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_RELATION_H
10 #define _LIBCPP___CONCEPTS_RELATION_H
11 
12 #include <__concepts/predicate.h>
13 #include <__config>
14 
15 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
16 #  pragma GCC system_header
17 #endif
18 
19 _LIBCPP_BEGIN_NAMESPACE_STD
20 
21 #if _LIBCPP_STD_VER >= 20
22 
23 // [concept.relation]
24 
25 template <class _Rp, class _Tp, class _Up>
26 concept relation =
27     predicate<_Rp, _Tp, _Tp> && predicate<_Rp, _Up, _Up> && predicate<_Rp, _Tp, _Up> && predicate<_Rp, _Up, _Tp>;
28 
29 // [concept.equiv]
30 
31 template <class _Rp, class _Tp, class _Up>
32 concept equivalence_relation = relation<_Rp, _Tp, _Up>;
33 
34 // [concept.strictweakorder]
35 
36 template <class _Rp, class _Tp, class _Up>
37 concept strict_weak_order = relation<_Rp, _Tp, _Up>;
38 
39 #endif // _LIBCPP_STD_VER >= 20
40 
41 _LIBCPP_END_NAMESPACE_STD
42 
43 #endif // _LIBCPP___CONCEPTS_RELATION_H
44