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
49namespace std _GLIBCXX_VISIBILITY(default)
50{
51_GLIBCXX_BEGIN_NAMESPACE_VERSION
52
53namespace __detail
54{
55 template<typename _CharT>
56 _Scanner<_CharT>::
57 _Scanner(const _CharT* __begin, const _CharT* __end,
58 _FlagT __flags, std::locale __loc)
59 : _ScannerBase(__flags),
60 _M_current(__begin), _M_end(__end),
61 _M_ctype(std::use_facet<_CtypeT>(__loc)),
62 _M_eat_escape(_M_is_ecma()
63 ? &_Scanner::_M_eat_escape_ecma
64 : &_Scanner::_M_eat_escape_posix)
65 { _M_advance(); }
66
67 template<typename _CharT>
68 void
69 _Scanner<_CharT>::
70 _M_advance()
71 {
72 if (_M_current == _M_end)
73 {
74 _M_token = _S_token_eof;
75 return;
76 }
77
78 if (_M_state == _S_state_normal)
79 _M_scan_normal();
80 else if (_M_state == _S_state_in_bracket)
81 _M_scan_in_bracket();
82 else if (_M_state == _S_state_in_brace)
83 _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 _Scanner<_CharT>::
96 _M_scan_normal()
97 {
98 auto __c = *_M_current++;
99
100 if (std::strchr(_M_spec_char, _M_ctype.narrow(__c, ' ')) == nullptr)
101 {
102 _M_token = _S_token_ord_char;
103 _M_value.assign(1, __c);
104 return;
105 }
106 if (__c == '\\')
107 {
108 if (_M_current == _M_end)
109 __throw_regex_error(
110 ecode: regex_constants::error_escape,
111 what: "Unexpected end of regex when escaping.");
112
113 if (!_M_is_basic()
114 || (*_M_current != '('
115 && *_M_current != ')'
116 && *_M_current != '{'))
117 {
118 (this->*_M_eat_escape)();
119 return;
120 }
121 __c = *_M_current++;
122 }
123 if (__c == '(')
124 {
125 if (_M_is_ecma() && *_M_current == '?')
126 {
127 if (++_M_current == _M_end)
128 __throw_regex_error(
129 ecode: regex_constants::error_paren,
130 what: "Unexpected end of regex when in an open parenthesis.");
131
132 if (*_M_current == ':')
133 {
134 ++_M_current;
135 _M_token = _S_token_subexpr_no_group_begin;
136 }
137 else if (*_M_current == '=')
138 {
139 ++_M_current;
140 _M_token = _S_token_subexpr_lookahead_begin;
141 _M_value.assign(1, 'p');
142 }
143 else if (*_M_current == '!')
144 {
145 ++_M_current;
146 _M_token = _S_token_subexpr_lookahead_begin;
147 _M_value.assign(1, 'n');
148 }
149 else
150 __throw_regex_error(
151 ecode: regex_constants::error_paren,
152 what: "Invalid special open parenthesis.");
153 }
154 else if (_M_flags & regex_constants::nosubs)
155 _M_token = _S_token_subexpr_no_group_begin;
156 else
157 _M_token = _S_token_subexpr_begin;
158 }
159 else if (__c == ')')
160 _M_token = _S_token_subexpr_end;
161 else if (__c == '[')
162 {
163 _M_state = _S_state_in_bracket;
164 _M_at_bracket_start = true;
165 if (_M_current != _M_end && *_M_current == '^')
166 {
167 _M_token = _S_token_bracket_neg_begin;
168 ++_M_current;
169 }
170 else
171 _M_token = _S_token_bracket_begin;
172 }
173 else if (__c == '{')
174 {
175 _M_state = _S_state_in_brace;
176 _M_token = _S_token_interval_begin;
177 }
178 else if (__builtin_expect(__c == _CharT(0), false))
179 {
180 if (!_M_is_ecma())
181 {
182 __throw_regex_error(ecode: regex_constants::_S_null,
183 what: "Unexpected null character in regular expression");
184 }
185 _M_token = _S_token_ord_char;
186 _M_value.assign(1, __c);
187 }
188 else if (__c != ']' && __c != '}')
189 {
190 auto __it = _M_token_tbl;
191 auto __narrowc = _M_ctype.narrow(__c, '\0');
192 for (; __it->first != '\0'; ++__it)
193 if (__it->first == __narrowc)
194 {
195 _M_token = __it->second;
196 return;
197 }
198 __glibcxx_assert(false);
199 }
200 else
201 {
202 _M_token = _S_token_ord_char;
203 _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 _Scanner<_CharT>::
213 _M_scan_in_bracket()
214 {
215 if (_M_current == _M_end)
216 __throw_regex_error(
217 ecode: regex_constants::error_brack,
218 what: "Unexpected end of regex when in bracket expression.");
219
220 auto __c = *_M_current++;
221
222 if (__c == '-')
223 _M_token = _S_token_bracket_dash;
224 else if (__c == '[')
225 {
226 if (_M_current == _M_end)
227 __throw_regex_error(ecode: regex_constants::error_brack,
228 what: "Unexpected character class open bracket.");
229
230 if (*_M_current == '.')
