libstdc++-v3/include/bits/regex_automaton.h

   1 // class template regex -*- C++ -*-
   2
   3 // Copyright (C) 2013-2024 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_automaton.h
  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 // This macro defines the maximal state number a NFA can have.
  32 #ifndef _GLIBCXX_REGEX_STATE_LIMIT
  33 #define _GLIBCXX_REGEX_STATE_LIMIT 100000
  34 #endif
  35
  36 namespace std _GLIBCXX_VISIBILITY(default)
  37 {
  38 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  39
  40 namespace __detail
  41 {
  42   /**
  43    *  @defgroup regex-detail Base and Implementation Classes
  44    *  @ingroup regex
  45    *  @{
  46    */
  47
  48   typedef long _StateIdT;
  49   _GLIBCXX17_INLINE constexpr _StateIdT _S_invalid_state_id  = -1;
  50
  51   template<typename _CharT>
  52     using _Matcher = std::function<bool (_CharT)>;
  53
  54   /// Operation codes that define the type of transitions within the base NFA
  55   /// that represents the regular expression.
  56   enum _Opcode : int
  57   {
  58       _S_opcode_unknown,
  59       _S_opcode_alternative,
  60       _S_opcode_repeat,
  61       _S_opcode_backref,
  62       _S_opcode_line_begin_assertion,
  63       _S_opcode_line_end_assertion,
  64       _S_opcode_word_boundary,
  65       _S_opcode_subexpr_lookahead,
  66       _S_opcode_subexpr_begin,
  67       _S_opcode_subexpr_end,
  68       _S_opcode_dummy,
  69       _S_opcode_match,
  70       _S_opcode_accept,
  71   };
  72
  73   struct _State_base
  74   {
  75   protected:
  76     _Opcode      _M_opcode;           // type of outgoing transition
  77
  78   public:
  79     _StateIdT    _M_next;             // outgoing transition
  80     union // Since they are mutually exclusive.
  81     {
  82       size_t _M_subexpr;        // for _S_opcode_subexpr_*
  83       size_t _M_backref_index;  // for _S_opcode_backref
  84       struct
  85       {
  86         // for _S_opcode_alternative, _S_opcode_repeat and
  87         // _S_opcode_subexpr_lookahead
  88         _StateIdT  _M_alt;
  89         // for _S_opcode_word_boundary or _S_opcode_subexpr_lookahead or
  90         // quantifiers (ungreedy if set true)
  91         bool       _M_neg;
  92       };
  93       // For _S_opcode_match
  94       __gnu_cxx::__aligned_membuf<_Matcher<char>> _M_matcher_storage;
  95     };
  96
  97   protected:
  98     explicit _State_base(_Opcode __opcode) noexcept
  99     : _M_opcode(__opcode), _M_next(_S_invalid_state_id)
 100     { }
 101
 102   public:
 103     bool
 104     _M_has_alt() const noexcept
 105     {
 106       return _M_opcode == _S_opcode_alternative
 107         || _M_opcode == _S_opcode_repeat
 108         || _M_opcode == _S_opcode_subexpr_lookahead;
 109     }
 110
 111 #ifdef _GLIBCXX_DEBUG
 112     std::ostream&
 113     _M_print(std::ostream& __ostr) const;
 114
 115     // Prints graphviz dot commands for state.
 116     std::ostream&
 117     _M_dot(std::ostream& __ostr, _StateIdT __id) const;
 118 #endif
 119   };
 120
 121   template<typename _Char_type>
 122     struct _State : _State_base
 123     {
 124       typedef _Matcher<_Char_type> _MatcherT;
 125       static_assert(sizeof(_MatcherT) == sizeof(_Matcher<char>),
 126                     "std::function<bool(T)> has the same size as "
 127                     "std::function<bool(char)>");
 128       static_assert(alignof(_MatcherT) == alignof(_Matcher<char>),
 129                     "std::function<bool(T)> has the same alignment as "
 130                     "std::function<bool(char)>");
 131
 132       explicit
 133       _State(_Opcode __opcode) noexcept : _State_base(__opcode)
 134       {
 135         if (_M_opcode() == _S_opcode_match)
 136           new (this->_M_matcher_storage._M_addr()) _MatcherT();
 137       }
 138
 139       _State(const _State& __rhs) : _State_base(__rhs)
 140       {
 141         if (__rhs._M_opcode() == _S_opcode_match)
 142           new (this->_M_matcher_storage._M_addr())
 143             _MatcherT(__rhs._M_get_matcher());
 144       }
 145
 146       _State(_State&& __rhs) noexcept : _State_base(__rhs)
 147       {
 148         if (__rhs._M_opcode() == _S_opcode_match)
 149           new (this->_M_matcher_storage._M_addr())
 150             _MatcherT(std::move(__rhs._M_get_matcher()));
 151       }
 152
 153       _State&
 154       operator=(const _State&) = delete;
 155
 156       ~_State()
 157       {
 158         if (_M_opcode() == _S_opcode_match)
 159           _M_get_matcher().~_MatcherT();
 160       }
 161
 162       // Since correct ctor and dtor rely on _M_opcode, it's better not to
 163       // change it over time.
