feat():initial version

install/boost_1_75_0/include/boost/json/visit.hpp

@@ -0,0 +1,48 @@
+//
+// Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// Official repository: https://github.com/boostorg/json
+//
+
+#ifndef BOOST_JSON_VISIT_HPP
+#define BOOST_JSON_VISIT_HPP
+
+#include <boost/json/detail/config.hpp>
+#include <boost/json/value.hpp>
+#include <type_traits>
+#include <utility>
+
+BOOST_JSON_NS_BEGIN
+
+/** Invoke a function object with the contents of a @ref value
+
+    @return The value returned by Visitor.
+
+    @param v The visitation function to invoke
+
+    @param jv The value to visit.
+*/
+/** @{ */
+template<class Visitor>
+auto
+visit(
+    Visitor&& v,
+    value& jv) -> decltype(
+        std::declval<Visitor>()(nullptr));
+
+template<class Visitor>
+auto
+visit(
+    Visitor &&v,
+    value const &jv) -> decltype(
+        std::declval<Visitor>()(nullptr));
+/** @} */
+
+BOOST_JSON_NS_END
+
+#include <boost/json/impl/visit.hpp>
+
+#endif