1// class template regex -*- C++ -*-
2
3// Copyright (C) 2013-2017 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{
51namespace __detail
52{
53_GLIBCXX_BEGIN_NAMESPACE_VERSION
54
55 template<typename _CharT>
56 _Scanner<_CharT>::
57 _Scanner(typename _Scanner::_IterT __begin,
58 typename _Scanner::_IterT __end,
59 _FlagT __flags, std::locale __loc)
60 : _ScannerBase(__flags),
61 _M_current(__begin), _M_end(__end),
62 _M_ctype(std::use_facet<_CtypeT>(__loc)),
63 _M_eat_escape(_M_is_ecma()
64 ? &_Scanner::_M_eat_escape_ecma
65 : &_Scanner::_M_eat_escape_posix)
66 { _M_advance(); }
67
68 template<typename _CharT>
69 void
70 _Scanner<_CharT>::
71 _M_advance()
72 {
73 if (_M_current == _M_end)
74 {
75 _M_token = _S_token_eof;
76 return;
77 }
78
79 if (_M_state == _S_state_normal)
80 _M_scan_normal();
81 else if (_M_state == _S_state_in_bracket)
82 _M_scan_in_bracket();
83 else if (_M_state == _S_state_in_brace)
84 _M_scan_in_brace();
85 else
86 {
87 __glibcxx_assert(false);
88 }
89 }
90
91 // Differences between styles:
92 // 1) "\(", "\)", "\{" in basic. It's not escaping.
93 // 2) "(?:", "(?=", "(?!" in ECMAScript.
94 template<typename _CharT>
95 void
96 _Scanner<_CharT>::
97 _M_scan_normal()
98 {
99 auto __c = *_M_current++;
100
101 if (std::strchr(_M_spec_char, _M_ctype.narrow(__c, ' ')) == nullptr)
102 {
103 _M_token = _S_token_ord_char;
104 _M_value.assign(1, __c);
105 return;
106 }
107 if (__c == '\\')
108 {
109 if (_M_current == _M_end)
110 __throw_regex_error(
111 regex_constants::error_escape,
112 "Unexpected end of regex when escaping.");
113
114 if (!_M_is_basic()
115 || (*_M_current != '('
116 && *_M_current != ')'
117 && *_M_current != '{'))
118 {
119 (this->*_M_eat_escape)();
120 return;
121 }
122 __c = *_M_current++;
123 }
124 if (__c == '(')
125 {
126 if (_M_is_ecma() && *_M_current == '?')
127 {
128 if (++_M_current == _M_end)
129 __throw_regex_error(
130 regex_constants::error_paren,
131 "Unexpected end of regex when in an open parenthesis.");
132
133 if (*_M_current == ':')
134 {
135 ++_M_current;
136 _M_token = _S_token_subexpr_no_group_begin;
137 }
138 else if (*_M_current == '=')
139 {
140 ++_M_current;
141 _M_token = _S_token_subexpr_lookahead_begin;
142 _M_value.assign(1, 'p');
143 }
144 else if (*_M_current == '!')
145 {
146 ++_M_current;
147 _M_token = _S_token_subexpr_lookahead_begin;
148 _M_value.assign(1, 'n');
149 }
150 else
151 __throw_regex_error(
152 regex_constants::error_paren,
153 "Invalid special open parenthesis.");
154 }
155 else if (_M_flags & regex_constants::nosubs)
156 _M_token = _S_token_subexpr_no_group_begin;
157 else
158 _M_token = _S_token_subexpr_begin;
159 }
160 else if (__c == ')')
161 _M_token = _S_token_subexpr_end;
162 else if (__c == '[')
163 {
164 _M_state = _S_state_in_bracket;
165 _M_at_bracket_start = true;
166 if (_M_current != _M_end && *_M_current == '^')
167 {
168 _M_token = _S_token_bracket_neg_begin;
169 ++_M_current;
170 }
171 else
172 _M_token = _S_token_bracket_begin;
173 }
174 else if (__c == '{')
175 {
176 _M_state = _S_state_in_brace;
177 _M_token = _S_token_interval_begin;
178 }
179 else if (__c != ']' && __c != '}')
180 {
181 auto __it = _M_token_tbl;
182 auto __narrowc = _M_ctype.narrow(__c, '\0');
183 for (; __it->first != '\0'; ++__it)
184 if (__it->first == __narrowc)
185 {
186 _M_token = __it->second;
187 return;
188 }
189 __glibcxx_assert(false);
190 }
191 else
192 {
193 _M_token = _S_token_ord_char;
194 _M_value.assign(1, __c);
195 }
196 }
197
198 // Differences between styles:
199 // 1) different semantics of "[]" and "[^]".
