1 | // class template regex -*- C++ -*- |
2 | |
3 | // Copyright (C) 2013-2024 Free Software Foundation, Inc. |
4 | // |
5 | // This file is part of the GNU ISO C++ Library. This library is free |
6 | // software; you can redistribute it and/or modify it under the |
7 | // terms of the GNU General Public License as published by the |
8 | // Free Software Foundation; either version 3, or (at your option) |
9 | // any later version. |
10 | |
11 | // This library is distributed in the hope that it will be useful, |
12 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
14 | // GNU General Public License for more details. |
15 | |
16 | // Under Section 7 of GPL version 3, you are granted additional |
17 | // permissions described in the GCC Runtime Library Exception, version |
18 | // 3.1, as published by the Free Software Foundation. |
19 | |
20 | // You should have received a copy of the GNU General Public License and |
21 | // a copy of the GCC Runtime Library Exception along with this program; |
22 | // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
23 | // <http://www.gnu.org/licenses/>. |
24 | |
25 | /** |
26 | * @file bits/regex_executor.tcc |
27 | * This is an internal header file, included by other library headers. |
28 | * Do not attempt to use it directly. @headername{regex} |
29 | */ |
30 | |
31 | namespace std _GLIBCXX_VISIBILITY(default) |
32 | { |
33 | _GLIBCXX_BEGIN_NAMESPACE_VERSION |
34 | |
35 | namespace __detail |
36 | { |
37 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
38 | bool __dfs_mode> |
39 | bool _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
40 | _M_search() |
41 | { |
42 | if (_M_search_from_first()) |
43 | return true; |
44 | if (_M_flags & regex_constants::match_continuous) |
45 | return false; |
46 | _M_flags |= regex_constants::match_prev_avail; |
47 | while (_M_begin != _M_end) |
48 | { |
49 | ++_M_begin; |
50 | if (_M_search_from_first()) |
51 | return true; |
52 | } |
53 | return false; |
54 | } |
55 | |
56 | // The _M_main function operates in different modes, DFS mode or BFS mode, |
57 | // indicated by template parameter __dfs_mode, and dispatches to one of the |
58 | // _M_main_dispatch overloads. |
59 | // |
60 | // ------------------------------------------------------------ |
61 | // |
62 | // DFS mode: |
63 | // |
64 | // It applies a Depth-First-Search (aka backtracking) on given NFA and input |
65 | // string. |
66 | // At the very beginning the executor stands in the start state, then it |
67 | // tries every possible state transition in current state recursively. Some |
68 | // state transitions consume input string, say, a single-char-matcher or a |
69 | // back-reference matcher; some don't, like assertion or other anchor nodes. |
70 | // When the input is exhausted and/or the current state is an accepting |
71 | // state, the whole executor returns true. |
72 | // |
73 | // TODO: This approach is exponentially slow for certain input. |
74 | // Try to compile the NFA to a DFA. |
75 | // |
76 | // Time complexity: \Omega(match_length), O(2^(_M_nfa.size())) |
77 | // Space complexity: \theta(match_results.size() + match_length) |
78 | // |
79 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
80 | bool __dfs_mode> |
81 | bool _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
82 | _M_main_dispatch(_Match_mode __match_mode, __dfs) |
83 | { |
84 | _M_has_sol = false; |
85 | *_M_states._M_get_sol_pos() = _BiIter(); |
86 | _M_cur_results = _M_results; |
87 | _M_dfs(__match_mode, start: _M_states._M_start); |
