1 // class template regex -*- C++ -*-
2
3 // Copyright (C) 2013-2023 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>