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_flags((__flags
  67                 & (regex_constants::ECMAScript
  68                    | regex_constants::basic
  69                    | regex_constants::extended
  70                    | regex_constants::grep
  71                    | regex_constants::egrep
  72                    | regex_constants::awk))
  73                ? __flags
  74                : __flags | regex_constants::ECMAScript),
  75     _M_traits(__traits),
  76     _M_ctype(std::use_facet<std::ctype<_CharT>>(_M_traits.getloc())),
  77     _M_scanner(__b, __e, _M_flags, _M_traits.getloc()),
  78     _M_nfa(_M_flags)
  79     {
  80       _StateSeqT __r(_M_nfa, _M_nfa._M_start());
  81       __r._M_append(_M_nfa._M_insert_subexpr_begin());
  82       this->_M_disjunction();
  83       if (!_M_match_token(_ScannerT::_S_token_eof))
  84         __throw_regex_error(regex_constants::error_paren);
  85       __r._M_append(_M_pop());
  86       _GLIBCXX_DEBUG_ASSERT(_M_stack.empty());
  87       __r._M_append(_M_nfa._M_insert_subexpr_end());
  88       __r._M_append(_M_nfa._M_insert_accept());
  89       _M_nfa._M_eliminate_dummy();
  90     }
  91
  92   template<typename _FwdIter, typename _CharT, typename _TraitsT>
  93     void
  94     _Compiler<_FwdIter, _CharT, _TraitsT>::
  95     _M_disjunction()
  96     {
  97       this->_M_alternative();
  98       while (_M_match_token(_ScannerT::_S_token_or))
  99         {
 100           _StateSeqT __alt1 = _M_pop();
 101           this->_M_alternative();
 102           _StateSeqT __alt2 = _M_pop();
 103           auto __end = _M_nfa._M_insert_dummy();
 104           __alt1._M_append(__end);
 105           __alt2._M_append(__end);
 106           _M_stack.push(_StateSeqT(_M_nfa,
 107                                    _M_nfa._M_insert_alt(__alt1._M_start,
 108                                                         __alt2._M_start, false),
 109                                    __end));
 110         }
 111     }
 112
 113   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 114     void
 115     _Compiler<_FwdIter, _CharT, _TraitsT>::
 116     _M_alternative()
 117     {
 118       if (this->_M_term())
 119         {
 120           _StateSeqT __re = _M_pop();
 121           this->_M_alternative();
 122           __re._M_append(_M_pop());
 123           _M_stack.push(__re);
 124         }
 125       else
 126         _M_stack.push(_StateSeqT(_M_nfa, _M_nfa._M_insert_dummy()));
 127     }
 128
 129   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 130     bool
 131     _Compiler<_FwdIter, _CharT, _TraitsT>::
 132     _M_term()
 133     {
 134       if (this->_M_assertion())
 135         return true;
 136       if (this->_M_atom())
 137         {
 138           this->_M_quantifier();
 139           return true;
 140         }
 141       return false;
 142     }
 143
 144   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 145     bool
 146     _Compiler<_FwdIter, _CharT, _TraitsT>::
 147     _M_assertion()
 148     {
 149       if (_M_match_token(_ScannerT::_S_token_line_begin))
 150         _M_stack.push(_StateSeqT(_M_nfa, _M_nfa._M_insert_line_begin()));
 151       else if (_M_match_token(_ScannerT::_S_token_line_end))
 152         _M_stack.push(_StateSeqT(_M_nfa, _M_nfa._M_insert_line_end()));
 153       else if (_M_match_token(_ScannerT::_S_token_word_bound))
 154         // _M_value[0] == 'n' means it's negtive, say "not word boundary".
 155         _M_stack.push(_StateSeqT(_M_nfa, _M_nfa.
