    basic_json unflatten() const
+    {
+        return json_pointer::unflatten(*this);
+    }
+
+    /// @}
+
+    //////////////////////////
+    // JSON Patch functions //
+    //////////////////////////
+
+    /// @name JSON Patch functions
+    /// @{
+
+    /*!
+    @brief applies a JSON patch
+
+    [JSON Patch](http://jsonpatch.com) defines a JSON document structure for
+    expressing a sequence of operations to apply to a JSON) document. With
+    this function, a JSON Patch is applied to the current JSON value by
+    executing all operations from the patch.
+
+    @param[in] json_patch  JSON patch document
+    @return patched document
+
+    @note The application of a patch is atomic: Either all operations succeed
+          and the patched document is returned or an exception is thrown. In
+          any case, the original value is not changed: the patch is applied
+          to a copy of the value.
+
+    @throw std::out_of_range if a JSON pointer inside the patch could not
+    be resolved successfully in the current JSON value; example: `"key baz
+    not found"`
+    @throw invalid_argument if the JSON patch is malformed (e.g., mandatory
+    attributes are missing); example: `"operation add must have member path"`
+
+    @complexity Linear in the size of the JSON value and the length of the
+    JSON patch. As usually only a fraction of the JSON value is affected by
+    the patch, the complexity can usually be neglected.
+
+    @liveexample{The following code shows how a JSON patch is applied to a
+    value.,patch}
+
+    @sa @ref diff -- create a JSON patch by comparing two JSON values
+
+    @sa [RFC 6902 (JSON Patch)](https://tools.ietf.org/html/rfc6902)
+    @sa [RFC 6901 (JSON Pointer)](https://tools.ietf.org/html/rfc6901)
+
+    @since version 2.0.0
+    */
+    basic_json patch(const basic_json& json_patch) const
+    {
+        // make a working copy to apply the patch to
+        basic_json result = *this;
+
+        // the valid JSON Patch operations
+        enum class patch_operations {add, remove, replace, move, copy, test, invalid};
+
+        const auto get_op = [](const std::string op)
+        {
+            if (op == "add")
+            {
+                return patch_operations::add;
+            }
+            if (op == "remove")
+            {
+                return patch_operations::remove;
+            }
+            if (op == "replace")
+            {
+                return patch_operations::replace;
+            }
+            if (op == "move")
+            {
+                return patch_operations::move;
+            }
+            if (op == "copy")
+            {
+                return patch_operations::copy;
+            }
+            if (op == "test")
+            {
+                return patch_operations::test;
+            }
+
+            return patch_operations::invalid;
+        };
+
+        // wrapper for "add" operation; add value at ptr
+        const auto operation_add = [&result](json_pointer & ptr, basic_json val)
+        {
+            // adding to the root of the target document means replacing it
+            if (ptr.is_root())
+            {
+                result = val;
+            }
+            else
+            {
+                // make sure the top element of the pointer exists
+                json_pointer top_pointer = ptr.top();
+                if (top_pointer != ptr)
+                {
+                    result.at(top_pointer);
+                }
+
+                // get reference to parent of JSON pointer ptr
+                const auto last_path = ptr.pop_back();
+                basic_json& parent = result[ptr];
+
+                switch (parent.m_type)
+                {
+                    case value_t::null:
+                    case value_t::object:
+                    {
+                        // use operator[] to add value
+                        parent[last_path] = val;
+                        break;
+                    }
+
+                    case value_t::array:
+                    {
+                        if (last_path == "-")
+                        {
+                            // special case: append to back
+                            parent.push_back(val);
+                        }
+                        else
+                        {
+                            const auto idx = std::stoi(last_path);
+                            if (static_cast<size_type>(idx) > parent.size())
+                            {
+                                // avoid undefined behavior
+                                JSON_THROW(std::out_of_range("array index " + std::to_string(idx) + " is out of range"));
+                            }
