fa79e0a400
## Introduction This patch implements `ranges::elements_of` from [P2502R2](https://wg21.link/P2502R2). Specializations of `elements_of` encapsulate a range and act as a tag in overload sets to disambiguate when a range should be treated as a sequence rather than a single value. ```cpp template <bool YieldElements> std::generator<std::any> f(std::ranges::input_range auto &&r) { if constexpr (YieldElements) { co_yield std::ranges::elements_of(r); } else { co_yield r; } } ``` ## Reference - [P2502R2: `std::generator`: Synchronous Coroutine Generator for Ranges](https://wg21.link/P2502R2) - [[range.elementsof]](https://eel.is/c++draft/range.elementsof) Partially addresses #105226 --------- Co-authored-by: Louis Dionne <ldionne.2@gmail.com> Co-authored-by: A. Jiang <de34@live.cn>
50 lines
1.3 KiB
C++
50 lines
1.3 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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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___RANGES_ELEMENTS_OF_H
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#define _LIBCPP___RANGES_ELEMENTS_OF_H
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#include <__config>
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#include <__cstddef/byte.h>
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#include <__memory/allocator.h>
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#include <__ranges/concepts.h>
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#include <__utility/forward.h>
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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_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER >= 23
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namespace ranges {
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template <range _Range, class _Allocator = allocator<byte>>
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struct elements_of {
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_LIBCPP_NO_UNIQUE_ADDRESS _Range range;
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_LIBCPP_NO_UNIQUE_ADDRESS _Allocator allocator = _Allocator();
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};
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template <class _Range, class _Allocator = allocator<byte>>
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elements_of(_Range&&, _Allocator = _Allocator()) -> elements_of<_Range&&, _Allocator>;
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} // namespace ranges
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#endif // _LIBCPP_STD_VER >= 23
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___RANGES_ELEMENTS_OF_H
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