$parser = new Parse::RecDescent (q{
              startrule : PlaceHolder Comment | PlaceHolder

              Comment : DD_Style

              DD_Style : m{(\s+?--.*$)}
                         { print "Comment  : \n\t", $item[1], "\n\n" }

              PlaceHolder : Xopen | Sprintf

              Sprintf : /.*=\s+?%s.*?/
                        { $item[1] =~ s{%s}{%%s}g; 
                          print "After  : \n\t", $item[1], "\n\n" }
              Xopen   : /.*=\s+?\?.*?/
                        { $item[1] =~ s{\?}{%s}g; 
                          print "After  : \n\t", $item[1], "\n\n" }

    }) unless $parser;