Finding the text a rule matched

I wanted to know, after matching a rule, what text the rule matched.
So I used two variables to remember what the remaining text and
offset were before and after the rule and just determined the
difference.

   report : <rulevar: local $rule_text>
   report : <rulevar: local $rule_offset>

   report :
             {
                 $rule_text   = $text;
                 $rule_offset = $thisoffset;
             }

         ...some subrules...

             {
                 my $str = substr($rule_text, 0, $thisoffset - 
$rule_offset);

                 # remove all sorts of whitespace

                 $str =~ s/^\s*//s;
                 $str =~ s/\s*$//s;
                 $str =~ s/\s+/ /gs;

                 # Now $str contains the text matched by this rule
             }

This is the kind of thing I thought would have been possible a lot
easier. Did I miss something?

If not, is there a way to make this available in every parser,
e.g. by providing a new directive or something like that?

Marcel

--
Aspect-Oriented Perl            http://codewerk.unixbeard.net/aspects/
cpan> install Aspect