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_SPLIT_VIEW_H
11#define _LIBCPP___RANGES_SPLIT_VIEW_H
12
13#include <__algorithm/ranges_search.h>
14#include <__concepts/constructible.h>
15#include <__config>
16#include <__functional/bind_back.h>
17#include <__functional/ranges_operations.h>
18#include <__iterator/indirectly_comparable.h>
19#include <__iterator/iterator_traits.h>
20#include <__memory/addressof.h>
21#include <__ranges/access.h>
22#include <__ranges/all.h>
23#include <__ranges/concepts.h>
24#include <__ranges/empty.h>
25#include <__ranges/non_propagating_cache.h>
26#include <__ranges/range_adaptor.h>
27#include <__ranges/single_view.h>
28#include <__ranges/subrange.h>
29#include <__ranges/view_interface.h>
30#include <__type_traits/decay.h>
31#include <__type_traits/is_nothrow_constructible.h>
32#include <__utility/forward.h>
33#include <__utility/move.h>
34
35#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
36#  pragma GCC system_header
37#endif
38
39_LIBCPP_BEGIN_NAMESPACE_STD
40
41#if _LIBCPP_STD_VER >= 20
42
43namespace ranges {
44
45template <forward_range _View, forward_range _Pattern>
46  requires view<_View> && view<_Pattern> &&
47           indirectly_comparable<iterator_t<_View>, iterator_t<_Pattern>, ranges::equal_to>
48class split_view : public view_interface<split_view<_View, _Pattern>> {
49private:
50  _LIBCPP_NO_UNIQUE_ADDRESS _View __base_       = _View();
51  _LIBCPP_NO_UNIQUE_ADDRESS _Pattern __pattern_ = _Pattern();
52  using _Cache                                  = __non_propagating_cache<subrange<iterator_t<_View>>>;
53  _Cache __cached_begin_                        = _Cache();
54
55  template <class, class>
56  friend struct __iterator;
57
58  template <class, class>
59  friend struct __sentinel;
60
61  struct __iterator;
62  struct __sentinel;
63
64  _LIBCPP_HIDE_FROM_ABI constexpr subrange<iterator_t<_View>> __find_next(iterator_t<_View> __it) {
65    auto [__begin, __end] = ranges::search(subrange(__it, ranges::end(__base_)), __pattern_);
66    if (__begin != ranges::end(__base_) && ranges::empty(__pattern_)) {
67      ++__begin;
68      ++__end;
69    }
70    return {__begin, __end};
71  }
72
73public:
74  _LIBCPP_HIDE_FROM_ABI split_view()
75    requires default_initializable<_View> && default_initializable<_Pattern>
76  = default;
77
78  _LIBCPP_HIDE_FROM_ABI constexpr split_view(_View __base, _Pattern __pattern)
79      : __base_(std::move(__base)), __pattern_(std::move((__pattern))) {}
80
81  template <forward_range _Range>
82    requires constructible_from<_View, views::all_t<_Range>> &&
83                 constructible_from<_Pattern, single_view<range_value_t<_Range>>>
84  _LIBCPP_HIDE_FROM_ABI constexpr split_view(_Range&& __range, range_value_t<_Range> __elem)
85      : __base_(views::all(std::forward<_Range>(__range))), __pattern_(views::single(std::move(__elem))) {}
86
87  _LIBCPP_HIDE_FROM_ABI constexpr _View base() const&
88    requires copy_constructible<_View>
89  {
90    return __base_;
91  }
92
93  _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }
94
95  _LIBCPP_HIDE_FROM_ABI constexpr __iterator begin() {
96    if (!__cached_begin_.__has_value()) {
97      __cached_begin_.__emplace(__find_next(ranges::begin(__base_)));
98    }
99    return {*this, ranges::begin(__base_), *__cached_begin_};
100  }
101
102  _LIBCPP_HIDE_FROM_ABI constexpr auto end() {
103    if constexpr (common_range<_View>) {
104      return __iterator{*this, ranges::end(__base_), {}};
105    } else {
106      return __sentinel{*this};
107    }
108  }
109};
110
111template <class _Range, class _Pattern>
112split_view(_Range&&, _Pattern&&) -> split_view<views::all_t<_Range>, views::all_t<_Pattern>>;
113
114template <forward_range _Range>
115split_view(_Range&&, range_value_t<_Range>) -> split_view<views::all_t<_Range>, single_view<range_value_t<_Range>>>;
116
117template <forward_range _View, forward_range _Pattern>
118  requires view<_View> && view<_Pattern> &&
119           indirectly_comparable<iterator_t<_View>, iterator_t<_Pattern>, ranges::equal_to>
120struct split_view<_View, _Pattern>::__iterator {
121private:
122  split_view* __parent_                                         = nullptr;
