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
24template <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>
30inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator
31copy_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
46template <class _InputIterator,
47          class _Size,
48          class _OutputIterator,
49          __enable_if_t<__has_random_access_iterator_category<_InputIterator>::value, int> = 0>
50inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator
51copy_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