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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_MOVE_BACKWARD_H
#define _LIBCPP___ALGORITHM_MOVE_BACKWARD_H
#include <__algorithm/copy_move_common.h>
#include <__algorithm/iterator_operations.h>
#include <__algorithm/min.h>
#include <__config>
#include <__iterator/segmented_iterator.h>
#include <__type_traits/common_type.h>
#include <__type_traits/is_copy_constructible.h>
#include <__utility/move.h>
#include <__utility/pair.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
template <class _AlgPolicy, class _BidirectionalIterator1, class _Sentinel, class _BidirectionalIterator2>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_BidirectionalIterator1, _BidirectionalIterator2>
__move_backward(_BidirectionalIterator1 __first, _Sentinel __last, _BidirectionalIterator2 __result);
template <class _AlgPolicy>
struct __move_backward_loop {
template <class _InIter, class _Sent, class _OutIter>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_InIter, _OutIter>
operator()(_InIter __first, _Sent __last, _OutIter __result) const {
auto __last_iter = _IterOps<_AlgPolicy>::next(__first, __last);
auto __original_last_iter = __last_iter;
while (__first != __last_iter) {
*--__result = _IterOps<_AlgPolicy>::__iter_move(--__last_iter);
}
return std::make_pair(std::move(__original_last_iter), std::move(__result));
}
template <class _InIter, class _OutIter, __enable_if_t<__is_segmented_iterator<_InIter>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_InIter, _OutIter>
operator()(_InIter __first, _InIter __last, _OutIter __result) const {
using _Traits = __segmented_iterator_traits<_InIter>;
auto __sfirst = _Traits::__segment(__first);
auto __slast = _Traits::__segment(__last);
if (__sfirst == __slast) {
auto __iters =
std::__move_backward<_AlgPolicy>(_Traits::__local(__first), _Traits::__local(__last), std::move(__result));
return std::make_pair(__last, __iters.second);
}
__result =
std::__move_backward<_AlgPolicy>(_Traits::__begin(__slast), _Traits::__local(__last), std::move(__result))
.second;
--__slast;
while (__sfirst != __slast) {
__result =
std::__move_backward<_AlgPolicy>(_Traits::__begin(__slast), _Traits::__end(__slast), std::move(__result))
.second;
--__slast;
}
__result = std::__move_backward<_AlgPolicy>(_Traits::__local(__first), _Traits::__end(__slast), std::move(__result))
.second;
return std::make_pair(__last, std::move(__result));
}
template <class _InIter,
class _OutIter,
__enable_if_t<__has_random_access_iterator_category<_InIter>::value &&
!__is_segmented_iterator<_InIter>::value && __is_segmented_iterator<_OutIter>::value,
int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_InIter, _OutIter>
operator()(_InIter __first, _InIter __last, _OutIter __result) const {
using _Traits = __segmented_iterator_traits<_OutIter>;
using _DiffT = typename common_type<__iter_diff_t<_InIter>, __iter_diff_t<_OutIter> >::type;
// When the range contains no elements, __result might not be a valid iterator
if (__first == __last)
return std::make_pair(__first, __result);
auto __orig_last = __last;
auto __local_last = _Traits::__local(__result);
auto __segment_iterator = _Traits::__segment(__result);
while (true) {
auto __local_first = _Traits::__begin(__segment_iterator);
auto __size = std::min<_DiffT>(__local_last - __local_first, __last - __first);
auto __iter = std::__move_backward<_AlgPolicy>(__last - __size, __last, __local_last).second;
__last -= __size;
if (__first == __last)
return std::make_pair(std::move(__orig_last), _Traits::__compose(__segment_iterator, std::move(__iter)));
__local_last = _Traits::__end(--__segment_iterator);
}
}
};
struct __move_backward_trivial {
// At this point, the iterators have been unwrapped so any `contiguous_iterator` has been unwrapped to a pointer.
template <class _In, class _Out,
__enable_if_t<__can_lower_move_assignment_to_memmove<_In, _Out>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_In*, _Out*>
operator()(_In* __first, _In* __last, _Out* __result) const {
return std::__copy_backward_trivial_impl(__first, __last, __result);
}
};
template <class _AlgPolicy, class _BidirectionalIterator1, class _Sentinel, class _BidirectionalIterator2>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_BidirectionalIterator1, _BidirectionalIterator2>
__move_backward(_BidirectionalIterator1 __first, _Sentinel __last, _BidirectionalIterator2 __result) {
static_assert(std::is_copy_constructible<_BidirectionalIterator1>::value &&
std::is_copy_constructible<_BidirectionalIterator1>::value, "Iterators must be copy constructible.");
return std::__dispatch_copy_or_move<_AlgPolicy, __move_backward_loop<_AlgPolicy>, __move_backward_trivial>(
std::move(__first), std::move(__last), std::move(__result));
}
template <class _BidirectionalIterator1, class _BidirectionalIterator2>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 _BidirectionalIterator2
move_backward(_BidirectionalIterator1 __first, _BidirectionalIterator1 __last, _BidirectionalIterator2 __result) {
return std::__move_backward<_ClassicAlgPolicy>(std::move(__first), std::move(__last), std::move(__result)).second;
}
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___ALGORITHM_MOVE_BACKWARD_H
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