libstdc++
regex_compiler.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_compiler.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 /*
34 // This compiler refers to "Regular Expression Matching Can Be Simple And Fast"
35 // (http://swtch.com/~rsc/regexp/regexp1.html),
36 // but doesn't strictly follow it.
37 //
38 // When compiling, states are *chained* instead of tree- or graph-constructed.
39 // It's more like structured programs: there's if statement and loop statement.
40 //
41 // For alternative structure (say "a|b"), aka "if statement", two branches
42 // should be constructed. However, these two shall merge to an "end_tag" at
43 // the end of this operator:
44 //
45 // branch1
46 // / \
47 // => begin_tag end_tag =>
48 // \ /
49 // branch2
50 //
51 // This is the difference between this implementation and that in Russ's
52 // article.
53 //
54 // That's why we introduced dummy node here ------ "end_tag" is a dummy node.
55 // All dummy nodes will be eliminated at the end of compilation.
56 */
57 
58 namespace std _GLIBCXX_VISIBILITY(default)
59 {
60 _GLIBCXX_BEGIN_NAMESPACE_VERSION
61 
62 namespace __detail
63 {
64  template<typename _TraitsT>
65  _Compiler<_TraitsT>::
66  _Compiler(const _CharT* __b, const _CharT* __e,
67  const typename _TraitsT::locale_type& __loc, _FlagT __flags)
68  : _M_flags(_S_validate(__flags)),
69  _M_scanner(__b, __e, _M_flags, __loc),
70  _M_nfa(make_shared<_RegexT>(__loc, _M_flags)),
71  _M_traits(_M_nfa->_M_traits),
72  _M_ctype(std::use_facet<_CtypeT>(__loc))
73  {
74  _StateSeqT __r(*_M_nfa, _M_nfa->_M_start());
75  __r._M_append(_M_nfa->_M_insert_subexpr_begin());
76  this->_M_disjunction();
77  if (!_M_match_token(_ScannerT::_S_token_eof))
78  __throw_regex_error(regex_constants::error_paren);
79  __r._M_append(_M_pop());
80  __glibcxx_assert(_M_stack.empty());
81  __r._M_append(_M_nfa->_M_insert_subexpr_end());
82  __r._M_append(_M_nfa->_M_insert_accept());
83  _M_nfa->_M_eliminate_dummy();
84  }
85 
86  template<typename _TraitsT>
87  void
88  _Compiler<_TraitsT>::
89  _M_disjunction()
90  {
91  this->_M_alternative();
92  while (_M_match_token(_ScannerT::_S_token_or))
93  {
94  _StateSeqT __alt1 = _M_pop();
95  this->_M_alternative();
96  _StateSeqT __alt2 = _M_pop();
97  auto __end = _M_nfa->_M_insert_dummy();
98  __alt1._M_append(__end);
99  __alt2._M_append(__end);
100  // __alt2 is state._M_next, __alt1 is state._M_alt. The executor
101  // executes _M_alt before _M_next, as well as executing left
102  // alternative before right one.
103  _M_stack.push(_StateSeqT(*_M_nfa,
104  _M_nfa->_M_insert_alt(
105  __alt2._M_start, __alt1._M_start, false),
106  __end));
107  }
108  }
109 
110  template<typename _TraitsT>
111  void
112  _Compiler<_TraitsT>::
113  _M_alternative()
114  {
115  if (this->_M_term())
116  {
117  _StateSeqT __re = _M_pop();
118  this->_M_alternative();
119  __re._M_append(_M_pop());
120  _M_stack.push(__re);
121  }
122  else
123  _M_stack.push(_StateSeqT(*_M_nfa, _M_nfa->_M_insert_dummy()));
124  }
125 
126  template<typename _TraitsT>
127  bool
128  _Compiler<_TraitsT>::
129  _M_term()
130  {
131  if (this->_M_assertion())
132  return true;
133  if (this->_M_atom())
134  {
135  while (this->_M_quantifier())
136  ;
137  return true;
138  }
139  return false;
140  }
141 
142  template<typename _TraitsT>
143  bool
144  _Compiler<_TraitsT>::
145  _M_assertion()
146  {
147  if (_M_match_token(_ScannerT::_S_token_line_begin))
148  _M_stack.push(_StateSeqT(*_M_nfa, _M_nfa->_M_insert_line_begin()));
149  else if (_M_match_token(_ScannerT::_S_token_line_end))
150  _M_stack.push(_StateSeqT(*_M_nfa, _M_nfa->_M_insert_line_end()));
151  else if (_M_match_token(_ScannerT::_S_token_word_bound))
152  // _M_value[0] == 'n' means it's negative, say "not word boundary".
