[Emacs-bug-tracker] bug#5970: closed (regex won't do lazy matching)

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Your message dated Tue, 27 Apr 2010 16:30:26 -0600
with message-id <address@hidden>
and subject line Re: bug#5970: regex won't do lazy matching
has caused the GNU bug report #5970,
regarding regex won't do lazy matching
to be marked as done.

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5970: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=5970
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--- Begin Message --- Subject: regex won't do lazy matching Date: Sun, 18 Apr 2010 21:33:30 -0400

This may be a usage problem, but it does not exist with other regex packages (such as slre) and I can't find anything in the documentation to indicate that the syntax should be different for coreutils. I am using coreutils 8.4 on ubuntu AMD64, version 9.10. I cannot get the coreutils regex matcher to do lazy matching. Here is my code:

/**** regex_test.cpp ***/

#include <stdio.h>

#include <stdlib.h>

#include "xalloc.h"

#include "regex.h"

// compile:

// gcc -I coreutils-8.4/lib/ -c regex_test.cpp

// g++ -o regex_test regex_test.o coreutils-8.4/lib/xmalloc.o coreutils-8.4/lib/xalloc-die.o coreutils-8.4/lib/exitfail.o coreutils-8.4/lib/regex.o 

void print_regerror (int errcode, regex_t *compiled)

{

  size_t length = regerror (errcode, compiled, NULL, 0);

  char *buffer = (char *)xmalloc (length);

  if(!buffer) printf("error: regerror malloc failed!\n");

  else {

    (void) regerror (errcode, compiled, buffer, length);

    printf("error: %s\n", buffer);

    free(buffer);

  }

}

int main(int argc, char *argv[]){

  if(argc < 3) printf("usage: regex_test pattern string\n");

  else {

    regex_t rx;

    int err;

    if((err = regcomp(&rx, argv[1], REG_EXTENDED)))

      print_regerror(err, &rx);

    else {

      regmatch_t matches[4];

      if(!regexec(&rx, argv[2], 4, matches, 0)) {

int i;

printf("match! \n");

for(i = 0; i < 4; i++) {

          if(matches[i].rm_so != -1) 

            printf("  s:%i, e:%i", matches[i].rm_so, matches[i].rm_eo);

}

printf("\n");

      } else printf("match failed.\n");

      regfree(&rx);

    }

  }

}

/********/

Here is the problem. If you execute:

  regex_test "a[^x]*?a" "a1a2a"

then you get:

  match! 

    s:0, e:5

But, you should get the same result as when you execute regex_test "a[^x]*?a" "a1a"-- that is:

  match! 

    s:0, e:3

Please advise. Thank you!

--- End Message ---

> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#5970: regex won't do lazy matching
>
>
>
>
> Date: 
>
> Tue, 27 Apr 2010 16:30:26 -0600
>
>
>
>
> User-agent: 
>
> Mutt/1.5.18 (2008-05-17)
>
>
>
>
> a g wrote:
> > thanks for everyone's help. I agree this can be closed, but not for the
> > reasons mentioned (though I appreciate them and they gave me the info I
> > needed to find the answer:
> > osdir.com/ml/lib.gnulib.bugs/2005-04/msg00027.html). Off to try emacs'
> > regex.c instead.
>
> Okay.  I will close the bug.
>
> > It would be nice if coreutils could offer the emacs regex.c (or some other
> > regex that supported non-greedy matching) at least as an additional library
> > if not the standard one... but, not my call...
>
> Though you did not answer my question as to your use of the regex
> engine in coreutils I assume by this that you are trying to use it as
> some type of general purpose library.  That really isn't its intended
> purpose.  In coreutils it is there to support the regular expression
> matching done in 'expr'.  For a general purpose library items it would
> be better if you were to use gnulib or pcre or one of the other
> libraries that is intended to be used as a library.
>
> Bob
>
>
> --- End Message ---