88 | return _M_has_sol; |
89 | } |
90 | |
91 | // ------------------------------------------------------------ |
92 | // |
93 | // BFS mode: |
94 | // |
95 | // Russ Cox's article (http://swtch.com/~rsc/regexp/regexp1.html) |
96 | // explained this algorithm clearly. |
97 | // |
98 | // It first computes epsilon closure (states that can be achieved without |
99 | // consuming characters) for every state that's still matching, |
100 | // using the same DFS algorithm, but doesn't re-enter states (using |
101 | // _M_states._M_visited to check), nor follow _S_opcode_match. |
102 | // |
103 | // Then apply DFS using every _S_opcode_match (in _M_states._M_match_queue) |
104 | // as the start state. |
105 | // |
106 | // It significantly reduces potential duplicate states, so has a better |
107 | // upper bound; but it requires more overhead. |
108 | // |
109 | // Time complexity: \Omega(match_length * match_results.size()) |
110 | // O(match_length * _M_nfa.size() * match_results.size()) |
111 | // Space complexity: \Omega(_M_nfa.size() + match_results.size()) |
112 | // O(_M_nfa.size() * match_results.size()) |
113 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
114 | bool __dfs_mode> |
115 | bool _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
116 | _M_main_dispatch(_Match_mode __match_mode, __bfs) |
117 | { |
118 | _M_states._M_queue(_M_states._M_start, _M_results); |
119 | bool __ret = false; |
120 | while (1) |
121 | { |
122 | _M_has_sol = false; |
123 | if (_M_states._M_match_queue.empty()) |
124 | break; |
125 | std::fill_n(_M_states._M_visited_states, _M_nfa.size(), false); |
126 | auto __old_queue = std::move(_M_states._M_match_queue); |
127 | auto __alloc = _M_cur_results.get_allocator(); |
128 | for (auto& __task : __old_queue) |
129 | { |
130 | _M_cur_results = _ResultsVec(std::move(__task.second), __alloc); |
131 | _M_dfs(__match_mode, start: __task.first); |
132 | } |
133 | if (__match_mode == _Match_mode::_Prefix) |
134 | __ret |= _M_has_sol; |
135 | if (_M_current == _M_end) |
136 | break; |
137 | ++_M_current; |
138 | } |
139 | if (__match_mode == _Match_mode::_Exact) |
140 | __ret = _M_has_sol; |
141 | _M_states._M_match_queue.clear(); |
142 | return __ret; |
143 | } |
144 | |
145 | // Return whether now match the given sub-NFA. |
146 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
147 | bool __dfs_mode> |
148 | bool _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
149 | _M_lookahead(_StateIdT __next) |
150 | { |
151 | // Backreferences may refer to captured content. |
152 | // We may want to make this faster by not copying, |
153 | // but let's not be clever prematurely. |
154 | _ResultsVec __what(_M_cur_results); |
155 | _Executor __sub(_M_current, _M_end, __what, _M_re, _M_flags); |
156 | __sub._M_states._M_start = __next; |
157 | if (__sub._M_search_from_first()) |
158 | { |
159 | for (size_t __i = 0; __i < __what.size(); __i++) |
160 | if (__what[__i].matched) |
161 | _M_cur_results[__i] = __what[__i]; |
162 | return true; |
163 | } |
164 | return false; |
165 | } |
166 | |
167 | // __rep_count records how many times (__rep_count.second) |
168 | // this node is visited under certain input iterator |
169 | // (__rep_count.first). This prevent the executor from entering |
170 | // infinite loop by refusing to continue when it's already been |
171 | // visited more than twice. It's `twice` instead of `once` because |
172 | // we need to spare one more time for potential group capture. |
173 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
