libcxx/include/__concepts/totally_ordered.h

   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_TOTALLY_ORDERED_H
  10 #define _LIBCPP___CONCEPTS_TOTALLY_ORDERED_H
  11
  12 #include <__concepts/boolean_testable.h>
  13 #include <__concepts/equality_comparable.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.totallyordered]
  27
  28 template <class _Tp, class _Up>
  29 concept __partially_ordered_with = requires(__make_const_lvalue_ref<_Tp> __t, __make_const_lvalue_ref<_Up> __u) {
  30   { __t < __u } -> __boolean_testable;
  31   { __t > __u } -> __boolean_testable;
  32   { __t <= __u } -> __boolean_testable;
  33   { __t >= __u } -> __boolean_testable;
  34   { __u < __t } -> __boolean_testable;
  35   { __u > __t } -> __boolean_testable;
  36   { __u <= __t } -> __boolean_testable;
  37   { __u >= __t } -> __boolean_testable;
  38 };
  39
  40 template <class _Tp>
  41 concept totally_ordered = equality_comparable<_Tp> && __partially_ordered_with<_Tp, _Tp>;
  42
  43 // clang-format off
  44 template <class _Tp, class _Up>
  45 concept totally_ordered_with =
  46     totally_ordered<_Tp> && totally_ordered<_Up> &&
  47     equality_comparable_with<_Tp, _Up> &&
  48     totally_ordered<
  49         common_reference_t<
  50             __make_const_lvalue_ref<_Tp>,
  51             __make_const_lvalue_ref<_Up>>> &&
  52     __partially_ordered_with<_Tp, _Up>;
  53 // clang-format on
  54
  55 #endif // _LIBCPP_STD_VER >= 20
  56
  57 _LIBCPP_END_NAMESPACE_STD
  58
  59 #endif // _LIBCPP___CONCEPTS_TOTALLY_ORDERED_H