+                            else
+                            {
+                                // default case: insert add offset
+                                parent.insert(parent.begin() + static_cast<difference_type>(idx), val);
+                            }
+                        }
+                        break;
+                    }
+
+                    default:
+                    {
+                        // if there exists a parent it cannot be primitive
+                        assert(false);  // LCOV_EXCL_LINE
+                    }
+                }
+            }
+        };
+
+        // wrapper for "remove" operation; remove value at ptr
+        const auto operation_remove = [&result](json_pointer & ptr)
+        {
+            // get reference to parent of JSON pointer ptr
+            const auto last_path = ptr.pop_back();
+            basic_json& parent = result.at(ptr);
+
+            // remove child
+            if (parent.is_object())
+            {
+                // perform range check
+                auto it = parent.find(last_path);
+                if (it != parent.end())
+                {
+                    parent.erase(it);
+                }
+                else
+                {
+                    JSON_THROW(std::out_of_range("key '" + last_path + "' not found"));
+                }
+            }
+            else if (parent.is_array())
+            {
+                // note erase performs range check
+                parent.erase(static_cast<size_type>(std::stoi(last_path)));
+            }
+        };
+
+        // type check
+        if (not json_patch.is_array())
+        {
+            // a JSON patch must be an array of objects
+            JSON_THROW(std::invalid_argument("JSON patch must be an array of objects"));
+        }
+
+        // iterate and apply the operations
+        for (const auto& val : json_patch)
+        {
+            // wrapper to get a value for an operation
+            const auto get_value = [&val](const std::string & op,
+                                          const std::string & member,
+                                          bool string_type) -> basic_json&
+            {
+                // find value
+                auto it = val.m_value.object->find(member);
+
+                // context-sensitive error message
+                const auto error_msg = (op == "op") ? "operation" : "operation '" + op + "'";
+
+                // check if desired value is present
+                if (it == val.m_value.object->end())
+                {
+                    JSON_THROW(std::invalid_argument(error_msg + " must have member '" + member + "'"));
+                }
+
+                // check if result is of type string
+                if (string_type and not it->second.is_string())
+                {
+                    JSON_THROW(std::invalid_argument(error_msg + " must have string member '" + member + "'"));
+                }
+
+                // no error: return value
+                return it->second;
+            };
+
+            // type check
+            if (not val.is_object())
+            {
+                JSON_THROW(std::invalid_argument("JSON patch must be an array of objects"));
+            }
+
+            // collect mandatory members
+            const std::string op = get_value("op", "op", true);
+            const std::string path = get_value(op, "path", true);
+            json_pointer ptr(path);
+
+            switch (get_op(op))
+            {
+                case patch_operations::add:
+                {
+                    operation_add(ptr, get_value("add", "value", false));
+                    break;
+                }
+
+                case patch_operations::remove:
+                {
+                    operation_remove(ptr);
+                    break;
+                }
+
+                case patch_operations::replace:
+                {
+                    // the "path" location must exist - use at()
+                    result.at(ptr) = get_value("replace", "value", false);
+                    break;
+                }
+
+                case patch_operations::move:
+                {
+                    const std::string from_path = get_value("move", "from", true);
+                    json_pointer from_ptr(from_path);
+
+                    // the "from" location must exist - use at()
+                    basic_json v = result.at(from_ptr);
+
+                    // The move operation is functionally identical to a
+                    // "remove" operation on the "from" location, followed
+                    // immediately by an "add" operation at the target
+                    // location with the value that was just removed.
