Why don't you create tag handlers for "thread" and "node" that build up your hierachy?

Here something to get you started

#!/usr/bin/perl
use strict;
use warnings;
use XML::Twig;
use Data::Dumper;

my %result;

my $thread= new XML::Twig(
    twig_handlers => {
        thread => \&thread,
        node => \&node,
    }
);

$thread->safe_parse(join('',<DATA>));
print Dumper( \%result );

sub thread {
    $result{$_->{'att'}->{'id'}}= childrenhash($_->children( 'node' ))
+;
}

sub node {
    $_->set_att( structure => { $_->{'att'}->{'id'}, childrenhash($_->
+children( 'node' ))} );
}

sub childrenhash {
    my %result;
    foreach my $child (@_) {
        my $ch= $child->{'att'}->{'structure'};
        @result{keys %$ch}= values %$ch;
    }
    return \%result;
}

__DATA__
<?xml version="1.0" encoding="ISO-8859-1"?>
<thread id="504929">
<node id="504941">
</node>
<node id="504942">
<node id="504950">
<node id="504964">
</node>
</node>
<node id="504953">
</node>
</node>
<node id="504944">
</node>
</thread>
[download]

You could patch the ticker to return the data in its flat record, parent pointer form instead of as a recursive data structure. Building the tree from the flat structure is a lot easier than reading the nested XML.

And now ive patched the ticker to do just this. And return some additional information. Try using 'flattree=1' to get the new output. Also, the ticker now responds to xmlstyle settings and has the customary info tag with data about the ticker and stuff like that.

You can build a fully connected tree structure from the "flattree" output quite easily. The algorithm is as follows:

my $res = $o->pm_get( node_id => 180684, id => 505536, flattree => 1 )
+;

my $data = XMLin( $res->content, ForceArray => 0 );

my %nodes;

foreach my $node ( @{ $data->{node} } ) {

    my $nid = $node->{node_id};

    # register this node so children can find it
    $nodes{ $nid } = $node;

    if ( my $pid = $node->{parent_node} ) {

        # tell the parent about this child
        $nodes{$pid}{kids}{$nid} = $node;

        # make the reference to the parent "hard" and not "soft"
        $node->{parent} = $nodes{$pid};

    }

}
[download]

You are guaranteed that this will work. You dont need to worry about the parent not existing, or anything like that.