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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-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef _LIBCPP___COMPARE_COMPARE_WEAK_ORDER_FALLBACK10#define _LIBCPP___COMPARE_COMPARE_WEAK_ORDER_FALLBACK11 12#include <__compare/ordering.h>13#include <__compare/weak_order.h>14#include <__concepts/boolean_testable.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_HEADER22# pragma GCC system_header23#endif24 25_LIBCPP_BEGIN_NAMESPACE_STD26 27#if _LIBCPP_STD_VER >= 2028 29// [cmp.alg]30namespace __compare_weak_order_fallback {31struct __fn {32 template <class _Tp, class _Up>33 requires is_same_v<decay_t<_Tp>, decay_t<_Up>>34 _LIBCPP_HIDE_FROM_ABI static constexpr auto __go(_Tp&& __t, _Up&& __u, __priority_tag<1>) noexcept(35 noexcept(std::weak_order(std::forward<_Tp>(__t), std::forward<_Up>(__u))))36 -> decltype(std::weak_order(std::forward<_Tp>(__t), std::forward<_Up>(__u))) {37 return std::weak_order(std::forward<_Tp>(__t), std::forward<_Up>(__u));38 }39 40 template <class _Tp, class _Up>41 requires is_same_v<decay_t<_Tp>, decay_t<_Up>> && requires(_Tp&& __t, _Up&& __u) {42 { std::forward<_Tp>(__t) == std::forward<_Up>(__u) } -> __boolean_testable;43 { std::forward<_Tp>(__t) < std::forward<_Up>(__u) } -> __boolean_testable;44 }45 _LIBCPP_HIDE_FROM_ABI static constexpr weak_ordering __go(_Tp&& __t, _Up&& __u, __priority_tag<0>) noexcept(noexcept(46 std::forward<_Tp>(__t) == std::forward<_Up>(__u) ? weak_ordering::equivalent47 : std::forward<_Tp>(__t) < std::forward<_Up>(__u)48 ? weak_ordering::less49 : weak_ordering::greater)) {50 return std::forward<_Tp>(__t) == std::forward<_Up>(__u) ? weak_ordering::equivalent51 : std::forward<_Tp>(__t) < std::forward<_Up>(__u)52 ? weak_ordering::less53 : weak_ordering::greater;54 }55 56 template <class _Tp, class _Up>57 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t, _Up&& __u) const58 noexcept(noexcept(__go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<1>())))59 -> decltype(__go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<1>())) {60 return __go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<1>());61 }62};63} // namespace __compare_weak_order_fallback64 65inline namespace __cpo {66inline constexpr auto compare_weak_order_fallback = __compare_weak_order_fallback::__fn{};67} // namespace __cpo68 69#endif // _LIBCPP_STD_VER >= 2070 71_LIBCPP_END_NAMESPACE_STD72 73#endif // _LIBCPP___COMPARE_COMPARE_WEAK_ORDER_FALLBACK74