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diff --git a/afb-utilities/wrap-json.md b/afb-utilities/wrap-json.md deleted file mode 100644 index 92940f1..0000000 --- a/afb-utilities/wrap-json.md +++ /dev/null @@ -1,305 +0,0 @@ -WRAP-JSON facility -================== - -The facility wrap-json is based on the pack/unpack API on the -libray jansson. The two chapters below are copied from the -documentation of jansson library copyrighted by Petri Lehtinen -(see at end). - -Building Values ---------------- - -This section describes functions that help to create, or *pack*, complex -JSON values, especially nested objects and arrays. Value building is -based on a *format string* that is used to tell the functions about the -expected arguments. - -For example, the format string `"i"` specifies a single integer value, -while the format string `"[ssb]"` or the equivalent `"[s, s, b]"` -specifies an array value with two strings and a boolean as its items: - - /* Create the JSON integer 42 */ - wrap_json_pack(&result, "i", 42); - - /* Create the JSON array ["foo", "bar", true] */ - wrap_json_pack(&result, "[ssb]", "foo", "bar", 1); - -Here's the full list of format specifiers. The type in parentheses -denotes the resulting JSON type, and the type in brackets (if any) -denotes the C type that is expected as the corresponding argument or -arguments. - -`s` (string) \[const char \*\] - -: Convert a null terminated UTF-8 string to a JSON string. - -`s?` (string) \[const char \*\] - -: Like `s`, but if the argument is *NULL*, output a JSON null value. - -`s*` (string) \[const char \*\] - -: Like `s`, but if the argument is *NULL*, do not output any value. - This format can only be used inside an object or an array. If used - inside an object, the corresponding key is additionally suppressed - when the value is omitted. See below for an example. - -`s#` (string) \[const char \*, int\] - -: Convert a UTF-8 buffer of a given length to a JSON string. - -`s%` (string) \[const char \*, size\_t\] - -: Like `s#` but the length argument is of type size\_t. - -`+` \[const char \*\] - -: Like `s`, but concatenate to the previous string. Only valid after - `s`, `s#`, `+` or `+#`. - -`+#` \[const char \*, int\] - -: Like `s#`, but concatenate to the previous string. Only valid after - `s`, `s#`, `+` or `+#`. - -`+%` (string) \[const char \*, size\_t\] - -: Like `+#` but the length argument is of type size\_t. - -`n` (null) - -: Output a JSON null value. No argument is consumed. - -`b` (boolean) \[int\] - -: Convert a C int to JSON boolean value. Zero is converted to `false` - and non-zero to `true`. - -`i` (integer) \[int\] - -: Convert a C int to JSON integer. - -`I` (integer) \[json\_int\_t\] - -: Convert a C json\_int\_t to JSON integer. - -`f` (real) \[double\] - -: Convert a C double to JSON real. - -`o` (any value) \[json\_t \*\] - -: Output any given JSON value as-is. If the value is added to an array - or object, the reference to the value passed to `o` is stolen by the - container. - -`O` (any value) \[json\_t \*\] - -: Like `o`, but the argument's reference count is incremented. This is - useful if you pack into an array or object and want to keep the - reference for the JSON value consumed by `O` to yourself. - -`o?`, `O?` (any value) \[json\_t \*\] - -: Like `o` and `O`, respectively, but if the argument is *NULL*, - output a JSON null value. - -`o*`, `O*` (any value) \[json\_t \*\] - -: Like `o` and `O`, respectively, but if the argument is *NULL*, do - not output any value. This format can only be used inside an object - or an array. If used inside an object, the corresponding key is - additionally suppressed. See below for an example. - -`[fmt]` (array) - -: Build an array with contents from the inner format string. `fmt` may - contain objects and arrays, i.e. recursive value building is - supported. - -`{fmt}` (object) - -: Build an object with contents from the inner format string `fmt`. - The first, third, etc. format specifier represent a key, and must be - a string (see `s`, `s#`, `+` and `+#` above), as object keys are - always strings. The second, fourth, etc. format specifier represent - a value. Any value may be an object or array, i.e. recursive value - building is supported. - -Whitespace, `:` and `,` are ignored. - -More examples: - - /* Build an empty JSON object */ - wrap_json_pack(&result, "{}"); - - /* Build the JSON object {"foo": 42, "bar": 7} */ - wrap_json_pack(&result, "{sisi}", "foo", 42, "bar", 7); - - /* Like above, ':', ',' and whitespace are ignored */ - wrap_json_pack(&result, "{s:i, s:i}", "foo", 42, "bar", 7); - - /* Build the JSON array [[1, 2], {"cool": true}] */ - wrap_json_pack(&result, "[[i,i],{s:b}]", 1, 2, "cool", 1); - - /* Build