153  _M_stack.push(_StateSeqT(*_M_nfa, _M_nfa->
154  _M_insert_word_bound(_M_value[0] == 'n')));
155  else if (_M_match_token(_ScannerT::_S_token_subexpr_lookahead_begin))
156  {
157  auto __neg = _M_value[0] == 'n';
158  this->_M_disjunction();
159  if (!_M_match_token(_ScannerT::_S_token_subexpr_end))
160  __throw_regex_error(regex_constants::error_paren,
161  "Parenthesis is not closed.");
162  auto __tmp = _M_pop();
163  __tmp._M_append(_M_nfa->_M_insert_accept());
164  _M_stack.push(
165  _StateSeqT(
166  *_M_nfa,
167  _M_nfa->_M_insert_lookahead(__tmp._M_start, __neg)));
168  }
169  else
170  return false;
171  return true;
172  }
173 
174  template<typename _TraitsT>
175  bool
176  _Compiler<_TraitsT>::
177  _M_quantifier()
178  {
179  bool __neg = (_M_flags & regex_constants::ECMAScript);
180  auto __init = [this, &__neg]()
181  {
182  if (_M_stack.empty())
183  __throw_regex_error(regex_constants::error_badrepeat,
184  "Nothing to repeat before a quantifier.");
185  __neg = __neg && _M_match_token(_ScannerT::_S_token_opt);
186  };
187  if (_M_match_token(_ScannerT::_S_token_closure0))
188  {
189  __init();
190  auto __e = _M_pop();
191  _StateSeqT __r(*_M_nfa,
192  _M_nfa->_M_insert_repeat(_S_invalid_state_id,
193  __e._M_start, __neg));
194  __e._M_append(__r);
195  _M_stack.push(__r);
196  }
197  else if (_M_match_token(_ScannerT::_S_token_closure1))
198  {
199  __init();
200  auto __e = _M_pop();
201  __e._M_append(_M_nfa->_M_insert_repeat(_S_invalid_state_id,
202  __e._M_start, __neg));
203  _M_stack.push(__e);
204  }
205  else if (_M_match_token(_ScannerT::_S_token_opt))
206  {
207  __init();
208  auto __e = _M_pop();
209  auto __end = _M_nfa->_M_insert_dummy();
210  _StateSeqT __r(*_M_nfa,
211  _M_nfa->_M_insert_repeat(_S_invalid_state_id,
212  __e._M_start, __neg));
213  __e._M_append(__end);
214  __r._M_append(__end);
215  _M_stack.push(__r);
216  }
217  else if (_M_match_token(_ScannerT::_S_token_interval_begin))
218  {
219  if (_M_stack.empty())
220  __throw_regex_error(regex_constants::error_badrepeat,
221  "Nothing to repeat before a quantifier.");
222  if (!_M_match_token(_ScannerT::_S_token_dup_count))
223  __throw_regex_error(regex_constants::error_badbrace,
224  "Unexpected token in brace expression.");
225  _StateSeqT __r(_M_pop());
226  _StateSeqT __e(*_M_nfa, _M_nfa->_M_insert_dummy());
227  long __min_rep = _M_cur_int_value(10);
228  bool __infi = false;
229  long __n = 0;
230 
231  // {3
232  if (_M_match_token(_ScannerT::_S_token_comma))
233  {
234  if (_M_match_token(_ScannerT::_S_token_dup_count)) // {3,7}
235  __n = _M_cur_int_value(10) - __min_rep;
236  else
237  __infi = true;
238  }
239  if (!_M_match_token(_ScannerT::_S_token_interval_end))
240  __throw_regex_error(regex_constants::error_brace,
241  "Unexpected end of brace expression.");
