1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef _LIBCPP___UTILITY_EXCHANGE_H
10#define _LIBCPP___UTILITY_EXCHANGE_H
11
12#include <__config>
13#include <__type_traits/is_nothrow_assignable.h>
14#include <__type_traits/is_nothrow_move_constructible.h>
15#include <__utility/forward.h>
16#include <__utility/move.h>
17
18#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
19#  pragma GCC system_header
20#endif
21
22_LIBCPP_PUSH_MACROS
23#include <__undef_macros>
24
25_LIBCPP_BEGIN_NAMESPACE_STD
26
27#if _LIBCPP_STD_VER >= 14
28template <class _T1, class _T2 = _T1>
29inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _T1 exchange(_T1& __obj, _T2&& __new_value) noexcept(
30    is_nothrow_move_constructible<_T1>::value && is_nothrow_assignable<_T1&, _T2>::value) {
31  _T1 __old_value = std::move(__obj);
32  __obj           = std::forward<_T2>(__new_value);
33  return __old_value;
34}
35#endif // _LIBCPP_STD_VER >= 14
36
37_LIBCPP_END_NAMESPACE_STD
38
39_LIBCPP_POP_MACROS
40
41#endif // _LIBCPP___UTILITY_EXCHANGE_H
42