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___RANGES_REND_H
11#define _LIBCPP___RANGES_REND_H
12
13#include <__concepts/class_or_enum.h>
14#include <__concepts/same_as.h>
15#include <__config>
16#include <__iterator/concepts.h>
17#include <__iterator/readable_traits.h>
18#include <__iterator/reverse_iterator.h>
19#include <__ranges/access.h>
20#include <__ranges/rbegin.h>
21#include <__type_traits/decay.h>
22#include <__type_traits/is_reference.h>
23#include <__type_traits/remove_cvref.h>
24#include <__type_traits/remove_reference.h>
25#include <__utility/auto_cast.h>
26
27#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
28# pragma GCC system_header
29#endif
30
31_LIBCPP_BEGIN_NAMESPACE_STD
32
33#if _LIBCPP_STD_VER >= 20
34
35// [range.access.rend]
36
37namespace ranges {
38namespace __rend {
39template <class _Tp>
40concept __member_rend = __can_borrow<_Tp> && requires(_Tp&& __t) {
41 ranges::rbegin(__t);
42 { _LIBCPP_AUTO_CAST(__t.rend()) } -> sentinel_for<decltype(ranges::rbegin(__t))>;
43};
44
45void rend() = delete;
46
47template <class _Tp>
48concept __unqualified_rend =
49 !__member_rend<_Tp> && __can_borrow<_Tp> && __class_or_enum<remove_cvref_t<_Tp>> && requires(_Tp&& __t) {
50 ranges::rbegin(__t);
51 { _LIBCPP_AUTO_CAST(rend(__t)) } -> sentinel_for<decltype(ranges::rbegin(__t))>;
52 };
53
54template <class _Tp>
55concept __can_reverse = __can_borrow<_Tp> && !__member_rend<_Tp> && !__unqualified_rend<_Tp> && requires(_Tp&& __t) {
56 { ranges::begin(__t) } -> same_as<decltype(ranges::end(__t))>;
57 { ranges::begin(__t) } -> bidirectional_iterator;
58};
59
60class __fn {
61public:
62 template <class _Tp>
63 requires __member_rend<_Tp>
64 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
65 noexcept(noexcept(_LIBCPP_AUTO_CAST(__t.rend()))) {
66 return _LIBCPP_AUTO_CAST(__t.rend());
67 }
68
69 template <class _Tp>
70 requires __unqualified_rend<_Tp>
71 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
72 noexcept(noexcept(_LIBCPP_AUTO_CAST(rend(__t)))) {
73 return _LIBCPP_AUTO_CAST(rend(__t));
74 }
75
76 template <class _Tp>
77 requires __can_reverse<_Tp>
78 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
79 noexcept(noexcept(ranges::begin(__t))) {
80 return std::make_reverse_iterator(ranges::begin(__t));
81 }
82
83 void operator()(auto&&) const = delete;
84};
85} // namespace __rend
86
87inline namespace __cpo {
88inline constexpr auto rend = __rend::__fn{};
89} // namespace __cpo
90} // namespace ranges
91
92// [range.access.crend]
93
94namespace ranges {
95namespace __crend {
96struct __fn {
97 template <class _Tp>
98 requires is_lvalue_reference_v<_Tp&&>
99 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
100 noexcept(noexcept(ranges::rend(static_cast<const remove_reference_t<_Tp>&>(__t))))
101 -> decltype(ranges::rend(static_cast<const remove_reference_t<_Tp>&>(__t))) {
102 return ranges::rend(static_cast<const remove_reference_t<_Tp>&>(__t));
103 }
104
105 template <class _Tp>
106 requires is_rvalue_reference_v<_Tp&&>
107 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const noexcept(
108 noexcept(ranges::rend(static_cast<const _Tp&&>(__t)))) -> decltype(ranges::rend(static_cast<const _Tp&&>(__t))) {
109 return ranges::rend(static_cast<const _Tp&&>(__t));
110 }
111};
112} // namespace __crend
113
114inline namespace __cpo {
115inline constexpr auto crend = __crend::__fn{};
116} // namespace __cpo
117} // namespace ranges
118
119#endif // _LIBCPP_STD_VER >= 20
120
121_LIBCPP_END_NAMESPACE_STD
122
123#endif // _LIBCPP___RANGES_REND_H
124