libstdc++
regex_scanner.tcc
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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  _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(
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(
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(
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(
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(
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(
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(
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 } // namespace __detail
588 _GLIBCXX_END_NAMESPACE_VERSION
589 } // namespace
const _Facet & use_facet(const locale &__loc)
Return a facet.
ISO C++ entities toplevel namespace is std.
constexpr error_type error_ctype(_S_error_ctype)
constexpr error_type error_brace(_S_error_brace)
constexpr error_type error_badbrace(_S_error_badbrace)
constexpr error_type error_escape(_S_error_escape)
constexpr error_type error_paren(_S_error_paren)
constexpr error_type error_brack(_S_error_brack)
constexpr syntax_option_type nosubs
constexpr error_type error_collate(_S_error_collate)
Container class for localization functionality.