use strict;
use HTML::PullParser;

my $p = HTML::PullParser->new(
    file  => shift @ARGV,
    start => 'tagname, @attr'
);

while(my $t = $p->get_token()) {
    my($tagname, %attr) = @$t;
    print "alt text is $attr{alt}", $/
        if exists $attr{alt};
}