174 | bool __dfs_mode> |
175 | void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
176 | _M_rep_once_more(_Match_mode __match_mode, _StateIdT __i) |
177 | { |
178 | const auto& __state = _M_nfa[__i]; |
179 | auto& __rep_count = _M_rep_count[__i]; |
180 | if (__rep_count.second == 0 || __rep_count.first != _M_current) |
181 | { |
182 | auto __back = __rep_count; |
183 | __rep_count.first = _M_current; |
184 | __rep_count.second = 1; |
185 | _M_dfs(__match_mode, start: __state._M_alt); |
186 | __rep_count = __back; |
187 | } |
188 | else |
189 | { |
190 | if (__rep_count.second < 2) |
191 | { |
192 | __rep_count.second++; |
193 | _M_dfs(__match_mode, start: __state._M_alt); |
194 | __rep_count.second--; |
195 | } |
196 | } |
197 | } |
198 | |
199 | // _M_alt branch is "match once more", while _M_next is "get me out |
200 | // of this quantifier". Executing _M_next first or _M_alt first don't |
201 | // mean the same thing, and we need to choose the correct order under |
202 | // given greedy mode. |
203 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
204 | bool __dfs_mode> |
205 | void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
206 | _M_handle_repeat(_Match_mode __match_mode, _StateIdT __i) |
207 | { |
208 | const auto& __state = _M_nfa[__i]; |
209 | |
210 | // Greedy. |
211 | if (!__state._M_neg) |
212 | { |
213 | _M_rep_once_more(__match_mode, __i); |
214 | // If it's DFS executor and already accepted, we're done. |
215 | if (!__dfs_mode || !_M_has_sol) |
216 | _M_dfs(__match_mode, start: __state._M_next); |
217 | } |
218 | else // Non-greedy mode |
219 | { |
220 | if (__dfs_mode) |
221 | { |
222 | // vice-versa. |
223 | _M_dfs(__match_mode, start: __state._M_next); |
224 | if (!_M_has_sol) |
225 | _M_rep_once_more(__match_mode, __i); |
226 | } |
227 | else |
228 | { |
229 | // DON'T attempt anything, because there's already another |
230 | // state with higher priority accepted. This state cannot |
231 | // be better by attempting its next node. |
232 | if (!_M_has_sol) |
233 | { |
234 | _M_dfs(__match_mode, start: __state._M_next); |
235 | // DON'T attempt anything if it's already accepted. An |
236 | // accepted state *must* be better than a solution that |
237 | // matches a non-greedy quantifier one more time. |
238 | if (!_M_has_sol) |
239 | _M_rep_once_more(__match_mode, __i); |
240 | } |
241 | } |
242 | } |
243 | } |
244 | |
245 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
246 | bool __dfs_mode> |
247 | void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
248 | _M_handle_subexpr_begin(_Match_mode __match_mode, _StateIdT __i) |
249 | { |
250 | const auto& __state = _M_nfa[__i]; |
251 | |
252 | auto& __res = _M_cur_results[__state._M_subexpr]; |
253 | auto __back = __res.first; |
254 | __res.first = _M_current; |
255 | _M_dfs(__match_mode, start: __state._M_next); |
256 | __res.first = __back; |
257 | } |
258 | |
259 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
260 | bool __dfs_mode> |
261 | void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
262 | _M_handle_subexpr_end(_Match_mode __match_mode, _StateIdT __i) |
263 | { |
264 | const auto& __state = _M_nfa[__i]; |
265 | |
266 | auto& __res = _M_cur_results[__state._M_subexpr]; |
267 | auto __back = __res; |
268 | __res.second = _M_current; |
269 | __res.matched = true; |
270 | _M_dfs(__match_mode, start: __state._M_next); |
271 | __res = __back; |
272 | } |
273 | |
274 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
275 | bool __dfs_mode> |
