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+/* dfa.h - declarations for GNU deterministic regexp compiler
+   Copyright (C) 1988, 1998, 2007, 2009-2016 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc.,
+   51 Franklin Street - Fifth Floor, Boston, MA  02110-1301, USA */
+
+/* Written June, 1988 by Mike Haertel */
+
+#include <regex.h>
+#ifdef HAVE_STDBOOL_H
+#include <stdbool.h>
+#else
+#include "missing_d/gawkbool.h"
+#endif /* HAVE_STDBOOL_H */
+#include <stddef.h>
+
+#if 3 <= __GNUC__
+# define _GL_ATTRIBUTE_MALLOC __attribute__ ((__malloc__))
+#else
+# define _GL_ATTRIBUTE_MALLOC
+#endif
+
+struct localeinfo; /* See localeinfo.h.  */
+
+/* Element of a list of strings, at least one of which is known to
+   appear in any R.E. matching the DFA. */
+struct dfamust
+{
+  bool exact;
+  bool begline;
+  bool endline;
+  char *must;
+};
+
+/* The dfa structure. It is completely opaque. */
+struct dfa;
+
+/* Entry points. */
+
+/* Allocate a struct dfa.  The struct dfa is completely opaque.
+   The returned pointer should be passed directly to free() after
+   calling dfafree() on it. */
+extern struct dfa *dfaalloc (void) _GL_ATTRIBUTE_MALLOC;
+
+/* DFA options that can be ORed together, for dfasyntax's 4th arg.  */
+enum
+  {
+    /* ^ and $ match only the start and end of data, and do not match
+       end-of-line within data.  This is always false for grep, but
+       possibly true for other apps.  */
+    DFA_ANCHOR = 1 << 0,
+
+    /* '\0' in data is end-of-line, instead of the traditional '\n'.  */
+    DFA_EOL_NUL = 1 << 1
+  };
+
+/* Initialize or reinitialize a DFA.  This must be called before
+   any of the routines below.  The arguments are:
+   1. The DFA to operate on.
+   2. Information about the current locale.
+   3. Syntax bits described in regex.h.
+   4. Additional DFA options described above.  */
+extern void dfasyntax (struct dfa *, struct localeinfo const *,
+                       reg_syntax_t, int);
+
+/* Build and return the struct dfamust from the given struct dfa. */
+extern struct dfamust *dfamust (struct dfa const *);
+
+/* Free the storage held by the components of a struct dfamust. */
+extern void dfamustfree (struct dfamust *);
+
+/* Compile the given string of the given length into the given struct dfa.
+   Final argument is a flag specifying whether to build a searching or an
+   exact matcher. */
+extern void dfacomp (char const *, size_t, struct dfa *, bool);
+
+/* Search through a buffer looking for a match to the given struct dfa.
+   Find the first occurrence of a string matching the regexp in the
+   buffer, and the shortest possible version thereof.  Return a pointer to
+   the first character after the match, or NULL if none is found.  BEGIN
+   points to the beginning of the buffer, and END points to the first byte
+   after its end.  Note however that we store a sentinel byte (usually
+   newline) in *END, so the actual buffer must be one byte longer.
+   When ALLOW_NL is true, newlines may appear in the matching string.
+   If COUNT is non-NULL, increment *COUNT once for each newline processed.
+   Finally, if BACKREF is non-NULL set *BACKREF to indicate whether we
+   encountered a back-reference.  The caller can use this to decide
+   whether to fall back on a backtracking matcher.  */
+extern char *dfaexec (struct dfa *d, char const *begin, char *end,
+                      bool allow_nl, size_t *count, bool *backref);
+
+/* Return a superset for D.  The superset matches everything that D
+   matches, along with some other strings (though the latter should be
+   rare, for efficiency reasons).  Return a null pointer if no useful
+   superset is available.  */
+extern struct dfa *dfasuperset (struct dfa const *d) _GL_ATTRIBUTE_PURE;
+
+/* The DFA is likely to be fast.  */
+extern bool dfaisfast (struct dfa const *) _GL_ATTRIBUTE_PURE;
+
+/* Copy the syntax settings from one dfa instance to another.
+   Saves considerable computation time if compiling many regular expressions
+   based on the same setting.  */
+extern void dfacopysyntax (struct dfa *to, const struct dfa *from);
+
+/* Free the storage held by the components of a struct dfa. */
+extern void dfafree (struct dfa *);
+
+/* Error handling. */
+
+/* dfawarn() is called by the regexp routines whenever a regex is compiled
+   that likely doesn't do what the user wanted.  It takes a single
+   argument, a NUL-terminated string describing the situation.  The user
+   must supply a dfawarn.  */
+extern void dfawarn (const char *);
+
+/* dfaerror() is called by the regexp routines whenever an error occurs.  It
+   takes a single argument, a NUL-terminated string describing the error.
+   The user must supply a dfaerror.  */
+extern _Noreturn void dfaerror (const char *);