libstdc++-v3/include/bits/regex_compiler.tcc

   1 // class template regex -*- C++ -*-
   2
   3 // Copyright (C) 2013 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 // This compiler refers to "Regular Expression Matching Can Be Simple And Fast"
  34 // (http://swtch.com/~rsc/regexp/regexp1.html"),
  35 // but doesn't strictly follow it.
  36 //
  37 // When compiling, states are *chained* instead of tree- or graph-constructed.
  38 // It's more like structured programs: there's if statement and loop statement.
  39 //
  40 // For alternative structure(say "a|b"), aka "if statement", two branchs should
  41 // be constructed. However, these two shall merge to an "end_tag" at the end of
  42 // this operator:
  43 //
  44 //                branch1
  45 //              /        \
  46 // => begin_tag            end_tag =>
  47 //              \        /
  48 //                branch2
  49 //
  50 // This is the difference between this implementation and that in Russ's
  51 // article.
  52 //
  53 // That's why we introduced dummy node here ------ "end_tag" is a dummy node.
  54 // All dummy node will be eliminated at the end of compiling process.
  55
  56 namespace std _GLIBCXX_VISIBILITY(default)
  57 {
  58 namespace __detail
  59 {
  60 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  61
  62   template<typename _FwdIter, typename _CharT, typename _TraitsT>
  63     _Compiler<_FwdIter, _CharT, _TraitsT>::
  64     _Compiler(_FwdIter __b, _FwdIter __e,
  65               const _TraitsT& __traits, _FlagT __flags)
  66     : _M_traits(__traits), _M_scanner(__b, __e, __flags, _M_traits.getloc()),
  67       _M_ctype(std::use_facet<std::ctype<_CharT>>(_M_traits.getloc())),
  68       _M_nfa(__flags), _M_flags(__flags)
  69     {
  70       _StateSeqT __r(_M_nfa, _M_nfa._M_start());
  71       __r._M_append(_M_nfa._M_insert_subexpr_begin());
  72       this->_M_disjunction();
  73       if (!_M_match_token(_ScannerT::_S_token_eof))
  74         __throw_regex_error(regex_constants::error_paren);
  75       __r._M_append(_M_pop());
  76       _GLIBCXX_DEBUG_ASSERT(_M_stack.empty());
  77       __r._M_append(_M_nfa._M_insert_subexpr_end());
  78       __r._M_append(_M_nfa._M_insert_accept());
  79       _M_nfa._M_eliminate_dummy();
  80     }
  81
  82   template<typename _FwdIter, typename _CharT, typename _TraitsT>
  83     void
  84     _Compiler<_FwdIter, _CharT, _TraitsT>::
  85     _M_disjunction()
  86     {
  87       this->_M_alternative();
  88       // TODO empty alternative like, um, "(|asdf)"
  89       while (_M_match_token(_ScannerT::_S_token_or))
  90         {
  91           _StateSeqT __alt1 = _M_pop();
  92           this->_M_alternative();
  93           _StateSeqT __alt2 = _M_pop();
  94           auto __end = _M_nfa._M_insert_dummy();
  95           __alt1._M_append(__end);
  96           __alt2._M_append(__end);
  97           _M_stack.push(_StateSeqT(_M_nfa,
  98                                    _M_nfa._M_insert_alt(__alt1._M_start,
  99                                                         __alt2._M_start, false),
 100                                    __end));
 101         }
 102     }
 103
 104   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 105     void
 106     _Compiler<_FwdIter, _CharT, _TraitsT>::
 107     _M_alternative()
 108     {
 109       if (this->_M_term())
 110         {
 111           _StateSeqT __re = _M_pop();
 112           this->_M_alternative();
 113           __re._M_append(_M_pop());
 114           _M_stack.push(__re);
 115         }
 116       else
 117         _M_stack.push(_StateSeqT(_M_nfa, _M_nfa._M_insert_dummy()));
 118     }
 119
 120   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 121     bool
 122     _Compiler<_FwdIter, _CharT, _TraitsT>::
 123     _M_term()
 124     {
 125       if (this->_M_assertion())
 126         return true;
 127       if (this->_M_atom())
 128         {
 129           this->_M_quantifier();
 130           return true;
 131         }
 132       return false;
 133     }
 134
 135   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 136     bool
 137     _Compiler<_FwdIter, _CharT, _TraitsT>::
 138     _M_assertion()
 139     {
 140       if (_M_match_token(_ScannerT::_S_token_line_begin))
 141         _M_stack.push(_StateSeqT(_M_nfa, _M_nfa.
