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-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef _LIBCPP___ALGORITHM_COPY_N_H 10 #define _LIBCPP___ALGORITHM_COPY_N_H 11 12 #include <__algorithm/copy.h> 13 #include <__config> 14 #include <__iterator/iterator_traits.h> 15 #include <__type_traits/enable_if.h> 16 #include <__utility/convert_to_integral.h> 17 18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 19 # pragma GCC system_header 20 #endif 21 22 _LIBCPP_BEGIN_NAMESPACE_STD 23 24 template <class _InputIterator, 25 class _Size, 26 class _OutputIterator, 27 __enable_if_t<__has_input_iterator_category<_InputIterator>::value && 28 !__has_random_access_iterator_category<_InputIterator>::value, 29 int> = 0> 30 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator 31 copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result) { 32 typedef decltype(std::__convert_to_integral(__orig_n)) _IntegralSize; 33 _IntegralSize __n = __orig_n; 34 if (__n > 0) { 35 *__result = *__first; 36 ++__result; 37 for (--__n; __n > 0; --__n) { 38 ++__first; 39 *__result = *__first; 40 ++__result; 41 } 42 } 43 return __result; 44 } 45 46 template <class _InputIterator, 47 class _Size, 48 class _OutputIterator, 49 __enable_if_t<__has_random_access_iterator_category<_InputIterator>::value, int> = 0> 50 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator 51 copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result) { 52 typedef typename iterator_traits<_InputIterator>::difference_type difference_type; 53 typedef decltype(std::__convert_to_integral(__orig_n)) _IntegralSize; 54 _IntegralSize __n = __orig_n; 55 return std::copy(__first, __first + difference_type(__n), __result); 56 } 57 58 _LIBCPP_END_NAMESPACE_STD 59 60 #endif // _LIBCPP___ALGORITHM_COPY_N_H 61