my $prd_grammar = q(

  startrule   : PlaceHolder Comment | PlaceHolder

  PlaceHolder : Xopen | Sprintf

  Comment     : DD_Style

  DD_Style    : '--' /.*/
                { print "Comment  : \n\t" . $item[2] . "\n\n" }

  Sprintf     : '=' /.*/ '%s' /.*/
                { print "After  : \n\t%%s" . $item[4] . "\n\n" }

  Xopen       : /.*/ '?' /.*/
                { print "After  : \n\t%s", $item[3], "\n\n" }
);

new Parse::RecDescent($prd_grammar);