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1 : // class template regex -*- C++ -*-
2 :
3 : // Copyright (C) 2013-2021 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_scanner.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 : // FIXME make comments doxygen format.
32 :
33 : // N3376 specified 6 regex styles: ECMAScript, basic, extended, grep, egrep
34 : // and awk
35 : // 1) grep is basic except '\n' is treated as '|'
36 : // 2) egrep is extended except '\n' is treated as '|'
37 : // 3) awk is extended except special escaping rules, and there's no
38 : // back-reference.
39 : //
40 : // References:
41 : //
42 : // ECMAScript: ECMA-262 15.10
43 : //
44 : // basic, extended:
45 : // http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap09.html
46 : //
47 : // awk: http://pubs.opengroup.org/onlinepubs/000095399/utilities/awk.html
48 :
49 : namespace std _GLIBCXX_VISIBILITY(default)
50 : {
51 : _GLIBCXX_BEGIN_NAMESPACE_VERSION
52 :
53 : namespace __detail
54 : {
55 : template<typename _CharT>
56 368 : _Scanner<_CharT>::
57 : _Scanner(const _CharT* __begin, const _CharT* __end,
58 : _FlagT __flags, std::locale __loc)
59 : : _ScannerBase(__flags),
60 368 : _M_current(__begin), _M_end(__end),
61 368 : _M_ctype(std::use_facet<_CtypeT>(__loc)),
62 368 : _M_eat_escape(_M_is_ecma()
63 : ? &_Scanner::_M_eat_escape_ecma
64 736 : : &_Scanner::_M_eat_escape_posix)
65 368 : { _M_advance(); }
66 :
67 : template<typename _CharT>
68 : void
69 11981 : _Scanner<_CharT>::
70 : _M_advance()
71 : {
72 11981 : if (_M_current == _M_end)
73 : {
74 736 : _M_token = _S_token_eof;
75 736 : return;
76 : }
77 :
78 11245 : if (_M_state == _S_state_normal)
79 8134 : _M_scan_normal();
80 3111 : else if (_M_state == _S_state_in_bracket)
81 2695 : _M_scan_in_bracket();
82 416 : else if (_M_state == _S_state_in_brace)
83 416 : _M_scan_in_brace();
84 : else
85 : {
86 : __glibcxx_assert(false);
87 : }
88 : }
89 :
90 : // Differences between styles:
91 : // 1) "\(", "\)", "\{" in basic. It's not escaping.
92 : // 2) "(?:", "(?=", "(?!" in ECMAScript.
93 : template<typename _CharT>
94 : void
95 8134 : _Scanner<_CharT>::
96 : _M_scan_normal()
97 : {
98 8134 : auto __c = *_M_current++;
99 :
100 8134 : if (std::strchr(_M_spec_char, _M_ctype.narrow(__c, ' ')) == nullptr)
101 : {
102 3554 : _M_token = _S_token_ord_char;
103 3554 : _M_value.assign(1, __c);
104 3554 : return;
105 : }
106 4580 : if (__c == '\\')
107 : {
108 582 : if (_M_current == _M_end)
109 0 : __throw_regex_error(
110 : regex_constants::error_escape,
111 : "Unexpected end of regex when escaping.");
112 :
113 582 : if (!_M_is_basic()
114 582 : || (*_M_current != '('
115 0 : && *_M_current != ')'
116 0 : && *_M_current != '{'))
117 : {
118 582 : (this->*_M_eat_escape)();
119 582 : return;
120 : }
121 0 : __c = *_M_current++;
122 : }
123 3998 : if (__c == '(')
124 : {
125 828 : if (_M_is_ecma() && *_M_current == '?')
126 : {
127 141 : if (++_M_current == _M_end)
128 0 : __throw_regex_error(
129 : regex_constants::error_paren,
130 : "Unexpected end of regex when in an open parenthesis.");
131 :
132 141 : if (*_M_current == ':')
133 : {
134 141 : ++_M_current;
135 141 : _M_token = _S_token_subexpr_no_group_begin;
136 : }
137 0 : else if (*_M_current == '=')
138 : {
139 0 : ++_M_current;
140 0 : _M_token = _S_token_subexpr_lookahead_begin;
141 0 : _M_value.assign(1, 'p');
142 : }
143 0 : else if (*_M_current == '!')