276 | inline void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
277 | _M_handle_line_begin_assertion(_Match_mode __match_mode, _StateIdT __i) |
278 | { |
279 | const auto& __state = _M_nfa[__i]; |
280 | if (_M_at_begin()) |
281 | _M_dfs(__match_mode, start: __state._M_next); |
282 | } |
283 | |
284 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
285 | bool __dfs_mode> |
286 | inline void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
287 | _M_handle_line_end_assertion(_Match_mode __match_mode, _StateIdT __i) |
288 | { |
289 | const auto& __state = _M_nfa[__i]; |
290 | if (_M_at_end()) |
291 | _M_dfs(__match_mode, start: __state._M_next); |
292 | } |
293 | |
294 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
295 | bool __dfs_mode> |
296 | inline void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
297 | _M_handle_word_boundary(_Match_mode __match_mode, _StateIdT __i) |
298 | { |
299 | const auto& __state = _M_nfa[__i]; |
300 | if (_M_word_boundary() == !__state._M_neg) |
301 | _M_dfs(__match_mode, start: __state._M_next); |
302 | } |
303 | |
304 | // Here __state._M_alt offers a single start node for a sub-NFA. |
305 | // We recursively invoke our algorithm to match the sub-NFA. |
306 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
307 | bool __dfs_mode> |
308 | void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
309 | _M_handle_subexpr_lookahead(_Match_mode __match_mode, _StateIdT __i) |
310 | { |
311 | const auto& __state = _M_nfa[__i]; |
312 | if (_M_lookahead(next: __state._M_alt) == !__state._M_neg) |
313 | _M_dfs(__match_mode, start: __state._M_next); |
314 | } |
315 | |
316 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
317 | bool __dfs_mode> |
318 | void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
319 | _M_handle_match(_Match_mode __match_mode, _StateIdT __i) |
320 | { |
321 | const auto& __state = _M_nfa[__i]; |
322 | |
323 | if (_M_current == _M_end) |
324 | return; |
325 | if (__dfs_mode) |
326 | { |
327 | if (__state._M_matches(*_M_current)) |
328 | { |
329 | ++_M_current; |
330 | _M_dfs(__match_mode, start: __state._M_next); |
331 | --_M_current; |
332 | } |
333 | } |
334 | else |
335 | if (__state._M_matches(*_M_current)) |
336 | _M_states._M_queue(__state._M_next, _M_cur_results); |
337 | } |
338 | |
339 | template<typename _BiIter, typename _TraitsT> |
340 | struct _Backref_matcher |
341 | { |
342 | _Backref_matcher(bool /* __icase */, const _TraitsT& __traits) |
343 | : _M_traits(__traits) { } |
344 | |
345 | bool |
346 | _M_apply(_BiIter __expected_begin, |
347 | _BiIter __expected_end, _BiIter __actual_begin, |
348 | _BiIter __actual_end) |
349 | { |
350 | return _M_traits.transform(__expected_begin, __expected_end) |
351 | == _M_traits.transform(__actual_begin, __actual_end); |
352 | } |
353 | |
354 | const _TraitsT& _M_traits; |
355 | }; |
356 | |
357 | template<typename _BiIter, typename _CharT> |
358 | struct _Backref_matcher<_BiIter, std::regex_traits<_CharT>> |
359 | { |
360 | using _TraitsT = std::regex_traits<_CharT>; |
361 | _Backref_matcher(bool __icase, const _TraitsT& __traits) |
362 | : _M_icase(__icase), _M_traits(__traits) { } |
363 | |
364 | bool |
365 | _M_apply(_BiIter __expected_begin, |
366 | _BiIter __expected_end, _BiIter __actual_begin, |
367 | _BiIter __actual_end) |
368 | { |
369 | if (!_M_icase) |
370 | return _GLIBCXX_STD_A::__equal4(__expected_begin, __expected_end, |
371 | __actual_begin, __actual_end); |
372 | typedef std::ctype<_CharT> __ctype_type; |
