Hi!

I am writing a script to parse IDL file and to generate graphviz file from it. I encountered following problem, which I isolated below:

Regexp tries to find 'module <module_name> { content };' text globally (//g) and if found, content is parsed recursively to create nested 'subgraph {}' sequences. Code below hangs. And if I remove innemost parens - it works good. Can anyone enlighten me what can be wrong? I am using this regexp (nested parens) for more than year in several scripts and it works (uhm, worked) perfectly since now.

With 'use warnings;' it prints 'Use of uninitialized value in pattern match (m//)', but it doesn't help me in any way to understand the problem.

Thank for any help.

#!perl

$_=join"",<DATA>;

sub parse
{
    my ($text) = @_;
    $nw++;
    
    my $parens = qr{(?:[^{}]+?|\{(??{$parens})\})*}x;
    
    while($text =~ /module (\w+) \{ ($parens) \};?/gx)
    {
        ($name, $content)=($1, $2);
#         print "[$&]";
        print '  'x$nw, "subgraph $name\n";
        print '  'x$nw, "{\n";
        parse($content);
        print '  'x$nw, "}\n";
    }
    $nw--;
}

print "digraph G\n{\n";

parse($_);

print "}\n";

__DATA__
module abc
{
    module def
    {
        module ghi
        {
        };
    };
};

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In reply to balanced parens regexp hangs - solved by grizzley

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