use XML::Rules;

@ARGV == 5 or die "Usage: BookStore3.pl roottag datatag idtag fitertag filtervalue\n";

my ( $roottag, $datatag, $idtag, $fitertag, $filtervalue) = @ARGV;


my $parser = XML::Rules->new(
	rules => [
		_default => 'content',
		$datatag => sub {
			return unless $_[1]->{$fitertag} eq $_[4]->{parameters};
			my $id = delete $_[1]->{$idtag};
			delete $_[1]->{'_content'};
			return $id => $_[1]
		},
		$roottag => 'pass no content',
	]
);


my $data = $parser->parse(\*DATA, $filtervalue);

use Data::Dumper;
print Dumper( $data);

__DATA__
<?xml version="1.0" encoding="ISO-8859-1"?>
<bookstore>

##</code><code>##

BookStore3.pl bookstore book title category CHILDREN