1fe6060f1SDimitry Andric //===----------------------------------------------------------------------===// 2fe6060f1SDimitry Andric // 3fe6060f1SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4fe6060f1SDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 5fe6060f1SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6fe6060f1SDimitry Andric // 7fe6060f1SDimitry Andric //===----------------------------------------------------------------------===// 8fe6060f1SDimitry Andric 9fe6060f1SDimitry Andric #ifndef _LIBCPP___UTILITY_EXCHANGE_H 10fe6060f1SDimitry Andric #define _LIBCPP___UTILITY_EXCHANGE_H 11fe6060f1SDimitry Andric 12fe6060f1SDimitry Andric #include <__config> 13fe6060f1SDimitry Andric #include <__utility/forward.h> 14fe6060f1SDimitry Andric #include <__utility/move.h> 15*349cc55cSDimitry Andric #include <type_traits> 16fe6060f1SDimitry Andric 17fe6060f1SDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 18fe6060f1SDimitry Andric #pragma GCC system_header 19fe6060f1SDimitry Andric #endif 20fe6060f1SDimitry Andric 21fe6060f1SDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD 22fe6060f1SDimitry Andric 23fe6060f1SDimitry Andric #if _LIBCPP_STD_VER > 11 24fe6060f1SDimitry Andric template<class _T1, class _T2 = _T1> 25fe6060f1SDimitry Andric inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 26fe6060f1SDimitry Andric _T1 exchange(_T1& __obj, _T2&& __new_value) 27*349cc55cSDimitry Andric noexcept(is_nothrow_move_constructible<_T1>::value && is_nothrow_assignable<_T1&, _T2>::value) 28fe6060f1SDimitry Andric { 29fe6060f1SDimitry Andric _T1 __old_value = _VSTD::move(__obj); 30fe6060f1SDimitry Andric __obj = _VSTD::forward<_T2>(__new_value); 31fe6060f1SDimitry Andric return __old_value; 32fe6060f1SDimitry Andric } 33fe6060f1SDimitry Andric #endif // _LIBCPP_STD_VER > 11 34fe6060f1SDimitry Andric 35fe6060f1SDimitry Andric _LIBCPP_END_NAMESPACE_STD 36fe6060f1SDimitry Andric 37fe6060f1SDimitry Andric #endif // _LIBCPP___UTILITY_EXCHANGE_H 38