sub {
        printf 'regex: ';
        my $mask = shift;
        my $re = '^' . join('', map $_ ? '(.)' : '.', split '', $mask ) . '$';
        return sub {
            my $fh = shift;
            my $out;
            my $count = 0;
            $out = join( '', m[$re]o ), ++$count while <$fh>;
            $count;
        }
    },

__END__
C:\test>1023727 -OPT=4
regex: Took 274.157906 seconds for 2606 records (9.505471 recs/second)