242 
243  __neg = __neg && _M_match_token(_ScannerT::_S_token_opt);
244 
245  for (long __i = 0; __i < __min_rep; ++__i)
246  __e._M_append(__r._M_clone());
247 
248  if (__infi)
249  {
250  auto __tmp = __r._M_clone();
251  _StateSeqT __s(*_M_nfa,
252  _M_nfa->_M_insert_repeat(_S_invalid_state_id,
253  __tmp._M_start, __neg));
254  __tmp._M_append(__s);
255  __e._M_append(__s);
256  }
257  else
258  {
259  if (__n < 0)
260  __throw_regex_error(regex_constants::error_badbrace,
261  "Invalid range in brace expression.");
262  auto __end = _M_nfa->_M_insert_dummy();
263  // _M_alt is the "match more" branch, and _M_next is the
264  // "match less" one. Switch _M_alt and _M_next of all created
265  // nodes. This is a hack but IMO works well.
266  std::stack<_StateIdT> __stack;
267  for (long __i = 0; __i < __n; ++__i)
268  {
269  auto __tmp = __r._M_clone();
270  auto __alt = _M_nfa->_M_insert_repeat(__tmp._M_start,
271  __end, __neg);
272  __stack.push(__alt);
273  __e._M_append(_StateSeqT(*_M_nfa, __alt, __tmp._M_end));
274  }
275  __e._M_append(__end);
276  while (!__stack.empty())
277  {
278  auto& __tmp = (*_M_nfa)[__stack.top()];
279  __stack.pop();
280  std::swap(__tmp._M_next, __tmp._M_alt);
281  }
282  }
283  _M_stack.push(__e);
284  }
285  else
286  return false;
287  return true;
288  }
289 
290 #define __INSERT_REGEX_MATCHER(__func, ...)\
291  do {\
292  if (!(_M_flags & regex_constants::icase))\
293  if (!(_M_flags & regex_constants::collate))\
294  __func<false, false>(__VA_ARGS__);\
295  else\
296  __func<false, true>(__VA_ARGS__);\
297  else\
298  if (!(_M_flags & regex_constants::collate))\
299  __func<true, false>(__VA_ARGS__);\
300  else\
301  __func<true, true>(__VA_ARGS__);\
302  } while (false)
303 
304  template<typename _TraitsT>
305  bool
306  _Compiler<_TraitsT>::
307  _M_atom()
308  {
309  if (_M_match_token(_ScannerT::_S_token_anychar))
310  {
311  if (!(_M_flags & regex_constants::ECMAScript))
312  __INSERT_REGEX_MATCHER(_M_insert_any_matcher_posix);
313  else
314  __INSERT_REGEX_MATCHER(_M_insert_any_matcher_ecma);
315  }
316  else if (_M_try_char())
317  __INSERT_REGEX_MATCHER(_M_insert_char_matcher);
318  else if (_M_match_token(_ScannerT::_S_token_backref))
319  _M_stack.push(_StateSeqT(*_M_nfa, _M_nfa->
320  _M_insert_backref(_M_cur_int_value(10))));
321  else if (_M_match_token(_ScannerT::_S_token_quoted_class))
322  __INSERT_REGEX_MATCHER(_M_insert_character_class_matcher);
323  else if (_M_match_token(_ScannerT::_S_token_subexpr_no_group_begin))
324  {
325  _StateSeqT __r(*_M_nfa, _M_nfa->_M_insert_dummy());
326  this->_M_disjunction();
327  if (!_M_match_token(_ScannerT::_S_token_subexpr_end))
328  __throw_regex_error(regex_constants::error_paren,
329  "Parenthesis is not closed.");
330  __r._M_append(_M_pop());
331  _M_stack.push(__r);