123  _LIBCPP_NO_UNIQUE_ADDRESS iterator_t<_View> __cur_            = iterator_t<_View>();
124  _LIBCPP_NO_UNIQUE_ADDRESS subrange<iterator_t<_View>> __next_ = subrange<iterator_t<_View>>();
125  bool __trailing_empty_                                        = false;
126
127  friend struct __sentinel;
128
129public:
130  using iterator_concept  = forward_iterator_tag;
131  using iterator_category = input_iterator_tag;
132  using value_type        = subrange<iterator_t<_View>>;
133  using difference_type   = range_difference_t<_View>;
134
135  _LIBCPP_HIDE_FROM_ABI __iterator() = default;
136
137  _LIBCPP_HIDE_FROM_ABI constexpr __iterator(
138      split_view<_View, _Pattern>& __parent, iterator_t<_View> __current, subrange<iterator_t<_View>> __next)
139      : __parent_(std::addressof(__parent)), __cur_(std::move(__current)), __next_(std::move(__next)) {}
140
141  _LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_View> base() const { return __cur_; }
142
143  _LIBCPP_HIDE_FROM_ABI constexpr value_type operator*() const { return {__cur_, __next_.begin()}; }
144
145  _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator++() {
146    __cur_ = __next_.begin();
147    if (__cur_ != ranges::end(__parent_->__base_)) {
148      __cur_ = __next_.end();
149      if (__cur_ == ranges::end(__parent_->__base_)) {
150        __trailing_empty_ = true;
151        __next_           = {__cur_, __cur_};
152      } else {
153        __next_ = __parent_->__find_next(__cur_);
154      }
155    } else {
156      __trailing_empty_ = false;
157    }
158    return *this;
159  }
160
161  _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator++(int) {
162    auto __tmp = *this;
163    ++*this;
164    return __tmp;
165  }
166
167  _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator& __x, const __iterator& __y) {
168    return __x.__cur_ == __y.__cur_ && __x.__trailing_empty_ == __y.__trailing_empty_;
169  }
170};
171
172template <forward_range _View, forward_range _Pattern>
173  requires view<_View> && view<_Pattern> &&
174           indirectly_comparable<iterator_t<_View>, iterator_t<_Pattern>, ranges::equal_to>
175struct split_view<_View, _Pattern>::__sentinel {
176private:
177  _LIBCPP_NO_UNIQUE_ADDRESS sentinel_t<_View> __end_ = sentinel_t<_View>();
178
179  _LIBCPP_HIDE_FROM_ABI static constexpr bool __equals(const __iterator& __x, const __sentinel& __y) {
180    return __x.__cur_ == __y.__end_ && !__x.__trailing_empty_;
181  }
182
183public:
184  _LIBCPP_HIDE_FROM_ABI __sentinel() = default;
185
186  _LIBCPP_HIDE_FROM_ABI constexpr explicit __sentinel(split_view<_View, _Pattern>& __parent)
187      : __end_(ranges::end(__parent.__base_)) {}
188
189  _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator& __x, const __sentinel& __y) {
190    return __equals(__x, __y);
191  }
192};
193
194namespace views {
195namespace __split_view {
196struct __fn : __range_adaptor_closure<__fn> {
197  // clang-format off
198  template <class _Range, class _Pattern>
199  _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI
200  constexpr auto operator()(_Range&& __range, _Pattern&& __pattern) const
201    noexcept(noexcept(split_view(std::forward<_Range>(__range), std::forward<_Pattern>(__pattern))))
202    -> decltype(      split_view(std::forward<_Range>(__range), std::forward<_Pattern>(__pattern)))
203    { return          split_view(std::forward<_Range>(__range), std::forward<_Pattern>(__pattern)); }
204  // clang-format on
205
206  template <class _Pattern>
207    requires constructible_from<decay_t<_Pattern>, _Pattern>
208  _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Pattern&& __pattern) const
209      noexcept(is_nothrow_constructible_v<decay_t<_Pattern>, _Pattern>) {
210    return __range_adaptor_closure_t(std::__bind_back(*this, std::forward<_Pattern>(__pattern)));
211  }
212};
213} // namespace __split_view
214
215inline namespace __cpo {
216inline constexpr auto split = __split_view::__fn{};
217} // namespace __cpo
218} // namespace views
219
220} // namespace ranges
221
222#endif // _LIBCPP_STD_VER >= 20
223
224_LIBCPP_END_NAMESPACE_STD
225
226#endif // _LIBCPP___RANGES_SPLIT_VIEW_H
227