 164       _Opcode
 165       _M_opcode() const noexcept
 166       { return _State_base::_M_opcode; }
 167
 168       bool
 169       _M_matches(_Char_type __char) const
 170       { return _M_get_matcher()(__char); }
 171
 172       _MatcherT&
 173       _M_get_matcher() noexcept
 174       { return *static_cast<_MatcherT*>(this->_M_matcher_storage._M_addr()); }
 175
 176       const _MatcherT&
 177       _M_get_matcher() const noexcept
 178       {
 179         return *static_cast<const _MatcherT*>(
 180             this->_M_matcher_storage._M_addr());
 181       }
 182     };
 183
 184   struct _NFA_base
 185   {
 186     typedef regex_constants::syntax_option_type _FlagT;
 187
 188     explicit
 189     _NFA_base(_FlagT __f) noexcept
 190     : _M_flags(__f), _M_start_state(0), _M_subexpr_count(0),
 191     _M_has_backref(false)
 192     { }
 193
 194     _NFA_base(_NFA_base&&) = default;
 195
 196   protected:
 197     ~_NFA_base() = default;
 198
 199   public:
 200     _FlagT
 201     _M_options() const noexcept
 202     { return _M_flags; }
 203
 204     _StateIdT
 205     _M_start() const noexcept
 206     { return _M_start_state; }
 207
 208     size_t
 209     _M_sub_count() const noexcept
 210     { return _M_subexpr_count; }
 211
 212     _GLIBCXX_STD_C::vector<size_t> _M_paren_stack;
 213     _FlagT                    _M_flags;
 214     _StateIdT                 _M_start_state;
 215     size_t                    _M_subexpr_count;
 216     bool                      _M_has_backref;
 217   };
 218
 219   template<typename _TraitsT>
 220     struct _NFA
 221     : _NFA_base, _GLIBCXX_STD_C::vector<_State<typename _TraitsT::char_type>>
 222     {
 223       typedef typename _TraitsT::char_type      _Char_type;
 224       typedef _State<_Char_type>                _StateT;
 225       typedef _Matcher<_Char_type>              _MatcherT;
 226
 227       _NFA(const typename _TraitsT::locale_type& __loc, _FlagT __flags)
 228       : _NFA_base(__flags)
 229       { _M_traits.imbue(__loc); }
 230
 231       // for performance reasons _NFA objects should only be moved not copied
 232       _NFA(const _NFA&) = delete;
 233       _NFA(_NFA&&) = default;
 234
 235       _StateIdT
 236       _M_insert_accept()
 237       {
 238         auto __ret = _M_insert_state(_StateT(_S_opcode_accept));
 239         return __ret;
 240       }
 241
 242       _StateIdT
 243       _M_insert_alt(_StateIdT __next, _StateIdT __alt,
 244                     bool __neg __attribute__((__unused__)))
 245       {
 246         _StateT __tmp(_S_opcode_alternative);
 247         // It labels every quantifier to make greedy comparison easier in BFS
 248         // approach.
 249         __tmp._M_next = __next;
 250         __tmp._M_alt = __alt;
 251         return _M_insert_state(std::move(__tmp));
 252       }
 253
 254       _StateIdT
 255       _M_insert_repeat(_StateIdT __next, _StateIdT __alt, bool __neg)
 256       {
 257         _StateT __tmp(_S_opcode_repeat);
 258         // It labels every quantifier to make greedy comparison easier in BFS
 259         // approach.
