#!/usr/bin/perl

use strict;
use warnings;
 
use XML::Parser;
use XML::LibXML;

my $doc_file= shift @ARGV;

my $xml=qq{<!DOCTYPE doc [<!ENTITY real_doc SYSTEM "$doc_file">]><doc>&real_doc;</doc>};

{ print "XML::Parser:\n";
  my $t= XML::Parser->new( Style => 'Stream')->parse( $xml);
}

{ print "XML::LibXML:\n";
  my $parser = XML::LibXML->new();
  my $doc = $parser->parse_string($xml);
  print $doc->toString;
}