332  }
333  else if (_M_match_token(_ScannerT::_S_token_subexpr_begin))
334  {
335  _StateSeqT __r(*_M_nfa, _M_nfa->_M_insert_subexpr_begin());
336  this->_M_disjunction();
337  if (!_M_match_token(_ScannerT::_S_token_subexpr_end))
338  __throw_regex_error(regex_constants::error_paren,
339  "Parenthesis is not closed.");
340  __r._M_append(_M_pop());
341  __r._M_append(_M_nfa->_M_insert_subexpr_end());
342  _M_stack.push(__r);
343  }
344  else if (!_M_bracket_expression())
345  return false;
346  return true;
347  }
348 
349  template<typename _TraitsT>
350  bool
351  _Compiler<_TraitsT>::
352  _M_bracket_expression()
353  {
354  bool __neg =
355  _M_match_token(_ScannerT::_S_token_bracket_neg_begin);
356  if (!(__neg || _M_match_token(_ScannerT::_S_token_bracket_begin)))
357  return false;
358  __INSERT_REGEX_MATCHER(_M_insert_bracket_matcher, __neg);
359  return true;
360  }
361 #undef __INSERT_REGEX_MATCHER
362 
363  template<typename _TraitsT>
364  template<bool __icase, bool __collate>
365  void
366  _Compiler<_TraitsT>::
367  _M_insert_any_matcher_ecma()
368  {
369  _M_stack.push(_StateSeqT(*_M_nfa,
370  _M_nfa->_M_insert_matcher
371  (_AnyMatcher<_TraitsT, true, __icase, __collate>
372  (_M_traits))));
373  }
374 
375  template<typename _TraitsT>
376  template<bool __icase, bool __collate>
377  void
378  _Compiler<_TraitsT>::
379  _M_insert_any_matcher_posix()
380  {
381  _M_stack.push(_StateSeqT(*_M_nfa,
382  _M_nfa->_M_insert_matcher
383  (_AnyMatcher<_TraitsT, false, __icase, __collate>
384  (_M_traits))));
385  }
386 
387  template<typename _TraitsT>
388  template<bool __icase, bool __collate>
389  void
390  _Compiler<_TraitsT>::
391  _M_insert_char_matcher()
392  {
393  _M_stack.push(_StateSeqT(*_M_nfa,
394  _M_nfa->_M_insert_matcher
395  (_CharMatcher<_TraitsT, __icase, __collate>
396  (_M_value[0], _M_traits))));
397  }
398 
399  template<typename _TraitsT>
400  template<bool __icase, bool __collate>
401  void
402  _Compiler<_TraitsT>::
403  _M_insert_character_class_matcher()
404  {
405  __glibcxx_assert(_M_value.size() == 1);
406  _BracketMatcher<__icase, __collate> __matcher
407  (_M_ctype.is(_CtypeT::upper, _M_value[0]), _M_traits);
408  __matcher._M_add_character_class(_M_value, false);
409  __matcher._M_ready();
410  _M_stack.push(_StateSeqT(*_M_nfa,
411  _M_nfa->_M_insert_matcher(std::move(__matcher))));
412  }
413 
414  template<typename _TraitsT>
415  template<bool __icase, bool __collate>
416  void
417  _Compiler<_TraitsT>::
418  _M_insert_bracket_matcher(bool __neg)
419  {
420  _BracketMatcher<__icase, __collate> __matcher(__neg, _M_traits);
421  _BracketState __last_char;
422  if (_M_try_char())
423  __last_char.set(_M_value[0]);
424  else if (_M_match_token(_ScannerT::_S_token_bracket_dash))
425  // Dash as first character is a normal character.
