use strict;
use warnings;

use XML::Rules;
use Data::Dumper;

my $parser = XML::Rules->new(
	rules => [
		substrate => sub {return '@substrates' => $_[1]->{name}},
		product => sub {return '@products' => $_[1]->{name}},
		reaction => sub {
			my $name = delete($_[1]->{name});
			delete($_[1]->{_content});
			return $name => $_[1];
		},
		root => 'pass no content',
	],
);

my $result = $parser->parse(\*DATA);
print Dumper($result);

while (my ($reaction, $data) = each(%$result)) {
	print "$reaction ($data->{type})\n";
	print "\tSubstrates: ", join(", ", @{$data->{substrates}}), "\n";
	print "\tProducts:   ", join(", ", @{$data->{products}}), "\n\n";
}

__DATA__
<root>
    <reaction name="rn:R00710" type="reversible">
        <substrate name="cpd:C00084"/>
        <product name="cpd:C00033"/>
    </reaction>
    <reaction name="rn:R00014" type="irreversible">
        <substrate name="cpd:C00068"/>
        <substrate name="cpd:C00022"/>
        <product name="cpd:C05125"/>
    </reaction>
</root>