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___COMPARE_PARTIAL_ORDER
10#define _LIBCPP___COMPARE_PARTIAL_ORDER
11
12#include <__compare/compare_three_way.h>
13#include <__compare/ordering.h>
14#include <__compare/weak_order.h>
15#include <__config>
16#include <__type_traits/decay.h>
17#include <__type_traits/is_same.h>
18#include <__utility/forward.h>
19#include <__utility/priority_tag.h>
20
21#ifndef _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER
22# pragma GCC system_header
23#endif
24
25_LIBCPP_BEGIN_NAMESPACE_STD
26
27#if _LIBCPP_STD_VER >= 20
28
29// [cmp.alg]
30namespace __partial_order {
31void partial_order() = delete;
32
33struct __fn {
34 // NOLINTBEGIN(libcpp-robust-against-adl) partial_order should use ADL, but only here
35 template <class _Tp, class _Up>
36 requires is_same_v<decay_t<_Tp>, decay_t<_Up>>
37 _LIBCPP_HIDE_FROM_ABI static constexpr auto __go(_Tp&& __t, _Up&& __u, __priority_tag<2>) noexcept(
38 noexcept(partial_ordering(partial_order(std::forward<_Tp>(__t), std::forward<_Up>(__u)))))
39 -> decltype(partial_ordering(partial_order(std::forward<_Tp>(__t), std::forward<_Up>(__u)))) {
40 return partial_ordering(partial_order(std::forward<_Tp>(__t), std::forward<_Up>(__u)));
41 }
42 // NOLINTEND(libcpp-robust-against-adl)
43
44 template <class _Tp, class _Up>
45 requires is_same_v<decay_t<_Tp>, decay_t<_Up>>
46 _LIBCPP_HIDE_FROM_ABI static constexpr auto __go(_Tp&& __t, _Up&& __u, __priority_tag<1>) noexcept(
47 noexcept(partial_ordering(compare_three_way()(std::forward<_Tp>(__t), std::forward<_Up>(__u)))))
48 -> decltype(partial_ordering(compare_three_way()(std::forward<_Tp>(__t), std::forward<_Up>(__u)))) {
49 return partial_ordering(compare_three_way()(std::forward<_Tp>(__t), std::forward<_Up>(__u)));
50 }
51
52 template <class _Tp, class _Up>
53 requires is_same_v<decay_t<_Tp>, decay_t<_Up>>
54 _LIBCPP_HIDE_FROM_ABI static constexpr auto __go(_Tp&& __t, _Up&& __u, __priority_tag<0>) noexcept(
55 noexcept(partial_ordering(std::weak_order(std::forward<_Tp>(__t), std::forward<_Up>(__u)))))
56 -> decltype(partial_ordering(std::weak_order(std::forward<_Tp>(__t), std::forward<_Up>(__u)))) {
57 return partial_ordering(std::weak_order(std::forward<_Tp>(__t), std::forward<_Up>(__u)));
58 }
59
60 template <class _Tp, class _Up>
61 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t, _Up&& __u) const
62 noexcept(noexcept(__go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<2>())))
63 -> decltype(__go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<2>())) {
64 return __go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<2>());
65 }
66};
67} // namespace __partial_order
68
69inline namespace __cpo {
70inline constexpr auto partial_order = __partial_order::__fn{};
71} // namespace __cpo
72
73#endif // _LIBCPP_STD_VER >= 20
74
75_LIBCPP_END_NAMESPACE_STD
76
77#endif // _LIBCPP___COMPARE_PARTIAL_ORDER
78