67432f2049
This is the first part of the "Freezing C++03 headers" proposal explained in https://discourse.llvm.org/t/rfc-freezing-c-03-headers-in-libc/77319/58. This patch mechanically copies the headers as of the LLVM 19.1 release into a subdirectory of libc++ so that we can start using these headers when building in C++03 mode. We are going to be backporting important changes to that copy of the headers until the LLVM 21 release. After the LLVM 21 release, only critical bugfixes will be fixed in the C++03 copy of the headers. This patch only performs a copy of the headers -- these headers are still unused by the rest of the codebase.
76 lines
2.6 KiB
C++
76 lines
2.6 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___ALGORITHM_PREV_PERMUTATION_H
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#define _LIBCPP___ALGORITHM_PREV_PERMUTATION_H
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#include <__algorithm/comp.h>
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#include <__algorithm/comp_ref_type.h>
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#include <__algorithm/iterator_operations.h>
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#include <__algorithm/reverse.h>
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#include <__config>
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#include <__iterator/iterator_traits.h>
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#include <__utility/move.h>
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#include <__utility/pair.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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template <class _AlgPolicy, class _Compare, class _BidirectionalIterator, class _Sentinel>
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_BidirectionalIterator, bool>
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__prev_permutation(_BidirectionalIterator __first, _Sentinel __last, _Compare&& __comp) {
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using _Result = pair<_BidirectionalIterator, bool>;
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_BidirectionalIterator __last_iter = _IterOps<_AlgPolicy>::next(__first, __last);
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_BidirectionalIterator __i = __last_iter;
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if (__first == __last || __first == --__i)
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return _Result(std::move(__last_iter), false);
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while (true) {
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_BidirectionalIterator __ip1 = __i;
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if (__comp(*__ip1, *--__i)) {
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_BidirectionalIterator __j = __last_iter;
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while (!__comp(*--__j, *__i))
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;
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_IterOps<_AlgPolicy>::iter_swap(__i, __j);
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std::__reverse<_AlgPolicy>(__ip1, __last_iter);
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return _Result(std::move(__last_iter), true);
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}
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if (__i == __first) {
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std::__reverse<_AlgPolicy>(__first, __last_iter);
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return _Result(std::move(__last_iter), false);
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}
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}
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}
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template <class _BidirectionalIterator, class _Compare>
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inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool
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prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp) {
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return std::__prev_permutation<_ClassicAlgPolicy>(
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std::move(__first), std::move(__last), static_cast<__comp_ref_type<_Compare> >(__comp))
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.second;
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}
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template <class _BidirectionalIterator>
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inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool
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prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last) {
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return std::prev_permutation(__first, __last, __less<>());
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}
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___ALGORITHM_PREV_PERMUTATION_H
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