Listing 1 grammar.dat

Command    :nooptcmd EndOfString
           { $return = $item[1]; }
      |    oneoptcmd anoption EndOfString
           { $return = "$item[1] $item[2]"; }
      |    twooptcmd anoption anoption EndOfString
           { $return = "$item[1] $item[2] $item[3]";}
      |    { $return = 0; }

oneoptcmd    :    'script1'

twooptcmd    :    'script2' | 'script1'

nooptcmd    :    'script3'

anoption    :    /[A-Za-z0-9\-\_\*\.]+/

EndOfString :    /\Z/