| //===----------------------------------------------------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef _LIBCPP___COMPARE_STRONG_ORDER |
| #define _LIBCPP___COMPARE_STRONG_ORDER |
| |
| #include <__bit/bit_cast.h> |
| #include <__compare/compare_three_way.h> |
| #include <__compare/ordering.h> |
| #include <__config> |
| #include <__utility/forward.h> |
| #include <__utility/priority_tag.h> |
| #include <cmath> |
| #include <cstdint> |
| #include <limits> |
| #include <type_traits> |
| |
| #ifndef _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER |
| #pragma GCC system_header |
| #endif |
| |
| _LIBCPP_PUSH_MACROS |
| #include <__undef_macros> |
| |
| _LIBCPP_BEGIN_NAMESPACE_STD |
| |
| #if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS) |
| |
| // [cmp.alg] |
| namespace __strong_order { |
| struct __fn { |
| template<class _Tp, class _Up> |
| requires is_same_v<decay_t<_Tp>, decay_t<_Up>> |
| _LIBCPP_HIDE_FROM_ABI static constexpr auto |
| __go(_Tp&& __t, _Up&& __u, __priority_tag<2>) |
| noexcept(noexcept(strong_ordering(strong_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))))) |
| -> decltype( strong_ordering(strong_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)))) |
| { return strong_ordering(strong_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))); } |
| |
| template<class _Tp, class _Up, class _Dp = decay_t<_Tp>> |
| requires is_same_v<_Dp, decay_t<_Up>> && is_floating_point_v<_Dp> |
| _LIBCPP_HIDE_FROM_ABI static constexpr strong_ordering |
| __go(_Tp&& __t, _Up&& __u, __priority_tag<1>) noexcept |
| { |
| if constexpr (numeric_limits<_Dp>::is_iec559 && sizeof(_Dp) == sizeof(int32_t)) { |
| int32_t __rx = _VSTD::bit_cast<int32_t>(__t); |
| int32_t __ry = _VSTD::bit_cast<int32_t>(__u); |
| __rx = (__rx < 0) ? (numeric_limits<int32_t>::min() - __rx - 1) : __rx; |
| __ry = (__ry < 0) ? (numeric_limits<int32_t>::min() - __ry - 1) : __ry; |
| return (__rx <=> __ry); |
| } else if constexpr (numeric_limits<_Dp>::is_iec559 && sizeof(_Dp) == sizeof(int64_t)) { |
| int64_t __rx = _VSTD::bit_cast<int64_t>(__t); |
| int64_t __ry = _VSTD::bit_cast<int64_t>(__u); |
| __rx = (__rx < 0) ? (numeric_limits<int64_t>::min() - __rx - 1) : __rx; |
| __ry = (__ry < 0) ? (numeric_limits<int64_t>::min() - __ry - 1) : __ry; |
| return (__rx <=> __ry); |
| } else if (__t < __u) { |
| return strong_ordering::less; |
| } else if (__t > __u) { |
| return strong_ordering::greater; |
| } else if (__t == __u) { |
| if constexpr (numeric_limits<_Dp>::radix == 2) { |
| return _VSTD::signbit(__u) <=> _VSTD::signbit(__t); |
| } else { |
| // This is bullet 3 of the IEEE754 algorithm, relevant |
| // only for decimal floating-point; |
| // see https://stackoverflow.com/questions/69068075/ |
| if (__t == 0 || _VSTD::isinf(__t)) { |
| return _VSTD::signbit(__u) <=> _VSTD::signbit(__t); |
| } else { |
| int __texp, __uexp; |
| (void)_VSTD::frexp(__t, &__texp); |
| (void)_VSTD::frexp(__u, &__uexp); |
| return (__t < 0) ? (__texp <=> __uexp) : (__uexp <=> __texp); |
| } |
| } |
| } else { |
| // They're unordered, so one of them must be a NAN. |
| // The order is -QNAN, -SNAN, numbers, +SNAN, +QNAN. |
| bool __t_is_nan = _VSTD::isnan(__t); |
| bool __u_is_nan = _VSTD::isnan(__u); |
| bool __t_is_negative = _VSTD::signbit(__t); |
| bool __u_is_negative = _VSTD::signbit(__u); |
| using _IntType = std::conditional_t< |
| sizeof(__t) == sizeof(int32_t), int32_t, std::conditional_t< |
| sizeof(__t) == sizeof(int64_t), int64_t, void> |
| >; |
| if constexpr (std::is_same_v<_IntType, void>) { |
| static_assert(sizeof(_Dp) == 0, "std::strong_order is unimplemented for this floating-point type"); |
| } else if (__t_is_nan && __u_is_nan) { |
| // Order by sign bit, then by "payload bits" (we'll just use bit_cast). |
| if (__t_is_negative != __u_is_negative) { |
| return (__u_is_negative <=> __t_is_negative); |
| } else { |
| return _VSTD::bit_cast<_IntType>(__t) <=> _VSTD::bit_cast<_IntType>(__u); |
| } |
| } else if (__t_is_nan) { |
| return __t_is_negative ? strong_ordering::less : strong_ordering::greater; |
| } else { |
| return __u_is_negative ? strong_ordering::greater : strong_ordering::less; |
| } |
| } |
| } |
| |
| template<class _Tp, class _Up> |
| requires is_same_v<decay_t<_Tp>, decay_t<_Up>> |
| _LIBCPP_HIDE_FROM_ABI static constexpr auto |
| __go(_Tp&& __t, _Up&& __u, __priority_tag<0>) |
| noexcept(noexcept(strong_ordering(compare_three_way()(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))))) |
| -> decltype( strong_ordering(compare_three_way()(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)))) |
| { return strong_ordering(compare_three_way()(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))); } |
| |
| template<class _Tp, class _Up> |
| _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t, _Up&& __u) const |
| noexcept(noexcept(__go(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u), __priority_tag<2>()))) |
| -> decltype( __go(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u), __priority_tag<2>())) |
| { return __go(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u), __priority_tag<2>()); } |
| }; |
| } // namespace __strong_order |
| |
| inline namespace __cpo { |
| inline constexpr auto strong_order = __strong_order::__fn{}; |
| } // namespace __cpo |
| |
| #endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS) |
| |
| _LIBCPP_END_NAMESPACE_STD |
| |
| _LIBCPP_POP_MACROS |
| |
| #endif // _LIBCPP___COMPARE_STRONG_ORDER |
