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> 13bdd1243dSDimitry Andric #include <__type_traits/is_nothrow_assignable.h> 14*0fca6ea1SDimitry Andric #include <__type_traits/is_nothrow_constructible.h> 15fe6060f1SDimitry Andric #include <__utility/forward.h> 16fe6060f1SDimitry Andric #include <__utility/move.h> 17fe6060f1SDimitry Andric 18fe6060f1SDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 19fe6060f1SDimitry Andric # pragma GCC system_header 20fe6060f1SDimitry Andric #endif 21fe6060f1SDimitry Andric 2206c3fb27SDimitry Andric _LIBCPP_PUSH_MACROS 2306c3fb27SDimitry Andric #include <__undef_macros> 2406c3fb27SDimitry Andric 25fe6060f1SDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD 26fe6060f1SDimitry Andric 2706c3fb27SDimitry Andric #if _LIBCPP_STD_VER >= 14 28fe6060f1SDimitry Andric template <class _T1, class _T2 = _T1> 29cb14a3feSDimitry Andric inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _T1 exchange(_T1& __obj, _T2&& __new_value) noexcept( 30cb14a3feSDimitry Andric is_nothrow_move_constructible<_T1>::value && is_nothrow_assignable<_T1&, _T2>::value) { 315f757f3fSDimitry Andric _T1 __old_value = std::move(__obj); 325f757f3fSDimitry Andric __obj = std::forward<_T2>(__new_value); 33fe6060f1SDimitry Andric return __old_value; 34fe6060f1SDimitry Andric } 3506c3fb27SDimitry Andric #endif // _LIBCPP_STD_VER >= 14 36fe6060f1SDimitry Andric 37fe6060f1SDimitry Andric _LIBCPP_END_NAMESPACE_STD 38fe6060f1SDimitry Andric 3906c3fb27SDimitry Andric _LIBCPP_POP_MACROS 4006c3fb27SDimitry Andric 41fe6060f1SDimitry Andric #endif // _LIBCPP___UTILITY_EXCHANGE_H 42