libstdc++: regex_scanner.h Source File

libstdc++

regex_scanner.h
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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_scanner.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
31namespace std _GLIBCXX_VISIBILITY(default)
32{
33_GLIBCXX_BEGIN_NAMESPACE_VERSION
34
35namespace __detail
36{
37 /**
38 * @addtogroup regex-detail
39 * @{
40 */
41
42 struct _ScannerBase
43 {
44 public:
45 /// Token types returned from the scanner.
46 enum _TokenT : unsigned
47 {
48 _S_token_anychar,
49 _S_token_ord_char,
50 _S_token_oct_num,
51 _S_token_hex_num,
52 _S_token_backref,
53 _S_token_subexpr_begin,
54 _S_token_subexpr_no_group_begin,
55 _S_token_subexpr_lookahead_begin, // neg if _M_value[0] == 'n'
56 _S_token_subexpr_end,
57 _S_token_bracket_begin,
58 _S_token_bracket_neg_begin,
59 _S_token_bracket_end,
60 _S_token_interval_begin,
61 _S_token_interval_end,
62 _S_token_quoted_class,
63 _S_token_char_class_name,
64 _S_token_collsymbol,
65 _S_token_equiv_class_name,
66 _S_token_opt,
67 _S_token_or,
68 _S_token_closure0,
69 _S_token_closure1,
70 _S_token_line_begin,
71 _S_token_line_end,
72 _S_token_word_bound, // neg if _M_value[0] == 'n'
73 _S_token_comma,
74 _S_token_dup_count,
75 _S_token_eof,
76 _S_token_bracket_dash,
77 _S_token_unknown = -1u
78 };
79
80 protected:
81 typedef regex_constants::syntax_option_type _FlagT;
82
83 enum _StateT
84 {
85 _S_state_normal,
86 _S_state_in_brace,
87 _S_state_in_bracket,
88 };
89
90 protected:
91 _ScannerBase(_FlagT __flags)
92 : _M_state(_S_state_normal),
93 _M_flags(__flags),
94 _M_escape_tbl(_M_is_ecma()
95 ? _M_ecma_escape_tbl
96 : _M_awk_escape_tbl),
97 _M_spec_char(_M_is_ecma()
98 ? _M_ecma_spec_char
99 : _M_flags & regex_constants::basic
100 ? _M_basic_spec_char
101 : _M_flags & regex_constants::extended
102 ? _M_extended_spec_char
103 : _M_flags & regex_constants::grep
104 ? ".[\\*^$\n"
105 : _M_flags & regex_constants::egrep
106 ? ".[\\()*+?{|^$\n"
107 : _M_flags & regex_constants::awk
108 ? _M_extended_spec_char
109 : nullptr),
110 _M_at_bracket_start(false)
111 { __glibcxx_assert(_M_spec_char); }
112
113 protected:
114 const char*
115 _M_find_escape(char __c)
116 {
117 auto __it = _M_escape_tbl;
118 for (; __it->first != '\0'; ++__it)
119 if (__it->first == __c)
120 return &__it->second;
121 return nullptr;
122 }
123
124 bool
125 _M_is_ecma() const
126 { return _M_flags & regex_constants::ECMAScript; }
127
128 bool
129 _M_is_basic() const
130 { return _M_flags & (regex_constants::basic | regex_constants::grep); }
131
132 bool
133 _M_is_extended() const
134 {
135 return _M_flags & (regex_constants::extended
136 | regex_constants::egrep
137 | regex_constants::awk);
138 }
139
140 bool
141 _M_is_grep() const
142 { return _M_flags & (regex_constants::grep | regex_constants::egrep); }
143
144 bool
145 _M_is_awk() const
146 { return _M_flags & regex_constants::awk; }
147
148 protected:
149 // TODO: Make them static in the next abi change.