+                    operation_remove(from_ptr);
+                    operation_add(ptr, v);
+                    break;
+                }
+
+                case patch_operations::copy:
+                {
+                    const std::string from_path = get_value("copy", "from", true);;
+                    const json_pointer from_ptr(from_path);
+
+                    // the "from" location must exist - use at()
+                    result[ptr] = result.at(from_ptr);
+                    break;
+                }
+
+                case patch_operations::test:
+                {
+                    bool success = false;
+                    JSON_TRY
+                    {
+                        // check if "value" matches the one at "path"
+                        // the "path" location must exist - use at()
+                        success = (result.at(ptr) == get_value("test", "value", false));
+                    }
+                    JSON_CATCH (std::out_of_range&)
+                    {
+                        // ignore out of range errors: success remains false
+                    }
+
+                    // throw an exception if test fails
+                    if (not success)
+                    {
+                        JSON_THROW(std::domain_error("unsuccessful: " + val.dump()));
+                    }
+
+                    break;
+                }
+
+                case patch_operations::invalid:
+                {
+                    // op must be "add", "remove", "replace", "move", "copy", or
+                    // "test"
+                    JSON_THROW(std::invalid_argument("operation value '" + op + "' is invalid"));
+                }
+            }
+        }
+
+        return result;
+    }
+
+    /*!
+    @brief creates a diff as a JSON patch
+
+    Creates a [JSON Patch](http://jsonpatch.com) so that value @a source can
+    be changed into the value @a target by calling @ref patch function.
+
+    @invariant For two JSON values @a source and @a target, the following code
+    yields always `true`:
+    @code {.cpp}
+    source.patch(diff(source, target)) == target;
+    @endcode
+
+    @note Currently, only `remove`, `add`, and `replace` operations are
+          generated.
+
+    @param[in] source  JSON value to compare from
+    @param[in] target  JSON value to compare against
+    @param[in] path    helper value to create JSON pointers
+
+    @return a JSON patch to convert the @a source to @a target
+
+    @complexity Linear in the lengths of @a source and @a target.
+
+    @liveexample{The following code shows how a JSON patch is created as a
+    diff for two JSON values.,diff}
+
+    @sa @ref patch -- apply a JSON patch
+
+    @sa [RFC 6902 (JSON Patch)](https://tools.ietf.org/html/rfc6902)
+
+    @since version 2.0.0
+    */
+    static basic_json diff(const basic_json& source,
+                           const basic_json& target,
+                           const std::string& path = "")
+    {
+        // the patch
+        basic_json result(value_t::array);
+
+        // if the values are the same, return empty patch
+        if (source == target)
+        {
+            return result;
+        }
+
+        if (source.type() != target.type())
+        {
+            // different types: replace value
+            result.push_back(
+            {
+                {"op", "replace"},
+                {"path", path},
+                {"value", target}
+            });
+        }
+        else
+        {
+            switch (source.type())
+            {
+                case value_t::array:
+                {
+                    // first pass: traverse common elements
+                    size_t i = 0;
+                    while (i < source.size() and i < target.size())
+                    {
+                        // recursive call to compare array values at index i
+                        auto temp_diff = diff(source[i], target[i], path + "/" + std::to_string(i));
+                        result.insert(result.end(), temp_diff.begin(), temp_diff.end());
+                        ++i;
+                    }
+
+                    // i now reached the end of at least one array
+                    // in a second pass, traverse the remaining elements
+
+                    // remove my remaining elements
+                    const auto end_index = static_cast<difference_type>(result.size());
+                    while (i < source.size())
+                    {
+                        // add operations in reverse order to avoid invalid
+                        // indices
+                        result.insert(result.begin() + end_index, object(
+                        {
+                            {"op", "remove"},
+                            {"path", path + "/" + std::to_string(i)}
+                        }));
+                        ++i;
+                    }
+
+                    // add other remaining elements
+                    while (i < target.size())
+                    {
+                        result.push_back(
+                        {
+                            {"op", "add"},
+                            {"path", path + "/" + std::to_string(i)},
