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___FWD_SUBRANGE_H
10#define _LIBCPP___FWD_SUBRANGE_H
11
12#include <__concepts/copyable.h>
13#include <__config>
14#include <__iterator/concepts.h>
15#include <cstddef>
16
17#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
18# pragma GCC system_header
19#endif
20
21#if _LIBCPP_STD_VER >= 20
22
23_LIBCPP_BEGIN_NAMESPACE_STD
24
25namespace ranges {
26
27enum class subrange_kind : bool { unsized, sized };
28
29template <input_or_output_iterator _Iter, sentinel_for<_Iter> _Sent, subrange_kind _Kind>
30 requires(_Kind == subrange_kind::sized || !sized_sentinel_for<_Sent, _Iter>)
31class _LIBCPP_TEMPLATE_VIS subrange;
32
33template <size_t _Index, class _Iter, class _Sent, subrange_kind _Kind>
34 requires((_Index == 0 && copyable<_Iter>) || _Index == 1)
35_LIBCPP_HIDE_FROM_ABI constexpr auto get(const subrange<_Iter, _Sent, _Kind>&);
36
37template <size_t _Index, class _Iter, class _Sent, subrange_kind _Kind>
38 requires(_Index < 2)
39_LIBCPP_HIDE_FROM_ABI constexpr auto get(subrange<_Iter, _Sent, _Kind>&&);
40
41} // namespace ranges
42
43using ranges::get;
44
45_LIBCPP_END_NAMESPACE_STD
46
47#endif // _LIBCPP_STD_VER >= 20
48
49#endif // _LIBCPP___FWD_SUBRANGE_H
50