1679b27959
The exposition-only type trait `pair-like` includes `ranges::subrange`, but in every single case excludes `ranges::subrange` from the list. This patch introduces two new traits `__tuple_like_no_subrange` and `__pair_like_no_subrange`, which exclude `ranges::subrange` from the possible matches. `__pair_like` is no longer required, and thus removed. `__tuple_like` is implemented as `__tuple_like_no_subrange` or a `ranges::subrange` specialization.
62 lines
1.9 KiB
C++
62 lines
1.9 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___TUPLE_TUPLE_LIKE_NO_SUBRANGE_H
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#define _LIBCPP___TUPLE_TUPLE_LIKE_NO_SUBRANGE_H
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#include <__config>
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#include <__fwd/array.h>
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#include <__fwd/complex.h>
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#include <__fwd/pair.h>
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#include <__fwd/tuple.h>
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#include <__tuple/tuple_size.h>
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#include <__type_traits/remove_cvref.h>
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#include <cstddef>
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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 >= 20
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template <class _Tp>
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inline constexpr bool __tuple_like_no_subrange_impl = false;
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template <class... _Tp>
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inline constexpr bool __tuple_like_no_subrange_impl<tuple<_Tp...>> = true;
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template <class _T1, class _T2>
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inline constexpr bool __tuple_like_no_subrange_impl<pair<_T1, _T2>> = true;
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template <class _Tp, size_t _Size>
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inline constexpr bool __tuple_like_no_subrange_impl<array<_Tp, _Size>> = true;
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# if _LIBCPP_STD_VER >= 26
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template <class _Tp>
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inline constexpr bool __tuple_like_no_subrange_impl<complex<_Tp>> = true;
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# endif
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template <class _Tp>
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concept __tuple_like_no_subrange = __tuple_like_no_subrange_impl<remove_cvref_t<_Tp>>;
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// This is equivalent to the exposition-only type trait `pair-like`, except that it is false for specializations of
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// `ranges::subrange`. This is more useful than the pair-like concept in the standard because every use of `pair-like`
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// excludes `ranges::subrange`.
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template <class _Tp>
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concept __pair_like_no_subrange = __tuple_like_no_subrange<_Tp> && tuple_size<remove_cvref_t<_Tp>>::value == 2;
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#endif // _LIBCPP_STD_VER >= 20
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___TUPLE_TUPLE_LIKE_NO_SUBRANGE_H
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