sol2/sol/in_place.hpp

// The MIT License (MIT) 

// Copyright (c) 2013-2017 Rapptz, ThePhD and contributors

// 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.

#ifndef SOL_IN_PLACE_HPP
#define SOL_IN_PLACE_HPP

#include <cstddef>
#include <utility>

namespace sol {

#ifdef SOL_CXX17_FEATURES
	using in_place_t = std::in_place_t;
	constexpr std::in_place_t in_place{};

	template <typename T> using in_place_type_t = std::in_place_type_t<T>;
	template <typename T>
	constexpr std::in_place_type_t<T> in_place_type{};
	
	template <size_t I> using in_place_index_t = std::in_place_index_t<I>;
	template <size_t I>
	constexpr in_place_index_t<I> in_place_index{};
#else
	namespace detail {
		struct in_place_of {};
		template <std::size_t I>
		struct in_place_of_i {};
		template <typename T>
		struct in_place_of_t {};
	} // detail

	struct in_place_tag { constexpr in_place_tag() = default; };
	
	constexpr inline in_place_tag in_place (detail::in_place_of) { return in_place_tag(); }
	template <typename T>
	constexpr inline in_place_tag in_place (detail::in_place_of_t<T>) { return in_place_tag(); }
	template <std::size_t I>
	constexpr inline in_place_tag in_place (detail::in_place_of_i<I>) { return in_place_tag(); }

	template <typename T>
	constexpr inline in_place_tag in_place_type (detail::in_place_of_t<T>) { return in_place_tag(); }
	template <std::size_t I>
	constexpr inline in_place_tag in_place_index (detail::in_place_of_i<I>) { return in_place_tag(); }

	using in_place_t = in_place_tag(&)(detail::in_place_of);
	template <typename T>
	using in_place_type_t = in_place_tag(&)(detail::in_place_of_t<T>);
	template <std::size_t I>
	using in_place_index_t = in_place_tag(&)(detail::in_place_of_i<I>);
#endif

} // sol

#endif // SOL_IN_PLACE_HPP