 142               _M_insert_line_begin()));
 143       else if (_M_match_token(_ScannerT::_S_token_line_end))
 144         _M_stack.push(_StateSeqT(_M_nfa, _M_nfa.
 145               _M_insert_line_end()));
 146       else if (_M_match_token(_ScannerT::_S_token_word_bound))
 147         // _M_value[0] == 'n' means it's negtive, say "not word boundary".
 148         _M_stack.push(_StateSeqT(_M_nfa, _M_nfa.
 149               _M_insert_word_bound(_M_value[0] == 'n')));
 150       else if (_M_match_token(_ScannerT::_S_token_subexpr_lookahead_begin))
 151         {
 152           auto __neg = _M_value[0] == 'n';
 153           this->_M_disjunction();
 154           if (!_M_match_token(_ScannerT::_S_token_subexpr_end))
 155             __throw_regex_error(regex_constants::error_paren);
 156           auto __tmp = _M_pop();
 157           __tmp._M_append(_M_nfa._M_insert_accept());
 158           _M_stack.push(
 159               _StateSeqT(
 160                 _M_nfa,
 161                 _M_nfa._M_insert_lookahead(__tmp._M_start, __neg)));
 162         }
 163       else
 164         return false;
 165       return true;
 166     }
 167
 168   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 169     void
 170     _Compiler<_FwdIter, _CharT, _TraitsT>::
 171     _M_quantifier()
 172     {
 173       bool __neg = regex_constants::ECMAScript;
 174       auto __init = [this, &__neg]()
 175         {
 176           if (_M_stack.empty())
 177             __throw_regex_error(regex_constants::error_badrepeat);
 178           __neg = __neg && _M_match_token(_ScannerT::_S_token_opt);
 179         };
 180       if (_M_match_token(_ScannerT::_S_token_closure0))
 181         {
 182           __init();
 183           auto __e = _M_pop();
 184           _StateSeqT __r(_M_nfa, _M_nfa._M_insert_alt(_S_invalid_state_id,
 185                                                       __e._M_start, __neg));
 186           __e._M_append(__r);
 187           _M_stack.push(__r);
 188         }
 189       else if (_M_match_token(_ScannerT::_S_token_closure1))
 190         {
 191           __init();
 192           auto __e = _M_pop();
 193           __e._M_append(_M_nfa._M_insert_alt(_S_invalid_state_id, __e._M_start,
 194                                              __neg));
 195           _M_stack.push(__e);
 196         }
 197       else if (_M_match_token(_ScannerT::_S_token_opt))
 198         {
 199           __init();
 200           auto __e = _M_pop();
 201           auto __end = _M_nfa._M_insert_dummy();
 202           _StateSeqT __r(_M_nfa, _M_nfa._M_insert_alt(_S_invalid_state_id,
 203                                                       __e._M_start, __neg));
 204           __e._M_append(__end);
 205           __r._M_append(__end);
 206           _M_stack.push(__r);
 207         }
 208       else if (_M_match_token(_ScannerT::_S_token_interval_begin))
 209         {
 210           __init();
 211           if (!_M_match_token(_ScannerT::_S_token_dup_count))
 212             __throw_regex_error(regex_constants::error_badbrace);
 213           _StateSeqT __r(_M_pop());
 214           _StateSeqT __e(_M_nfa, _M_nfa._M_insert_dummy());
 215           int __min_rep = _M_cur_int_value(10);
 216           // {3
 217           for (int __i = 0; __i < __min_rep; ++__i)
 218             __e._M_append(__r._M_clone());
 219           if (_M_match_token(_ScannerT::_S_token_comma))
 220             if (_M_match_token(_ScannerT::_S_token_dup_count)) // {3,7}
 221               {
 222                 int __n = _M_cur_int_value(10) - __min_rep;
 223                 if (__n < 0)
 224                   __throw_regex_error(regex_constants::error_badbrace);
 225                 auto __end = _M_nfa._M_insert_dummy();
 226                 // _M_alt is the "match more" branch, and _M_next is the
 227                 // "match less" one. Switch _M_alt and _M_next of all created
 228                 // nodes. This is a hacking but IMO works well.
