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-rw-r--r--include/mapbox/variant_visitor.hpp38
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diff --git a/include/mapbox/variant_visitor.hpp b/include/mapbox/variant_visitor.hpp
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+++ b/include/mapbox/variant_visitor.hpp
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+#ifndef MAPBOX_UTIL_VARIANT_VISITOR_HPP
+#define MAPBOX_UTIL_VARIANT_VISITOR_HPP
+
+namespace mapbox {
+namespace util {
+
+template <typename... Fns>
+struct visitor;
+
+template <typename Fn>
+struct visitor<Fn> : Fn
+{
+ using type = Fn;
+ using Fn::operator();
+
+ visitor(Fn fn) : Fn(fn) {}
+};
+
+template <typename Fn, typename... Fns>
+struct visitor<Fn, Fns...> : Fn, visitor<Fns...>
+{
+ using type = visitor;
+ using Fn::operator();
+ using visitor<Fns...>::operator();
+
+ visitor(Fn fn, Fns... fns) : Fn(fn), visitor<Fns...>(fns...) {}
+};
+
+template <typename... Fns>
+visitor<Fns...> make_visitor(Fns... fns)
+{
+ return visitor<Fns...>(fns...);
+}
+
+} // namespace util
+} // namespace mapbox
+
+#endif // MAPBOX_UTIL_VARIANT_VISITOR_HPP