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_LAZY_SPLIT_VIEW_H
11#define _LIBCPP___RANGES_LAZY_SPLIT_VIEW_H
12
13#include <__algorithm/ranges_find.h>
14#include <__algorithm/ranges_mismatch.h>
15#include <__assert>
16#include <__concepts/constructible.h>
17#include <__concepts/convertible_to.h>
18#include <__concepts/derived_from.h>
19#include <__config>
20#include <__functional/bind_back.h>
21#include <__functional/ranges_operations.h>
22#include <__iterator/concepts.h>
23#include <__iterator/default_sentinel.h>
24#include <__iterator/incrementable_traits.h>
25#include <__iterator/indirectly_comparable.h>
26#include <__iterator/iter_move.h>
27#include <__iterator/iter_swap.h>
28#include <__iterator/iterator_traits.h>
29#include <__memory/addressof.h>
30#include <__ranges/access.h>
31#include <__ranges/all.h>
32#include <__ranges/concepts.h>
33#include <__ranges/non_propagating_cache.h>
34#include <__ranges/range_adaptor.h>
35#include <__ranges/single_view.h>
36#include <__ranges/subrange.h>
37#include <__ranges/view_interface.h>
38#include <__type_traits/conditional.h>
39#include <__type_traits/decay.h>
40#include <__type_traits/is_nothrow_constructible.h>
41#include <__type_traits/maybe_const.h>
42#include <__type_traits/remove_reference.h>
43#include <__utility/forward.h>
44#include <__utility/move.h>
45
46#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
47# pragma GCC system_header
48#endif
49
50_LIBCPP_PUSH_MACROS
51#include <__undef_macros>
52
53_LIBCPP_BEGIN_NAMESPACE_STD
54
55#if _LIBCPP_STD_VER >= 20
56
57namespace ranges {
58
59template <auto>
60struct __require_constant;
61
62template <class _Range>
63concept __tiny_range = sized_range<_Range> && requires {
64 typename __require_constant<remove_reference_t<_Range>::size()>;
65} && (remove_reference_t<_Range>::size() <= 1);
66
67template <input_range _View, forward_range _Pattern>
68 requires view<_View> && view<_Pattern> &&
69 indirectly_comparable<iterator_t<_View>, iterator_t<_Pattern>, ranges::equal_to> &&
70 (forward_range<_View> || __tiny_range<_Pattern>)
71class lazy_split_view : public view_interface<lazy_split_view<_View, _Pattern>> {
72 _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View();
73 _LIBCPP_NO_UNIQUE_ADDRESS _Pattern __pattern_ = _Pattern();
74
75 using _MaybeCurrent = _If<!forward_range<_View>, __non_propagating_cache<iterator_t<_View>>, __empty_cache>;
76 _LIBCPP_NO_UNIQUE_ADDRESS _MaybeCurrent __current_ = _MaybeCurrent();
77
78 template <bool>
79 struct __outer_iterator;
80 template <bool>
81 struct __inner_iterator;
82
83public:
84 _LIBCPP_HIDE_FROM_ABI lazy_split_view()
85 requires default_initializable<_View> && default_initializable<_Pattern>
86 = default;
87
88 _LIBCPP_HIDE_FROM_ABI constexpr _LIBCPP_EXPLICIT_SINCE_CXX23 lazy_split_view(_View __base, _Pattern __pattern)
89 : __base_(std::move(__base)), __pattern_(std::move(__pattern)) {}
90
91 template <input_range _Range>
92 requires constructible_from<_View, views::all_t<_Range>> &&
93 constructible_from<_Pattern, single_view<range_value_t<_Range>>>
94 _LIBCPP_HIDE_FROM_ABI constexpr _LIBCPP_EXPLICIT_SINCE_CXX23 lazy_split_view(_Range&& __r, range_value_t<_Range> __e)
95 : __base_(views::all(std::forward<_Range>(__r))), __pattern_(views::single(std::move(__e))) {}
96
97 _LIBCPP_HIDE_FROM_ABI constexpr _View base() const&
98 requires copy_constructible<_View>
99 {
100 return __base_;
101 }
102 _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }
103
104 _LIBCPP_HIDE_FROM_ABI constexpr auto begin() {
105 if constexpr (forward_range<_View>) {
106 return __outer_iterator < __simple_view<_View> && __simple_view < _Pattern >> {*this, ranges::begin(__base_)};
107 } else {
108 __current_.__emplace(ranges::begin(__base_));
109 return __outer_iterator<false>{*this};
110 }
111 }
112
113 _LIBCPP_HIDE_FROM_ABI constexpr auto begin() const
114 requires forward_range<_View> && forward_range<const _View>
115 {
116 return __outer_iterator<true>{*this, ranges::begin(__base_)};
117 }
118
