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1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef _LIBCPP___ALGORITHM_MOVE_BACKWARD_H10#define _LIBCPP___ALGORITHM_MOVE_BACKWARD_H11 12#include <__algorithm/copy_backward.h>13#include <__algorithm/copy_move_common.h>14#include <__algorithm/iterator_operations.h>15#include <__algorithm/min.h>16#include <__config>17#include <__fwd/bit_reference.h>18#include <__iterator/iterator_traits.h>19#include <__iterator/segmented_iterator.h>20#include <__type_traits/common_type.h>21#include <__type_traits/enable_if.h>22#include <__type_traits/is_constructible.h>23#include <__utility/move.h>24#include <__utility/pair.h>25 26#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)27# pragma GCC system_header28#endif29 30_LIBCPP_PUSH_MACROS31#include <__undef_macros>32 33_LIBCPP_BEGIN_NAMESPACE_STD34 35template <class _AlgPolicy, class _BidirectionalIterator1, class _Sentinel, class _BidirectionalIterator2>36_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_BidirectionalIterator1, _BidirectionalIterator2>37__move_backward(_BidirectionalIterator1 __first, _Sentinel __last, _BidirectionalIterator2 __result);38 39template <class _AlgPolicy>40struct __move_backward_impl {41 template <class _InIter, class _Sent, class _OutIter>42 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_InIter, _OutIter>43 operator()(_InIter __first, _Sent __last, _OutIter __result) const {44 auto __last_iter = _IterOps<_AlgPolicy>::next(__first, __last);45 auto __original_last_iter = __last_iter;46 47 while (__first != __last_iter) {48 *--__result = _IterOps<_AlgPolicy>::__iter_move(--__last_iter);49 }50 51 return std::make_pair(std::move(__original_last_iter), std::move(__result));52 }53 54 template <class _InIter, class _OutIter, __enable_if_t<__is_segmented_iterator_v<_InIter>, int> = 0>55 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_InIter, _OutIter>56 operator()(_InIter __first, _InIter __last, _OutIter __result) const {57 using _Traits = __segmented_iterator_traits<_InIter>;58 auto __sfirst = _Traits::__segment(__first);59 auto __slast = _Traits::__segment(__last);60 if (__sfirst == __slast) {61 auto __iters =62 std::__move_backward<_AlgPolicy>(_Traits::__local(__first), _Traits::__local(__last), std::move(__result));63 return std::make_pair(__last, __iters.second);64 }65 66 __result =67 std::__move_backward<_AlgPolicy>(_Traits::__begin(__slast), _Traits::__local(__last), std::move(__result))68 .second;69 --__slast;70 while (__sfirst != __slast) {71 __result =72 std::__move_backward<_AlgPolicy>(_Traits::__begin(__slast), _Traits::__end(__slast), std::move(__result))73 .second;74 --__slast;75 }76 __result = std::__move_backward<_AlgPolicy>(_Traits::__local(__first), _Traits::__end(__slast), std::move(__result))77 .second;78 return std::make_pair(__last, std::move(__result));79 }80 81 template <class _InIter,82 class _OutIter,83 __enable_if_t<__has_random_access_iterator_category<_InIter>::value &&84 !__is_segmented_iterator_v<_InIter> && __is_segmented_iterator_v<_OutIter>,85 int> = 0>86 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_InIter, _OutIter>87 operator()(_InIter __first, _InIter __last, _OutIter __result) const {88 using _Traits = __segmented_iterator_traits<_OutIter>;89 using _DiffT =90 typename common_type<__iterator_difference_type<_InIter>, __iterator_difference_type<_OutIter> >::type;91 92 // When the range contains no elements, __result might not be a valid iterator93 if (__first == __last)94 return std::make_pair(__first, __result);95 96 auto __orig_last = __last;97 98 auto __local_last = _Traits::__local(__result);99 auto __segment_iterator = _Traits::__segment(__result);100 while (true) {101 auto __local_first = _Traits::__begin(__segment_iterator);102 auto __size = std::min<_DiffT>(__local_last - __local_first, __last - __first);103 auto __iter = std::__move_backward<_AlgPolicy>(__last - __size, __last, __local_last).second;104 __last -= __size;105 106 if (__first == __last)107 return std::make_pair(std::move(__orig_last), _Traits::__compose(__segment_iterator, std::move(__iter)));108 109 __local_last = _Traits::__end(--__segment_iterator);110 }111 }112 113 template <class _Cp, bool _IsConst>114 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<__bit_iterator<_Cp, _IsConst>, __bit_iterator<_Cp, false> >115 operator()(__bit_iterator<_Cp, _IsConst> __first,116 __bit_iterator<_Cp, _IsConst> __last,117 __bit_iterator<_Cp, false> __result) {118 return std::__copy_backward<_ClassicAlgPolicy>(__first, __last, __result);119 }120 121 // At this point, the iterators have been unwrapped so any `contiguous_iterator` has been unwrapped to a pointer.122 template <class _In, class _Out, __enable_if_t<__can_lower_move_assignment_to_memmove<_In, _Out>::value, int> = 0>123 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_In*, _Out*>124 operator()(_In* __first, _In* __last, _Out* __result) const {125 return std::__copy_backward_trivial_impl(__first, __last, __result);126 }127};128 129template <class _AlgPolicy, class _BidirectionalIterator1, class _Sentinel, class _BidirectionalIterator2>130_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_BidirectionalIterator1, _BidirectionalIterator2>131__move_backward(_BidirectionalIterator1 __first, _Sentinel __last, _BidirectionalIterator2 __result) {132 static_assert(std::is_copy_constructible<_BidirectionalIterator1>::value &&133 std::is_copy_constructible<_BidirectionalIterator1>::value,134 "Iterators must be copy constructible.");135 136 return std::__copy_move_unwrap_iters<__move_backward_impl<_AlgPolicy> >(137 std::move(__first), std::move(__last), std::move(__result));138}139 140template <class _BidirectionalIterator1, class _BidirectionalIterator2>141inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _BidirectionalIterator2142move_backward(_BidirectionalIterator1 __first, _BidirectionalIterator1 __last, _BidirectionalIterator2 __result) {143 return std::__move_backward<_ClassicAlgPolicy>(std::move(__first), std::move(__last), std::move(__result)).second;144}145 146_LIBCPP_END_NAMESPACE_STD147 148_LIBCPP_POP_MACROS149 150#endif // _LIBCPP___ALGORITHM_MOVE_BACKWARD_H151