libcxx/include/__compare/partial_order.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___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 <__utility/forward.h>
  17 #include <__utility/priority_tag.h>
  18 #include <type_traits>
  19
  20 #ifndef _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER
  21 #pragma GCC system_header
  22 #endif
  23
  24 _LIBCPP_BEGIN_NAMESPACE_STD
  25
  26 #if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS)
  27
  28 // [cmp.alg]
  29 namespace __partial_order {
  30     struct __fn {
  31         template<class _Tp, class _Up>
  32             requires is_same_v<decay_t<_Tp>, decay_t<_Up>>
  33         _LIBCPP_HIDE_FROM_ABI static constexpr auto
  34         __go(_Tp&& __t, _Up&& __u, __priority_tag<2>)
  35             noexcept(noexcept(partial_ordering(partial_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)))))
  36             -> decltype(      partial_ordering(partial_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))))
  37             { return          partial_ordering(partial_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))); }
  38
  39         template<class _Tp, class _Up>
  40             requires is_same_v<decay_t<_Tp>, decay_t<_Up>>
  41         _LIBCPP_HIDE_FROM_ABI static constexpr auto
  42         __go(_Tp&& __t, _Up&& __u, __priority_tag<1>)
  43             noexcept(noexcept(partial_ordering(compare_three_way()(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)))))
  44             -> decltype(      partial_ordering(compare_three_way()(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))))
  45             { return          partial_ordering(compare_three_way()(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))); }
  46
  47         template<class _Tp, class _Up>
  48             requires is_same_v<decay_t<_Tp>, decay_t<_Up>>
  49         _LIBCPP_HIDE_FROM_ABI static constexpr auto
  50         __go(_Tp&& __t, _Up&& __u, __priority_tag<0>)
  51             noexcept(noexcept(partial_ordering(_VSTD::weak_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)))))
  52             -> decltype(      partial_ordering(_VSTD::weak_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))))
  53             { return          partial_ordering(_VSTD::weak_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))); }
  54
  55         template<class _Tp, class _Up>
  56         _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t, _Up&& __u) const
  57             noexcept(noexcept(__go(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u), __priority_tag<2>())))
  58             -> decltype(      __go(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u), __priority_tag<2>()))
  59             { return          __go(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u), __priority_tag<2>()); }
  60     };
  61 } // namespace __partial_order
  62
  63 inline namespace __cpo {
  64     inline constexpr auto partial_order = __partial_order::__fn{};
  65 } // namespace __cpo
  66
  67 #endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS)
  68
  69 _LIBCPP_END_NAMESPACE_STD
  70
  71 #endif // _LIBCPP___COMPARE_PARTIAL_ORDER