373 | const auto& __fctyp = use_facet<__ctype_type>(_M_traits.getloc()); |
374 | return _GLIBCXX_STD_A::__equal4(__expected_begin, __expected_end, |
375 | __actual_begin, __actual_end, |
376 | [this, &__fctyp](_CharT __lhs, _CharT __rhs) |
377 | { |
378 | return __fctyp.tolower(__lhs) |
379 | == __fctyp.tolower(__rhs); |
380 | }); |
381 | } |
382 | |
383 | bool _M_icase; |
384 | const _TraitsT& _M_traits; |
385 | }; |
386 | |
387 | // First fetch the matched result from _M_cur_results as __submatch; |
388 | // then compare it with |
389 | // (_M_current, _M_current + (__submatch.second - __submatch.first)). |
390 | // If matched, keep going; else just return and try another state. |
391 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
392 | bool __dfs_mode> |
393 | void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
394 | _M_handle_backref(_Match_mode __match_mode, _StateIdT __i) |
395 | { |
396 | __glibcxx_assert(__dfs_mode); |
397 | |
398 | const auto& __state = _M_nfa[__i]; |
399 | auto& __submatch = _M_cur_results[__state._M_backref_index]; |
400 | if (!__submatch.matched) |
401 | return; |
402 | auto __last = _M_current; |
403 | for (auto __tmp = __submatch.first; |
404 | __last != _M_end && __tmp != __submatch.second; |
405 | ++__tmp) |
406 | ++__last; |
407 | if (_Backref_matcher<_BiIter, _TraitsT>( |
408 | _M_re.flags() & regex_constants::icase, |
409 | _M_re._M_automaton->_M_traits)._M_apply( |
410 | __submatch.first, __submatch.second, _M_current, __last)) |
411 | { |
412 | if (__last != _M_current) |
413 | { |
414 | auto __backup = _M_current; |
415 | _M_current = __last; |
416 | _M_dfs(__match_mode, start: __state._M_next); |
417 | _M_current = __backup; |
418 | } |
419 | else |
420 | _M_dfs(__match_mode, start: __state._M_next); |
421 | } |
422 | } |
423 | |
424 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
425 | bool __dfs_mode> |
426 | void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
427 | _M_handle_accept(_Match_mode __match_mode, _StateIdT) |
428 | { |
429 | if _GLIBCXX17_CONSTEXPR (__dfs_mode) |
430 | { |
431 | __glibcxx_assert(!_M_has_sol); |
432 | if (__match_mode == _Match_mode::_Exact) |
433 | _M_has_sol = _M_current == _M_end; |
434 | else |
435 | _M_has_sol = true; |
436 | if (_M_current == _M_begin |
437 | && (_M_flags & regex_constants::match_not_null)) |
438 | _M_has_sol = false; |
439 | if (_M_has_sol) |
440 | { |
441 | if (_M_nfa._M_flags & regex_constants::ECMAScript) |
442 | _M_results = _M_cur_results; |
443 | else // POSIX |
444 | { |
445 | __glibcxx_assert(_M_states._M_get_sol_pos()); |
446 | // Here's POSIX's logic: match the longest one. However |
447 | // we never know which one (lhs or rhs of "|") is longer |
448 | // unless we try both of them and compare the results. |
449 | // The member variable _M_sol_pos records the end |
450 | // position of the last successful match. It's better |
451 | // to be larger, because POSIX regex is always greedy. |
452 | // TODO: This could be slow. |
453 | if (*_M_states._M_get_sol_pos() == _BiIter() |
454 | || std::distance(_M_begin, |
455 | *_M_states._M_get_sol_pos()) |
456 | < std::distance(_M_begin, _M_current)) |
457 | { |
458 | *_M_states._M_get_sol_pos() = _M_current; |
459 | _M_results = _M_cur_results; |
460 | } |
461 | } |
462 | } |
463 | } |
464 | else |
465 | { |
466 | if (_M_current == _M_begin |
467 | && (_M_flags & regex_constants::match_not_null)) |
468 | return; |
469 | if (__match_mode == _Match_mode::_Prefix || _M_current == _M_end) |
470 | if (!_M_has_sol) |
