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 <__utility/convert_to_integral.h> 16 #include <type_traits> 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, class _Size, class _OutputIterator> 25 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 26 typename enable_if 27 < 28 __is_cpp17_input_iterator<_InputIterator>::value && 29 !__is_cpp17_random_access_iterator<_InputIterator>::value, 30 _OutputIterator 31 >::type 32 copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result) 33 { 34 typedef decltype(_VSTD::__convert_to_integral(__orig_n)) _IntegralSize; 35 _IntegralSize __n = __orig_n; 36 if (__n > 0) 37 { 38 *__result = *__first; 39 ++__result; 40 for (--__n; __n > 0; --__n) 41 { 42 ++__first; 43 *__result = *__first; 44 ++__result; 45 } 46 } 47 return __result; 48 } 49 50 template<class _InputIterator, class _Size, class _OutputIterator> 51 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 52 typename enable_if 53 < 54 __is_cpp17_random_access_iterator<_InputIterator>::value, 55 _OutputIterator 56 >::type 57 copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result) 58 { 59 typedef typename iterator_traits<_InputIterator>::difference_type difference_type; 60 typedef decltype(_VSTD::__convert_to_integral(__orig_n)) _IntegralSize; 61 _IntegralSize __n = __orig_n; 62 return _VSTD::copy(__first, __first + difference_type(__n), __result); 63 } 64 65 _LIBCPP_END_NAMESPACE_STD 66 67 #endif // _LIBCPP___ALGORITHM_COPY_N_H 68