| //===----------------------------------------------------------------------===// |
| // |
| // 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_COPY_BACKWARD_H |
| #define _LIBCPP___ALGORITHM_COPY_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 _InIter, class _Sent, class _OutIter> |
| _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_InIter, _OutIter> |
| __copy_backward(_InIter __first, _Sent __last, _OutIter __result); |
| |
| template <class _AlgPolicy> |
| struct __copy_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 = *--__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::__copy_backward<_AlgPolicy>(_Traits::__local(__first), _Traits::__local(__last), std::move(__result)); |
| return std::make_pair(__last, __iters.second); |
| } |
| |
| __result = |
| std::__copy_backward<_AlgPolicy>(_Traits::__begin(__slast), _Traits::__local(__last), std::move(__result)) |
| .second; |
| --__slast; |
| while (__sfirst != __slast) { |
| __result = |
| std::__copy_backward<_AlgPolicy>(_Traits::__begin(__slast), _Traits::__end(__slast), std::move(__result)) |
| .second; |
| --__slast; |
| } |
| __result = std::__copy_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<__is_cpp17_random_access_iterator<_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) { |
| using _Traits = __segmented_iterator_traits<_OutIter>; |
| auto __orig_last = __last; |
| auto __segment_iterator = _Traits::__segment(__result); |
| |
| // When the range contains no elements, __result might not be a valid iterator |
| if (__first == __last) |
| return std::make_pair(__first, __result); |
| |
| auto __local_last = _Traits::__local(__result); |
| while (true) { |
| using _DiffT = typename common_type<__iter_diff_t<_InIter>, __iter_diff_t<_OutIter> >::type; |
| |
| auto __local_first = _Traits::__begin(__segment_iterator); |
| auto __size = std::min<_DiffT>(__local_last - __local_first, __last - __first); |
| auto __iter = std::__copy_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))); |
| --__segment_iterator; |
| __local_last = _Traits::__end(__segment_iterator); |
| } |
| } |
| }; |
| |
| struct __copy_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_copy_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> |
| __copy_backward(_BidirectionalIterator1 __first, _Sentinel __last, _BidirectionalIterator2 __result) { |
| return std::__dispatch_copy_or_move<_AlgPolicy, __copy_backward_loop<_AlgPolicy>, __copy_backward_trivial>( |
| std::move(__first), std::move(__last), std::move(__result)); |
| } |
| |
| template <class _BidirectionalIterator1, class _BidirectionalIterator2> |
| inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 |
| _BidirectionalIterator2 |
| copy_backward(_BidirectionalIterator1 __first, _BidirectionalIterator1 __last, |
| _BidirectionalIterator2 __result) |
| { |
| static_assert(std::is_copy_constructible<_BidirectionalIterator1>::value && |
| std::is_copy_constructible<_BidirectionalIterator1>::value, "Iterators must be copy constructible."); |
| |
| return std::__copy_backward<_ClassicAlgPolicy>( |
| std::move(__first), std::move(__last), std::move(__result)).second; |
| } |
| |
| _LIBCPP_END_NAMESPACE_STD |
| |
| _LIBCPP_POP_MACROS |
| |
| #endif // _LIBCPP___ALGORITHM_COPY_BACKWARD_H |