1// -*- C++ -*-
 2//===----------------------------------------------------------------------===//
 3//
 4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 5// See https://llvm.org/LICENSE.txt for license information.
 6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 7//
 8//===----------------------------------------------------------------------===//
 9
10#ifndef _LIBCPP___NUMERIC_RANGES_IOTA_H
11#define _LIBCPP___NUMERIC_RANGES_IOTA_H
12
13#include <__algorithm/out_value_result.h>
14#include <__config>
15#include <__iterator/concepts.h>
16#include <__ranges/access.h>
17#include <__ranges/concepts.h>
18#include <__ranges/dangling.h>
19#include <__utility/as_const.h>
20#include <__utility/move.h>
21
22#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
23#  pragma GCC system_header
24#endif
25
26_LIBCPP_PUSH_MACROS
27#include <__undef_macros>
28
29_LIBCPP_BEGIN_NAMESPACE_STD
30
31#if _LIBCPP_STD_VER >= 23
32namespace ranges {
33template <typename _Out, typename _Tp>
34using iota_result = ranges::out_value_result<_Out, _Tp>;
35
36struct __iota_fn {
37public:
38  template <input_or_output_iterator _Out, sentinel_for<_Out> _Sent, weakly_incrementable _Tp>
39    requires indirectly_writable<_Out, const _Tp&>
40  _LIBCPP_HIDE_FROM_ABI static constexpr iota_result<_Out, _Tp> operator()(_Out __first, _Sent __last, _Tp __value) {
41    while (__first != __last) {
42      *__first = std::as_const(__value);
43      ++__first;
44      ++__value;
45    }
46    return {std::move(__first), std::move(__value)};
47  }
48
49  template <weakly_incrementable _Tp, ranges::output_range<const _Tp&> _Range>
50  _LIBCPP_HIDE_FROM_ABI static constexpr iota_result<ranges::borrowed_iterator_t<_Range>, _Tp>
51  operator()(_Range&& __r, _Tp __value) {
52    return operator()(ranges::begin(__r), ranges::end(__r), std::move(__value));
53  }
54};
55
56inline constexpr auto iota = __iota_fn{};
57} // namespace ranges
58
59#endif // _LIBCPP_STD_VER >= 23
60
61_LIBCPP_END_NAMESPACE_STD
62
63_LIBCPP_POP_MACROS
64
65#endif // _LIBCPP___NUMERIC_RANGES_IOTA_H