231 {
232 _M_token = _S_token_collsymbol;
233 _M_eat_class(*_M_current++);
234 }
235 else if (*_M_current == ':')
236 {
237 _M_token = _S_token_char_class_name;
238 _M_eat_class(*_M_current++);
239 }
240 else if (*_M_current == '=')
241 {
242 _M_token = _S_token_equiv_class_name;
243 _M_eat_class(*_M_current++);
244 }
245 else
246 {
247 _M_token = _S_token_ord_char;
248 _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 else if (__c == ']' && (_M_is_ecma() || !_M_at_bracket_start))
255 {
256 _M_token = _S_token_bracket_end;
257 _M_state = _S_state_normal;
258 }
259 // ECMAScript and awk permits escaping in bracket.
260 else if (__c == '\\' && (_M_is_ecma() || _M_is_awk()))
261 (this->*_M_eat_escape)();
262 else
263 {
264 _M_token = _S_token_ord_char;
265 _M_value.assign(1, __c);
266 }
267 _M_at_bracket_start = false;
268 }
269
270 // Differences between styles:
271 // 1) "\}" in basic style.
272 template<typename _CharT>
273 void
274 _Scanner<_CharT>::
275 _M_scan_in_brace()
276 {
277 if (_M_current == _M_end)
278 __throw_regex_error(
279 ecode: regex_constants::error_brace,
280 what: "Unexpected end of regex when in brace expression.");
281
282 auto __c = *_M_current++;
283
284 if (_M_ctype.is(_CtypeT::digit, __c))
285 {
286 _M_token = _S_token_dup_count;
287 _M_value.assign(1, __c);
288 while (_M_current != _M_end
289 && _M_ctype.is(_CtypeT::digit, *_M_current))
290 _M_value += *_M_current++;
291 }
292 else if (__c == ',')
293 _M_token = _S_token_comma;
294 // basic use \}.
295 else if (_M_is_basic())
296 {
297 if (__c == '\\' && _M_current != _M_end && *_M_current == '}')
298 {
299 _M_state = _S_state_normal;
300 _M_token = _S_token_interval_end;
301 ++_M_current;
302 }
303 else
304 __throw_regex_error(ecode: regex_constants::error_badbrace,
305 what: "Unexpected character in brace expression.");
306 }
307 else if (__c == '}')
308 {
309 _M_state = _S_state_normal;
310 _M_token = _S_token_interval_end;
311 }
312 else
313 __throw_regex_error(ecode: regex_constants::error_badbrace,
314 what: "Unexpected character in brace expression.");
315 }
316
317 template<typename _CharT>
318 void
319 _Scanner<_CharT>::
320 _M_eat_escape_ecma()
321 {
322 if (_M_current == _M_end)
323 __throw_regex_error(ecode: regex_constants::error_escape,
324 what: "Unexpected end of regex when escaping.");
325
326 auto __c = *_M_current++;
327 auto __pos = _M_find_escape(c: _M_ctype.narrow(__c, '\0'));
328
329 if (__pos != nullptr && (__c != 'b' || _M_state == _S_state_in_bracket))
330 {
331 _M_token = _S_token_ord_char;
332 _M_value.assign(1, *__pos);
333 }
334 else if (__c == 'b')
335 {
336 _M_token = _S_token_word_bound;
337 _M_value.assign(1, 'p');
338 }
339 else if (__c == 'B')
340 {
341 _M_token = _S_token_word_bound;
342 _M_value.assign(1, 'n');
343 }
344 // N3376 28.13
345 else if (__c == 'd'
346 || __c == 'D'
347 || __c == 's'
348 || __c == 'S'
349 || __c == 'w'
350 || __c == 'W')
351 {
352 _M_token = _S_token_quoted_class;
353 _M_value.assign(1, __c);
354 }
355 else if (__c == 'c')
356 {
357 if (_M_current == _M_end)
358 __throw_regex_error(
359 ecode: regex_constants::error_escape,
360 what: "Unexpected end of regex when reading control code.");
361 _M_token = _S_token_ord_char;
362 _M_value.assign(1, *_M_current++);
363 }
364 else if (__c == 'x' || __c == 'u')
365 {
366 _M_value.erase();
367 for (int __i = 0; __i < (__c == 'x' ? 2 : 4); __i++)
368 {
369 if (_M_current == _M_end
370 || !_M_ctype.is(_CtypeT::xdigit, *_M_current))
371 __throw_regex_error(
372 ecode: regex_constants::error_escape,
373 what: "Unexpected end of regex when ascii character.");
374 _M_value += *_M_current++;
375 }
376 _M_token = _S_token_hex_num;
377 }
378 // ECMAScript recognizes multi-digit back-references.