119 _LIBCPP_HIDE_FROM_ABI constexpr auto end()
120 requires forward_range<_View> && common_range<_View>
121 {
122 return __outer_iterator < __simple_view<_View> && __simple_view < _Pattern >> {*this, ranges::end(__base_)};
123 }
124
125 _LIBCPP_HIDE_FROM_ABI constexpr auto end() const {
126 if constexpr (forward_range<_View> && forward_range<const _View> && common_range<const _View>) {
127 return __outer_iterator<true>{*this, ranges::end(__base_)};
128 } else {
129 return default_sentinel;
130 }
131 }
132
133private:
134 template <class>
135 struct __outer_iterator_category {};
136
137 template <forward_range _Tp>
138 struct __outer_iterator_category<_Tp> {
139 using iterator_category = input_iterator_tag;
140 };
141
142 template <bool _Const>
143 struct __outer_iterator : __outer_iterator_category<__maybe_const<_Const, _View>> {
144 private:
145 template <bool>
146 friend struct __inner_iterator;
147 friend __outer_iterator<true>;
148
149 using _Parent = __maybe_const<_Const, lazy_split_view>;
150 using _Base = __maybe_const<_Const, _View>;
151
152 _Parent* __parent_ = nullptr;
153 using _MaybeCurrent = _If<forward_range<_View>, iterator_t<_Base>, __empty_cache>;
154 _LIBCPP_NO_UNIQUE_ADDRESS _MaybeCurrent __current_ = _MaybeCurrent();
155 bool __trailing_empty_ = false;
156
157 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto& __current() noexcept {
158 if constexpr (forward_range<_View>) {
159 return __current_;
160 } else {
161 return *__parent_->__current_;
162 }
163 }
164
165 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const auto& __current() const noexcept {
166 if constexpr (forward_range<_View>) {
167 return __current_;
168 } else {
169 return *__parent_->__current_;
170 }
171 }
172
173 // Workaround for the GCC issue that doesn't allow calling `__parent_->__base_` from friend functions (because
174 // `__base_` is private).
175 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto& __parent_base() const noexcept { return __parent_->__base_; }
176
177 public:
178 // using iterator_category = inherited;
179 using iterator_concept = conditional_t<forward_range<_Base>, forward_iterator_tag, input_iterator_tag>;
180 using difference_type = range_difference_t<_Base>;
181
182 struct value_type : view_interface<value_type> {
183 private:
184 __outer_iterator __i_ = __outer_iterator();
185
186 public:
187 _LIBCPP_HIDE_FROM_ABI value_type() = default;
188 _LIBCPP_HIDE_FROM_ABI constexpr explicit value_type(__outer_iterator __i) : __i_(std::move(__i)) {}
189
190 _LIBCPP_HIDE_FROM_ABI constexpr __inner_iterator<_Const> begin() const { return __inner_iterator<_Const>{__i_}; }
191 _LIBCPP_HIDE_FROM_ABI constexpr default_sentinel_t end() const noexcept { return default_sentinel; }
192 };
193
194 _LIBCPP_HIDE_FROM_ABI __outer_iterator() = default;
195
196 _LIBCPP_HIDE_FROM_ABI constexpr explicit __outer_iterator(_Parent& __parent)
197 requires(!forward_range<_Base>)
198 : __parent_(std::addressof(__parent)) {}
199
200 _LIBCPP_HIDE_FROM_ABI constexpr __outer_iterator(_Parent& __parent, iterator_t<_Base> __current)
201 requires forward_range<_Base>
202 : __parent_(std::addressof(__parent)), __current_(std::move(__current)) {}
203
204 _LIBCPP_HIDE_FROM_ABI constexpr __outer_iterator(__outer_iterator<!_Const> __i)
205 requires _Const && convertible_to<iterator_t<_View>, iterator_t<_Base>>
206 : __parent_(__i.__parent_), __current_(std::move(__i.__current_)) {}
207
208 _LIBCPP_HIDE_FROM_ABI constexpr value_type operator*() const { return value_type{*this}; }
209
210 _LIBCPP_HIDE_FROM_ABI constexpr __outer_iterator& operator++() {
211 const auto __end = ranges::end(__parent_->__base_);
212 if (__current() == __end) {
213 __trailing_empty_ = false;
214 return *this;
215 }
216
217 const auto [__pbegin, __pend] = ranges::subrange{__parent_->__pattern_};
218 if (__pbegin == __pend) {
219 // Empty pattern: split on every element in the input range
220 ++__current();
221
222 } else if constexpr (__tiny_range<_Pattern>) {
223 // One-element pattern: we can use `ranges::find`.