144 : {
145 0 : ++_M_current;
146 0 : _M_token = _S_token_subexpr_lookahead_begin;
147 0 : _M_value.assign(1, 'n');
148 : }
149 : else
150 0 : __throw_regex_error(
151 : regex_constants::error_paren,
152 : "Invalid special open parenthesis.");
153 : }
154 687 : else if (_M_flags & regex_constants::nosubs)
155 0 : _M_token = _S_token_subexpr_no_group_begin;
156 : else
157 687 : _M_token = _S_token_subexpr_begin;
158 : }
159 3170 : else if (__c == ')')
160 828 : _M_token = _S_token_subexpr_end;
161 2342 : else if (__c == '[')
162 : {
163 400 : _M_state = _S_state_in_bracket;
164 400 : _M_at_bracket_start = true;
165 400 : if (_M_current != _M_end && *_M_current == '^')
166 : {
167 111 : _M_token = _S_token_bracket_neg_begin;
168 111 : ++_M_current;
169 : }
170 : else
171 289 : _M_token = _S_token_bracket_begin;
172 : }
173 1942 : else if (__c == '{')
174 : {
175 104 : _M_state = _S_state_in_brace;
176 104 : _M_token = _S_token_interval_begin;
177 : }
178 1838 : else if (__builtin_expect(__c == _CharT(0), false))
179 : {
180 0 : if (!_M_is_ecma())
181 : {
182 0 : __throw_regex_error(regex_constants::_S_null,
183 : "Unexpected null character in regular expression");
184 : }
185 0 : _M_token = _S_token_ord_char;
186 0 : _M_value.assign(1, __c);
187 : }
188 1838 : else if (__c != ']' && __c != '}')
189 : {
190 1838 : auto __it = _M_token_tbl;
191 1838 : auto __narrowc = _M_ctype.narrow(__c, '\0');
192 8725 : for (; __it->first != '\0'; ++__it)
193 8725 : if (__it->first == __narrowc)
194 : {
195 1838 : _M_token = __it->second;
196 1838 : return;
197 : }
198 : __glibcxx_assert(false);
199 0 : }
200 : else
201 : {
202 0 : _M_token = _S_token_ord_char;
203 0 : _M_value.assign(1, __c);
204 : }
205 : }
206 :
207 : // Differences between styles:
208 : // 1) different semantics of "[]" and "[^]".
209 : // 2) Escaping in bracket expr.
210 : template<typename _CharT>
211 : void
212 2695 : _Scanner<_CharT>::
213 : _M_scan_in_bracket()
214 : {
215 2695 : if (_M_current == _M_end)
216 0 : __throw_regex_error(
217 : regex_constants::error_brack,
218 : "Unexpected end of regex when in bracket expression.");
219 :
220 2695 : auto __c = *_M_current++;
221 :
222 2695 : if (__c == '-')
223 381 : _M_token = _S_token_bracket_dash;
224 2314 : else if (__c == '[')
225 : {
226 0 : if (_M_current == _M_end)
227 0 : __throw_regex_error(regex_constants::error_brack,
228 : "Unexpected character class open bracket.");
229 :
230 0 : if (*_M_current == '.')
231 : {
232 0 : _M_token = _S_token_collsymbol;
233 0 : _M_eat_class(*_M_current++);
234 : }
235 0 : else if (*_M_current == ':')
236 : {
237 0 : _M_token = _S_token_char_class_name;
238 0 : _M_eat_class(*_M_current++);
239 : }
240 0 : else if (*_M_current == '=')
241 : {
242 0 : _M_token = _S_token_equiv_class_name;
243 0 : _M_eat_class(*_M_current++);
244 : }
245 : else
246 : {
247 0 : _M_token = _S_token_ord_char;
248 0 : _M_value.assign(1, __c);
249 : }
250 : }
251 : // In POSIX, when encountering "[]" or "[^]", the ']' is interpreted
252 : // literally. So "[]]" and "[^]]" are valid regexes. See the testcases
253 : // `*/empty_range.cc`.
