boost/json/visit.hpp

0001 //
0002 // Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.com)
0003 //
0004 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0005 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0006 //
0007 // Official repository: https://github.com/boostorg/json
0008 //
0009
0010 #ifndef BOOST_JSON_VISIT_HPP
0011 #define BOOST_JSON_VISIT_HPP
0012
0013 #include <boost/json/detail/config.hpp>
0014 #include <boost/json/value.hpp>
0015 #include <type_traits>
0016 #include <utility>
0017
0018 namespace boost {
0019 namespace json {
0020
0021 /** Invoke a function object with the contents of a @ref value
0022
0023     Invokes `v` as if by `std::forward<Visitor>(v)( X )`, where `X` is
0024
0025     @li `jv.get_array()` if `jv.is_array()`, or
0026
0027     @li `jv.get_object()` if `jv.is_object()`, or
0028
0029     @li `jv.get_string()` if `jv.is_string()`, or
0030
0031     @li `jv.get_int64()` if `jv.is_int64()`, or
0032
0033     @li `jv.get_uint64()` if `jv.is_uint64()`, or
0034
0035     @li `jv.get_double()` if `jv.is_double()`, or
0036
0037     @li `jv.get_bool()` if `jv.is_bool()`, or
0038
0039     @li reference to an object of type `std::nullptr_t` if `jv.is_null()`.
0040
0041     @return The value returned by Visitor.
0042
0043     @param v The visitation function to invoke
0044
0045     @param jv The value to visit.
0046 */
0047 template<class Visitor>
0048 auto
0049 visit(
0050     Visitor&& v,
0051     value& jv) -> decltype(
0052         static_cast<Visitor&&>(v)( std::declval<std::nullptr_t&>() ) );
0053
0054 /** Invoke a function object with the contents of a @ref value
0055
0056     Invokes `v` as if by `std::forward<Visitor>(v)( X )`, where `X` is
0057
0058     @li `jv.get_array()` if `jv.is_array()`, or
0059
0060     @li `jv.get_object()` if `jv.is_object()`, or
0061
0062     @li `jv.get_string()` if `jv.is_string()`, or
0063
0064     @li `jv.get_int64()` if `jv.is_int64()`, or
0065
0066     @li `jv.get_uint64()` if `jv.is_uint64()`, or
0067
0068     @li `jv.get_double()` if `jv.is_double()`, or
0069
0070     @li `jv.get_bool()` if `jv.is_bool()`, or
0071
0072     @li reference to an object of type `const std::nullptr_t` if `jv.is_null()`.
0073
0074     @return The value returned by Visitor.
0075
0076     @param v The visitation function to invoke
0077
0078     @param jv The value to visit.
0079 */
0080 template<class Visitor>
0081 auto
0082 visit(
0083     Visitor &&v,
0084     value const &jv) -> decltype(
0085         static_cast<Visitor&&>(v)( std::declval<std::nullptr_t const&>() ) );
0086
0087 /** Invoke a function object with the contents of a @ref value
0088
0089     Invokes `v` as if by `std::forward<Visitor>(v)( X )`, where `X` is
0090
0091     @li `std::move( jv.get_array() )` if `jv.is_array()`, or
0092
0093     @li `std::move( jv.get_object() )` if `jv.is_object()`, or
0094
0095     @li `std::move( jv.get_string() )` if `jv.is_string()`, or
0096
0097     @li `std::move( jv.get_int64() )` if `jv.is_int64()`, or
0098
0099     @li `std::move( jv.get_uint64() )` if `jv.is_uint64()`, or
0100
0101     @li `std::move( jv.get_double() )` if `jv.is_double()`, or
0102
0103     @li `std::move( jv.get_bool() )` if `jv.is_bool()`, or
0104
0105     @li `std::nullptr_t()` if `jv.is_null()`.
0106
0107     @return The value returned by Visitor.
0108
0109     @param v The visitation function to invoke
0110
0111     @param jv The value to visit.
0112 */
0113 template<class Visitor>
0114 auto
0115 visit(
0116     Visitor &&v,
0117     value&& jv) -> decltype(
0118         static_cast<Visitor&&>(v)( std::declval<std::nullptr_t&&>() ) );
0119
0120 } // namespace json
0121 } // namespace boost
0122
0123 #include <boost/json/impl/visit.hpp>
0124
0125 #endif