1e78f53d1SNikolas Klauser //===----------------------------------------------------------------------===// 2e78f53d1SNikolas Klauser // 3e78f53d1SNikolas Klauser // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4e78f53d1SNikolas Klauser // See https://llvm.org/LICENSE.txt for license information. 5e78f53d1SNikolas Klauser // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6e78f53d1SNikolas Klauser // 7e78f53d1SNikolas Klauser //===----------------------------------------------------------------------===// 8e78f53d1SNikolas Klauser 9*ce777190SNikolas Klauser #ifndef _LIBCPP___CXX03___CONCEPTS_ASSIGNABLE_H 10*ce777190SNikolas Klauser #define _LIBCPP___CXX03___CONCEPTS_ASSIGNABLE_H 11e78f53d1SNikolas Klauser 1273fbae83SNikolas Klauser #include <__cxx03/__concepts/common_reference_with.h> 1373fbae83SNikolas Klauser #include <__cxx03/__concepts/same_as.h> 1473fbae83SNikolas Klauser #include <__cxx03/__config> 1573fbae83SNikolas Klauser #include <__cxx03/__type_traits/is_reference.h> 1673fbae83SNikolas Klauser #include <__cxx03/__type_traits/make_const_lvalue_ref.h> 1773fbae83SNikolas Klauser #include <__cxx03/__utility/forward.h> 18e78f53d1SNikolas Klauser 19e78f53d1SNikolas Klauser #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 20e78f53d1SNikolas Klauser # pragma GCC system_header 21e78f53d1SNikolas Klauser #endif 22e78f53d1SNikolas Klauser 23e78f53d1SNikolas Klauser _LIBCPP_BEGIN_NAMESPACE_STD 24e78f53d1SNikolas Klauser 25e78f53d1SNikolas Klauser #if _LIBCPP_STD_VER >= 20 26e78f53d1SNikolas Klauser 27e78f53d1SNikolas Klauser // [concept.assignable] 28e78f53d1SNikolas Klauser 29e78f53d1SNikolas Klauser template <class _Lhs, class _Rhs> 30e78f53d1SNikolas Klauser concept assignable_from = 31e78f53d1SNikolas Klauser is_lvalue_reference_v<_Lhs> && 32e78f53d1SNikolas Klauser common_reference_with<__make_const_lvalue_ref<_Lhs>, __make_const_lvalue_ref<_Rhs>> && 33e78f53d1SNikolas Klauser requires(_Lhs __lhs, _Rhs&& __rhs) { 34e78f53d1SNikolas Klauser { __lhs = std::forward<_Rhs>(__rhs) } -> same_as<_Lhs>; 35e78f53d1SNikolas Klauser }; 36e78f53d1SNikolas Klauser 37e78f53d1SNikolas Klauser #endif // _LIBCPP_STD_VER >= 20 38e78f53d1SNikolas Klauser 39e78f53d1SNikolas Klauser _LIBCPP_END_NAMESPACE_STD 40e78f53d1SNikolas Klauser 41*ce777190SNikolas Klauser #endif // _LIBCPP___CXX03___CONCEPTS_ASSIGNABLE_H 42