224 __current() = ranges::find(std::move(__current()), __end, *__pbegin);
225 if (__current() != __end) {
226 // Make sure we point to after the separator we just found.
227 ++__current();
228 if (__current() == __end)
229 __trailing_empty_ = true;
230 }
231
232 } else {
233 // General case for n-element pattern.
234 do {
235 const auto [__b, __p] = ranges::mismatch(__current(), __end, __pbegin, __pend);
236 if (__p == __pend) {
237 __current() = __b;
238 if (__current() == __end) {
239 __trailing_empty_ = true;
240 }
241 break; // The pattern matched; skip it.
242 }
243 } while (++__current() != __end);
244 }
245
246 return *this;
247 }
248
249 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator++(int) {
250 if constexpr (forward_range<_Base>) {
251 auto __tmp = *this;
252 ++*this;
253 return __tmp;
254
255 } else {
256 ++*this;
257 }
258 }
259
260 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __outer_iterator& __x, const __outer_iterator& __y)
261 requires forward_range<_Base>
262 {
263 return __x.__current_ == __y.__current_ && __x.__trailing_empty_ == __y.__trailing_empty_;
264 }
265
266 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __outer_iterator& __x, default_sentinel_t) {
267 _LIBCPP_ASSERT_NON_NULL(__x.__parent_ != nullptr, "Cannot call comparison on a default-constructed iterator.");
268 return __x.__current() == ranges::end(__x.__parent_base()) && !__x.__trailing_empty_;
269 }
270 };
271
272 template <class>
273 struct __inner_iterator_category {};
274
275 template <forward_range _Tp>
276 struct __inner_iterator_category<_Tp> {
277 using iterator_category =
278 _If< derived_from<typename iterator_traits<iterator_t<_Tp>>::iterator_category, forward_iterator_tag>,
279 forward_iterator_tag,
280 typename iterator_traits<iterator_t<_Tp>>::iterator_category >;
281 };
282
283 template <bool _Const>
284 struct __inner_iterator : __inner_iterator_category<__maybe_const<_Const, _View>> {
285 private:
286 using _Base = __maybe_const<_Const, _View>;
287 // Workaround for a GCC issue.
288 static constexpr bool _OuterConst = _Const;
289 __outer_iterator<_Const> __i_ = __outer_iterator<_OuterConst>();
290 bool __incremented_ = false;
291
292 // Note: these private functions are necessary because GCC doesn't allow calls to private members of `__i_` from
293 // free functions that are friends of `inner-iterator`.