254 2314 : else if (__c == ']' && (_M_is_ecma() || !_M_at_bracket_start))
255 : {
256 400 : _M_token = _S_token_bracket_end;
257 400 : _M_state = _S_state_normal;
258 : }
259 : // ECMAScript and awk permits escaping in bracket.
260 1914 : else if (__c == '\\' && (_M_is_ecma() || _M_is_awk()))
261 339 : (this->*_M_eat_escape)();
262 : else
263 : {
264 1575 : _M_token = _S_token_ord_char;
265 1575 : _M_value.assign(1, __c);
266 : }
267 2695 : _M_at_bracket_start = false;
268 2695 : }
269 :
270 : // Differences between styles:
271 : // 1) "\}" in basic style.
272 : template<typename _CharT>
273 : void
274 416 : _Scanner<_CharT>::
275 : _M_scan_in_brace()
276 : {
277 416 : if (_M_current == _M_end)
278 0 : __throw_regex_error(
279 : regex_constants::error_brace,
280 : "Unexpected end of regex when in brace expression.");
281 :
282 416 : auto __c = *_M_current++;
283 :
284 416 : if (_M_ctype.is(_CtypeT::digit, __c))
285 : {
286 208 : _M_token = _S_token_dup_count;
287 208 : _M_value.assign(1, __c);
288 208 : while (_M_current != _M_end
289 290 : && _M_ctype.is(_CtypeT::digit, *_M_current))
290 82 : _M_value += *_M_current++;
291 : }
292 208 : else if (__c == ',')
293 104 : _M_token = _S_token_comma;
294 : // basic use \}.
295 104 : else if (_M_is_basic())
296 : {
297 0 : if (__c == '\\' && _M_current != _M_end && *_M_current == '}')
298 : {
299 0 : _M_state = _S_state_normal;
300 0 : _M_token = _S_token_interval_end;
301 0 : ++_M_current;
302 : }
303 : else
304 0 : __throw_regex_error(regex_constants::error_badbrace,
305 : "Unexpected character in brace expression.");
306 : }
307 104 : else if (__c == '}')
308 : {
309 104 : _M_state = _S_state_normal;
310 104 : _M_token = _S_token_interval_end;
311 : }
312 : else
313 0 : __throw_regex_error(regex_constants::error_badbrace,
314 : "Unexpected character in brace expression.");
315 416 : }
316 :
317 : template<typename _CharT>
318 : void
319 921 : _Scanner<_CharT>::
320 : _M_eat_escape_ecma()
321 : {
322 921 : if (_M_current == _M_end)
323 0 : __throw_regex_error(regex_constants::error_escape,
324 : "Unexpected end of regex when escaping.");
325 :
326 921 : auto __c = *_M_current++;
327 921 : auto __pos = _M_find_escape(_M_ctype.narrow(__c, '\0'));
328 :
329 921 : if (__pos != nullptr && (__c != 'b' || _M_state == _S_state_in_bracket))
330 : {
331 0 : _M_token = _S_token_ord_char;
332 0 : _M_value.assign(1, *__pos);
333 : }
334 921 : else if (__c == 'b')
335 : {
336 0 : _M_token = _S_token_word_bound;
337 0 : _M_value.assign(1, 'p');
338 : }
339 921 : else if (__c == 'B')
340 : {
341 0 : _M_token = _S_token_word_bound;
342 0 : _M_value.assign(1, 'n');
343 : }
344 : // N3376 28.13
345 921 : else if (__c == 'd'
346 880 : || __c == 'D'
347 880 : || __c == 's'
348 781 : || __c == 'S'
349 781 : || __c == 'w'
350 666 : || __c == 'W')
351 : {
352 255 : _M_token = _S_token_quoted_class;
353 255 : _M_value.assign(1, __c);
354 : }
355 666 : else if (__c == 'c')
356 : {
357 0 : if (_M_current == _M_end)
358 0 : __throw_regex_error(
359 : regex_constants::error_escape,
360 : "Unexpected end of regex when reading control code.");
361 0 : _M_token = _S_token_ord_char;
362 0 : _M_value.assign(1, *_M_current++);
363 : }
364 666 : else if (__c == 'x' || __c == 'u')
365 : {
366 0 : _M_value.erase();
367 0 : for (int __i = 0; __i < (__c == 'x' ? 2 : 4); __i++)
368 : {
369 0 : if (_M_current == _M_end
370 0 : || !_M_ctype.is(_CtypeT::xdigit, *_M_current))
371 0 : __throw_regex_error(
372 : regex_constants::error_escape,
373 : "Unexpected end of regex when ascii character.");
374 0 : _M_value += *_M_current++;
375 : }
376 0 : _M_token = _S_token_hex_num;
377 0 : }
378 : // ECMAScript recognizes multi-digit back-references.
