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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_COPY_N_H
#define _LIBCPP___ALGORITHM_COPY_N_H
#include <__algorithm/copy.h>
#include <__algorithm/iterator_operations.h>
#include <__config>
#include <__iterator/iterator_traits.h>
#include <__type_traits/enable_if.h>
#include <__utility/convert_to_integral.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 _OutIter,
__enable_if_t<__has_random_access_iterator_category<_InIter>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_InIter, _OutIter>
__copy_n(_InIter __first, typename _IterOps<_AlgPolicy>::template __difference_type<_InIter> __n, _OutIter __result) {
return std::__copy(__first, __first + __n, std::move(__result));
}
template <class _AlgPolicy,
class _InIter,
class _OutIter,
__enable_if_t<!__has_random_access_iterator_category<_InIter>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_InIter, _OutIter>
__copy_n(_InIter __first, typename _IterOps<_AlgPolicy>::template __difference_type<_InIter> __n, _OutIter __result) {
while (__n != 0) {
*__result = *__first;
++__first;
++__result;
--__n;
}
return std::make_pair(std::move(__first), std::move(__result));
}
// The InputIterator case is handled specially here because it's been written in a way to avoid incrementing __first
// if not absolutely required. This was done to allow its use with istream_iterator and we want to avoid breaking
// people, at least currently.
// See https://github.com/llvm/llvm-project/commit/99847d2bf132854fffa019bab19818768102ccad
template <class _InputIterator,
class _Size,
class _OutputIterator,
__enable_if_t<__has_exactly_input_iterator_category<_InputIterator>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator
copy_n(_InputIterator __first, _Size __n, _OutputIterator __result) {
using _IntegralSize = decltype(std::__convert_to_integral(__n));
_IntegralSize __converted = __n;
if (__converted > 0) {
*__result = *__first;
++__result;
for (--__converted; __converted > 0; --__converted) {
++__first;
*__result = *__first;
++__result;
}
}
return __result;
}
template <class _InputIterator,
class _Size,
class _OutputIterator,
__enable_if_t<!__has_exactly_input_iterator_category<_InputIterator>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator
copy_n(_InputIterator __first, _Size __n, _OutputIterator __result) {
using _IntegralSize = decltype(std::__convert_to_integral(__n));
_IntegralSize __converted = __n;
return std::__copy_n<_ClassicAlgPolicy>(__first, __iterator_difference_type<_InputIterator>(__converted), __result)
.second;
}
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___ALGORITHM_COPY_N_H
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