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//===----------------------------------------------------------------------===// 
// 
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 
// See https://llvm.org/LICENSE.txt for license information. 
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 
// 
//===----------------------------------------------------------------------===// 
 
#ifndef _LIBCPP___UTILITY_EXCHANGE_H 
#define _LIBCPP___UTILITY_EXCHANGE_H 
 
#include <__config> 
#include <__utility/forward.h> 
#include <__utility/move.h> 
#include <type_traits> 
 
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 
#pragma GCC system_header 
#endif 
 
_LIBCPP_BEGIN_NAMESPACE_STD 
 
#if _LIBCPP_STD_VER > 11 
template<class _T1, class _T2 = _T1> 
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 
_T1 exchange(_T1& __obj, _T2&& __new_value) 
    noexcept(is_nothrow_move_constructible<_T1>::value && is_nothrow_assignable<_T1&, _T2>::value) 
{ 
    _T1 __old_value = _VSTD::move(__obj); 
    __obj = _VSTD::forward<_T2>(__new_value); 
    return __old_value; 
} 
#endif // _LIBCPP_STD_VER > 11 
 
_LIBCPP_END_NAMESPACE_STD 
 
#endif // _LIBCPP___UTILITY_EXCHANGE_H