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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_STRONG_ORDER10#define _LIBCPP___COMPARE_STRONG_ORDER11 12#include <__bit/bit_cast.h>13#include <__compare/compare_three_way.h>14#include <__compare/ordering.h>15#include <__config>16#include <__math/traits.h>17#include <__type_traits/conditional.h>18#include <__type_traits/decay.h>19#include <__type_traits/is_floating_point.h>20#include <__type_traits/is_same.h>21#include <__utility/forward.h>22#include <__utility/priority_tag.h>23#include <cstdint>24#include <limits>25 26#ifndef _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER27# pragma GCC system_header28#endif29 30_LIBCPP_PUSH_MACROS31#include <__undef_macros>32 33_LIBCPP_BEGIN_NAMESPACE_STD34 35#if _LIBCPP_STD_VER >= 2036 37// [cmp.alg]38namespace __strong_order {39void strong_order() = delete;40 41struct __fn {42 // NOLINTBEGIN(libcpp-robust-against-adl) strong_order should use ADL, but only here43 template <class _Tp, class _Up>44 requires is_same_v<decay_t<_Tp>, decay_t<_Up>>45 _LIBCPP_HIDE_FROM_ABI static constexpr auto __go(_Tp&& __t, _Up&& __u, __priority_tag<2>) noexcept(46 noexcept(strong_ordering(strong_order(std::forward<_Tp>(__t), std::forward<_Up>(__u)))))47 -> decltype(strong_ordering(strong_order(std::forward<_Tp>(__t), std::forward<_Up>(__u)))) {48 return strong_ordering(strong_order(std::forward<_Tp>(__t), std::forward<_Up>(__u)));49 }50 // NOLINTEND(libcpp-robust-against-adl)51 52 template <class _Tp, class _Up, class _Dp = decay_t<_Tp>>53 requires is_same_v<_Dp, decay_t<_Up>> && is_floating_point_v<_Dp>54 _LIBCPP_HIDE_FROM_ABI static constexpr strong_ordering __go(_Tp&& __t, _Up&& __u, __priority_tag<1>) noexcept {55 if constexpr (numeric_limits<_Dp>::is_iec559 &&56 (sizeof(_Dp) == sizeof(int32_t) || sizeof(_Dp) == sizeof(int64_t))) {57 using _IntT = conditional_t<sizeof(_Dp) == sizeof(int32_t), int32_t, int64_t>;58 _IntT __rx = std::bit_cast<_IntT>(__t);59 _IntT __ry = std::bit_cast<_IntT>(__u);60 __rx = (__rx < 0) ? (numeric_limits<_IntT>::min() - __rx - 1) : __rx;61 __ry = (__ry < 0) ? (numeric_limits<_IntT>::min() - __ry - 1) : __ry;62 return (__rx <=> __ry);63 } else if (__t < __u) {64 return strong_ordering::less;65 } else if (__t > __u) {66 return strong_ordering::greater;67 } else if (__t == __u) {68 static_assert(numeric_limits<_Dp>::radix == 2, "floating point type with a radix other than 2?");69 return __math::signbit(__u) <=> __math::signbit(__t);70 } else {71 // They're unordered, so one of them must be a NAN.72 // The order is -QNAN, -SNAN, numbers, +SNAN, +QNAN.73 bool __t_is_nan = __math::isnan(__t);74 bool __u_is_nan = __math::isnan(__u);75 bool __t_is_negative = __math::signbit(__t);76 bool __u_is_negative = __math::signbit(__u);77 using _IntType =78 conditional_t<sizeof(__t) == sizeof(int32_t),79 int32_t,80 conditional_t<sizeof(__t) == sizeof(int64_t), int64_t, void>>;81 if constexpr (is_same_v<_IntType, void>) {82 static_assert(sizeof(_Dp) == 0, "std::strong_order is unimplemented for this floating-point type");83 } else if (__t_is_nan && __u_is_nan) {84 // Order by sign bit, then by "payload bits" (we'll just use bit_cast).85 if (__t_is_negative != __u_is_negative) {86 return (__u_is_negative <=> __t_is_negative);87 } else {88 return std::bit_cast<_IntType>(__t) <=> std::bit_cast<_IntType>(__u);89 }90 } else if (__t_is_nan) {91 return __t_is_negative ? strong_ordering::less : strong_ordering::greater;92 } else {93 return __u_is_negative ? strong_ordering::greater : strong_ordering::less;94 }95 }96 }97 98 template <class _Tp, class _Up>99 requires is_same_v<decay_t<_Tp>, decay_t<_Up>>100 _LIBCPP_HIDE_FROM_ABI static constexpr auto __go(_Tp&& __t, _Up&& __u, __priority_tag<0>) noexcept(101 noexcept(strong_ordering(compare_three_way()(std::forward<_Tp>(__t), std::forward<_Up>(__u)))))102 -> decltype(strong_ordering(compare_three_way()(std::forward<_Tp>(__t), std::forward<_Up>(__u)))) {103 return strong_ordering(compare_three_way()(std::forward<_Tp>(__t), std::forward<_Up>(__u)));104 }105 106 template <class _Tp, class _Up>107 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t, _Up&& __u) const108 noexcept(noexcept(__go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<2>())))109 -> decltype(__go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<2>())) {110 return __go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<2>());111 }112};113} // namespace __strong_order114 115inline namespace __cpo {116inline constexpr auto strong_order = __strong_order::__fn{};117} // namespace __cpo118 119#endif // _LIBCPP_STD_VER >= 20120 121_LIBCPP_END_NAMESPACE_STD122 123_LIBCPP_POP_MACROS124 125#endif // _LIBCPP___COMPARE_STRONG_ORDER126