dolphin/Source/Core/Common/Compat/in_place.h
Léo Lam b08653d69d Common: Add a std::optional implementation
std::optional makes a few things a bit neater and less error prone.
However, we still cannot use C++17 (unfortunately), so this commit
adds an implementation of std::optional that we can use right now.

Based on https://github.com/tensorflow/tensorflow/blob/master/tensorflow/core/lib/gtl/optional.h
which seems to be fairly similar to C++17's <optional> and standards
compliant. It's one of the few implementations that handle propagating
type traits like copy constructibility, just like libc++/libstdc++.
2017-06-03 12:36:24 +02:00

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// Copyright 2017 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.
#pragma once
// MPark.Variant
//
// Copyright Michael Park, 2015-2017
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
#include <cstddef>
namespace std
{
struct in_place_t
{
explicit in_place_t() = default;
};
template <std::size_t I>
struct in_place_index_t
{
explicit in_place_index_t() = default;
};
template <typename T>
struct in_place_type_t
{
explicit in_place_type_t() = default;
};
constexpr in_place_t in_place{};
template <std::size_t I>
constexpr in_place_index_t<I> in_place_index{};
template <typename T>
constexpr in_place_type_t<T> in_place_type{};
} // namespace std