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
copy_n(_InputIterator __first,_Size __orig_n,_OutputIterator __result)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
copy_n(_InputIterator __first,_Size __orig_n,_OutputIterator __result)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