 260         __tmp._M_next = __next;
 261         __tmp._M_alt = __alt;
 262         __tmp._M_neg = __neg;
 263         return _M_insert_state(std::move(__tmp));
 264       }
 265
 266       _StateIdT
 267       _M_insert_matcher(_MatcherT __m)
 268       {
 269         _StateT __tmp(_S_opcode_match);
 270         __tmp._M_get_matcher() = std::move(__m);
 271         return _M_insert_state(std::move(__tmp));
 272       }
 273
 274       _StateIdT
 275       _M_insert_subexpr_begin()
 276       {
 277         auto __id = this->_M_subexpr_count++;
 278         this->_M_paren_stack.push_back(__id);
 279         _StateT __tmp(_S_opcode_subexpr_begin);
 280         __tmp._M_subexpr = __id;
 281         return _M_insert_state(std::move(__tmp));
 282       }
 283
 284       _StateIdT
 285       _M_insert_subexpr_end()
 286       {
 287         _StateT __tmp(_S_opcode_subexpr_end);
 288         __tmp._M_subexpr = this->_M_paren_stack.back();
 289         this->_M_paren_stack.pop_back();
 290         return _M_insert_state(std::move(__tmp));
 291       }
 292
 293       _StateIdT
 294       _M_insert_backref(size_t __index);
 295
 296       _StateIdT
 297       _M_insert_line_begin()
 298       { return _M_insert_state(_StateT(_S_opcode_line_begin_assertion)); }
 299
 300       _StateIdT
 301       _M_insert_line_end()
 302       { return _M_insert_state(_StateT(_S_opcode_line_end_assertion)); }
 303
 304       _StateIdT
 305       _M_insert_word_bound(bool __neg)
 306       {
 307         _StateT __tmp(_S_opcode_word_boundary);
 308         __tmp._M_neg = __neg;
 309         return _M_insert_state(std::move(__tmp));
 310       }
 311
 312       _StateIdT
 313       _M_insert_lookahead(_StateIdT __alt, bool __neg)
 314       {
 315         _StateT __tmp(_S_opcode_subexpr_lookahead);
 316         __tmp._M_alt = __alt;
 317         __tmp._M_neg = __neg;
 318         return _M_insert_state(std::move(__tmp));
 319       }
 320
 321       _StateIdT
 322       _M_insert_dummy()
 323       { return _M_insert_state(_StateT(_S_opcode_dummy)); }
 324
 325       _StateIdT
 326       _M_insert_state(_StateT __s)
 327       {
 328         this->push_back(std::move(__s));
 329         if (this->size() > _GLIBCXX_REGEX_STATE_LIMIT)
 330           __throw_regex_error(
 331             regex_constants::error_space,
 332             "Number of NFA states exceeds limit. Please use shorter regex "
 333             "string, or use smaller brace expression, or make "
 334             "_GLIBCXX_REGEX_STATE_LIMIT larger.");
 335         return this->size() - 1;
 336       }
 337
 338       // Eliminate dummy node in this NFA to make it compact.
 339       void
 340       _M_eliminate_dummy();
 341
 342 #ifdef _GLIBCXX_DEBUG
 343       std::ostream&
 344       _M_dot(std::ostream& __ostr) const;
 345 #endif
 346     public:
 347       _TraitsT                  _M_traits;
 348     };
 349
 350   /// Describes a sequence of one or more %_State, its current start
 351   /// and end(s).  This structure contains fragments of an NFA during
 352   /// construction.
 353   template<typename _TraitsT>
 354     class _StateSeq
 355     {
 356     public:
 357       typedef _NFA<_TraitsT> _RegexT;
 358
 359     public:
 360       _StateSeq(_RegexT& __nfa, _StateIdT __s)
 361       : _M_nfa(__nfa), _M_start(__s), _M_end(__s)
 362       { }
 363
 364       _StateSeq(_RegexT& __nfa, _StateIdT __s, _StateIdT __end)
 365       : _M_nfa(__nfa), _M_start(__s), _M_end(__end)
 366       { }
 367
 368       // Append a state on *this and change *this to the new sequence.
 369       void
 370       _M_append(_StateIdT __id)
 371       {
 372         _M_nfa[_M_end]._M_next = __id;
 373         _M_end = __id;
 374       }
 375
 376       // Append a sequence on *this and change *this to the new sequence.
 377       void
 378       _M_append(const _StateSeq& __s)
 379       {
 380         _M_nfa[_M_end]._M_next = __s._M_start;
 381         _M_end = __s._M_end;
 382       }
 383
 384       // Clones an entire sequence.
 385       _StateSeq
 386       _M_clone();
 387
 388     public:
 389       _RegexT&  _M_nfa;
 390       _StateIdT _M_start;
 391       _StateIdT _M_end;
 392     };
 393
 394  ///@} regex-detail
 395 } // namespace __detail
 396
 397 _GLIBCXX_END_NAMESPACE_VERSION
 398 } // namespace std
 399
 400 #include <bits/regex_automaton.tcc>