libstdc++
regex_scanner.tcc
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1// class template regex -*- C++ -*-
2
3// Copyright (C) 2013-2016 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 {
215 if (_M_current == _M_end)
216 __throw_regex_error(regex_constants::error_brack,
217 "Unexpected character class open bracket.");
218
219 if (*_M_current == '.')
220 {
221 _M_token = _S_token_collsymbol;
222 _M_eat_class(*_M_current++);
223 }
224 else if (*_M_current == ':')
225 {
226 _M_token = _S_token_char_class_name;
227 _M_eat_class(*_M_current++);
228 }
229 else if (*_M_current == '=')
230 {
231 _M_token = _S_token_equiv_class_name;
232 _M_eat_class(*_M_current++);
233 }
234 else
235 {
236 _M_token = _S_token_ord_char;
237 _M_value.assign(1, __c);
238 }
239 }
240 // In POSIX, when encountering "[]" or "[^]", the ']' is interpreted
241 // literally. So "[]]" and "[^]]" are valid regexes. See the testcases
242 // `*/empty_range.cc`.
243 else if (__c == ']' && (_M_is_ecma() || !_M_at_bracket_start))
244 {
245 _M_token = _S_token_bracket_end;
246 _M_state = _S_state_normal;
247 }
248 // ECMAScript and awk permits escaping in bracket.
249 else if (__c == '\\' && (_M_is_ecma() || _M_is_awk()))
250 (this->*_M_eat_escape)();
251 else
252 {
253 _M_token = _S_token_ord_char;
254 _M_value.assign(1, __c);
255 }
256 _M_at_bracket_start = false;
257 }
258
259 // Differences between styles:
260 // 1) "\}" in basic style.
261 template<typename _CharT>
262 void
263 _Scanner<_CharT>::
264 _M_scan_in_brace()
265 {
266 if (_M_current == _M_end)
267 __throw_regex_error(
268 regex_constants::error_brace,
269 "Unexpected end of regex when in brace expression.");
270
271 auto __c = *_M_current++;
272
273 if (_M_ctype.is(_CtypeT::digit, __c))
274 {
275 _M_token = _S_token_dup_count;
276 _M_value.assign(1, __c);
277 while (_M_current != _M_end
278 && _M_ctype.is(_CtypeT::digit, *_M_current))
279 _M_value += *_M_current++;
280 }
281 else if (__c == ',')
282 _M_token = _S_token_comma;
283 // basic use \}.
284 else if (_M_is_basic())
285 {
286 if (__c == '\\' && _M_current != _M_end && *_M_current == '}')
287 {
288 _M_state = _S_state_normal;
289 _M_token = _S_token_interval_end;
290 ++_M_current;
291 }
292 else
293 __throw_regex_error(regex_constants::error_badbrace,
294 "Unexpected character in brace expression.");
295 }
296 else if (__c == '}')
297 {
298 _M_state = _S_state_normal;
299 _M_token = _S_token_interval_end;
300 }
301 else
302 __throw_regex_error(regex_constants::error_badbrace,
303 "Unexpected character in brace expression.");
304 }
305
306 template<typename _CharT>
307 void
308 _Scanner<_CharT>::
309 _M_eat_escape_ecma()
310 {
311 if (_M_current == _M_end)
312 __throw_regex_error(regex_constants::error_escape,
313 "Unexpected end of regex when escaping.");
314
315 auto __c = *_M_current++;
316 auto __pos = _M_find_escape(_M_ctype.narrow(__c, '\0'));
317
318 if (__pos != nullptr && (__c != 'b' || _M_state == _S_state_in_bracket))
319 {
320 _M_token = _S_token_ord_char;
321 _M_value.assign(1, *__pos);
322 }
323 else if (__c == 'b')
324 {
325 _M_token = _S_token_word_bound;
326 _M_value.assign(1, 'p');
327 }
328 else if (__c == 'B')
329 {
330 _M_token = _S_token_word_bound;
331 _M_value.assign(1, 'n');
332 }
333 // N3376 28.13
334 else if (__c == 'd'
335 || __c == 'D'
336 || __c == 's'
337 || __c == 'S'
338 || __c == 'w'
339 || __c == 'W')
340 {
341 _M_token = _S_token_quoted_class;
342 _M_value.assign(1, __c);
343 }
344 else if (__c == 'c')
345 {
346 if (_M_current == _M_end)
347 __throw_regex_error(
348 regex_constants::error_escape,
349 "Unexpected end of regex when reading control code.");
350 _M_token = _S_token_ord_char;
351 _M_value.assign(1, *_M_current++);
352 }
353 else if (__c == 'x' || __c == 'u')
354 {
355 _M_value.erase();
356 for (int __i = 0; __i < (__c == 'x' ? 2 : 4); __i++)
357 {
358 if (_M_current == _M_end
359 || !_M_ctype.is(_CtypeT::xdigit, *_M_current))
360 __throw_regex_error(
361 regex_constants::error_escape,
362 "Unexpected end of regex when ascii character.");
363 _M_value += *_M_current++;
364 }
365 _M_token = _S_token_hex_num;
366 }
367 // ECMAScript recognizes multi-digit back-references.
