|  | //===----------------------------------------------------------------------===// | 
|  | // | 
|  | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. | 
|  | // See https://llvm.org/LICENSE.txt for license information. | 
|  | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | 
|  | // | 
|  | //===----------------------------------------------------------------------===// | 
|  |  | 
|  | #ifndef _LIBCPP___CONCEPTS_RELATION_H | 
|  | #define _LIBCPP___CONCEPTS_RELATION_H | 
|  |  | 
|  | #include <__concepts/predicate.h> | 
|  | #include <__config> | 
|  |  | 
|  | #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) | 
|  | #  pragma GCC system_header | 
|  | #endif | 
|  |  | 
|  | _LIBCPP_BEGIN_NAMESPACE_STD | 
|  |  | 
|  | #if _LIBCPP_STD_VER >= 20 | 
|  |  | 
|  | // [concept.relation] | 
|  |  | 
|  | template <class _Rp, class _Tp, class _Up> | 
|  | concept relation = | 
|  | predicate<_Rp, _Tp, _Tp> && predicate<_Rp, _Up, _Up> && predicate<_Rp, _Tp, _Up> && predicate<_Rp, _Up, _Tp>; | 
|  |  | 
|  | // [concept.equiv] | 
|  |  | 
|  | template <class _Rp, class _Tp, class _Up> | 
|  | concept equivalence_relation = relation<_Rp, _Tp, _Up>; | 
|  |  | 
|  | // [concept.strictweakorder] | 
|  |  | 
|  | template <class _Rp, class _Tp, class _Up> | 
|  | concept strict_weak_order = relation<_Rp, _Tp, _Up>; | 
|  |  | 
|  | #endif // _LIBCPP_STD_VER >= 20 | 
|  |  | 
|  | _LIBCPP_END_NAMESPACE_STD | 
|  |  | 
|  | #endif // _LIBCPP___CONCEPTS_RELATION_H |