 156               _M_insert_word_bound(_M_value[0] == 'n')));
 157       else if (_M_match_token(_ScannerT::_S_token_subexpr_lookahead_begin))
 158         {
 159           auto __neg = _M_value[0] == 'n';
 160           this->_M_disjunction();
 161           if (!_M_match_token(_ScannerT::_S_token_subexpr_end))
 162             __throw_regex_error(regex_constants::error_paren);
 163           auto __tmp = _M_pop();
 164           __tmp._M_append(_M_nfa._M_insert_accept());
 165           _M_stack.push(
 166               _StateSeqT(
 167                 _M_nfa,
 168                 _M_nfa._M_insert_lookahead(__tmp._M_start, __neg)));
 169         }
 170       else
 171         return false;
 172       return true;
 173     }
 174
 175   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 176     void
 177     _Compiler<_FwdIter, _CharT, _TraitsT>::
 178     _M_quantifier()
 179     {
 180       bool __neg = (_M_flags & regex_constants::ECMAScript);
 181       auto __init = [this, &__neg]()
 182         {
 183           if (_M_stack.empty())
 184             __throw_regex_error(regex_constants::error_badrepeat);
 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, _M_nfa._M_insert_alt(_S_invalid_state_id,
 192                                                       __e._M_start, __neg));
 193           __e._M_append(__r);
 194           _M_stack.push(__r);
 195         }
 196       else if (_M_match_token(_ScannerT::_S_token_closure1))
 197         {
 198           __init();
 199           auto __e = _M_pop();
 200           __e._M_append(_M_nfa._M_insert_alt(_S_invalid_state_id, __e._M_start,
 201                                              __neg));
 202           _M_stack.push(__e);
 203         }
 204       else if (_M_match_token(_ScannerT::_S_token_opt))
 205         {
 206           __init();
 207           auto __e = _M_pop();
 208           auto __end = _M_nfa._M_insert_dummy();
 209           _StateSeqT __r(_M_nfa, _M_nfa._M_insert_alt(_S_invalid_state_id,
 210                                                       __e._M_start, __neg));
 211           __e._M_append(__end);
 212           __r._M_append(__end);
 213           _M_stack.push(__r);
 214         }
 215       else if (_M_match_token(_ScannerT::_S_token_interval_begin))
 216         {
 217           if (_M_stack.empty())
 218             __throw_regex_error(regex_constants::error_badrepeat);
 219           if (!_M_match_token(_ScannerT::_S_token_dup_count))
 220             __throw_regex_error(regex_constants::error_badbrace);
 221           _StateSeqT __r(_M_pop());
 222           _StateSeqT __e(_M_nfa, _M_nfa._M_insert_dummy());
 223           long __min_rep = _M_cur_int_value(10);
 224           bool __infi = false;
 225           long __n;
 226
 227           // {3
 228           if (_M_match_token(_ScannerT::_S_token_comma))
 229             if (_M_match_token(_ScannerT::_S_token_dup_count)) // {3,7}
 230               __n = _M_cur_int_value(10) - __min_rep;
 231             else
 232               __infi = true;
 233           else
 234             __n = 0;
 235           if (!_M_match_token(_ScannerT::_S_token_interval_end))
 236             __throw_regex_error(regex_constants::error_brace);
 237
 238           __neg = __neg && _M_match_token(_ScannerT::_S_token_opt);
 239
 240           for (long __i = 0; __i < __min_rep; ++__i)
 241             __e._M_append(__r._M_clone());
 242
 243           if (__infi)
 244             {
 245               auto __tmp = __r._M_clone();
 246               _StateSeqT __s(_M_nfa,
 247                              _M_nfa._M_insert_alt(_S_invalid_state_id,
 248                                                   __tmp._M_start, __neg));
 249               __tmp._M_append(__s);
 250               __e._M_append(__s);
 251             }
 252           else
 253             {
 254               if (__n < 0)
 255                 __throw_regex_error(regex_constants::error_badbrace);
 256               auto __end = _M_nfa._M_insert_dummy();
 257               // _M_alt is the "match more" branch, and _M_next is the
 258               // "match less" one. Switch _M_alt and _M_next of all created
 259               // nodes. This is a hacking but IMO works well.
