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_RANGES_COPY_N_H
10#define _LIBCPP___ALGORITHM_RANGES_COPY_N_H
11
12#include <__algorithm/copy.h>
13#include <__algorithm/in_out_result.h>
14#include <__algorithm/iterator_operations.h>
15#include <__algorithm/ranges_copy.h>
16#include <__config>
17#include <__functional/identity.h>
18#include <__iterator/concepts.h>
19#include <__iterator/incrementable_traits.h>
20#include <__iterator/unreachable_sentinel.h>
21#include <__iterator/wrap_iter.h>
22#include <__utility/move.h>
23
24#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
25#  pragma GCC system_header
26#endif
27
28_LIBCPP_BEGIN_NAMESPACE_STD
29
30#if _LIBCPP_STD_VER > 17
31
32namespace ranges {
33
34template <class _Ip, class _Op>
35using copy_n_result = in_out_result<_Ip, _Op>;
36
37namespace __copy_n {
38struct __fn {
39
40  template <class _InIter, class _DiffType, class _OutIter>
41  _LIBCPP_HIDE_FROM_ABI constexpr static
42  copy_n_result<_InIter, _OutIter> __go(_InIter __first, _DiffType __n, _OutIter __result) {
43    while (__n != 0) {
44      *__result = *__first;
45      ++__first;
46      ++__result;
47      --__n;
48    }
49    return {std::move(__first), std::move(__result)};
50  }
51
52  template <random_access_iterator _InIter, class _DiffType, random_access_iterator _OutIter>
53  _LIBCPP_HIDE_FROM_ABI constexpr static
54  copy_n_result<_InIter, _OutIter> __go(_InIter __first, _DiffType __n, _OutIter __result) {
55    auto __ret = std::__copy<_RangeAlgPolicy>(__first, __first + __n, __result);
56    return {__ret.first, __ret.second};
57  }
58
59  template <input_iterator _Ip, weakly_incrementable _Op>
60    requires indirectly_copyable<_Ip, _Op>
61  _LIBCPP_HIDE_FROM_ABI constexpr
62  copy_n_result<_Ip, _Op> operator()(_Ip __first, iter_difference_t<_Ip> __n, _Op __result) const {
63    return __go(std::move(__first), __n, std::move(__result));
64  }
65};
66} // namespace __copy_n
67
68inline namespace __cpo {
69  inline constexpr auto copy_n = __copy_n::__fn{};
70} // namespace __cpo
71} // namespace ranges
72
73#endif // _LIBCPP_STD_VER > 17
74
75_LIBCPP_END_NAMESPACE_STD
76
77#endif // _LIBCPP___ALGORITHM_RANGES_COPY_N_H
78