forked from OSchip/llvm-project
101 lines
4.5 KiB
C++
101 lines
4.5 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___COMPARE_WEAK_ORDER
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#define _LIBCPP___COMPARE_WEAK_ORDER
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#include <__compare/compare_three_way.h>
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#include <__compare/ordering.h>
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#include <__compare/strong_order.h>
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#include <__config>
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#include <__utility/forward.h>
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#include <__utility/priority_tag.h>
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#include <cmath>
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#include <type_traits>
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#ifndef _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER
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# pragma GCC system_header
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#endif
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_LIBCPP_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER > 17
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// [cmp.alg]
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namespace __weak_order {
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struct __fn {
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template<class _Tp, class _Up>
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requires is_same_v<decay_t<_Tp>, decay_t<_Up>>
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_LIBCPP_HIDE_FROM_ABI static constexpr auto
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__go(_Tp&& __t, _Up&& __u, __priority_tag<3>)
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noexcept(noexcept(weak_ordering(weak_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)))))
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-> decltype( weak_ordering(weak_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))))
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{ return weak_ordering(weak_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))); }
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template<class _Tp, class _Up, class _Dp = decay_t<_Tp>>
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requires is_same_v<_Dp, decay_t<_Up>> && is_floating_point_v<_Dp>
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_LIBCPP_HIDE_FROM_ABI static constexpr weak_ordering
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__go(_Tp&& __t, _Up&& __u, __priority_tag<2>) noexcept
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{
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partial_ordering __po = (__t <=> __u);
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if (__po == partial_ordering::less) {
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return weak_ordering::less;
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} else if (__po == partial_ordering::equivalent) {
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return weak_ordering::equivalent;
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} else if (__po == partial_ordering::greater) {
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return weak_ordering::greater;
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} else {
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// Otherwise, at least one of them is a NaN.
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bool __t_is_nan = _VSTD::isnan(__t);
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bool __u_is_nan = _VSTD::isnan(__u);
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bool __t_is_negative = _VSTD::signbit(__t);
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bool __u_is_negative = _VSTD::signbit(__u);
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if (__t_is_nan && __u_is_nan) {
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return (__u_is_negative <=> __t_is_negative);
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} else if (__t_is_nan) {
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return __t_is_negative ? weak_ordering::less : weak_ordering::greater;
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} else {
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return __u_is_negative ? weak_ordering::greater : weak_ordering::less;
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}
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}
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}
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template<class _Tp, class _Up>
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requires is_same_v<decay_t<_Tp>, decay_t<_Up>>
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_LIBCPP_HIDE_FROM_ABI static constexpr auto
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__go(_Tp&& __t, _Up&& __u, __priority_tag<1>)
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noexcept(noexcept(weak_ordering(compare_three_way()(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)))))
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-> decltype( weak_ordering(compare_three_way()(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))))
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{ return weak_ordering(compare_three_way()(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))); }
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template<class _Tp, class _Up>
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requires is_same_v<decay_t<_Tp>, decay_t<_Up>>
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_LIBCPP_HIDE_FROM_ABI static constexpr auto
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__go(_Tp&& __t, _Up&& __u, __priority_tag<0>)
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noexcept(noexcept(weak_ordering(_VSTD::strong_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)))))
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-> decltype( weak_ordering(_VSTD::strong_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))))
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{ return weak_ordering(_VSTD::strong_order(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))); }
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template<class _Tp, class _Up>
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_LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t, _Up&& __u) const
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noexcept(noexcept(__go(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u), __priority_tag<3>())))
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-> decltype( __go(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u), __priority_tag<3>()))
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{ return __go(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u), __priority_tag<3>()); }
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};
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} // namespace __weak_order
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inline namespace __cpo {
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inline constexpr auto weak_order = __weak_order::__fn{};
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} // namespace __cpo
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#endif // _LIBCPP_STD_VER > 17
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___COMPARE_WEAK_ORDER
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