#!/usr/bin/perl --
use strict;
use warnings;

use XML::SAX;
use Module::Load qw/ load /;

my @files = ( ... );

my $parsers = XML::SAX->parsers();
for my $parser ( @$parsers ){
        load( $parser->{Name} );
    print "\n$parser->{Name}\n";
    for my $file ( @files ){
        $parser->{Name}->new(
            Handler => MySAXHandler->new, 
        )->parse_file( $file );
    }
}

package MySAXHandler;
use base qw( XML::SAX::Base );
use Data::Dump qw/ pp /;
sub start_document  { _pper('doc', @_ ) }
sub start_dtd       { _pper('dtd', @_ ) }
sub xml_decl        { _pper('decl', @_ ) }
sub _pper {
    my ($name, $self, $doc) = @_;
    print " $name ", pp( %$doc ), "\n";
}
__END__

XML::SAX::Expat
 doc ("Version", "1.0", "Encoding", "UTF-8", "Standalone", "")
 doc ("Version", "1.0", "Encoding", "ISO-8859-1", "Standalone", "")
 doc ()

XML::LibXML::SAX::Parser
 doc ()
 decl ("Version", "1.0", "Encoding", "UTF-8")
 doc ()
 decl ("Version", "1.0", "Encoding", "ISO-8859-1")
 doc ()
 decl ("Version", "1.0", "Encoding", undef)

XML::LibXML::SAX
 doc ()
 decl ("Version", "1.0")
 doc ()
 decl ("Version", "1.0", "Encoding", "ISO-8859-1")
 doc ()
 decl ("Version", "1.0")