426  __last_char.set('-');
427  while (_M_expression_term(__last_char, __matcher))
428  ;
429  if (__last_char._M_is_char())
430  __matcher._M_add_char(__last_char.get());
431  __matcher._M_ready();
432  _M_stack.push(_StateSeqT(
433  *_M_nfa,
434  _M_nfa->_M_insert_matcher(std::move(__matcher))));
435  }
436 
437  template<typename _TraitsT>
438  template<bool __icase, bool __collate>
439  bool
440  _Compiler<_TraitsT>::
441  _M_expression_term(_BracketState& __last_char,
442  _BracketMatcher<__icase, __collate>& __matcher)
443  {
444  if (_M_match_token(_ScannerT::_S_token_bracket_end))
445  return false;
446 
447  // Add any previously cached char into the matcher and update cache.
448  const auto __push_char = [&](_CharT __ch)
449  {
450  if (__last_char._M_is_char())
451  __matcher._M_add_char(__last_char.get());
452  __last_char.set(__ch);
453  };
454  // Add any previously cached char into the matcher and update cache.
455  const auto __push_class = [&]
456  {
457  if (__last_char._M_is_char())
458  __matcher._M_add_char(__last_char.get());
459  // We don't cache anything here, just record that the last thing
460  // processed was a character class (or similar).
461  __last_char.reset(_BracketState::_Type::_Class);
462  };
463 
464  if (_M_match_token(_ScannerT::_S_token_collsymbol))
465  {
466  auto __symbol = __matcher._M_add_collate_element(_M_value);
467  if (__symbol.size() == 1)
468  __push_char(__symbol[0]);
469  else
470  __push_class();
471  }
472  else if (_M_match_token(_ScannerT::_S_token_equiv_class_name))
473  {
474  __push_class();
475  __matcher._M_add_equivalence_class(_M_value);
476  }
477  else if (_M_match_token(_ScannerT::_S_token_char_class_name))
478  {
479  __push_class();
480  __matcher._M_add_character_class(_M_value, false);
481  }
482  else if (_M_try_char())
483  __push_char(_M_value[0]);
484  // POSIX doesn't allow '-' as a start-range char (say [a-z--0]),
485  // except when the '-' is the first or last character in the bracket
486  // expression ([--0]). ECMAScript treats all '-' after a range as a
487  // normal character. Also see above, where _M_expression_term gets called.
488  //
489  // As a result, POSIX rejects [-----], but ECMAScript doesn't.
490  // Boost (1.57.0) always uses POSIX style even in its ECMAScript syntax.
491  // Clang (3.5) always uses ECMAScript style even in its POSIX syntax.
492  //
493  // It turns out that no one reads BNFs ;)
494  else if (_M_match_token(_ScannerT::_S_token_bracket_dash))
495  {
496  if (_M_match_token(_ScannerT::_S_token_bracket_end))
497  {
498  // For "-]" the dash is a literal character.
499  __push_char('-');
500  return false;
501  }
502  else if (__last_char._M_is_class())
503  {
504  // "\\w-" is invalid, start of range must be a single char.
505  __throw_regex_error(regex_constants::error_range,
506  "Invalid start of range in bracket expression.");
507  }
508  else if (__last_char._M_is_char())
509  {
510  if (_M_try_char())
511  {
512  // "x-y"
513  __matcher._M_make_range(__last_char.get(), _M_value[0]);
514  __last_char.reset();
515  }
516  else if (_M_match_token(_ScannerT::_S_token_bracket_dash))
517  {
518  // "x--"
519  __matcher._M_make_range(__last_char.get(), '-');
520  __last_char.reset();
521  }
522  else
523  __throw_regex_error(regex_constants::error_range,
524  "Invalid end of range in bracket expression.");
525  }
526  else if (_M_flags & regex_constants::ECMAScript)
527  {
528  // A dash that is not part of an existing range. Might be the
529  // start of a new range, or might just be a literal '-' char.
530  // Only ECMAScript allows that in the middle of a bracket expr.