379 666 : else if (_M_ctype.is(_CtypeT::digit, __c))
380 : {
381 0 : _M_value.assign(1, __c);
382 0 : while (_M_current != _M_end
383 0 : && _M_ctype.is(_CtypeT::digit, *_M_current))
384 0 : _M_value += *_M_current++;
385 0 : _M_token = _S_token_backref;
386 : }
387 : else
388 : {
389 666 : _M_token = _S_token_ord_char;
390 666 : _M_value.assign(1, __c);
391 : }
392 921 : }
393 :
394 : // Differences between styles:
395 : // 1) Extended doesn't support backref, but basic does.
396 : template<typename _CharT>
397 : void
398 0 : _Scanner<_CharT>::
399 : _M_eat_escape_posix()
400 : {
401 0 : if (_M_current == _M_end)
402 0 : __throw_regex_error(regex_constants::error_escape,
403 : "Unexpected end of regex when escaping.");
404 :
405 0 : auto __c = *_M_current;
406 0 : auto __pos = std::strchr(_M_spec_char, _M_ctype.narrow(__c, '\0'));
407 :
408 0 : if (__pos != nullptr && *__pos != '\0')
409 : {
410 0 : _M_token = _S_token_ord_char;
411 0 : _M_value.assign(1, __c);
412 : }
413 : // We MUST judge awk before handling backrefs. There's no backref in awk.
414 0 : else if (_M_is_awk())
415 : {
416 0 : _M_eat_escape_awk();
417 0 : return;
418 : }
419 0 : else if (_M_is_basic() && _M_ctype.is(_CtypeT::digit, __c) && __c != '0')
420 : {
421 0 : _M_token = _S_token_backref;
422 0 : _M_value.assign(1, __c);
423 : }
424 : else
425 : {
426 : #ifdef __STRICT_ANSI__
427 : // POSIX says it is undefined to escape ordinary characters
428 : __throw_regex_error(regex_constants::error_escape,
429 : "Unexpected escape character.");
430 : #else
431 0 : _M_token = _S_token_ord_char;
432 0 : _M_value.assign(1, __c);
433 : #endif
434 : }
435 0 : ++_M_current;
436 : }
437 :
438 : template<typename _CharT>
439 : void
440 0 : _Scanner<_CharT>::
441 : _M_eat_escape_awk()
442 : {
443 0 : auto __c = *_M_current++;
444 0 : auto __pos = _M_find_escape(_M_ctype.narrow(__c, '\0'));
445 :
446 0 : if (__pos != nullptr)
447 : {
448 0 : _M_token = _S_token_ord_char;
449 0 : _M_value.assign(1, *__pos);
450 : }
451 : // \ddd for oct representation
452 0 : else if (_M_ctype.is(_CtypeT::digit, __c)
453 0 : && __c != '8'
454 0 : && __c != '9')
455 : {
456 0 : _M_value.assign(1, __c);
457 0 : for (int __i = 0;
458 : __i < 2
459 0 : && _M_current != _M_end
460 0 : && _M_ctype.is(_CtypeT::digit, *_M_current)
461 0 : && *_M_current != '8'
462 0 : && *_M_current != '9';
463 : __i++)
464 0 : _M_value += *_M_current++;
465 0 : _M_token = _S_token_oct_num;
466 0 : return;
467 : }
468 : else
469 0 : __throw_regex_error(regex_constants::error_escape,
470 : "Unexpected escape character.");
471 : }
472 :
473 : // Eats a character class or throws an exception.
474 : // __ch could be ':', '.' or '=', _M_current is the char after ']' when
475 : // returning.
