sol2/include/sol/ebco.hpp

// sol3

// The MIT License (MIT)

// Copyright (c) 2013-2020 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
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#ifndef SOL_EBCO_HPP
#define SOL_EBCO_HPP

#include <type_traits>
#include <utility>

namespace sol { namespace detail {

	template <typename T, std::size_t tag = 0, typename = void>
	struct ebco {
		T value_;

		ebco() = default;
		ebco(const ebco&) = default;
		ebco(ebco&&) = default;
		ebco& operator=(const ebco&) = default;
		ebco& operator=(ebco&&) = default;
		ebco(const T& v) : value_(v){};
		ebco(T&& v) : value_(std::move(v)){};
		ebco& operator=(const T& v) {
			value_ = v;
			return *this;
		}
		ebco& operator=(T&& v) {
			value_ = std::move(v);
			return *this;
		};
		template <typename Arg, typename... Args,
		     typename = std::enable_if_t<!std::is_same_v<std::remove_reference_t<std::remove_cv_t<Arg>>,
		                                      ebco> && !std::is_same_v<std::remove_reference_t<std::remove_cv_t<Arg>>, T>>>
		ebco(Arg&& arg, Args&&... args) : T(std::forward<Arg>(arg), std::forward<Args>(args)...){}

		T& value() & {
			return value_;
		}

		T const& value() const & {
			return value_;
		}

		T&& value() && {
			return std::move(value_);
		}
	};

	template <typename T, std::size_t tag>
	struct ebco<T, tag, std::enable_if_t<!std::is_reference_v<T> && std::is_class_v<T> && !std::is_final_v<T>>> : T {
		ebco() = default;
		ebco(const ebco&) = default;
		ebco(ebco&&) = default;
		ebco(const T& v) : T(v){};
		ebco(T&& v) : T(std::move(v)){};
		template <typename Arg, typename... Args,
			typename = std::enable_if_t<!std::is_same_v<std::remove_reference_t<std::remove_cv_t<Arg>>,
			                                 ebco> && !std::is_same_v<std::remove_reference_t<std::remove_cv_t<Arg>>, T>>>
		ebco(Arg&& arg, Args&&... args) : T(std::forward<Arg>(arg), std::forward<Args>(args)...) {
		}

		ebco& operator=(const ebco&) = default;
		ebco& operator=(ebco&&) = default;
		ebco& operator=(const T& v) {
			static_cast<T&>(*this) = v;
			return *this;
		}
		ebco& operator=(T&& v) {
			static_cast<T&>(*this) = std::move(v);
			return *this;
		};

		T& value() & {
			return static_cast<T&>(*this);
		}

		T const& value() const & {
			return static_cast<T const&>(*this);
		}

		T&& value() && {
			return std::move(static_cast<T&>(*this));
		}
	};

	template <typename T, std::size_t tag>
	struct ebco<T&, tag> {
		T& ref;

		ebco() = default;
		ebco(const ebco&) = default;
		ebco(ebco&&) = default;
		ebco(T& v) : ref(v){};

		ebco& operator=(const ebco&) = default;
		ebco& operator=(ebco&&) = default;
		ebco& operator=(T& v) {
			ref = v;
			return *this;
		}

		T& value() const {
			return const_cast<ebco<T&, tag>&>(*this).ref;
		}
	};

	template <typename T, std::size_t tag>
	struct ebco<T&&, tag> {
		T&& ref;

		ebco() = default;
		ebco(const ebco&) = default;
		ebco(ebco&&) = default;
		ebco(T&& v) : ref(v){};

		ebco& operator=(const ebco&) = default;
		ebco& operator=(ebco&&) = default;
		ebco& operator=(T&& v) {
			ref = std::move(v);
			return *this;
		}

		T& value() & {
			return ref;
		}

		const T& value() const & {
			return ref;
		}

		T&& value() && {
			return std::move(ref);
		}
	};

}} // namespace sol::detail

#endif // SOL_EBCO_HPP