81 lines
2.8 KiB
C++
81 lines
2.8 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_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_AFTER_CXX17
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pair<_BidirectionalIterator, bool>
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__prev_permutation(_BidirectionalIterator __first, _Sentinel __last, _Compare&& __comp)
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{
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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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{
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_BidirectionalIterator __ip1 = __i;
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if (__comp(*__ip1, *--__i))
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{
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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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{
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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_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
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bool
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prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
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{
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using _Comp_ref = typename __comp_ref_type<_Compare>::type;
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return std::__prev_permutation<_ClassicAlgPolicy>(
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std::move(__first), std::move(__last), static_cast<_Comp_ref>(__comp)).second;
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}
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template <class _BidirectionalIterator>
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
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bool
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prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last)
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{
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return _VSTD::prev_permutation(__first, __last,
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__less<typename iterator_traits<_BidirectionalIterator>::value_type>());
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}
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___ALGORITHM_PREV_PERMUTATION_H
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