200 // 2) Escaping in bracket expr.
201 template<typename _CharT>
202 void
203 _Scanner<_CharT>::
204 _M_scan_in_bracket()
205 {
206 if (_M_current == _M_end)
207 __throw_regex_error(
208 regex_constants::error_brack,
209 "Unexpected end of regex when in bracket expression.");
210
211 auto __c = *_M_current++;
212
213 if (__c == '-')
214 _M_token = _S_token_bracket_dash;
215 else if (__c == '[')
216 {
217 if (_M_current == _M_end)
218 __throw_regex_error(regex_constants::error_brack,
219 "Unexpected character class open bracket.");
220
221 if (*_M_current == '.')
222 {
223 _M_token = _S_token_collsymbol;
224 _M_eat_class(*_M_current++);
225 }
226 else if (*_M_current == ':')
227 {
228 _M_token = _S_token_char_class_name;
229 _M_eat_class(*_M_current++);
230 }
231 else if (*_M_current == '=')
232 {
233 _M_token = _S_token_equiv_class_name;
234 _M_eat_class(*_M_current++);
235 }
236 else
237 {
238 _M_token = _S_token_ord_char;
239 _M_value.assign(1, __c);
240 }
241 }
242 // In POSIX, when encountering "[]" or "[^]", the ']' is interpreted
243 // literally. So "[]]" and "[^]]" are valid regexes. See the testcases
244 // `*/empty_range.cc`.
245 else if (__c == ']' && (_M_is_ecma() || !_M_at_bracket_start))
246 {
247 _M_token = _S_token_bracket_end;
248 _M_state = _S_state_normal;
249 }
250 // ECMAScript and awk permits escaping in bracket.
251 else if (__c == '\\' && (_M_is_ecma() || _M_is_awk()))
252 (this->*_M_eat_escape)();
253 else
254 {
255 _M_token = _S_token_ord_char;
256 _M_value.assign(1, __c);
257 }
258 _M_at_bracket_start = false;
259 }
260
261 // Differences between styles:
262 // 1) "\}" in basic style.
263 template<typename _CharT>
264 void
265 _Scanner<_CharT>::
266 _M_scan_in_brace()
267 {
268 if (_M_current == _M_end)
269 __throw_regex_error(
270 regex_constants::error_brace,
271 "Unexpected end of regex when in brace expression.");
272
273 auto __c = *_M_current++;
274
275 if (_M_ctype.is(_CtypeT::digit, __c))
276 {
277 _M_token = _S_token_dup_count;
278 _M_value.assign(1, __c);
279 while (_M_current != _M_end
280 && _M_ctype.is(_CtypeT::digit, *_M_current))
281 _M_value += *_M_current++;
282 }
283 else if (__c == ',')
284 _M_token = _S_token_comma;
285 // basic use \}.