379 else if (_M_ctype.is(_CtypeT::digit, __c))
380 {
381 _M_value.assign(1, __c);
382 while (_M_current != _M_end
383 && _M_ctype.is(_CtypeT::digit, *_M_current))
384 _M_value += *_M_current++;
385 _M_token = _S_token_backref;
386 }
387 else
388 {
389 _M_token = _S_token_ord_char;
390 _M_value.assign(1, __c);
391 }
392 }
393
394 // Differences between styles:
395 // 1) Extended doesn't support backref, but basic does.
396 template<typename _CharT>
397 void
398 _Scanner<_CharT>::
399 _M_eat_escape_posix()
400 {
401 if (_M_current == _M_end)
402 __throw_regex_error(ecode: regex_constants::error_escape,
403 what: "Unexpected end of regex when escaping.");
404
405 auto __c = *_M_current;
406 auto __pos = std::strchr(_M_spec_char, _M_ctype.narrow(__c, '\0'));
407
408 if (__pos != nullptr && *__pos != '\0')
409 {
410 _M_token = _S_token_ord_char;
411 _M_value.assign(1, __c);
412 }
413 // We MUST judge awk before handling backrefs. There's no backref in awk.
414 else if (_M_is_awk())
415 {
416 _M_eat_escape_awk();
417 return;
418 }
419 else if (_M_is_basic() && _M_ctype.is(_CtypeT::digit, __c) && __c != '0')
420 {
421 _M_token = _S_token_backref;
422 _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(ecode: regex_constants::error_escape,
429 what: "Unexpected escape character.");
430#else
431 _M_token = _S_token_ord_char;
432 _M_value.assign(1, __c);
433#endif
434 }
435 ++_M_current;
436 }
437
438 template<typename _CharT>
439 void
440 _Scanner<_CharT>::
441 _M_eat_escape_awk()
442 {
443 auto __c = *_M_current++;
444 auto __pos = _M_find_escape(c: _M_ctype.narrow(__c, '\0'));
445
446 if (__pos != nullptr)
447 {
448 _M_token = _S_token_ord_char;
449 _M_value.assign(1, *__pos);
450 }
451 // \ddd for oct representation
452 else if (_M_ctype.is(_CtypeT::digit, __c)
453 && __c != '8'
454 && __c != '9')
455 {
456 _M_value.assign(1, __c);
457 for (int __i = 0;
458 __i < 2
459 && _M_current != _M_end
460 && _M_ctype.is(_CtypeT::digit, *_M_current)
461 && *_M_current != '8'
462 && *_M_current != '9';
463 __i++)
464 _M_value += *_M_current++;
465 _M_token = _S_token_oct_num;
466 return;
467 }
468 else
469 __throw_regex_error(ecode: regex_constants::error_escape,
470 what: "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 _Scanner<_CharT>::
479 _M_eat_class(char __ch)
480 {
481 for (_M_value.clear(); _M_current != _M_end && *_M_current != __ch;)
482 _M_value += *_M_current++;
483 if (_M_current == _M_end
484 || *_M_current++ != __ch
485 || _M_current == _M_end // skip __ch
486 || *_M_current++ != ']') // skip ']'
487 {
488 if (__ch == ':')
489 __throw_regex_error(ecode: regex_constants::error_ctype,
490 what: "Unexpected end of character class.");
491 else
492 __throw_regex_error(ecode: regex_constants::error_collate,
493 what: "Unexpected end of character class.");
494 }
495 }
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
599

source code of include/c++/11/bits/regex_scanner.tcc