 229                 std::stack<_StateIdT> __stack;
 230                 for (int __i = 0; __i < __n; ++__i)
 231                   {
 232                     auto __tmp = __r._M_clone();
 233                     auto __alt = _M_nfa._M_insert_alt(__tmp._M_start,
 234                                                       __end, __neg);
 235                     __stack.push(__alt);
 236                     __e._M_append(_StateSeqT(_M_nfa, __alt, __tmp._M_end));
 237                   }
 238                 __e._M_append(__end);
 239                 while (!__stack.empty())
 240                   {
 241                     auto& __tmp = _M_nfa[__stack.top()];
 242                     __stack.pop();
 243                     swap(__tmp._M_next, __tmp._M_alt);
 244                   }
 245               }
 246             else // {3,}
 247               {
 248                 auto __tmp = __r._M_clone();
 249                 _StateSeqT __s(_M_nfa,
 250                                _M_nfa._M_insert_alt(_S_invalid_state_id,
 251                                                     __tmp._M_start, __neg));
 252                 __tmp._M_append(__s);
 253                 __e._M_append(__s);
 254               }
 255           if (!_M_match_token(_ScannerT::_S_token_interval_end))
 256             __throw_regex_error(regex_constants::error_brace);
 257           _M_stack.push(__e);
 258         }
 259     }
 260
 261   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 262     bool
 263     _Compiler<_FwdIter, _CharT, _TraitsT>::
 264     _M_atom()
 265     {
 266       if (_M_match_token(_ScannerT::_S_token_anychar))
 267         _M_stack.push(_StateSeqT(_M_nfa,
 268                                 _M_nfa._M_insert_matcher
 269                                 (_AnyMatcher<_CharT, _TraitsT>(_M_traits))));
 270       else if (_M_try_char())
 271         _M_stack.push(_StateSeqT(_M_nfa,
 272                                  _M_nfa._M_insert_matcher
 273                                  (_CharMatcher<_CharT, _TraitsT>(_M_value[0],
 274                                                                  _M_traits,
 275                                                                  _M_flags))));
 276       else if (_M_match_token(_ScannerT::_S_token_backref))
 277         _M_stack.push(_StateSeqT(_M_nfa, _M_nfa.
 278                                  _M_insert_backref(_M_cur_int_value(10))));
 279       else if (_M_match_token(_ScannerT::_S_token_quoted_class))
 280         {
 281           _GLIBCXX_DEBUG_ASSERT(_M_value.size() == 1);
 282           _BMatcherT __matcher(_M_ctype.is(_CtypeT::upper, _M_value[0]),
 283                                _M_traits, _M_flags);
 284           __matcher._M_add_character_class(_M_value);
 285           _M_stack.push(_StateSeqT(_M_nfa,
 286                 _M_nfa._M_insert_matcher(__matcher)));
 287         }
 288       else if (_M_match_token(_ScannerT::_S_token_subexpr_no_group_begin))
 289         {
 290           _StateSeqT __r(_M_nfa, _M_nfa._M_insert_dummy());
 291           this->_M_disjunction();
 292           if (!_M_match_token(_ScannerT::_S_token_subexpr_end))
 293             __throw_regex_error(regex_constants::error_paren);
 294           __r._M_append(_M_pop());
 295           _M_stack.push(__r);
 296         }
 297       else if (_M_match_token(_ScannerT::_S_token_subexpr_begin))
 298         {
 299           int __mark = _M_nfa._M_sub_count();
 300           _StateSeqT __r(_M_nfa, _M_nfa._M_insert_subexpr_begin());
 301           this->_M_disjunction();
 302           if (!_M_match_token(_ScannerT::_S_token_subexpr_end))
 303             __throw_regex_error(regex_constants::error_paren);
 304           __r._M_append(_M_pop());
 305           __r._M_append(_M_nfa._M_insert_subexpr_end());
 306           _M_stack.push(__r);
 307         }
 308       else if (!_M_bracket_expression())
 309         return false;
 310       return true;
 311     }
 312
 313   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 314     bool
 315     _Compiler<_FwdIter, _CharT, _TraitsT>::
 316     _M_bracket_expression()
 317     {
 318       bool __neg =
 319         _M_match_token(_ScannerT::_S_token_bracket_neg_begin);
 320       if (!(__neg || _M_match_token(_ScannerT::_S_token_bracket_begin)))
 321         return false;