 260               std::stack<_StateIdT> __stack;
 261               for (long __i = 0; __i < __n; ++__i)
 262                 {
 263                   auto __tmp = __r._M_clone();
 264                   auto __alt = _M_nfa._M_insert_alt(__tmp._M_start,
 265                                                     __end, __neg);
 266                   __stack.push(__alt);
 267                   __e._M_append(_StateSeqT(_M_nfa, __alt, __tmp._M_end));
 268                 }
 269               __e._M_append(__end);
 270               while (!__stack.empty())
 271                 {
 272                   auto& __tmp = _M_nfa[__stack.top()];
 273                   __stack.pop();
 274                   swap(__tmp._M_next, __tmp._M_alt);
 275                 }
 276             }
 277           _M_stack.push(__e);
 278         }
 279     }
 280
 281   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 282     bool
 283     _Compiler<_FwdIter, _CharT, _TraitsT>::
 284     _M_atom()
 285     {
 286       if (_M_match_token(_ScannerT::_S_token_anychar))
 287         _M_stack.push(_StateSeqT(_M_nfa,
 288                                 _M_nfa._M_insert_matcher
 289                                 (_AnyMatcher<_CharT, _TraitsT>(_M_traits))));
 290       else if (_M_try_char())
 291         _M_stack.push(_StateSeqT(_M_nfa,
 292                                  _M_nfa._M_insert_matcher
 293                                  (_CharMatcher<_CharT, _TraitsT>(_M_value[0],
 294                                                                  _M_traits,
 295                                                                  _M_flags))));
 296       else if (_M_match_token(_ScannerT::_S_token_backref))
 297         _M_stack.push(_StateSeqT(_M_nfa, _M_nfa.
 298                                  _M_insert_backref(_M_cur_int_value(10))));
 299       else if (_M_match_token(_ScannerT::_S_token_quoted_class))
 300         {
 301           _GLIBCXX_DEBUG_ASSERT(_M_value.size() == 1);
 302           _BMatcherT __matcher(_M_ctype.is(_CtypeT::upper, _M_value[0]),
 303                                _M_traits, _M_flags);
 304           __matcher._M_add_character_class(_M_value);
 305           _M_stack.push(_StateSeqT(_M_nfa,
 306                 _M_nfa._M_insert_matcher(std::move(__matcher))));
 307         }
 308       else if (_M_match_token(_ScannerT::_S_token_subexpr_no_group_begin))
 309         {
 310           _StateSeqT __r(_M_nfa, _M_nfa._M_insert_dummy());
 311           this->_M_disjunction();
 312           if (!_M_match_token(_ScannerT::_S_token_subexpr_end))
 313             __throw_regex_error(regex_constants::error_paren);
 314           __r._M_append(_M_pop());
 315           _M_stack.push(__r);
 316         }
 317       else if (_M_match_token(_ScannerT::_S_token_subexpr_begin))
 318         {
 319           _StateSeqT __r(_M_nfa, _M_nfa._M_insert_subexpr_begin());
 320           this->_M_disjunction();
 321           if (!_M_match_token(_ScannerT::_S_token_subexpr_end))
 322             __throw_regex_error(regex_constants::error_paren);
 323           __r._M_append(_M_pop());
 324           __r._M_append(_M_nfa._M_insert_subexpr_end());
 325           _M_stack.push(__r);
 326         }
 327       else if (!_M_bracket_expression())
 328         return false;
 329       return true;
 330     }
 331
 332   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 333     bool
 334     _Compiler<_FwdIter, _CharT, _TraitsT>::
 335     _M_bracket_expression()
 336     {
 337       bool __neg =
 338         _M_match_token(_ScannerT::_S_token_bracket_neg_begin);
 339       if (!(__neg || _M_match_token(_ScannerT::_S_token_bracket_begin)))
 340         return false;
 341       _BMatcherT __matcher(__neg, _M_traits, _M_flags);
 342       while (!_M_match_token(_ScannerT::_S_token_bracket_end))
 343         _M_expression_term(__matcher);
 344       _M_stack.push(_StateSeqT(_M_nfa,
 345                                _M_nfa._M_insert_matcher(std::move(__matcher))));
 346       return true;
 347     }
 348
 349   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 350     void
 351     _Compiler<_FwdIter, _CharT, _TraitsT>::
 352     _M_expression_term(_BMatcherT& __matcher)
 353     {
 354       if (_M_match_token(_ScannerT::_S_token_collsymbol))
 355         __matcher._M_add_collating_element(_M_value);
 356       else if (_M_match_token(_ScannerT::_S_token_equiv_class_name))
 357         __matcher._M_add_equivalence_class(_M_value);
 358       else if (_M_match_token(_ScannerT::_S_token_char_class_name))
 359         __matcher._M_add_character_class(_M_value);
 360       else if (_M_try_char()) // [a
 361         {
 362           auto __ch = _M_value[0];
 363           if (_M_try_char())
 364             {
 365               if (_M_value[0] == '-') // [a-
 366                 {
 367                   if (_M_try_char()) // [a-z]
 368                     {
 369                       __matcher._M_make_range(__ch, _M_value[0]);
 370                       return;
 371                     }
 372                   // If the dash is the last character in the bracket
 373                   // expression, it is not special.
