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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-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef _LIBCPP___UTILITY_EXCHANGE_H10#define _LIBCPP___UTILITY_EXCHANGE_H11 12#include <__config>13#include <__type_traits/is_nothrow_assignable.h>14#include <__type_traits/is_nothrow_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_header20#endif21 22_LIBCPP_PUSH_MACROS23#include <__undef_macros>24 25_LIBCPP_BEGIN_NAMESPACE_STD26 27#if _LIBCPP_STD_VER >= 1428template <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 >= 1436 37_LIBCPP_END_NAMESPACE_STD38 39_LIBCPP_POP_MACROS40 41#endif // _LIBCPP___UTILITY_EXCHANGE_H42