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 9 #ifndef _LIBCPP___CONCEPTS_EQUALITY_COMPARABLE_H 10 #define _LIBCPP___CONCEPTS_EQUALITY_COMPARABLE_H 11 12 #include <__concepts/boolean_testable.h> 13 #include <__concepts/common_reference_with.h> 14 #include <__config> 15 #include <__type_traits/common_reference.h> 16 #include <__type_traits/make_const_lvalue_ref.h> 17 18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 19 # pragma GCC system_header 20 #endif 21 22 _LIBCPP_BEGIN_NAMESPACE_STD 23 24 #if _LIBCPP_STD_VER >= 20 25 26 // [concept.equalitycomparable] 27 28 template <class _Tp, class _Up> 29 concept __weakly_equality_comparable_with = 30 requires(__make_const_lvalue_ref<_Tp> __t, __make_const_lvalue_ref<_Up> __u) { 31 { __t == __u } -> __boolean_testable; 32 { __t != __u } -> __boolean_testable; 33 { __u == __t } -> __boolean_testable; 34 { __u != __t } -> __boolean_testable; 35 }; 36 37 template <class _Tp> 38 concept equality_comparable = __weakly_equality_comparable_with<_Tp, _Tp>; 39 40 // clang-format off 41 template <class _Tp, class _Up> 42 concept equality_comparable_with = 43 equality_comparable<_Tp> && equality_comparable<_Up> && 44 common_reference_with<__make_const_lvalue_ref<_Tp>, __make_const_lvalue_ref<_Up>> && 45 equality_comparable< 46 common_reference_t< 47 __make_const_lvalue_ref<_Tp>, 48 __make_const_lvalue_ref<_Up>>> && 49 __weakly_equality_comparable_with<_Tp, _Up>; 50 // clang-format on 51 52 #endif // _LIBCPP_STD_VER >= 20 53 54 _LIBCPP_END_NAMESPACE_STD 55 56 #endif // _LIBCPP___CONCEPTS_EQUALITY_COMPARABLE_H 57