 322       _BMatcherT __matcher(__neg, _M_traits, _M_flags);
 323       while (!_M_match_token(_ScannerT::_S_token_bracket_end))
 324         _M_expression_term(__matcher);
 325       _M_stack.push(_StateSeqT(_M_nfa, _M_nfa._M_insert_matcher(__matcher)));
 326       return true;
 327     }
 328
 329   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 330     void
 331     _Compiler<_FwdIter, _CharT, _TraitsT>::
 332     _M_expression_term(_BMatcherT& __matcher)
 333     {
 334       if (_M_match_token(_ScannerT::_S_token_collsymbol))
 335         __matcher._M_add_collating_element(_M_value);
 336       else if (_M_match_token(_ScannerT::_S_token_equiv_class_name))
 337         __matcher._M_add_equivalence_class(_M_value);
 338       else if (_M_match_token(_ScannerT::_S_token_char_class_name))
 339         __matcher._M_add_character_class(_M_value);
 340       else if (_M_try_char()) // [a
 341         {
 342           auto __ch = _M_value[0];
 343           if (_M_try_char())
 344             {
 345               if (_M_value[0] == '-') // [a-
 346                 {
 347                   if (_M_try_char()) // [a-z]
 348                     {
 349                       __matcher._M_make_range(__ch, _M_value[0]);
 350                       return;
 351                     }
 352                   // If the dash is the last character in the bracket
 353                   // expression, it is not special.
 354                   if (_M_scanner._M_get_token()
 355                       != _ScannerT::_S_token_bracket_end)
 356                     __throw_regex_error(regex_constants::error_range);
 357                 }
 358               __matcher._M_add_char(_M_value[0]);
 359             }
 360           __matcher._M_add_char(__ch);
 361         }
 362       else
 363         __throw_regex_error(regex_constants::error_brack);
 364     }
 365
 366   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 367     bool
 368     _Compiler<_FwdIter, _CharT, _TraitsT>::
 369     _M_try_char()
 370     {
 371       bool __is_char = false;
 372       if (_M_match_token(_ScannerT::_S_token_oct_num))
 373         {
 374           __is_char = true;
 375           _M_value.assign(1, _M_cur_int_value(8));
 376         }
 377       else if (_M_match_token(_ScannerT::_S_token_hex_num))
 378         {
 379           __is_char = true;
 380           _M_value.assign(1, _M_cur_int_value(16));
 381         }
 382       else if (_M_match_token(_ScannerT::_S_token_ord_char))
 383         __is_char = true;
 384       return __is_char;
 385     }
 386
 387   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 388     bool
 389     _Compiler<_FwdIter, _CharT, _TraitsT>::
 390     _M_match_token(_TokenT token)
 391     {
 392       if (token == _M_scanner._M_get_token())
 393         {
 394           _M_value = _M_scanner._M_get_value();
 395           _M_scanner._M_advance();
 396           return true;
 397         }
 398       return false;
 399     }
 400
 401   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 402     int
 403     _Compiler<_FwdIter, _CharT, _TraitsT>::
 404     _M_cur_int_value(int __radix)
 405     {
 406       int __v = 0;
 407       for (typename _StringT::size_type __i = 0;
 408            __i < _M_value.length(); ++__i)
 409         __v =__v * __radix + _M_traits.value(_M_value[__i], __radix);
 410       return __v;
 411     }
 412
 413   template<typename _CharT, typename _TraitsT>
 414     bool _BracketMatcher<_CharT, _TraitsT>::
 415     operator()(_CharT __ch) const
 416     {
 417       bool __ret = false;
 418       if (_M_traits.isctype(__ch, _M_class_set))
 419         __ret = true;
 420       else if (_M_char_set.count(_M_translate(__ch)))
 421         __ret = true;
 422       else
 423         {
 424           _StringT __s = _M_get_str(_M_flags & regex_constants::collate
 425                                     ? _M_translate(__ch) : __ch);
 426           for (auto& __it : _M_range_set)
 427             if (__it.first <= __s && __s <= __it.second)
 428               {
 429                 __ret = true;
 430                 break;
 431               }
 432         }
 433       if (_M_is_non_matching)
 434         return !__ret;
 435       else
 436         return __ret;
 437     }
 438
 439 _GLIBCXX_END_NAMESPACE_VERSION
 440 } // namespace __detail
 441 } // namespace