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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_ROTATE_H
#define _LIBCPP___ALGORITHM_ROTATE_H
#include <__algorithm/move.h>
#include <__algorithm/move_backward.h>
#include <__algorithm/swap_ranges.h>
#include <__config>
#include <__iterator/iterator_traits.h>
#include <__iterator/next.h>
#include <__iterator/prev.h>
#include <__utility/swap.h>
#include <iterator>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
template <class _ForwardIterator>
_LIBCPP_CONSTEXPR_AFTER_CXX11 _ForwardIterator
__rotate_left(_ForwardIterator __first, _ForwardIterator __last)
{
typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
value_type __tmp = _VSTD::move(*__first);
_ForwardIterator __lm1 = _VSTD::move(_VSTD::next(__first), __last, __first);
*__lm1 = _VSTD::move(__tmp);
return __lm1;
}
template <class _BidirectionalIterator>
_LIBCPP_CONSTEXPR_AFTER_CXX11 _BidirectionalIterator
__rotate_right(_BidirectionalIterator __first, _BidirectionalIterator __last)
{
typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
_BidirectionalIterator __lm1 = _VSTD::prev(__last);
value_type __tmp = _VSTD::move(*__lm1);
_BidirectionalIterator __fp1 = _VSTD::move_backward(__first, __lm1, __last);
*__first = _VSTD::move(__tmp);
return __fp1;
}
template <class _ForwardIterator>
_LIBCPP_CONSTEXPR_AFTER_CXX14 _ForwardIterator
__rotate_forward(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last)
{
_ForwardIterator __i = __middle;
while (true)
{
swap(*__first, *__i);
++__first;
if (++__i == __last)
break;
if (__first == __middle)
__middle = __i;
}
_ForwardIterator __r = __first;
if (__first != __middle)
{
__i = __middle;
while (true)
{
swap(*__first, *__i);
++__first;
if (++__i == __last)
{
if (__first == __middle)
break;
__i = __middle;
}
else if (__first == __middle)
__middle = __i;
}
}
return __r;
}
template<typename _Integral>
inline _LIBCPP_INLINE_VISIBILITY
_LIBCPP_CONSTEXPR_AFTER_CXX14 _Integral
__algo_gcd(_Integral __x, _Integral __y)
{
do
{
_Integral __t = __x % __y;
__x = __y;
__y = __t;
} while (__y);
return __x;
}
template<typename _RandomAccessIterator>
_LIBCPP_CONSTEXPR_AFTER_CXX14 _RandomAccessIterator
__rotate_gcd(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last)
{
typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
const difference_type __m1 = __middle - __first;
const difference_type __m2 = __last - __middle;
if (__m1 == __m2)
{
_VSTD::swap_ranges(__first, __middle, __middle);
return __middle;
}
const difference_type __g = _VSTD::__algo_gcd(__m1, __m2);
for (_RandomAccessIterator __p = __first + __g; __p != __first;)
{
value_type __t(_VSTD::move(*--__p));
_RandomAccessIterator __p1 = __p;
_RandomAccessIterator __p2 = __p1 + __m1;
do
{
*__p1 = _VSTD::move(*__p2);
__p1 = __p2;
const difference_type __d = __last - __p2;
if (__m1 < __d)
__p2 += __m1;
else
__p2 = __first + (__m1 - __d);
} while (__p2 != __p);
*__p1 = _VSTD::move(__t);
}
return __first + __m2;
}
template <class _ForwardIterator>
inline _LIBCPP_INLINE_VISIBILITY
_LIBCPP_CONSTEXPR_AFTER_CXX11 _ForwardIterator
__rotate(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last,
_VSTD::forward_iterator_tag)
{
typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
if (is_trivially_move_assignable<value_type>::value)
{
if (_VSTD::next(__first) == __middle)
return _VSTD::__rotate_left(__first, __last);
}
return _VSTD::__rotate_forward(__first, __middle, __last);
}
template <class _BidirectionalIterator>
inline _LIBCPP_INLINE_VISIBILITY
_LIBCPP_CONSTEXPR_AFTER_CXX11 _BidirectionalIterator
__rotate(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
bidirectional_iterator_tag)
{
typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
if (is_trivially_move_assignable<value_type>::value)
{
if (_VSTD::next(__first) == __middle)
return _VSTD::__rotate_left(__first, __last);
if (_VSTD::next(__middle) == __last)
return _VSTD::__rotate_right(__first, __last);
}
return _VSTD::__rotate_forward(__first, __middle, __last);
}
template <class _RandomAccessIterator>
inline _LIBCPP_INLINE_VISIBILITY
_LIBCPP_CONSTEXPR_AFTER_CXX11 _RandomAccessIterator
__rotate(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
random_access_iterator_tag)
{
typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
if (is_trivially_move_assignable<value_type>::value)
{
if (_VSTD::next(__first) == __middle)
return _VSTD::__rotate_left(__first, __last);
if (_VSTD::next(__middle) == __last)
return _VSTD::__rotate_right(__first, __last);
return _VSTD::__rotate_gcd(__first, __middle, __last);
}
return _VSTD::__rotate_forward(__first, __middle, __last);
}
template <class _ForwardIterator>
inline _LIBCPP_INLINE_VISIBILITY
_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
rotate(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last)
{
if (__first == __middle)
return __last;
if (__middle == __last)
return __first;
return _VSTD::__rotate(__first, __middle, __last,
typename iterator_traits<_ForwardIterator>::iterator_category());
}
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___ALGORITHM_ROTATE_H
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