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_COMMON_VIEW_H
11#define _LIBCPP___RANGES_COMMON_VIEW_H
12
13#include <__concepts/constructible.h>
14#include <__concepts/copyable.h>
15#include <__config>
16#include <__iterator/common_iterator.h>
17#include <__iterator/iterator_traits.h>
18#include <__ranges/access.h>
19#include <__ranges/all.h>
20#include <__ranges/concepts.h>
21#include <__ranges/enable_borrowed_range.h>
22#include <__ranges/range_adaptor.h>
23#include <__ranges/size.h>
24#include <__ranges/view_interface.h>
25#include <__utility/forward.h>
26#include <__utility/move.h>
27
28#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
29# pragma GCC system_header
30#endif
31
32_LIBCPP_PUSH_MACROS
33#include <__undef_macros>
34
35_LIBCPP_BEGIN_NAMESPACE_STD
36
37#if _LIBCPP_STD_VER >= 20
38
39namespace ranges {
40
41template <view _View>
42 requires(!common_range<_View> && copyable<iterator_t<_View>>)
43class common_view : public view_interface<common_view<_View>> {
44 _View __base_ = _View();
45
46public:
47 _LIBCPP_HIDE_FROM_ABI common_view()
48 requires default_initializable<_View>
49 = default;
50
51 _LIBCPP_HIDE_FROM_ABI constexpr explicit common_view(_View __v) : __base_(std::move(__v)) {}
52
53 _LIBCPP_HIDE_FROM_ABI constexpr _View base() const&
54 requires copy_constructible<_View>
55 {
56 return __base_;
57 }
58
59 _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }
60
61 _LIBCPP_HIDE_FROM_ABI constexpr auto begin() {
62 if constexpr (random_access_range<_View> && sized_range<_View>)
63 return ranges::begin(__base_);
64 else
65 return common_iterator<iterator_t<_View>, sentinel_t<_View>>(ranges::begin(__base_));
66 }
67
68 _LIBCPP_HIDE_FROM_ABI constexpr auto begin() const
69 requires range<const _View>
70 {
71 if constexpr (random_access_range<const _View> && sized_range<const _View>)
72 return ranges::begin(__base_);
73 else
74 return common_iterator<iterator_t<const _View>, sentinel_t<const _View>>(ranges::begin(__base_));
75 }
76
77 _LIBCPP_HIDE_FROM_ABI constexpr auto end() {
78 if constexpr (random_access_range<_View> && sized_range<_View>)
79 return ranges::begin(__base_) + ranges::size(__base_);
80 else
81 return common_iterator<iterator_t<_View>, sentinel_t<_View>>(ranges::end(__base_));
82 }
83
84 _LIBCPP_HIDE_FROM_ABI constexpr auto end() const
85 requires range<const _View>
86 {
87 if constexpr (random_access_range<const _View> && sized_range<const _View>)
88 return ranges::begin(__base_) + ranges::size(__base_);
89 else
90 return common_iterator<iterator_t<const _View>, sentinel_t<const _View>>(ranges::end(__base_));
91 }
92
93 _LIBCPP_HIDE_FROM_ABI constexpr auto size()
94 requires sized_range<_View>
95 {
96 return ranges::size(__base_);
97 }
98
99 _LIBCPP_HIDE_FROM_ABI constexpr auto size() const
100 requires sized_range<const _View>
101 {
102 return ranges::size(__base_);
103 }
104};
105
106template <class _Range>
107common_view(_Range&&) -> common_view<views::all_t<_Range>>;
108
109template <class _View>
110inline constexpr bool enable_borrowed_range<common_view<_View>> = enable_borrowed_range<_View>;
111
112namespace views {
113namespace __common {
114struct __fn : __range_adaptor_closure<__fn> {
115 template <class _Range>
116 requires common_range<_Range>
117 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range) const noexcept(
118 noexcept(views::all(std::forward<_Range>(__range)))) -> decltype(views::all(std::forward<_Range>(__range))) {
119 return views::all(std::forward<_Range>(__range));
120 }
121
122 template <class _Range>
123 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range) const noexcept(noexcept(common_view{
124 std::forward<_Range>(__range)})) -> decltype(common_view{std::forward<_Range>(__range)}) {
125 return common_view{std::forward<_Range>(__range)};
126 }
127};
128} // namespace __common
129
130inline namespace __cpo {
131inline constexpr auto common = __common::__fn{};
132} // namespace __cpo
133} // namespace views
134} // namespace ranges
135
136#endif // _LIBCPP_STD_VER >= 20
137
138_LIBCPP_END_NAMESPACE_STD
139
140_LIBCPP_POP_MACROS
141
142#endif // _LIBCPP___RANGES_COMMON_VIEW_H
143