368 else if (_M_ctype.is(_CtypeT::digit, __c))
369 {
370 _M_value.assign(1, __c);
371 while (_M_current != _M_end
372 && _M_ctype.is(_CtypeT::digit, *_M_current))
373 _M_value += *_M_current++;
374 _M_token = _S_token_backref;
375 }
376 else
377 {
378 _M_token = _S_token_ord_char;
379 _M_value.assign(1, __c);
380 }
381 }
382
383 // Differences between styles:
384 // 1) Extended doesn't support backref, but basic does.
385 template<typename _CharT>
386 void
387 _Scanner<_CharT>::
388 _M_eat_escape_posix()
389 {
390 if (_M_current == _M_end)
391 __throw_regex_error(regex_constants::error_escape,
392 "Unexpected end of regex when escaping.");
393
394 auto __c = *_M_current;
395 auto __pos = std::strchr(_M_spec_char, _M_ctype.narrow(__c, '\0'));
396
397 if (__pos != nullptr && *__pos != '\0')
398 {
399 _M_token = _S_token_ord_char;
400 _M_value.assign(1, __c);
401 }
402 // We MUST judge awk before handling backrefs. There's no backref in awk.
403 else if (_M_is_awk())
404 {
405 _M_eat_escape_awk();
406 return;
407 }
408 else if (_M_is_basic() && _M_ctype.is(_CtypeT::digit, __c) && __c != '0')
409 {
410 _M_token = _S_token_backref;
411 _M_value.assign(1, __c);
412 }
413 else
414 {
415#ifdef __STRICT_ANSI__
416 // POSIX says it is undefined to escape ordinary characters
417 __throw_regex_error(regex_constants::error_escape,
418 "Unexpected escape character.");
419#else
420 _M_token = _S_token_ord_char;
421 _M_value.assign(1, __c);
422#endif
423 }
424 ++_M_current;
425 }
426
427 template<typename _CharT>
428 void
429 _Scanner<_CharT>::
430 _M_eat_escape_awk()
431 {
432 auto __c = *_M_current++;
433 auto __pos = _M_find_escape(_M_ctype.narrow(__c, '\0'));
434
435 if (__pos != nullptr)
436 {
437 _M_token = _S_token_ord_char;
438 _M_value.assign(1, *__pos);
439 }
440 // \ddd for oct representation
441 else if (_M_ctype.is(_CtypeT::digit, __c)
442 && __c != '8'
443 && __c != '9')
444 {
445 _M_value.assign(1, __c);
446 for (int __i = 0;
447 __i < 2
448 && _M_current != _M_end
449 && _M_ctype.is(_CtypeT::digit, *_M_current)
450 && *_M_current != '8'
451 && *_M_current != '9';
452 __i++)
453 _M_value += *_M_current++;
454 _M_token = _S_token_oct_num;
455 return;
456 }
457 else
458 __throw_regex_error(regex_constants::error_escape,
459 "Unexpected escape character.");
460 }
461
462 // Eats a character class or throws an exception.
