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