Correct usage of Text::Balanced perl module

Question

I'm trying to use the Text::Balanced perl module for the purpose of extracting the text enclosed in the curly brackets. In this particular case the input is a bind configuration file /etc/named.conf, but I'm looking for general use. The problem is, that the I'm getting undef result and as a consequence an uninitialized value error.

Here is my code ( it's just a stump now, not dealing with recursion and other stuff yet):

#!/usr/bin/env perl
use strict;
use diagnostics;

use Text::Balanced qw (
                       extract_bracketed
                      ) ;


my $config = '/etc/named.conf';

open my $fh, '<', $config or die "Cannot open $config: $!";
$/ = undef;
my $text = <$fh>;
close $fh;

my $content = extract_bracketed( $text, '{}' );
print $content ;

I have read http://perldoc.perl.org/Text/Balanced.html and cannot figure out, what am I doing wrong ( I use scalar variable instead of array, but this shouldn't be a problem )

Also there is a similar issue here Text::Balanced and multiline xml, but it gets answered in the way that does not fit my use case ( specific solution for .xml parsing)

Please advise

Thanks

Answer 1

In regex you can use this:

my $str = '
<statement-1> ["<statement-1-name>"] [<statement-1-class>] {
    { {<option-1>;}
   <option-2>;}
   <option-N>;
};

<statement-2> ["<statement-2-name>"] [<statement-2-class>] {
   <option-1>;
   <option-2>;
   <option-N>;
};

<statement-N> ["<statement-N-name>"] [<statement-N-class>] {
   <option-1>;
   <option-2>;
   <option-N>;
};';

print "L: $1\n" while($str=~m/\{((?:[^{}]++|\{(?1)\})++)\}/gs);