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_COMPARE_PARTIAL_ORDER_FALLBACK 10 #define _LIBCPP___COMPARE_COMPARE_PARTIAL_ORDER_FALLBACK 11 12 #include <__compare/ordering.h> 13 #include <__compare/partial_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_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 __compare_partial_order_fallback { 31 struct __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::partial_order(std::forward<_Tp>(__t), std::forward<_Up>(__u)))) 36 -> decltype(std::partial_order(std::forward<_Tp>(__t), std::forward<_Up>(__u))) { 37 return std::partial_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 { std::forward<_Up>(__u) < std::forward<_Tp>(__t) } -> __boolean_testable; 45 } 46 _LIBCPP_HIDE_FROM_ABI static constexpr partial_ordering __go(_Tp&& __t, _Up&& __u, __priority_tag<0>) noexcept( 47 noexcept(std::forward<_Tp>(__t) == std::forward<_Up>(__u) ? partial_ordering::equivalent 48 : std::forward<_Tp>(__t) < std::forward<_Up>(__u) ? partial_ordering::less 49 : std::forward<_Up>(__u) < std::forward<_Tp>(__t) ? partial_ordering::greater 50 : partial_ordering::unordered)) { 51 return std::forward<_Tp>(__t) == std::forward<_Up>(__u) ? partial_ordering::equivalent 52 : std::forward<_Tp>(__t) < std::forward<_Up>(__u) ? partial_ordering::less 53 : std::forward<_Up>(__u) < std::forward<_Tp>(__t) 54 ? partial_ordering::greater 55 : partial_ordering::unordered; 56 } 57 58 template <class _Tp, class _Up> 59 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t, _Up&& __u) const 60 noexcept(noexcept(__go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<1>()))) 61 -> decltype(__go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<1>())) { 62 return __go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<1>()); 63 } 64 }; 65 } // namespace __compare_partial_order_fallback 66 67 inline namespace __cpo { 68 inline constexpr auto compare_partial_order_fallback = __compare_partial_order_fallback::__fn{}; 69 } // namespace __cpo 70 71 #endif // _LIBCPP_STD_VER >= 20 72 73 _LIBCPP_END_NAMESPACE_STD 74 75 #endif // _LIBCPP___COMPARE_COMPARE_PARTIAL_ORDER_FALLBACK 76