471 | { |
472 | _M_has_sol = true; |
473 | _M_results = _M_cur_results; |
474 | } |
475 | } |
476 | } |
477 | |
478 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
479 | bool __dfs_mode> |
480 | void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
481 | _M_handle_alternative(_Match_mode __match_mode, _StateIdT __i) |
482 | { |
483 | const auto& __state = _M_nfa[__i]; |
484 | |
485 | if (_M_nfa._M_flags & regex_constants::ECMAScript) |
486 | { |
487 | // TODO: Fix BFS support. It is wrong. |
488 | _M_dfs(__match_mode, start: __state._M_alt); |
489 | // Pick lhs if it matches. Only try rhs if it doesn't. |
490 | if (!_M_has_sol) |
491 | _M_dfs(__match_mode, start: __state._M_next); |
492 | } |
493 | else |
494 | { |
495 | // Try both and compare the result. |
496 | // See "case _S_opcode_accept:" handling above. |
497 | _M_dfs(__match_mode, start: __state._M_alt); |
498 | auto __has_sol = _M_has_sol; |
499 | _M_has_sol = false; |
500 | _M_dfs(__match_mode, start: __state._M_next); |
501 | _M_has_sol |= __has_sol; |
502 | } |
503 | } |
504 | |
505 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
506 | bool __dfs_mode> |
507 | void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
508 | _M_dfs(_Match_mode __match_mode, _StateIdT __i) |
509 | { |
510 | if (_M_states._M_visited(__i)) |
511 | return; |
512 | |
513 | switch (_M_nfa[__i]._M_opcode()) |
514 | { |
515 | case _S_opcode_repeat: |
516 | _M_handle_repeat(__match_mode, __i); break; |
517 | case _S_opcode_subexpr_begin: |
518 | _M_handle_subexpr_begin(__match_mode, __i); break; |
519 | case _S_opcode_subexpr_end: |
520 | _M_handle_subexpr_end(__match_mode, __i); break; |
521 | case _S_opcode_line_begin_assertion: |
522 | _M_handle_line_begin_assertion(__match_mode, __i); break; |
523 | case _S_opcode_line_end_assertion: |
524 | _M_handle_line_end_assertion(__match_mode, __i); break; |
525 | case _S_opcode_word_boundary: |
526 | _M_handle_word_boundary(__match_mode, __i); break; |
527 | case _S_opcode_subexpr_lookahead: |
528 | _M_handle_subexpr_lookahead(__match_mode, __i); break; |
529 | case _S_opcode_match: |
530 | _M_handle_match(__match_mode, __i); break; |
531 | case _S_opcode_backref: |
532 | _M_handle_backref(__match_mode, __i); break; |
533 | case _S_opcode_accept: |
534 | _M_handle_accept(__match_mode, __i); break; |
535 | case _S_opcode_alternative: |
536 | _M_handle_alternative(__match_mode, __i); break; |
537 | default: |
538 | __glibcxx_assert(false); |
539 | } |
540 | } |
541 | |
542 | // Return whether now is at some word boundary. |
543 | template<typename _BiIter, typename _Alloc, typename _TraitsT, |
544 | bool __dfs_mode> |
545 | bool _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>:: |
546 | _M_word_boundary() const |
547 | { |
548 | if (_M_current == _M_begin && (_M_flags & regex_constants::match_not_bow)) |
549 | return false; |
550 | if (_M_current == _M_end && (_M_flags & regex_constants::match_not_eow)) |
551 | return false; |
552 | |
553 | bool __left_is_word = false; |
554 | if (_M_current != _M_begin |
555 | || (_M_flags & regex_constants::match_prev_avail)) |
556 | { |
557 | auto __prev = _M_current; |
558 | if (_M_is_word(ch: *std::prev(__prev))) |
559 | __left_is_word = true; |
560 | } |
561 | bool __right_is_word = |
562 | _M_current != _M_end && _M_is_word(ch: *_M_current); |
563 | |
564 | return __left_is_word != __right_is_word; |
565 | } |
566 | } // namespace __detail |
567 | |
568 | _GLIBCXX_END_NAMESPACE_VERSION |
569 | } // namespace |
570 | |