294
295 _LIBCPP_HIDE_FROM_ABI constexpr bool __is_done() const {
296 _LIBCPP_ASSERT_NON_NULL(__i_.__parent_ != nullptr, "Cannot call comparison on a default-constructed iterator.");
297
298 auto [__pcur, __pend] = ranges::subrange{__i_.__parent_->__pattern_};
299 auto __end = ranges::end(__i_.__parent_->__base_);
300
301 if constexpr (__tiny_range<_Pattern>) {
302 const auto& __cur = __i_.__current();
303 if (__cur == __end)
304 return true;
305 if (__pcur == __pend)
306 return __incremented_;
307
308 return *__cur == *__pcur;
309
310 } else {
311 auto __cur = __i_.__current();
312 if (__cur == __end)
313 return true;
314 if (__pcur == __pend)
315 return __incremented_;
316
317 do {
318 if (*__cur != *__pcur)
319 return false;
320 if (++__pcur == __pend)
321 return true;
322 } while (++__cur != __end);
323
324 return false;
325 }
326 }
327
328 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto& __outer_current() noexcept { return __i_.__current(); }
329
330 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const auto& __outer_current() const noexcept {
331 return __i_.__current();
332 }
333
334 public:
335 // using iterator_category = inherited;
336 using iterator_concept = typename __outer_iterator<_Const>::iterator_concept;
337 using value_type = range_value_t<_Base>;
338 using difference_type = range_difference_t<_Base>;
339
340 _LIBCPP_HIDE_FROM_ABI __inner_iterator() = default;
341
342 _LIBCPP_HIDE_FROM_ABI constexpr explicit __inner_iterator(__outer_iterator<_Const> __i) : __i_(std::move(__i)) {}
343
344 _LIBCPP_HIDE_FROM_ABI constexpr const iterator_t<_Base>& base() const& noexcept { return __i_.__current(); }
345 _LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_Base> base() &&
346 requires forward_range<_View>
347 {
348 return std::move(__i_.__current());
349 }
350
351 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator*() const { return *__i_.__current(); }
352
353 _LIBCPP_HIDE_FROM_ABI constexpr __inner_iterator& operator++() {
354 __incremented_ = true;
355
356 if constexpr (!forward_range<_Base>) {
357 if constexpr (_Pattern::size() == 0) {
358 return *this;
359 }
360 }
361
362 ++__i_.__current();
363 return *this;
364 }
365
366 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator++(int) {
367 if constexpr (forward_range<_Base>) {
368 auto __tmp = *this;
369 ++*this;
370 return __tmp;
371
372 } else {
373 ++*this;
374 }
375 }
376
377 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __inner_iterator& __x, const __inner_iterator& __y)
378 requires forward_range<_Base>
379 {
380 return __x.__outer_current() == __y.__outer_current();
381 }
382
383 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __inner_iterator& __x, default_sentinel_t) {
384 return __x.__is_done();
385 }
386
387 _LIBCPP_HIDE_FROM_ABI friend constexpr decltype(auto)
388 iter_move(const __inner_iterator& __i) noexcept(noexcept(ranges::iter_move(__i.__outer_current()))) {
389 return ranges::iter_move(__i.__outer_current());
390 }
391
392 _LIBCPP_HIDE_FROM_ABI friend constexpr void iter_swap(
393 const __inner_iterator& __x,
394 const __inner_iterator& __y) noexcept(noexcept(ranges::iter_swap(__x.__outer_current(), __y.__outer_current())))
395 requires indirectly_swappable<iterator_t<_Base>>
396 {
397 ranges::iter_swap(__x.__outer_current(), __y.__outer_current());
398 }
399 };
400};
401
402template <class _Range, class _Pattern>
403lazy_split_view(_Range&&, _Pattern&&) -> lazy_split_view<views::all_t<_Range>, views::all_t<_Pattern>>;
404
405template <input_range _Range>
406lazy_split_view(_Range&&,
407 range_value_t<_Range>) -> lazy_split_view<views::all_t<_Range>, single_view<range_value_t<_Range>>>;
408
409namespace views {
410namespace __lazy_split_view {
411struct __fn {
412 template <class _Range, class _Pattern>
413 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range, _Pattern&& __pattern) const
414 noexcept(noexcept(lazy_split_view(std::forward<_Range>(__range), std::forward<_Pattern>(__pattern))))
415 -> decltype(lazy_split_view(std::forward<_Range>(__range), std::forward<_Pattern>(__pattern))) {
416 return lazy_split_view(std::forward<_Range>(__range), std::forward<_Pattern>(__pattern));
417 }
418
419 template <class _Pattern>
420 requires constructible_from<decay_t<_Pattern>, _Pattern>
421 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Pattern&& __pattern) const
422 noexcept(is_nothrow_constructible_v<decay_t<_Pattern>, _Pattern>) {
423 return __range_adaptor_closure_t(std::__bind_back(*this, std::forward<_Pattern>(__pattern)));
424 }
425};
426} // namespace __lazy_split_view
427
428inline namespace __cpo {
429inline constexpr auto lazy_split = __lazy_split_view::__fn{};
430} // namespace __cpo
431} // namespace views
432
433} // namespace ranges
434
435#endif // _LIBCPP_STD_VER >= 20
436
437_LIBCPP_END_NAMESPACE_STD
438
439_LIBCPP_POP_MACROS
440
441#endif // _LIBCPP___RANGES_LAZY_SPLIT_VIEW_H
442