150 const std::pair<char, _TokenT> _M_token_tbl[9] =
151 {
152 {'^', _S_token_line_begin},
153 {'$', _S_token_line_end},
154 {'.', _S_token_anychar},
155 {'*', _S_token_closure0},
156 {'+', _S_token_closure1},
157 {'?', _S_token_opt},
158 {'|', _S_token_or},
159 {'\n', _S_token_or}, // grep and egrep
160 {'\0', _S_token_or},
161 };
162 const std::pair<char, char> _M_ecma_escape_tbl[8] =
163 {
164 {'0', '\0'},
165 {'b', '\b'},
166 {'f', '\f'},
167 {'n', '\n'},
168 {'r', '\r'},
169 {'t', '\t'},
170 {'v', '\v'},
171 {'\0', '\0'},
172 };
173 const std::pair<char, char> _M_awk_escape_tbl[11] =
174 {
175 {'"', '"'},
176 {'/', '/'},
177 {'\\', '\\'},
178 {'a', '\a'},
179 {'b', '\b'},
180 {'f', '\f'},
181 {'n', '\n'},
182 {'r', '\r'},
183 {'t', '\t'},
184 {'v', '\v'},
185 {'\0', '\0'},
186 };
187 const char* _M_ecma_spec_char = "^$\\.*+?()[]{}|";
188 const char* _M_basic_spec_char = ".[\\*^$";
189 const char* _M_extended_spec_char = ".[\\()*+?{|^$";
190
191 _StateT _M_state;
192 _FlagT _M_flags;
193 _TokenT _M_token;
194 const std::pair<char, char>* _M_escape_tbl;
195 const char* _M_spec_char;
196 bool _M_at_bracket_start;
197 };
198
199 /**
200 * @brief Scans an input range for regex tokens.
201 *
202 * The %_Scanner class interprets the regular expression pattern in
203 * the input range passed to its constructor as a sequence of parse
204 * tokens passed to the regular expression compiler. The sequence
205 * of tokens provided depends on the flag settings passed to the
206 * constructor: different regular expression grammars will interpret
207 * the same input pattern in syntactically different ways.
208 */
209 template<typename _CharT>
210 class _Scanner
211 : public _ScannerBase
212 {
213 public:
214 typedef std::basic_string<_CharT> _StringT;
215 typedef regex_constants::syntax_option_type _FlagT;
216 typedef const std::ctype<_CharT> _CtypeT;
217
218 _Scanner(const _CharT* __begin, const _CharT* __end,
219 _FlagT __flags, std::locale __loc);
220
221 void
222 _M_advance();
223
224 _TokenT
225 _M_get_token() const noexcept
226 { return _M_token; }
227
228 const _StringT&
229 _M_get_value() const noexcept
230 { return _M_value; }
231
232#ifdef _GLIBCXX_DEBUG
233 std::ostream&
234 _M_print(std::ostream&);
235#endif
236
237 private:
238 void
239 _M_scan_normal();
240
241 void
242 _M_scan_in_bracket();
243
244 void
245 _M_scan_in_brace();
246
247 void
248 _M_eat_escape_ecma();
249
250 void
251 _M_eat_escape_posix();
252
253 void
254 _M_eat_escape_awk();
255
256 void
257 _M_eat_class(char);
258
259 const _CharT* _M_current;
260 const _CharT* _M_end;
261 _CtypeT& _M_ctype;
262 _StringT _M_value;
263 void (_Scanner::* _M_eat_escape)();
264 };
265
266 ///@} regex-detail
267} // namespace __detail
268_GLIBCXX_END_NAMESPACE_VERSION
269} // namespace std
270
271#include <bits/regex_scanner.tcc>
regex_scanner.tcc
std::ostream
basic_ostream< char > ostream
Base class for char output streams.
Definition iosfwd:145
std
ISO C++ entities toplevel namespace is std.
std::__detail
Implementation details not part of the namespace std interface.
std::regex_constants::ECMAScript
constexpr syntax_option_type ECMAScript
Definition regex_constants.h:120
std::regex_constants::egrep
constexpr syntax_option_type egrep
Definition regex_constants.h:163
std::regex_constants::syntax_option_type
syntax_option_type
This is a bitmask type indicating how to interpret the regex.
Definition regex_constants.h:70
std::regex_constants::awk
constexpr syntax_option_type awk
Definition regex_constants.h:147
std::regex_constants::extended
constexpr syntax_option_type extended
Definition regex_constants.h:137
std::regex_constants::basic
constexpr syntax_option_type basic
Definition regex_constants.h:129
std::regex_constants::grep
constexpr syntax_option_type grep
Definition regex_constants.h:155
std::basic_string
Managing sequences of characters and character-like objects.
Definition basic_string.h:94
std::locale
Container class for localization functionality.
Definition locale_classes.h:70
std::ctype
Primary class template ctype facet.
Definition locale_facets.h:618