531  __push_char('-');
532  }
533  else
534  __throw_regex_error(regex_constants::error_range,
535  "Invalid dash in bracket expression.");
536  }
537  else if (_M_match_token(_ScannerT::_S_token_quoted_class))
538  {
539  __push_class();
540  __matcher._M_add_character_class(_M_value,
541  _M_ctype.is(_CtypeT::upper,
542  _M_value[0]));
543  }
544  else
545  __throw_regex_error(regex_constants::error_brack,
546  "Unexpected character in bracket expression.");
547 
548  return true;
549  }
550 
551  template<typename _TraitsT>
552  bool
553  _Compiler<_TraitsT>::
554  _M_try_char()
555  {
556  bool __is_char = false;
557  if (_M_match_token(_ScannerT::_S_token_oct_num))
558  {
559  __is_char = true;
560  _M_value.assign(1, _M_cur_int_value(8));
561  }
562  else if (_M_match_token(_ScannerT::_S_token_hex_num))
563  {
564  __is_char = true;
565  _M_value.assign(1, _M_cur_int_value(16));
566  }
567  else if (_M_match_token(_ScannerT::_S_token_ord_char))
568  __is_char = true;
569  return __is_char;
570  }
571 
572  template<typename _TraitsT>
573  bool
574  _Compiler<_TraitsT>::
575  _M_match_token(_TokenT __token)
576  {
577  if (__token == _M_scanner._M_get_token())
578  {
579  _M_value = _M_scanner._M_get_value();
580  _M_scanner._M_advance();
581  return true;
582  }
583  return false;
584  }
585 
586  template<typename _TraitsT>
587  int
588  _Compiler<_TraitsT>::
589  _M_cur_int_value(int __radix)
590  {
591  int __v = 0;
592  for (_CharT __c : _M_value)
593  if (__builtin_mul_overflow(__v, __radix, &__v)
594  || __builtin_add_overflow(__v, _M_traits.value(__c, __radix), &__v))
595  std::__throw_regex_error(regex_constants::error_backref,
596  "invalid back reference");
597  return __v;
598  }
599 
600  template<typename _TraitsT, bool __icase, bool __collate>
601  bool
602  _BracketMatcher<_TraitsT, __icase, __collate>::
603  _M_apply(_CharT __ch, false_type) const
604  {
605  return [this, __ch]
606  {
607  if (std::binary_search(_M_char_set.begin(), _M_char_set.end(),
608  _M_translator._M_translate(__ch)))
609  return true;
610  auto __s = _M_translator._M_transform(__ch);
611  for (auto& __it : _M_range_set)
612  if (_M_translator._M_match_range(__it.first, __it.second, __s))
613  return true;
614  if (_M_traits.isctype(__ch, _M_class_set))
615  return true;
616  if (std::find(_M_equiv_set.begin(), _M_equiv_set.end(),
617  _M_traits.transform_primary(&__ch, &__ch+1))
618  != _M_equiv_set.end())
619  return true;
620  for (auto& __it : _M_neg_class_set)
621  if (!_M_traits.isctype(__ch, __it))
622  return true;
623  return false;
624  }() ^ _M_is_non_matching;
625  }
626 } // namespace __detail
627 
628 _GLIBCXX_END_NAMESPACE_VERSION
629 } // namespace
integral_constant< bool, false > false_type
The type used as a compile-time boolean with false value.
Definition: type_traits:86
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:104
void swap(any &__x, any &__y) noexcept
Exchange the states of two any objects.
Definition: any:428
const _Facet & use_facet(const locale &__loc)
Return a facet.
ISO C++ entities toplevel namespace is std.
constexpr error_type error_brace(_S_error_brace)
constexpr error_type error_badbrace(_S_error_badbrace)
constexpr error_type error_range(_S_error_range)
constexpr syntax_option_type ECMAScript
constexpr error_type error_badrepeat(_S_error_badrepeat)
constexpr error_type error_paren(_S_error_paren)
constexpr error_type error_brack(_S_error_brack)
constexpr error_type error_backref(_S_error_backref)
A standard container giving FILO behavior.
Definition: stl_stack.h:100
void pop()
Removes first element.
Definition: stl_stack.h:272
void push(const value_type &__x)
Add data to the top of the stack.
Definition: stl_stack.h:239
bool empty() const
Definition: stl_stack.h:199
reference top()
Definition: stl_stack.h:212