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60 lines
2.1 KiB
C++
60 lines
2.1 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___ALGORITHM_COPY_N_H
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#define _LIBCPP___ALGORITHM_COPY_N_H
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#include <__algorithm/copy.h>
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#include <__config>
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#include <__iterator/iterator_traits.h>
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#include <__type_traits/enable_if.h>
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#include <__utility/convert_to_integral.h>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_BEGIN_NAMESPACE_STD
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template <class _InputIterator,
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class _Size,
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class _OutputIterator,
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__enable_if_t<__has_input_iterator_category<_InputIterator>::value &&
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!__has_random_access_iterator_category<_InputIterator>::value,
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int> = 0>
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inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator
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copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result) {
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typedef decltype(std::__convert_to_integral(__orig_n)) _IntegralSize;
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_IntegralSize __n = __orig_n;
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if (__n > 0) {
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*__result = *__first;
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++__result;
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for (--__n; __n > 0; --__n) {
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++__first;
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*__result = *__first;
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++__result;
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}
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}
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return __result;
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}
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template <class _InputIterator,
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class _Size,
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class _OutputIterator,
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__enable_if_t<__has_random_access_iterator_category<_InputIterator>::value, int> = 0>
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inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator
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copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result) {
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typedef typename iterator_traits<_InputIterator>::difference_type difference_type;
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typedef decltype(std::__convert_to_integral(__orig_n)) _IntegralSize;
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_IntegralSize __n = __orig_n;
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return std::copy(__first, __first + difference_type(__n), __result);
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}
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___ALGORITHM_COPY_N_H
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