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 <__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]
  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 >= 20
  71
  72 _LIBCPP_END_NAMESPACE_STD
  73
  74 #endif // _LIBCPP___COMPARE_PARTIAL_ORDER