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 > 17
28 
29 // [cmp.alg]
30 namespace __partial_order {
31     struct __fn {
32     // NOLINTBEGIN(libcpp-robust-against-adl) partial_order should use ADL, but only here
33         template<class _Tp, class _Up>
34             requires is_same_v<decay_t<_Tp>, decay_t<_Up>>
35         _LIBCPP_HIDE_FROM_ABI static constexpr auto
36         __go(_Tp&& __t, _Up&& __u, __priority_tag<2>)
37             noexcept(noexcept(partial_ordering(partial_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)))))
38             -> decltype(      partial_ordering(partial_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))))
39             { return          partial_ordering(partial_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))); }
40     // NOLINTEND(libcpp-robust-against-adl)
41 
42         template<class _Tp, class _Up>
43             requires is_same_v<decay_t<_Tp>, decay_t<_Up>>
44         _LIBCPP_HIDE_FROM_ABI static constexpr auto
45         __go(_Tp&& __t, _Up&& __u, __priority_tag<1>)
46             noexcept(noexcept(partial_ordering(compare_three_way()(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)))))
47             -> decltype(      partial_ordering(compare_three_way()(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))))
48             { return          partial_ordering(compare_three_way()(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))); }
49 
50         template<class _Tp, class _Up>
51             requires is_same_v<decay_t<_Tp>, decay_t<_Up>>
52         _LIBCPP_HIDE_FROM_ABI static constexpr auto
53         __go(_Tp&& __t, _Up&& __u, __priority_tag<0>)
54             noexcept(noexcept(partial_ordering(_VSTD::weak_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)))))
55             -> decltype(      partial_ordering(_VSTD::weak_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))))
56             { return          partial_ordering(_VSTD::weak_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))); }
57 
58         template<class _Tp, class _Up>
59         _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t, _Up&& __u) const
60             noexcept(noexcept(__go(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u), __priority_tag<2>())))
61             -> decltype(      __go(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u), __priority_tag<2>()))
62             { return          __go(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u), __priority_tag<2>()); }
63     };
64 } // namespace __partial_order
65 
66 inline namespace __cpo {
67     inline constexpr auto partial_order = __partial_order::__fn{};
68 } // namespace __cpo
69 
70 #endif // _LIBCPP_STD_VER > 17
71 
72 _LIBCPP_END_NAMESPACE_STD
73 
74 #endif // _LIBCPP___COMPARE_PARTIAL_ORDER
75