67 lines
2.0 KiB
C++
67 lines
2.0 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>
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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, class _Size, class _OutputIterator>
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
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typename enable_if
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<
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__is_cpp17_input_iterator<_InputIterator>::value &&
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!__is_cpp17_random_access_iterator<_InputIterator>::value,
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_OutputIterator
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>::type
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copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result)
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{
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typedef decltype(_VSTD::__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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{
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*__result = *__first;
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++__result;
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for (--__n; __n > 0; --__n)
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{
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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, class _Size, class _OutputIterator>
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
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typename enable_if
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<
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__is_cpp17_random_access_iterator<_InputIterator>::value,
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_OutputIterator
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>::type
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copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result)
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{
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typedef typename iterator_traits<_InputIterator>::difference_type difference_type;
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typedef decltype(_VSTD::__convert_to_integral(__orig_n)) _IntegralSize;
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_IntegralSize __n = __orig_n;
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return _VSTD::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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