a string from a non-null terminated buffer */ - char buffer[4] = {'t', 'e', 's', 't'}; - wrap_json_pack(&result, "s#", buffer, 4); - - /* Concatenate strings together to build the JSON string "foobarbaz" */ - wrap_json_pack(&result, "s++", "foo", "bar", "baz"); - - /* Create an empty object or array when optional members are missing */ - wrap_json_pack(&result, "{s:s*,s:o*,s:O*}", "foo", NULL, "bar", NULL, "baz", NULL); - wrap_json_pack(&result, "[s*,o*,O*]", NULL, NULL, NULL); - -Parsing and Validating Values ------------------------------ - -This section describes functions that help to validate complex values -and extract, or *unpack*, data from them. Like building values -<apiref-pack>, this is also based on format strings. - -While a JSON value is unpacked, the type specified in the format string -is checked to match that of the JSON value. This is the validation part -of the process. In addition to this, the unpacking functions can also -check that all items of arrays and objects are unpacked. This check be -enabled with the format specifier `!` or by using the flag -`JSON_STRICT`. See below for details. - -Here's the full list of format specifiers. The type in parentheses -denotes the JSON type, and the type in brackets (if any) denotes the C -type whose address should be passed. - -`s` (string) \[const char \*\] - -: Convert a JSON string to a pointer to a null terminated UTF-8 - string. The resulting string is extracted by using - json\_string\_value() internally, so it exists as long as there are - still references to the corresponding JSON string. - -`s%` (string) \[const char \*, size\_t \*\] - -: Convert a JSON string to a pointer to a null terminated UTF-8 string - and its length. - -`n` (null) - -: Expect a JSON null value. Nothing is extracted. - -`b` (boolean) \[int\] - -: Convert a JSON boolean value to a C int, so that `true` is converted - to 1 and `false` to 0. - -`i` (integer) \[int\] - -: Convert a JSON integer to C int. - -`I` (integer) \[json\_int\_t\] - -: Convert a JSON integer to C json\_int\_t. - -`f` (real) \[double\] - -: Convert a JSON real to C double. - -`F` (integer or real) \[double\] - -: Convert a JSON number (integer or real) to C double. - -`o` (any value) \[json\_t \*\] - -: Store a JSON value with no conversion to a json\_t pointer. - -`O` (any value) \[json\_t \*\] - -: Like `O`, but the JSON value's reference count is incremented. - -`[fmt]` (array) - -: Convert each item in the JSON array according to the inner format - string. `fmt` may contain objects and arrays, i.e. recursive value - extraction is supported. - -`{fmt}` (object) - -: Convert each item in the JSON object according to the inner format - string `fmt`. The first, third, etc. format specifier represent a - key, and must be `s`. The corresponding argument to unpack functions - is read as the object key. The second fourth, etc. format specifier - represent a value and is written to the address given as the - corresponding argument. **Note** that every other argument is read - from and every other is written to. - - `fmt` may contain objects and arrays as values, i.e. recursive value - extraction is supported. - -`!` - -: This special format specifier is used to enable the check that all - object and array items are accessed, on a per-value basis. It must - appear inside an array or object as the last format specifier before - the closing bracket or brace. - -`*` - -: This special format specifier is the opposite of `!`. This is the default. - It must appear inside an array or object as the last format specifier - before the closing bracket or brace. - -Whitespace, `:` and `,` are ignored. - -Examples: - - /* root is the JSON integer 42 */ - int myint; - wrap_json_unpack(root, "i", &myint); - assert(myint == 42); - - /* root is the JSON object {"foo": "bar", "quux": true} */ - const char *str; - int boolean; - wrap_json_unpack(root, "{s:s, s:b}", "foo", &str, "quux", &boolean); - assert(strcmp(str, "bar") == 0 && boolean == 1); - - /* root is the JSON array [[1, 2], {"baz": null} */ - wrap_json_check(root, "[[i,i], {s:n}]", "baz"); - /* returns 0 for validation success, nothing is extracted */ - - /* root is the JSON array [1, 2, 3, 4, 5] */ - int myint1, myint2; - wrap_json_unpack(root, "[ii!]", &myint1, &myint2); - /* returns -1 for failed validation */ - - /* root is an empty JSON object */ - int myint = 0, myint2 = 0, myint3 = 0; - wrap_json_unpack(root, "{s?i, s?[ii]}", - "foo", &myint1, - "bar", &myint2, &myint3); - /* myint1, myint2 or myint3 is no touched as "foo" and "bar" don't exist */ - - -Copyright ---------- - -Copyright (c) 2009-2016 Petri Lehtinen <petri@digip.org> - -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. - |