+                            {"value", target[i]}
+                        });
+                        ++i;
+                    }
+
+                    break;
+                }
+
+                case value_t::object:
+                {
+                    // first pass: traverse this object's elements
+                    for (auto it = source.begin(); it != source.end(); ++it)
+                    {
+                        // escape the key name to be used in a JSON patch
+                        const auto key = json_pointer::escape(it.key());
+
+                        if (target.find(it.key()) != target.end())
+                        {
+                            // recursive call to compare object values at key it
+                            auto temp_diff = diff(it.value(), target[it.key()], path + "/" + key);
+                            result.insert(result.end(), temp_diff.begin(), temp_diff.end());
+                        }
+                        else
+                        {
+                            // found a key that is not in o -> remove it
+                            result.push_back(object(
+                            {
+                                {"op", "remove"},
+                                {"path", path + "/" + key}
+                            }));
+                        }
+                    }
+
+                    // second pass: traverse other object's elements
+                    for (auto it = target.begin(); it != target.end(); ++it)
+                    {
+                        if (source.find(it.key()) == source.end())
+                        {
+                            // found a key that is not in this -> add it
+                            const auto key = json_pointer::escape(it.key());
+                            result.push_back(
+                            {
+                                {"op", "add"},
+                                {"path", path + "/" + key},
+                                {"value", it.value()}
+                            });
+                        }
+                    }
+
+                    break;
+                }
+
+                default:
+                {
+                    // both primitive type: replace value
+                    result.push_back(
+                    {
+                        {"op", "replace"},
+                        {"path", path},
+                        {"value", target}
+                    });
+                    break;
+                }
+            }
+        }
+
+        return result;
+    }
+
+    /// @}
+};
+
+/////////////
+// presets //
+/////////////
+
+/*!
+@brief default JSON class
+
+This type is the default specialization of the @ref basic_json class which
+uses the standard template types.
+
+@since version 1.0.0
+*/
+using json = basic_json<>;
+} // namespace nlohmann
+
+
+///////////////////////
+// nonmember support //
+///////////////////////
+
+// specialization of std::swap, and std::hash
+namespace std
+{
+/*!
+@brief exchanges the values of two JSON objects
+
+@since version 1.0.0
+*/
+template<>
+inline void swap(nlohmann::json& j1,
+                 nlohmann::json& j2) noexcept(
+                     is_nothrow_move_constructible<nlohmann::json>::value and
+                     is_nothrow_move_assignable<nlohmann::json>::value
+                 )
+{
+    j1.swap(j2);
+}
+
+/// hash value for JSON objects
+template<>
+struct hash<nlohmann::json>
+{
+    /*!
+    @brief return a hash value for a JSON object
+
+    @since version 1.0.0
+    */
+    std::size_t operator()(const nlohmann::json& j) const
+    {
+        // a naive hashing via the string representation
+        const auto& h = hash<nlohmann::json::string_t>();
+        return h(j.dump());
+    }
+};
+} // namespace std
+
+/*!
+@brief user-defined string literal for JSON values
+
+This operator implements a user-defined string literal for JSON objects. It
+can be used by adding `"_json"` to a string literal and returns a JSON object
+if no parse error occurred.
+
+@param[in] s  a string representation of a JSON object
+@param[in] n  the length of string @a s
+@return a JSON object
+
+@since version 1.0.0
+*/
+inline nlohmann::json operator "" _json(const char* s, std::size_t n)
+{
+    return nlohmann::json::parse(s, s + n);
+}
+
+/*!
+@brief user-defined string literal for JSON pointer
+
+This operator implements a user-defined string literal for JSON Pointers. It
+can be used by adding `"_json_pointer"` to a string literal and returns a JSON pointer
+object if no parse error occurred.
+
+@param[in] s  a string representation of a JSON Pointer
+@param[in] n  the length of string @a s
+@return a JSON pointer object
+
+@since version 2.0.0
+*/
+inline nlohmann::json::json_pointer operator "" _json_pointer(const char* s, std::size_t n)
+{
+    return nlohmann::json::json_pointer(std::string(s, n));
+}
+
+// restore GCC/clang diagnostic settings
+#if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
+    #pragma GCC diagnostic pop
+#endif
+
+// clean up
+#undef JSON_CATCH
+#undef JSON_DEPRECATED
+#undef JSON_THROW
+#undef JSON_TRY
+
+#endif