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implement as and pack for std::variant

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This commit is contained in:
Uy Ha
2023-07-03 13:37:37 +00:00
parent ac062e28cb
commit 327f3d1ad0
4 changed files with 164 additions and 0 deletions
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16
include/msgpack/adaptor/cpp17/variant.hpp Normal file
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@@ -0,0 +1,16 @@
//
// MessagePack for C++ static resolution routine
//
// Copyright (C) 2023 Uy Ha
//
// 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)
//
#ifndef MSGPACK_TYPE_CPP17_VARIANT_HPP
#define MSGPACK_TYPE_CPP17_VARIANT_HPP
#include "msgpack/v1/adaptor/cpp17/variant.hpp"
#endif // MSGPACK_TYPE_CPP17_VARIANT_HPP

4
include/msgpack/type.hpp
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@@ -63,6 +63,10 @@
#include "adaptor/cpp17/carray_byte.hpp"
#include "adaptor/cpp17/vector_byte.hpp"
#if MSGPACK_HAS_INCLUDE(<variant>)
#include "adaptor/cpp17/variant.hpp"
#endif // MSGPACK_HAS_INCLUDE(<variant>)
#if MSGPACK_HAS_INCLUDE(<span>)
#include "adaptor/cpp20/span.hpp"
#endif // MSGPACK_HAS_INCLUDE(<span>)

133
include/msgpack/v1/adaptor/cpp17/variant.hpp Normal file
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@@ -0,0 +1,133 @@
//
// MessagePack for C++ static resolution routine
//
// Copyright (C) 2023 Uy Ha
//
// 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)
//
#ifndef MSGPACK_V1_TYPE_VARIANT_HPP
#define MSGPACK_V1_TYPE_VARIANT_HPP
#define MSGPACK_USE_STD_VARIANT_ADAPTOR
#if defined(MSGPACK_USE_STD_VARIANT_ADAPTOR)
#include "msgpack/cpp_version.hpp"
#if MSGPACK_CPP_VERSION >= 201703
#include "msgpack/adaptor/adaptor_base.hpp"
#include "msgpack/object.hpp"
#include "msgpack/versioning.hpp"
#include <variant>
namespace msgpack {
MSGPACK_API_VERSION_NAMESPACE(v1) {
namespace adaptor {
namespace detail {
template <typename Variant, typename T, typename... Ts, std::size_t current_index, std::size_t... indices>
Variant construct_variant(std::size_t index,
msgpack::object &object,
std::index_sequence<current_index, indices...>) {
if constexpr(sizeof...(Ts) == 0) {
return object.as<T>();
} else {
if (index == current_index) {
return object.as<T>();
}
return construct_variant<Variant, Ts...>(index, object, std::index_sequence<indices...>());
}
}
} // namespace detail
template <typename... Ts>
struct as<std::variant<Ts...>, std::enable_if_t<(msgpack::has_as<Ts>::value && ...)>> {
std::variant<Ts...> operator()(msgpack::object const &o) const {
if (o.type != msgpack::type::ARRAY) {
throw msgpack::type_error{};
}
if (o.via.array.size != 2) {
throw msgpack::type_error{};
}
if (o.via.array.ptr[0].type != msgpack::type::POSITIVE_INTEGER) {
throw msgpack::type_error{};
}
return detail::construct_variant<std::variant<Ts...>, Ts...>(
o.via.array.ptr[0].as<std::size_t>(),
o.via.array.ptr[1],
std::make_index_sequence<sizeof...(Ts)>()
);
}
};
template<typename... Ts>
struct convert<std::variant<Ts...>> {
msgpack::object const &operator()(msgpack::object const &o, std::variant<Ts...> &v) const {
if (o.type != msgpack::type::ARRAY) {
throw msgpack::type_error{};
}
if (o.via.array.size != 2) {
throw msgpack::type_error{};
}
if (o.via.array.ptr[0].type != msgpack::type::POSITIVE_INTEGER) {
throw msgpack::type_error{};
}
v = detail::construct_variant<std::variant<Ts...>, Ts...>(
o.via.array.ptr[0].as<std::size_t>(),
o.via.array.ptr[1],
std::make_index_sequence<sizeof...(Ts)>()
);
return o;
}
};
template <typename... Ts>
struct pack<std::variant<Ts...>>{
template<typename Stream>
msgpack::packer<Stream>& operator()(msgpack::packer<Stream> &o, std::variant<Ts...> const &v) const {
o.pack_array(2);
o.pack_uint64(v.index());
std::visit([&o](auto const &real_value){o.pack(real_value);}, v);
return o;
}
};
// template <typename... Ts>
// struct object<std::variant<Ts...>> {
// void operator()(msgpack::object &o, std::variant<Ts...> const &v) const {
// o.type = msgpack::type::ARRAY;
// o.via.array.size = 2;
// msgpack::adaptor::object<std::size_t>(o.via.array.ptr[0], v.index());
// std::visit([&o](auto const &value) {
// msgpack::adaptor::object(o.via.array.ptr[1], value);
// }, v);
// }
// };
//
// template<typename... Ts>
// struct object_with_zone<std::variant<Ts...>> {
// void operator()(msgpack::object::with_zone &o, std::variant<Ts...> const &v) const {
// o.type = msgpack::type::ARRAY;
//
// msgpack::object *p = static_cast<msgpack::object *>(o.zone.allocate_align(sizeof(msgpack::object) * 2, MSGPACK_ZONE_ALIGNOF(msgpack::object)));
//
// o.via.array.size = 2;
// o.via.array.ptr = p;
// msgpack::adaptor::object_with_zone<std::size_t>()(o.via.array.ptr[0], v.index(), o.zone);
// std::visit([&o](auto const &real_value){
// o.via.array.ptr[1] = msgpack::adaptor::object()(real_value, o.zone);
// }, v);
// }
// };
} // namespace adaptor
}
} // namespace msgpack
#endif // MSGPACK_CPP_VERSION >= 201703
#endif // defined(MSGPACK_USE_STD_VARIANT_ADAPTOR)
#endif // MSGPACK_V1_TYPE_VARIANT_HPP

11
test/msgpack_cpp17.cpp
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@@ -461,4 +461,15 @@ BOOST_AUTO_TEST_CASE(carray_byte_object_with_zone)
}
}
BOOST_AUTO_TEST_CASE(variant_as) {
std::stringstream ss;
std::variant<bool, int, float, double> val1{1.0};
msgpack::pack(ss, val1);
std::string const& str = ss.str();
msgpack::object_handle oh =
msgpack::unpack(str.data(), str.size());
std::variant<bool, int, float, double> val2 = oh.get().as<std::variant<bool, int, float, double> >();
BOOST_CHECK(val1 == val2);
}
#endif // MSGPACK_CPP_VERSION >= 201703