Reuben Thomas wrote:
> > it's a function which transforms a string to a string.
> > I'm sure this function has been implemented many times already. The one I
> > wrote is called 'regexp-quote' [1][2].
>
> Great, can we have it in gnulib? Does it work for all syntaxes?
It needs a flag to distinguish the syntax, since BRE and ERE have different
syntaxes. Here's a suggested module:
2010-09-18 Bruno Haible <br...@clisp.org>
New module 'regex-quote'.
* lib/regex-quote.h: New file.
* lib/regex-quote.c: New file.
* modules/regex-quote: New file.
Suggested by Reuben Thomas <r...@sc3d.org>.
============================== lib/regex-quote.h ==============================
/* Construct a regular expression from a literal string.
Copyright (C) 1995, 2010 Free Software Foundation, Inc.
Written by Bruno Haible <hai...@clisp.cons.org>, 2010.
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 of the License, 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, see <http://www.gnu.org/licenses/>. */
#include <stddef.h>
/* regex_quote converts a literal string to a regular expression that will
look for this literal string.
cflags can be 0 or REG_EXTENDED.
If it is 0, the result is a Basic Regular Expression (BRE)
<http://www.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_03>.
If it is REG_EXTENDED, the result is an Extended Regular Expression (ERE)
<http://www.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_04>.
The result is not anchored; if you want it to match only complete lines,
you need to add "^" at the beginning of the result and "$" at the end of the
result.
*/
/* Returns the number of bytes needed for the quoted string. */
extern size_t regex_quote_length (const char *string, int cflags);
/* Copies the quoted string to p and returns the incremented p.
There must be room for regex_quote_length (string, cflags) + 1 bytes at p.
*/
extern char * regex_quote_copy (char *p, const char *string, int cflags);
/* Returns the freshly allocated quoted string. */
extern char * regex_quote (const char *string, int cflags);
============================== lib/regex-quote.c ==============================
/* Construct a regular expression from a literal string.
Copyright (C) 1995, 2010 Free Software Foundation, Inc.
Written by Bruno Haible <hai...@clisp.cons.org>, 2010.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <config.h>
/* Specification. */
#include "regex-quote.h"
#include <string.h>
#include "mbuiter.h"
#include "xalloc.h"
/* Characters that are special in a BRE. */
static const char bre_special[] = "$^.*[]\\";
/* Characters that are special in an ERE. */
static const char ere_special[] = "$^.*[]\\+?()";
size_t
regex_quote_length (const char *string, int cflags)
{
const char *special = (cflags != 0 ? ere_special : bre_special);
size_t length;
mbui_iterator_t iter;
length = 0;
for (mbui_init (iter, string); mbui_avail (iter); mbui_advance (iter))
{
/* We know that special contains only ASCII characters. */
if (mb_len (mbui_cur (iter)) == 1
&& strchr (special, * mbui_cur_ptr (iter)))
length += 1;
length += mb_len (mbui_cur (iter));
}
return length;
}
/* Copies the quoted string to p and returns the incremented p.
There must be room for regex_quote_length (string, cflags) + 1 bytes at p.
*/
char *
regex_quote_copy (char *p, const char *string, int cflags)
{
const char *special = (cflags != 0 ? ere_special : bre_special);
mbui_iterator_t iter;
for (mbui_init (iter, string); mbui_avail (iter); mbui_advance (iter))
{
/* We know that special contains only ASCII characters. */
if (mb_len (mbui_cur (iter)) == 1
&& strchr (special, * mbui_cur_ptr (iter)))
*p++ = '\\';
memcpy (p, mbui_cur_ptr (iter), mb_len (mbui_cur (iter)));
p += mb_len (mbui_cur (iter));
}
return p;
}
/* Returns the freshly allocated quoted string. */
char *
regex_quote (const char *string, int cflags)
{
size_t length = regex_quote_length (string, cflags);
char *result = XNMALLOC (length + 1, char);
char *p;
p = result;
p = regex_quote_copy (p, string, cflags);
*p = '\0';
return result;
}
============================= modules/regex-quote =============================
Description:
Construct a regular expression from a literal string.
Files:
lib/regex-quote.h
lib/regex-quote.c
Depends-on:
xalloc
mbuiter
configure.ac:
Makefile.am:
lib_SOURCES += regex-quote.c
Include:
"regex-quote.h"
License:
GPL
Maintainer:
Bruno Haible
