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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-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | |
| 9 | #ifndef _LIBCPP___COMPARE_COMMON_COMPARISON_CATEGORY_H |
| 10 | #define _LIBCPP___COMPARE_COMMON_COMPARISON_CATEGORY_H |
| 11 | |
| 12 | #include <__compare/ordering.h> |
| 13 | #include <__config> |
| 14 | #include <__cstddef/size_t.h> |
| 15 | #include <__type_traits/is_same.h> |
| 16 | |
| 17 | #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) |
| 18 | # pragma GCC system_header |
| 19 | #endif |
| 20 | |
| 21 | _LIBCPP_BEGIN_NAMESPACE_STD |
| 22 | |
| 23 | #if _LIBCPP_STD_VER >= 20 |
| 24 | |
| 25 | namespace __comp_detail { |
| 26 | |
| 27 | enum _ClassifyCompCategory : unsigned { _None, _PartialOrd, _WeakOrd, _StrongOrd, _CCC_Size }; |
| 28 | |
| 29 | template <class _Tp> |
| 30 | _LIBCPP_HIDE_FROM_ABI constexpr _ClassifyCompCategory __type_to_enum() noexcept { |
| 31 | if (is_same_v<_Tp, partial_ordering>) |
| 32 | return _PartialOrd; |
| 33 | if (is_same_v<_Tp, weak_ordering>) |
| 34 | return _WeakOrd; |
| 35 | if (is_same_v<_Tp, strong_ordering>) |
| 36 | return _StrongOrd; |
| 37 | return _None; |
| 38 | } |
| 39 | |
| 40 | template <size_t _Size> |
| 41 | _LIBCPP_HIDE_FROM_ABI constexpr _ClassifyCompCategory |
| 42 | __compute_comp_type(const _ClassifyCompCategory (&__types)[_Size]) { |
| 43 | int __seen[_CCC_Size] = {}; |
| 44 | for (auto __type : __types) |
| 45 | ++__seen[__type]; |
| 46 | if (__seen[_None]) |
| 47 | return _None; |
| 48 | if (__seen[_PartialOrd]) |
| 49 | return _PartialOrd; |
| 50 | if (__seen[_WeakOrd]) |
| 51 | return _WeakOrd; |
| 52 | return _StrongOrd; |
| 53 | } |
| 54 | |
| 55 | template <class... _Ts, bool _False = false> |
| 56 | _LIBCPP_HIDE_FROM_ABI constexpr auto __get_comp_type() { |
| 57 | using _CCC = _ClassifyCompCategory; |
| 58 | constexpr _CCC __type_kinds[] = {_StrongOrd, __comp_detail::__type_to_enum<_Ts>()...}; |
| 59 | constexpr _CCC __cat = __comp_detail::__compute_comp_type(__type_kinds); |
| 60 | if constexpr (__cat == _None) |
| 61 | return void(); |
| 62 | else if constexpr (__cat == _PartialOrd) |
| 63 | return partial_ordering::equivalent; |
| 64 | else if constexpr (__cat == _WeakOrd) |
| 65 | return weak_ordering::equivalent; |
| 66 | else if constexpr (__cat == _StrongOrd) |
| 67 | return strong_ordering::equivalent; |
| 68 | else |
| 69 | static_assert(_False, "unhandled case"); |
| 70 | } |
| 71 | } // namespace __comp_detail |
| 72 | |
| 73 | // [cmp.common], common comparison category type |
| 74 | template <class... _Ts> |
| 75 | struct common_comparison_category { |
| 76 | using type _LIBCPP_NODEBUG = decltype(__comp_detail::__get_comp_type<_Ts...>()); |
| 77 | }; |
| 78 | |
| 79 | template <class... _Ts> |
| 80 | using common_comparison_category_t = typename common_comparison_category<_Ts...>::type; |
| 81 | |
| 82 | #endif // _LIBCPP_STD_VER >= 20 |
| 83 | |
| 84 | _LIBCPP_END_NAMESPACE_STD |
| 85 | |
| 86 | #endif // _LIBCPP___COMPARE_COMMON_COMPARISON_CATEGORY_H |
| 87 |
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