8ce2675b13
Implementation of `three_way_comparable` and `three_way_comparable_with` concepts from <compare> header. Please note that I have temporarily removed `<compare>` header from `<utility>` due to cyclic dependency that prevents using `<concepts>` header in `<compare>` one. I tried to quickly resolve those issues including applying suggestions from @cjdb and dive deeper by myself but the problem seems more complicated that we thought initially. I am in progress to prepare the patch with resolving this cyclic dependency between headers but for now I decided to put all that I have to the review to unblock people that depend on that functionality. At first glance the patch with resolving cyclic dependency is not so small (unless I find the way to make it smaller and cleaner) so I don't want to mix everything to one review. Reviewed By: ldionne, cjdb, #libc, Quuxplusone Differential Revision: https://reviews.llvm.org/D103478
59 lines
2.2 KiB
C++
59 lines
2.2 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_THREE_WAY_COMPARABLE_H
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#define _LIBCPP___COMPARE_THREE_WAY_COMPARABLE_H
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#include <__compare/common_comparison_category.h>
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#include <__compare/ordering.h>
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#include <__concepts/common_reference_with.h>
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#include <__concepts/equality_comparable.h>
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#include <__concepts/same_as.h>
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#include <__concepts/totally_ordered.h>
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#include <__config>
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#include <type_traits>
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#if !defined(_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 && !defined(_LIBCPP_HAS_NO_SPACESHIP_OPERATOR) && !defined(_LIBCPP_HAS_NO_CONCEPTS)
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template<class _Tp, class _Cat>
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concept __compares_as =
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same_as<common_comparison_category_t<_Tp, _Cat>, _Cat>;
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template<class _Tp, class _Cat = partial_ordering>
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concept three_way_comparable =
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__weakly_equality_comparable_with<_Tp, _Tp> &&
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__partially_ordered_with<_Tp, _Tp> &&
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requires(__make_const_lvalue_ref<_Tp> __a, __make_const_lvalue_ref<_Tp> __b) {
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{ __a <=> __b } -> __compares_as<_Cat>;
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};
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template<class _Tp, class _Up, class _Cat = partial_ordering>
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concept three_way_comparable_with =
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three_way_comparable<_Tp, _Cat> &&
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three_way_comparable<_Up, _Cat> &&
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common_reference_with<__make_const_lvalue_ref<_Tp>, __make_const_lvalue_ref<_Up>> &&
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three_way_comparable<common_reference_t<__make_const_lvalue_ref<_Tp>, __make_const_lvalue_ref<_Up>>, _Cat> &&
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__weakly_equality_comparable_with<_Tp, _Up> &&
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__partially_ordered_with<_Tp, _Up> &&
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requires(__make_const_lvalue_ref<_Tp> __t, __make_const_lvalue_ref<_Up> __u) {
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{ __t <=> __u } -> __compares_as<_Cat>;
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{ __u <=> __t } -> __compares_as<_Cat>;
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};
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#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_SPACESHIP_OPERATOR) && !defined(_LIBCPP_HAS_NO_CONCEPTS)
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___COMPARE_THREE_WAY_COMPARABLE_H
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