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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___ALGORITHM_PREV_PERMUTATION_H
#define _LIBCPP___ALGORITHM_PREV_PERMUTATION_H
#include <__algorithm/comp.h>
#include <__algorithm/comp_ref_type.h>
#include <__algorithm/iterator_operations.h>
#include <__algorithm/reverse.h>
#include <__config>
#include <__iterator/iterator_traits.h>
#include <__utility/move.h>
#include <__utility/pair.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
template <class _AlgPolicy, class _Compare, class _BidirectionalIterator, class _Sentinel>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
pair<_BidirectionalIterator, bool>
__prev_permutation(_BidirectionalIterator __first, _Sentinel __last, _Compare&& __comp)
{
using _Result = pair<_BidirectionalIterator, bool>;
_BidirectionalIterator __last_iter = _IterOps<_AlgPolicy>::next(__first, __last);
_BidirectionalIterator __i = __last_iter;
if (__first == __last || __first == --__i)
return _Result(std::move(__last_iter), false);
while (true)
{
_BidirectionalIterator __ip1 = __i;
if (__comp(*__ip1, *--__i))
{
_BidirectionalIterator __j = __last_iter;
while (!__comp(*--__j, *__i))
;
_IterOps<_AlgPolicy>::iter_swap(__i, __j);
std::__reverse<_AlgPolicy>(__ip1, __last_iter);
return _Result(std::move(__last_iter), true);
}
if (__i == __first)
{
std::__reverse<_AlgPolicy>(__first, __last_iter);
return _Result(std::move(__last_iter), false);
}
}
}
template <class _BidirectionalIterator, class _Compare>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
bool
prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
{
return std::__prev_permutation<_ClassicAlgPolicy>(
std::move(__first), std::move(__last), static_cast<__comp_ref_type<_Compare> >(__comp)).second;
}
template <class _BidirectionalIterator>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
bool
prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last)
{
return _VSTD::prev_permutation(__first, __last, __less<>());
}
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___ALGORITHM_PREV_PERMUTATION_H
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