foreach my $node (@{$data->{node}}) {
    print $node->{name}.": ".$node->{text}."\n";
    if ( ... )  { # detect the existence of a subnode here somehow
        foreach my $subnode (@{$data->{node}{subnode}}) {
            print "\t".$subnode->{name}.": ".$subnode->{text}."\n";
        }
    }
}