#!/usr/bin/perl -w

use warnings;
use strict;

use XML::SAX::ParserFactory;

my $handler = TagListHandler->new;
my $parser  = XML::SAX::ParserFactory->parser(Handler => $handler);

my $filename = shift or die "No filename\n";

my $tags = $parser->parse_uri($filename);

print "$_\n" foreach @$tags;

exit;


package TagListHandler;

use base qw(XML::SAX::Base);

sub start_element {
    my($self, $data) = @_;
    $self->{tag}->{ $data->{Name} } = 1;
}

sub end_document {
    my($self) = @_;
    my @tags = sort keys %{ $self->{tag} || {} };
    return \@tags;
}