libstdc++: regex_automaton.tcc Source File

libstdc++

regex_automaton.tcc
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1// class template regex -*- C++ -*-
2
3// Copyright (C) 2013-2026 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.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#ifdef _GLIBCXX_DEBUG
32# include <ostream>
33#endif
34
35namespace std _GLIBCXX_VISIBILITY(default)
36{
37_GLIBCXX_BEGIN_NAMESPACE_VERSION
38
39namespace __detail
40{
41#ifdef _GLIBCXX_DEBUG
42 inline std::ostream&
43 _State_base::_M_print(std::ostream& __ostr) const
44 {
45 switch (_M_opcode)
46 {
47 case _S_opcode_alternative:
48 case _S_opcode_repeat:
49 __ostr << "alt next=" << _M_next << " alt=" << _M_alt;
50 break;
51 case _S_opcode_subexpr_begin:
52 __ostr << "subexpr begin next=" << _M_next << " index=" << _M_subexpr;
53 break;
54 case _S_opcode_subexpr_end:
55 __ostr << "subexpr end next=" << _M_next << " index=" << _M_subexpr;
56 break;
57 case _S_opcode_backref:
58 __ostr << "backref next=" << _M_next << " index=" << _M_backref_index;
59 break;
60 case _S_opcode_match:
61 __ostr << "match next=" << _M_next;
62 break;
63 case _S_opcode_accept:
64 __ostr << "accept next=" << _M_next;
65 break;
66 default:
67 __ostr << "unknown next=" << _M_next;
68 break;
69 }
70 return __ostr;
71 }
72
73 // Prints graphviz dot commands for state.
74 inline std::ostream&
75 _State_base::_M_dot(std::ostream& __ostr, _StateIdT __id) const
76 {
77 switch (_M_opcode)
78 {
79 case _S_opcode_alternative:
80 case _S_opcode_repeat:
81 __ostr << __id << " [label=\"" << __id << "\\nALT\"];\n"
82 << __id << " -> " << _M_next
83 << " [label=\"next\", tailport=\"s\"];\n"
84 << __id << " -> " << _M_alt
85 << " [label=\"alt\", tailport=\"n\"];\n";
86 break;
87 case _S_opcode_backref:
88 __ostr << __id << " [label=\"" << __id << "\\nBACKREF "
89 << _M_subexpr << "\"];\n"
90 << __id << " -> " << _M_next << " [label=\"<match>\"];\n";
91 break;
92 case _S_opcode_line_begin_assertion:
93 __ostr << __id << " [label=\"" << __id << "\\nLINE_BEGIN \"];\n"
94 << __id << " -> " << _M_next << " [label=\"epsilon\"];\n";
95 break;
96 case _S_opcode_line_end_assertion:
97 __ostr << __id << " [label=\"" << __id << "\\nLINE_END \"];\n"
98 << __id << " -> " << _M_next << " [label=\"epsilon\"];\n";
99 break;
100 case _S_opcode_word_boundary:
101 __ostr << __id << " [label=\"" << __id << "\\nWORD_BOUNDRY "
102 << _M_neg << "\"];\n"
103 << __id << " -> " << _M_next << " [label=\"epsilon\"];\n";
104 break;
105 case _S_opcode_subexpr_lookahead:
106 __ostr << __id << " [label=\"" << __id << "\\nLOOK_AHEAD\"];\n"
107 << __id << " -> " << _M_next
108 << " [label=\"epsilon\", tailport=\"s\"];\n"
109 << __id << " -> " << _M_alt
110 << " [label=\"<assert>\", tailport=\"n\"];\n";
111 break;
112 case _S_opcode_subexpr_begin:
113 __ostr << __id << " [label=\"" << __id << "\\nSBEGIN "
114 << _M_subexpr << "\"];\n"
115 << __id << " -> " << _M_next << " [label=\"epsilon\"];\n";
116 break;
117 case _S_opcode_subexpr_end:
118 __ostr << __id << " [label=\"" << __id << "\\nSEND "
119 << _M_subexpr << "\"];\n"
120 << __id << " -> " << _M_next << " [label=\"epsilon\"];\n";
121 break;
122 case _S_opcode_dummy:
123 break;
124 case _S_opcode_match:
125 __ostr << __id << " [label=\"" << __id << "\\nMATCH\"];\n"
126 << __id << " -> " << _M_next << " [label=\"<match>\"];\n";
127 break;
128 case _S_opcode_accept:
129 __ostr << __id << " [label=\"" << __id << "\\nACC\"];\n" ;
130 break;
131 default:
132 _GLIBCXX_DEBUG_ASSERT(false);
133 break;
134 }
135 return __ostr;
136 }
137
138 template<typename _TraitsT>
139 std::ostream&
140 _NFA<_TraitsT>::_M_dot(std::ostream& __ostr) const
141 {
142 __ostr << "digraph _Nfa {\n"
143 " rankdir=LR;\n";
144 for (size_t __i = 0; __i < this->size(); ++__i)
145 (*this)[__i]._M_dot(__ostr, __i);
146 __ostr << "}\n";
147 return __ostr;
148 }
149#endif
150
151 template<typename _TraitsT>
152 _StateIdT
153 _NFA<_TraitsT>::_M_insert_backref(size_t __index)
154 {
155 if (this->_M_flags & regex_constants::__polynomial)
156 __throw_regex_error(regex_constants::error_complexity,
157 "Unexpected back-reference in polynomial mode.");
158 // To figure out whether a backref is valid, a stack is used to store
159 // unfinished sub-expressions. For example, when parsing
160 // "(a(b)(c\\1(d)))" at '\\1', _M_subexpr_count is 3, indicating that 3
161 // sub expressions are parsed or partially parsed(in the stack), aka,
162 // "(a..", "(b)" and "(c..").
