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_WEAK_ORDER 10 #define _LIBCPP___COMPARE_WEAK_ORDER 11 12 #include <__compare/compare_three_way.h> 13 #include <__compare/ordering.h> 14 #include <__compare/strong_order.h> 15 #include <__config> 16 #include <__utility/forward.h> 17 #include <__utility/priority_tag.h> 18 #include <cmath> 19 #include <type_traits> 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 __weak_order { 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 35 __go(_Tp&& __t, _Up&& __u, __priority_tag<3>) 36 noexcept(noexcept(weak_ordering(weak_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))))) 37 -> decltype( weak_ordering(weak_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)))) 38 { return weak_ordering(weak_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))); } 39 40 template<class _Tp, class _Up, class _Dp = decay_t<_Tp>> 41 requires is_same_v<_Dp, decay_t<_Up>> && is_floating_point_v<_Dp> 42 _LIBCPP_HIDE_FROM_ABI static constexpr weak_ordering 43 __go(_Tp&& __t, _Up&& __u, __priority_tag<2>) noexcept 44 { 45 partial_ordering __po = (__t <=> __u); 46 if (__po == partial_ordering::less) { 47 return weak_ordering::less; 48 } else if (__po == partial_ordering::equivalent) { 49 return weak_ordering::equivalent; 50 } else if (__po == partial_ordering::greater) { 51 return weak_ordering::greater; 52 } else { 53 // Otherwise, at least one of them is a NaN. 54 bool __t_is_nan = _VSTD::isnan(__t); 55 bool __u_is_nan = _VSTD::isnan(__u); 56 bool __t_is_negative = _VSTD::signbit(__t); 57 bool __u_is_negative = _VSTD::signbit(__u); 58 if (__t_is_nan && __u_is_nan) { 59 return (__u_is_negative <=> __t_is_negative); 60 } else if (__t_is_nan) { 61 return __t_is_negative ? weak_ordering::less : weak_ordering::greater; 62 } else { 63 return __u_is_negative ? weak_ordering::greater : weak_ordering::less; 64 } 65 } 66 } 67 68 template<class _Tp, class _Up> 69 requires is_same_v<decay_t<_Tp>, decay_t<_Up>> 70 _LIBCPP_HIDE_FROM_ABI static constexpr auto 71 __go(_Tp&& __t, _Up&& __u, __priority_tag<1>) 72 noexcept(noexcept(weak_ordering(compare_three_way()(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))))) 73 -> decltype( weak_ordering(compare_three_way()(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)))) 74 { return weak_ordering(compare_three_way()(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))); } 75 76 template<class _Tp, class _Up> 77 requires is_same_v<decay_t<_Tp>, decay_t<_Up>> 78 _LIBCPP_HIDE_FROM_ABI static constexpr auto 79 __go(_Tp&& __t, _Up&& __u, __priority_tag<0>) 80 noexcept(noexcept(weak_ordering(_VSTD::strong_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))))) 81 -> decltype( weak_ordering(_VSTD::strong_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)))) 82 { return weak_ordering(_VSTD::strong_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))); } 83 84 template<class _Tp, class _Up> 85 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t, _Up&& __u) const 86 noexcept(noexcept(__go(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u), __priority_tag<3>()))) 87 -> decltype( __go(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u), __priority_tag<3>())) 88 { return __go(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u), __priority_tag<3>()); } 89 }; 90 } // namespace __weak_order 91 92 inline namespace __cpo { 93 inline constexpr auto weak_order = __weak_order::__fn{}; 94 } // namespace __cpo 95 96 #endif // _LIBCPP_STD_VER > 17 97 98 _LIBCPP_END_NAMESPACE_STD 99 100 #endif // _LIBCPP___COMPARE_WEAK_ORDER 101