463 // __ch could be ':', '.' or '=', _M_current is the char after ']' when
464 // returning.
465 template<typename _CharT>
466 void
467 _Scanner<_CharT>::
468 _M_eat_class(char __ch)
469 {
470 for (_M_value.clear(); _M_current != _M_end && *_M_current != __ch;)
471 _M_value += *_M_current++;
472 if (_M_current == _M_end
473 || *_M_current++ != __ch
474 || _M_current == _M_end // skip __ch
475 || *_M_current++ != ']') // skip ']'
476 {
477 if (__ch == ':')
478 __throw_regex_error(regex_constants::error_ctype,
479 "Unexpected end of character class.");
480 else
481 __throw_regex_error(regex_constants::error_collate,
482 "Unexpected end of character class.");
483 }
484 }
485
486#ifdef _GLIBCXX_DEBUG
487 template<typename _CharT>
489 _Scanner<_CharT>::
490 _M_print(std::ostream& ostr)
491 {
492 switch (_M_token)
493 {
494 case _S_token_anychar:
495 ostr << "any-character\n";
496 break;
497 case _S_token_backref:
498 ostr << "backref\n";
499 break;
500 case _S_token_bracket_begin:
501 ostr << "bracket-begin\n";
502 break;
503 case _S_token_bracket_neg_begin:
504 ostr << "bracket-neg-begin\n";
505 break;
506 case _S_token_bracket_end:
507 ostr << "bracket-end\n";
508 break;
509 case _S_token_char_class_name:
510 ostr << "char-class-name \"" << _M_value << "\"\n";
511 break;
512 case _S_token_closure0:
513 ostr << "closure0\n";
514 break;
515 case _S_token_closure1:
516 ostr << "closure1\n";
517 break;
518 case _S_token_collsymbol:
519 ostr << "collsymbol \"" << _M_value << "\"\n";
520 break;
521 case _S_token_comma:
522 ostr << "comma\n";
523 break;
524 case _S_token_dup_count:
525 ostr << "dup count: " << _M_value << "\n";
526 break;
527 case _S_token_eof:
528 ostr << "EOF\n";
529 break;
530 case _S_token_equiv_class_name:
531 ostr << "equiv-class-name \"" << _M_value << "\"\n";
532 break;
533 case _S_token_interval_begin:
534 ostr << "interval begin\n";
535 break;
536 case _S_token_interval_end:
537 ostr << "interval end\n";
538 break;
539 case _S_token_line_begin:
540 ostr << "line begin\n";
541 break;
542 case _S_token_line_end:
543 ostr << "line end\n";
544 break;
545 case _S_token_opt:
546 ostr << "opt\n";
547 break;
548 case _S_token_or:
549 ostr << "or\n";
550 break;
551 case _S_token_ord_char:
552 ostr << "ordinary character: \"" << _M_value << "\"\n";
553 break;
554 case _S_token_subexpr_begin:
555 ostr << "subexpr begin\n";
556 break;
557 case _S_token_subexpr_no_group_begin:
558 ostr << "no grouping subexpr begin\n";
559 break;
560 case _S_token_subexpr_lookahead_begin:
561 ostr << "lookahead subexpr begin\n";
562 break;
563 case _S_token_subexpr_end:
564 ostr << "subexpr end\n";
565 break;
566 case _S_token_unknown:
567 ostr << "-- unknown token --\n";
568 break;
569 case _S_token_oct_num:
570 ostr << "oct number " << _M_value << "\n";
571 break;
572 case _S_token_hex_num:
573 ostr << "hex number " << _M_value << "\n";
574 break;
575 case _S_token_quoted_class:
576 ostr << "quoted class " << "\\" << _M_value << "\n";
577 break;
578 default:
579 _GLIBCXX_DEBUG_ASSERT(false);
580 }
581 return ostr;
582 }
583#endif
584
585_GLIBCXX_END_NAMESPACE_VERSION
586} // namespace __detail
587} // namespace
const _Facet & use_facet(const locale &__loc)
Return a facet.
ISO C++ entities toplevel namespace is std.
Container class for localization functionality.