286 else if (_M_is_basic())
287 {
288 if (__c == '\\' && _M_current != _M_end && *_M_current == '}')
289 {
290 _M_state = _S_state_normal;
291 _M_token = _S_token_interval_end;
292 ++_M_current;
293 }
294 else
295 __throw_regex_error(regex_constants::error_badbrace,
296 "Unexpected character in brace expression.");
297 }
298 else if (__c == '}')
299 {
300 _M_state = _S_state_normal;
301 _M_token = _S_token_interval_end;
302 }
303 else
304 __throw_regex_error(regex_constants::error_badbrace,
305 "Unexpected character in brace expression.");
306 }
307
308 template<typename _CharT>
309 void
310 _Scanner<_CharT>::
311 _M_eat_escape_ecma()
312 {
313 if (_M_current == _M_end)
314 __throw_regex_error(regex_constants::error_escape,
315 "Unexpected end of regex when escaping.");
316
317 auto __c = *_M_current++;
318 auto __pos = _M_find_escape(_M_ctype.narrow(__c, '\0'));
319
320 if (__pos != nullptr && (__c != 'b' || _M_state == _S_state_in_bracket))
321 {
322 _M_token = _S_token_ord_char;
323 _M_value.assign(1, *__pos);
324 }
325 else if (__c == 'b')
326 {
327 _M_token = _S_token_word_bound;
328 _M_value.assign(1, 'p');
329 }
330 else if (__c == 'B')
331 {
332 _M_token = _S_token_word_bound;
333 _M_value.assign(1, 'n');
334 }
335 // N3376 28.13
336 else if (__c == 'd'
337 || __c == 'D'
338 || __c == 's'
339 || __c == 'S'
340 || __c == 'w'
341 || __c == 'W')
342 {
343 _M_token = _S_token_quoted_class;
344 _M_value.assign(1, __c);
345 }
346 else if (__c == 'c')
347 {
348 if (_M_current == _M_end)
349 __throw_regex_error(
350 regex_constants::error_escape,
351 "Unexpected end of regex when reading control code.");
352 _M_token = _S_token_ord_char;
353 _M_value.assign(1, *_M_current++);
354 }
355 else if (__c == 'x' || __c == 'u')
356 {
357 _M_value.erase();
358 for (int __i = 0; __i < (__c == 'x' ? 2 : 4); __i++)
359 {
360 if (_M_current == _M_end
361 || !_M_ctype.is(_CtypeT::xdigit, *_M_current))
362 __throw_regex_error(
363 regex_constants::error_escape,
364 "Unexpected end of regex when ascii character.");
365 _M_value += *_M_current++;
366 }
367 _M_token = _S_token_hex_num;
368 }
369 // ECMAScript recognizes multi-digit back-references.
370 else if (_M_ctype.is(_CtypeT::digit, __c))
371 {
372 _M_value.assign(1, __c);
373 while (_M_current != _M_end
374 && _M_ctype.is(_CtypeT::digit, *_M_current))
375 _M_value += *_M_current++;
376 _M_token = _S_token_backref;
377 }
378 else
379 {
380 _M_token = _S_token_ord_char;
381 _M_value.assign(1, __c);
382 }
383 }
384
385 // Differences between styles:
386 // 1) Extended doesn't support backref, but basic does.
387 template<typename _CharT>
388 void
389 _Scanner<_CharT>::
390 _M_eat_escape_posix()
391 {
392 if (_M_current == _M_end)
393 __throw_regex_error(regex_constants::error_escape,
394 "Unexpected end of regex when escaping.");
395
396 auto __c = *_M_current;
397 auto __pos = std::strchr(_M_spec_char, _M_ctype.narrow(__c, '\0'));
398
399 if (__pos != nullptr && *__pos != '\0')
400 {
401 _M_token = _S_token_ord_char;
402 _M_value.assign(1, __c);
403 }
404 // We MUST judge awk before handling backrefs. There's no backref in awk.
405 else if (_M_is_awk())
406 {
407 _M_eat_escape_awk();
408 return;
409 }
410 else if (_M_is_basic() && _M_ctype.is(_CtypeT::digit, __c) && __c != '0')
411 {
412 _M_token = _S_token_backref;
413 _M_value.assign(1, __c);
414 }
415 else
416 {
417#ifdef __STRICT_ANSI__
418 // POSIX says it is undefined to escape ordinary characters
419 __throw_regex_error(regex_constants::error_escape,
420 "Unexpected escape character.");
421#else
422 _M_token = _S_token_ord_char;
423 _M_value.assign(1, __c);
424#endif
425 }
426 ++_M_current;
427 }
428
429 template<typename _CharT>
430 void
431 _Scanner<_CharT>::
432 _M_eat_escape_awk()
433 {
434 auto __c = *_M_current++;
435 auto __pos = _M_find_escape(_M_ctype.narrow(__c, '\0'));
436
437 if (__pos != nullptr)
438 {
439 _M_token = _S_token_ord_char;
440 _M_value.assign(1, *__pos);
441 }
442 // \ddd for oct representation
443 else if (_M_ctype.is(_CtypeT::digit, __c)
444 && __c != '8'
445 && __c != '9')
446 {
447 _M_value.assign(1, __c);
448 for (int __i = 0;
449 __i < 2
450 && _M_current != _M_end
451 && _M_ctype.is(_CtypeT::digit, *_M_current)
452 && *_M_current != '8'
453 && *_M_current != '9';
454 __i++)
455 _M_value += *_M_current++;
456 _M_token = _S_token_oct_num;
457 return;
458 }
459 else
460 __throw_regex_error(regex_constants::error_escape,
461 "Unexpected escape character.");
462 }
463
464 // Eats a character class or throws an exception.