163 // _M_paren_stack is {1, 3}, for incomplete "(a.." and "(c..". At this
164 // time, "\\2" is valid, but "\\1" and "\\3" are not.
165 if (__index >= _M_subexpr_count)
166 __throw_regex_error(
167 regex_constants::error_backref,
168 "Back-reference index exceeds current sub-expression count.");
169 for (auto __it : this->_M_paren_stack)
170 if (__index == __it)
171 __throw_regex_error(
172 regex_constants::error_backref,
173 "Back-reference referred to an opened sub-expression.");
174 this->_M_has_backref = true;
175 _StateT __tmp(_S_opcode_backref);
176 __tmp._M_backref_index = __index;
177 return _M_insert_state(std::move(__tmp));
178 }
179
180 template<typename _TraitsT>
181 void
182 _NFA<_TraitsT>::_M_eliminate_dummy()
183 {
184 for (auto& __it : *this)
185 {
186 while (__it._M_next >= 0 && (*this)[__it._M_next]._M_opcode()
187 == _S_opcode_dummy)
188 __it._M_next = (*this)[__it._M_next]._M_next;
189 if (__it._M_has_alt())
190 while (__it._M_alt >= 0 && (*this)[__it._M_alt]._M_opcode()
191 == _S_opcode_dummy)
192 __it._M_alt = (*this)[__it._M_alt]._M_next;
193 }
194 }
195
196 // Just apply DFS on the sequence and re-link their links.
197 template<typename _TraitsT>
198 _StateSeq<_TraitsT>
199 _StateSeq<_TraitsT>::_M_clone()
200 {
201 _GLIBCXX_STD_C::map<_StateIdT, _StateIdT> __m;
202 std::stack<_StateIdT, _GLIBCXX_STD_C::deque<_StateIdT>> __stack;
203 __stack.push(_M_start);
204 while (!__stack.empty())
205 {
206 auto __u = __stack.top();
207 __stack.pop();
208 auto __dup = _M_nfa[__u];
209 // _M_insert_state() never return -1
210 auto __id = _M_nfa._M_insert_state(std::move(__dup));
211 __m[__u] = __id;
212 if (__dup._M_has_alt())
213 if (__dup._M_alt != _S_invalid_state_id
214 && __m.count(__dup._M_alt) == 0)
215 __stack.push(__dup._M_alt);
216 if (__u == _M_end)
217 continue;
218 if (__dup._M_next != _S_invalid_state_id
219 && __m.count(__dup._M_next) == 0)
220 __stack.push(__dup._M_next);
221 }
222 for (auto __it : __m)
223 {
224 auto __v = __it.second;
225 auto& __ref = _M_nfa[__v];
226 if (__ref._M_next != _S_invalid_state_id)
227 __ref._M_next = __m.find(__ref._M_next)->second;
228 if (__ref._M_has_alt() && __ref._M_alt != _S_invalid_state_id)
229 __ref._M_alt = __m.find(__ref._M_alt)->second;
230 }
231 return _StateSeq(_M_nfa, __m[_M_start], __m[_M_end]);
232 }
233} // namespace __detail
234
235_GLIBCXX_END_NAMESPACE_VERSION
236} // namespace
ostream
std::ostream
basic_ostream< char > ostream
Base class for char output streams.
Definition iosfwd:145
std::move
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition move.h:138
std
ISO C++ entities toplevel namespace is std.
std::size
constexpr auto size(const _Container &__cont) noexcept(noexcept(__cont.size())) -> decltype(__cont.size())
Return the size of a container.
Definition range_access.h:274
std::__detail
Implementation details not part of the namespace std interface.
std::regex_constants::__polynomial
constexpr syntax_option_type __polynomial
Definition regex_constants.h:187
std::regex_constants::error_backref
constexpr error_type error_backref(_S_error_backref)
std::regex_constants::error_complexity
constexpr error_type error_complexity(_S_error_complexity)
std::__detail::_StateSeq
Describes a sequence of one or more _State, its current start and end(s). This structure contains fra...
Definition regex_automaton.h:358
std::stack::pop
void pop()
Removes first element.
Definition stl_stack.h:331
std::stack::push
void push(const value_type &__x)
Add data to the top of the stack.
Definition stl_stack.h:286
std::stack::empty
bool empty() const
Definition stl_stack.h:243
std::stack::top
reference top()
Definition stl_stack.h:258