Package newnullid5; Helpers tab = 9; cr = 13; lf = 10; eol = [[cr + lf] + [cr + lf]]; white = [[' ' + tab] + eol]; lowercase = ['a' .. 'z']; uppercase = ['A' .. 'Z']; letter = [uppercase + lowercase]; digit = ['0'..'9']; id_part = lowercase (lowercase | digit)*; blank = (' ' | tab | eol)+; Tokens tar = 'tar'; id = id_part ('_' id_part)*; minus = '-'; semicolon = ';'; letter = letter; l_bkt = '['; r_bkt = ']'; blank = blank; Ignored Tokens /* These tokens are simply ignored by the parser. */ blank; /*****************/ Productions grammar = P.tar? {-> New grammar.first([])}; tar {-> id minus option } = T.tar+ minus letter+ id? {-> Null minus New option([letter])}; Abstract Syntax Tree grammar = {first} letter* | {second} ; tar = {both} option id* | {alone} id*; option = letter*;