1 /* dfa.h - declarations for GNU deterministic regexp compiler
2 Copyright (C) 1988, 1998, 2007, 2009-2023 Free Software Foundation, Inc.
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation, either version 3, or (at your option)
7 any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc.,
17 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA */
18
19 /* Written June, 1988 by Mike Haertel */
20
21 #ifndef DFA_H_
22 #define DFA_H_
23
24 /* This file uses _Noreturn, _GL_ATTRIBUTE_DEALLOC, _GL_ATTRIBUTE_MALLOC,
25 _GL_ATTRIBUTE_PURE, _GL_ATTRIBUTE_RETURNS_NONNULL. */
26 #if !_GL_CONFIG_H_INCLUDED
27 #error "Please include config.h first."
28 #endif
29
30 #include "idx.h"
31 #include <regex.h>
32 #include <stddef.h>
33 #include <stdlib.h>
34
35 #ifdef __cplusplus
36 extern "C" {
37 #endif
38
39 struct localeinfo; /* See localeinfo.h. */
40
41 /* Element of a list of strings, at least one of which is known to
42 appear in any R.E. matching the DFA. */
43 struct dfamust
44 {
45 bool exact;
46 bool begline;
47 bool endline;
48 char must[FLEXIBLE_ARRAY_MEMBER];
49 };
50
51 /* The dfa structure. It is completely opaque. */
52 struct dfa;
53
54 /* Needed when Gnulib is not used. */
55 #ifndef _GL_ATTRIBUTE_MALLOC
56 # define _GL_ATTRIBUTE_MALLOC
57 # define _GL_ATTRIBUTE_DEALLOC(f, i)
58 # define _GL_ATTRIBUTE_DEALLOC_FREE
59 # define _GL_ATTRIBUTE_RETURNS_NONNULL
60 #endif
61
62 /* Entry points. */
63
64 /* Allocate a struct dfa. The struct dfa is completely opaque.
65 It should be initialized via dfasyntax or dfacopysyntax before other use.
66 The returned pointer should be passed directly to free() after
67 calling dfafree() on it. */
68 extern struct dfa *dfaalloc (void)
69 _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_DEALLOC_FREE
70 _GL_ATTRIBUTE_RETURNS_NONNULL;
71
72 /* DFA options that can be ORed together, for dfasyntax's 4th arg. */
73 enum
74 {
75 /* ^ and $ match only the start and end of data, and do not match
76 end-of-line within data. This is always false for grep, but
77 possibly true for other apps. */
78 DFA_ANCHOR = 1 << 0,
79
80 /* '\0' in data is end-of-line, instead of the traditional '\n'. */
81 DFA_EOL_NUL = 1 << 1,
82
83 /* Treat [:alpha:] etc. as an error at the top level, instead of
84 merely a warning. */
85 DFA_CONFUSING_BRACKETS_ERROR = 1 << 2,
86
87 /* Warn about stray backslashes before ordinary characters other
88 than ] and } which are special because even though POSIX
89 says \] and \} have undefined interpretation, platforms
90 reliably ignore those stray backlashes and warning about them
91 would likely cause more trouble than it's worth. */
92 DFA_STRAY_BACKSLASH_WARN = 1 << 3,
93
94 /* Warn about * appearing out of context at the start of an
95 expression or subexpression. */
96 DFA_STAR_WARN = 1 << 4,
97
98 /* Warn about +, ?, {...} appearing out of context at the start of
99 an expression or subexpression. */
100 DFA_PLUS_WARN = 1 << 5,
101 };
102
103 /* Initialize or reinitialize a DFA. The arguments are:
104 1. The DFA to operate on.
105 2. Information about the current locale.
106 3. Syntax bits described in regex.h.
107 4. Additional DFA options described above. */
108 extern void dfasyntax (struct dfa *, struct localeinfo const *,
109 reg_syntax_t, int);
110
111 /* Initialize or reinitialize a DFA from an already-initialized DFA. */
112 extern void dfacopysyntax (struct dfa *, struct dfa const *);
113
114 /* Parse the given string of given length into the given struct dfa. */
115 extern void dfaparse (char const *, idx_t, struct dfa *);
116
117 struct dfamust;
118
119 /* Free the storage held by the components of a struct dfamust. */
120 extern void dfamustfree (struct dfamust *);
121
122 /* Allocate and return a struct dfamust from a struct dfa that was
123 initialized by dfaparse and not yet given to dfacomp. */
124 extern struct dfamust *dfamust (struct dfa const *)
125 _GL_ATTRIBUTE_DEALLOC (dfamustfree, 1);
126
127 /* Compile the given string of the given length into the given struct dfa.
128 The last argument says whether to build a searching or an exact matcher.
129 A null first argument means the struct dfa has already been
130 initialized by dfaparse; the second argument is ignored. */
131 extern void dfacomp (char const *, idx_t, struct dfa *, bool);
132
133 /* Search through a buffer looking for a match to the given struct dfa.
134 Find the first occurrence of a string matching the regexp in the
135 buffer, and the shortest possible version thereof. Return a pointer to
136 the first character after the match, or NULL if none is found. BEGIN
137 points to the beginning of the buffer, and END points to the first byte
138 after its end. Note however that we store a sentinel byte (usually
139 newline) in *END, so the actual buffer must be one byte longer.
140 When ALLOW_NL is true, newlines may appear in the matching string.
141 If COUNT is non-NULL, increment *COUNT once for each newline processed.
142 Finally, if BACKREF is non-NULL set *BACKREF to indicate whether we
143 encountered a back-reference. The caller can use this to decide
144 whether to fall back on a backtracking matcher. */
145 extern char *dfaexec (struct dfa *d, char const *begin, char *end,
146 bool allow_nl, idx_t *count, bool *backref);
147
148 /* Return a superset for D. The superset matches everything that D
149 matches, along with some other strings (though the latter should be
150 rare, for efficiency reasons). Return a null pointer if no useful
151 superset is available. */
152 extern struct dfa *dfasuperset (struct dfa const *d) _GL_ATTRIBUTE_PURE;
153
154 /* The DFA is likely to be fast. */
155 extern bool dfaisfast (struct dfa const *) _GL_ATTRIBUTE_PURE;
156
157 /* Return true if every construct in D is supported by this DFA matcher. */
158 extern bool dfasupported (struct dfa const *) _GL_ATTRIBUTE_PURE;
159
160 /* Free the storage held by the components of a struct dfa. */
161 extern void dfafree (struct dfa *);
162
163 /* Error handling. */
164
165 /* dfawarn() is called by the regexp routines whenever a regex is compiled
166 that likely doesn't do what the user wanted. It takes a single
167 argument, a NUL-terminated string describing the situation. The user
168 must supply a dfawarn. */
169 extern void dfawarn (const char *);
170
171 /* dfaerror() is called by the regexp routines whenever an error occurs. It
172 takes a single argument, a NUL-terminated string describing the error.
173 The user must supply a dfaerror. */
174 extern _Noreturn void dfaerror (const char *);
175
176 #ifdef __cplusplus
177 }
178 #endif
179
180 #endif /* dfa.h */