 374                   if (_M_scanner._M_get_token()
 375                       != _ScannerT::_S_token_bracket_end)
 376                     __throw_regex_error(regex_constants::error_range);
 377                 }
 378               __matcher._M_add_char(_M_value[0]);
 379             }
 380           __matcher._M_add_char(__ch);
 381         }
 382       else
 383         __throw_regex_error(regex_constants::error_brack);
 384     }
 385
 386   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 387     bool
 388     _Compiler<_FwdIter, _CharT, _TraitsT>::
 389     _M_try_char()
 390     {
 391       bool __is_char = false;
 392       if (_M_match_token(_ScannerT::_S_token_oct_num))
 393         {
 394           __is_char = true;
 395           _M_value.assign(1, _M_cur_int_value(8));
 396         }
 397       else if (_M_match_token(_ScannerT::_S_token_hex_num))
 398         {
 399           __is_char = true;
 400           _M_value.assign(1, _M_cur_int_value(16));
 401         }
 402       else if (_M_match_token(_ScannerT::_S_token_ord_char))
 403         __is_char = true;
 404       return __is_char;
 405     }
 406
 407   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 408     bool
 409     _Compiler<_FwdIter, _CharT, _TraitsT>::
 410     _M_match_token(_TokenT token)
 411     {
 412       if (token == _M_scanner._M_get_token())
 413         {
 414           _M_value = _M_scanner._M_get_value();
 415           _M_scanner._M_advance();
 416           return true;
 417         }
 418       return false;
 419     }
 420
 421   template<typename _FwdIter, typename _CharT, typename _TraitsT>
 422     int
 423     _Compiler<_FwdIter, _CharT, _TraitsT>::
 424     _M_cur_int_value(int __radix)
 425     {
 426       long __v = 0;
 427       for (typename _StringT::size_type __i = 0;
 428            __i < _M_value.length(); ++__i)
 429         __v =__v * __radix + _M_traits.value(_M_value[__i], __radix);
 430       return __v;
 431     }
 432
 433   template<typename _CharT, typename _TraitsT>
 434     bool
 435     _BracketMatcher<_CharT, _TraitsT>::operator()(_CharT __ch) const
 436     {
 437       bool __ret = false;
 438       if (_M_traits.isctype(__ch, _M_class_set)
 439           || _M_char_set.count(_M_translate(__ch))
 440           || _M_equiv_set.count(_M_traits.transform_primary(&__ch, &__ch+1)))
 441         __ret = true;
 442       else
 443         {
 444           _StringT __s = _M_get_str(_M_flags & regex_constants::collate
 445                                     ? _M_translate(__ch) : __ch);
 446           for (auto& __it : _M_range_set)
 447             if (__it.first <= __s && __s <= __it.second)
 448               {
 449                 __ret = true;
 450                 break;
 451               }
 452         }
 453       if (_M_is_non_matching)
 454         return !__ret;
 455       else
 456         return __ret;
 457     }
 458
 459 _GLIBCXX_END_NAMESPACE_VERSION
 460 } // namespace __detail
 461 } // namespace