exchange.h 1.1 KB

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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-exception
  6. //
  7. //===----------------------------------------------------------------------===//
  8. #ifndef _LIBCPP___UTILITY_EXCHANGE_H
  9. #define _LIBCPP___UTILITY_EXCHANGE_H
  10. #include <__config>
  11. #include <__utility/forward.h>
  12. #include <__utility/move.h>
  13. #include <type_traits>
  14. #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  15. # pragma GCC system_header
  16. #endif
  17. _LIBCPP_BEGIN_NAMESPACE_STD
  18. #if _LIBCPP_STD_VER > 11
  19. template<class _T1, class _T2 = _T1>
  20. inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
  21. _T1 exchange(_T1& __obj, _T2&& __new_value)
  22. noexcept(is_nothrow_move_constructible<_T1>::value && is_nothrow_assignable<_T1&, _T2>::value)
  23. {
  24. _T1 __old_value = _VSTD::move(__obj);
  25. __obj = _VSTD::forward<_T2>(__new_value);
  26. return __old_value;
  27. }
  28. #endif // _LIBCPP_STD_VER > 11
  29. _LIBCPP_END_NAMESPACE_STD
  30. #endif // _LIBCPP___UTILITY_EXCHANGE_H