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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_N_H10#define _LIBCPP___ALGORITHM_COPY_N_H11 12#include <__algorithm/copy.h>13#include <__algorithm/iterator_operations.h>14#include <__config>15#include <__iterator/iterator_traits.h>16#include <__type_traits/enable_if.h>17#include <__utility/convert_to_integral.h>18#include <__utility/move.h>19#include <__utility/pair.h>20 21#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)22# pragma GCC system_header23#endif24 25_LIBCPP_PUSH_MACROS26#include <__undef_macros>27 28_LIBCPP_BEGIN_NAMESPACE_STD29 30template <class _AlgPolicy,31 class _InIter,32 class _OutIter,33 __enable_if_t<__has_random_access_iterator_category<_InIter>::value, int> = 0>34_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_InIter, _OutIter>35__copy_n(_InIter __first, typename _IterOps<_AlgPolicy>::template __difference_type<_InIter> __n, _OutIter __result) {36 return std::__copy(__first, __first + __n, std::move(__result));37}38 39template <class _AlgPolicy,40 class _InIter,41 class _OutIter,42 __enable_if_t<!__has_random_access_iterator_category<_InIter>::value, int> = 0>43_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_InIter, _OutIter>44__copy_n(_InIter __first, typename _IterOps<_AlgPolicy>::template __difference_type<_InIter> __n, _OutIter __result) {45 while (__n != 0) {46 *__result = *__first;47 ++__first;48 ++__result;49 --__n;50 }51 return std::make_pair(std::move(__first), std::move(__result));52}53 54// The InputIterator case is handled specially here because it's been written in a way to avoid incrementing __first55// if not absolutely required. This was done to allow its use with istream_iterator and we want to avoid breaking56// people, at least currently.57// See https://github.com/llvm/llvm-project/commit/99847d2bf132854fffa019bab19818768102ccad58template <class _InputIterator,59 class _Size,60 class _OutputIterator,61 __enable_if_t<__has_exactly_input_iterator_category<_InputIterator>::value, int> = 0>62_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator63copy_n(_InputIterator __first, _Size __n, _OutputIterator __result) {64 using _IntegralSize = decltype(std::__convert_to_integral(__n));65 _IntegralSize __converted = __n;66 if (__converted > 0) {67 *__result = *__first;68 ++__result;69 for (--__converted; __converted > 0; --__converted) {70 ++__first;71 *__result = *__first;72 ++__result;73 }74 }75 return __result;76}77 78template <class _InputIterator,79 class _Size,80 class _OutputIterator,81 __enable_if_t<!__has_exactly_input_iterator_category<_InputIterator>::value, int> = 0>82_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator83copy_n(_InputIterator __first, _Size __n, _OutputIterator __result) {84 using _IntegralSize = decltype(std::__convert_to_integral(__n));85 _IntegralSize __converted = __n;86 return std::__copy_n<_ClassicAlgPolicy>(__first, __iterator_difference_type<_InputIterator>(__converted), __result)87 .second;88}89 90_LIBCPP_END_NAMESPACE_STD91 92_LIBCPP_POP_MACROS93 94#endif // _LIBCPP___ALGORITHM_COPY_N_H95