476 : template<typename _CharT>
477 : void
478 0 : _Scanner<_CharT>::
479 : _M_eat_class(char __ch)
480 : {
481 0 : for (_M_value.clear(); _M_current != _M_end && *_M_current != __ch;)
482 0 : _M_value += *_M_current++;
483 0 : if (_M_current == _M_end
484 0 : || *_M_current++ != __ch
485 0 : || _M_current == _M_end // skip __ch
486 0 : || *_M_current++ != ']') // skip ']'
487 : {
488 0 : if (__ch == ':')
489 0 : __throw_regex_error(regex_constants::error_ctype,
490 : "Unexpected end of character class.");
491 : else
492 0 : __throw_regex_error(regex_constants::error_collate,
493 : "Unexpected end of character class.");
494 : }
495 0 : }
496 :
497 : #ifdef _GLIBCXX_DEBUG
498 : template<typename _CharT>
499 : std::ostream&
500 : _Scanner<_CharT>::
501 : _M_print(std::ostream& ostr)
502 : {
503 : switch (_M_token)
504 : {
505 : case _S_token_anychar:
506 : ostr << "any-character\n";
507 : break;
508 : case _S_token_backref:
509 : ostr << "backref\n";
510 : break;
511 : case _S_token_bracket_begin:
512 : ostr << "bracket-begin\n";
513 : break;
514 : case _S_token_bracket_neg_begin:
515 : ostr << "bracket-neg-begin\n";
516 : break;
517 : case _S_token_bracket_end:
518 : ostr << "bracket-end\n";
519 : break;
520 : case _S_token_char_class_name:
521 : ostr << "char-class-name \"" << _M_value << "\"\n";
522 : break;
523 : case _S_token_closure0:
524 : ostr << "closure0\n";
525 : break;
526 : case _S_token_closure1:
527 : ostr << "closure1\n";
528 : break;
529 : case _S_token_collsymbol:
530 : ostr << "collsymbol \"" << _M_value << "\"\n";
531 : break;
532 : case _S_token_comma:
533 : ostr << "comma\n";
534 : break;
535 : case _S_token_dup_count:
536 : ostr << "dup count: " << _M_value << "\n";
537 : break;
538 : case _S_token_eof:
539 : ostr << "EOF\n";
540 : break;
541 : case _S_token_equiv_class_name:
542 : ostr << "equiv-class-name \"" << _M_value << "\"\n";
543 : break;
544 : case _S_token_interval_begin:
545 : ostr << "interval begin\n";
546 : break;
547 : case _S_token_interval_end:
548 : ostr << "interval end\n";
549 : break;
550 : case _S_token_line_begin:
551 : ostr << "line begin\n";
552 : break;
553 : case _S_token_line_end:
554 : ostr << "line end\n";
555 : break;
556 : case _S_token_opt:
557 : ostr << "opt\n";
558 : break;
559 : case _S_token_or:
560 : ostr << "or\n";
561 : break;
562 : case _S_token_ord_char:
563 : ostr << "ordinary character: \"" << _M_value << "\"\n";
564 : break;
565 : case _S_token_subexpr_begin:
566 : ostr << "subexpr begin\n";
567 : break;
568 : case _S_token_subexpr_no_group_begin:
569 : ostr << "no grouping subexpr begin\n";
570 : break;
571 : case _S_token_subexpr_lookahead_begin:
572 : ostr << "lookahead subexpr begin\n";
573 : break;
574 : case _S_token_subexpr_end:
575 : ostr << "subexpr end\n";
576 : break;
577 : case _S_token_unknown:
578 : ostr << "-- unknown token --\n";
579 : break;
580 : case _S_token_oct_num:
581 : ostr << "oct number " << _M_value << "\n";
582 : break;
583 : case _S_token_hex_num:
584 : ostr << "hex number " << _M_value << "\n";
585 : break;
586 : case _S_token_quoted_class:
587 : ostr << "quoted class " << "\\" << _M_value << "\n";
588 : break;
589 : default:
590 : _GLIBCXX_DEBUG_ASSERT(false);
591 : }
592 : return ostr;
593 : }
594 : #endif
595 :
596 : } // namespace __detail
597 : _GLIBCXX_END_NAMESPACE_VERSION
598 : } // namespace
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