465 // __ch could be ':', '.' or '=', _M_current is the char after ']' when
466 // returning.
467 template<typename _CharT>
468 void
469 _Scanner<_CharT>::
470 _M_eat_class(char __ch)
471 {
472 for (_M_value.clear(); _M_current != _M_end && *_M_current != __ch;)
473 _M_value += *_M_current++;
474 if (_M_current == _M_end
475 || *_M_current++ != __ch
476 || _M_current == _M_end // skip __ch
477 || *_M_current++ != ']') // skip ']'
478 {
479 if (__ch == ':')
480 __throw_regex_error(regex_constants::error_ctype,
481 "Unexpected end of character class.");
482 else
483 __throw_regex_error(regex_constants::error_collate,
484 "Unexpected end of character class.");
485 }
486 }
487
488#ifdef _GLIBCXX_DEBUG
489 template<typename _CharT>
490 std::ostream&
491 _Scanner<_CharT>::
492 _M_print(std::ostream& ostr)
493 {
494 switch (_M_token)
495 {
496 case _S_token_anychar:
497 ostr << "any-character\n";
498 break;
499 case _S_token_backref:
500 ostr << "backref\n";
501 break;
502 case _S_token_bracket_begin:
503 ostr << "bracket-begin\n";
504 break;
505 case _S_token_bracket_neg_begin:
506 ostr << "bracket-neg-begin\n";
507 break;
508 case _S_token_bracket_end:
509 ostr << "bracket-end\n";
510 break;
511 case _S_token_char_class_name:
512 ostr << "char-class-name \"" << _M_value << "\"\n";
513 break;
514 case _S_token_closure0:
515 ostr << "closure0\n";
516 break;
517 case _S_token_closure1:
518 ostr << "closure1\n";
519 break;
520 case _S_token_collsymbol:
521 ostr << "collsymbol \"" << _M_value << "\"\n";
522 break;
523 case _S_token_comma:
524 ostr << "comma\n";
525 break;
526 case _S_token_dup_count:
527 ostr << "dup count: " << _M_value << "\n";
528 break;
529 case _S_token_eof:
530 ostr << "EOF\n";
531 break;
532 case _S_token_equiv_class_name:
533 ostr << "equiv-class-name \"" << _M_value << "\"\n";
534 break;
535 case _S_token_interval_begin:
536 ostr << "interval begin\n";
537 break;
538 case _S_token_interval_end:
539 ostr << "interval end\n";
540 break;
541 case _S_token_line_begin:
542 ostr << "line begin\n";
543 break;
544 case _S_token_line_end:
545 ostr << "line end\n";
546 break;
547 case _S_token_opt:
548 ostr << "opt\n";
549 break;
550 case _S_token_or:
551 ostr << "or\n";
552 break;
553 case _S_token_ord_char:
554 ostr << "ordinary character: \"" << _M_value << "\"\n";
555 break;
556 case _S_token_subexpr_begin:
557 ostr << "subexpr begin\n";
558 break;
559 case _S_token_subexpr_no_group_begin:
560 ostr << "no grouping subexpr begin\n";
561 break;
562 case _S_token_subexpr_lookahead_begin:
563 ostr << "lookahead subexpr begin\n";
564 break;
565 case _S_token_subexpr_end:
566 ostr << "subexpr end\n";
567 break;
568 case _S_token_unknown:
569 ostr << "-- unknown token --\n";
570 break;
571 case _S_token_oct_num:
572 ostr << "oct number " << _M_value << "\n";
573 break;
574 case _S_token_hex_num:
575 ostr << "hex number " << _M_value << "\n";
576 break;
577 case _S_token_quoted_class:
578 ostr << "quoted class " << "\\" << _M_value << "\n";
579 break;
580 default:
581 _GLIBCXX_DEBUG_ASSERT(false);
582 }
583 return ostr;
584 }
585#endif
586
587_GLIBCXX_END_NAMESPACE_VERSION
588} // namespace __detail
589} // namespace
590