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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_COPY_MOVE_COMMON_H10#define _LIBCPP___ALGORITHM_COPY_MOVE_COMMON_H11 12#include <__algorithm/unwrap_iter.h>13#include <__algorithm/unwrap_range.h>14#include <__config>15#include <__cstddef/size_t.h>16#include <__iterator/iterator_traits.h>17#include <__memory/pointer_traits.h>18#include <__string/constexpr_c_functions.h>19#include <__type_traits/enable_if.h>20#include <__type_traits/is_always_bitcastable.h>21#include <__type_traits/is_constant_evaluated.h>22#include <__type_traits/is_constructible.h>23#include <__type_traits/is_trivially_assignable.h>24#include <__type_traits/is_volatile.h>25#include <__utility/move.h>26#include <__utility/pair.h>27 28#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)29# pragma GCC system_header30#endif31 32_LIBCPP_PUSH_MACROS33#include <__undef_macros>34 35_LIBCPP_BEGIN_NAMESPACE_STD36 37// Type traits.38 39template <class _From, class _To>40struct __can_lower_copy_assignment_to_memmove {41 static const bool value =42 // If the types are always bitcastable, it's valid to do a bitwise copy between them.43 __is_always_bitcastable<_From, _To>::value &&44 // Reject conversions that wouldn't be performed by the regular built-in assignment (e.g. between arrays).45 is_trivially_assignable<_To&, const _From&>::value &&46 // `memmove` doesn't accept `volatile` pointers, make sure the optimization SFINAEs away in that case.47 !is_volatile<_From>::value && !is_volatile<_To>::value;48};49 50template <class _From, class _To>51struct __can_lower_move_assignment_to_memmove {52 static const bool value =53 __is_always_bitcastable<_From, _To>::value && is_trivially_assignable<_To&, _From&&>::value &&54 !is_volatile<_From>::value && !is_volatile<_To>::value;55};56 57// `memmove` algorithms implementation.58 59template <class _In, class _Out>60_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_In*, _Out*>61__copy_trivial_impl(_In* __first, _In* __last, _Out* __result) {62 const size_t __n = static_cast<size_t>(__last - __first);63 64 std::__constexpr_memmove(__result, __first, __element_count(__n));65 66 return std::make_pair(__last, __result + __n);67}68 69template <class _In, class _Out>70_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_In*, _Out*>71__copy_backward_trivial_impl(_In* __first, _In* __last, _Out* __result) {72 const size_t __n = static_cast<size_t>(__last - __first);73 __result -= __n;74 75 std::__constexpr_memmove(__result, __first, __element_count(__n));76 77 return std::make_pair(__last, __result);78}79 80// Iterator unwrapping and dispatching to the correct overload.81 82template <class _InIter, class _OutIter>83struct __can_rewrap84 : integral_constant<bool, is_copy_constructible<_InIter>::value && is_copy_constructible<_OutIter>::value> {};85 86template <class _Algorithm,87 class _InIter,88 class _Sent,89 class _OutIter,90 __enable_if_t<__can_rewrap<_InIter, _OutIter>::value, int> = 0>91_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 pair<_InIter, _OutIter>92__copy_move_unwrap_iters(_InIter __first, _Sent __last, _OutIter __out_first) {93 auto __range = std::__unwrap_range(__first, std::move(__last));94 auto __result = _Algorithm()(std::move(__range.first), std::move(__range.second), std::__unwrap_iter(__out_first));95 return std::make_pair(std::__rewrap_range<_Sent>(std::move(__first), std::move(__result.first)),96 std::__rewrap_iter(std::move(__out_first), std::move(__result.second)));97}98 99template <class _Algorithm,100 class _InIter,101 class _Sent,102 class _OutIter,103 __enable_if_t<!__can_rewrap<_InIter, _OutIter>::value, int> = 0>104_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 pair<_InIter, _OutIter>105__copy_move_unwrap_iters(_InIter __first, _Sent __last, _OutIter __out_first) {106 return _Algorithm()(std::move(__first), std::move(__last), std::move(__out_first));107}108 109_LIBCPP_END_NAMESPACE_STD110 111_LIBCPP_POP_MACROS112 113#endif // _LIBCPP___ALGORITHM_COPY_MOVE_COMMON_H114