1 abstract class Parser[I, T] {

     2   def parse(ts: I): Set[(T, I)]

     3 

     4   def parse_all(ts: I) : Set[T] =

     5     for ((head, tail) <- parse(ts); if (tail.isEmpty)) 

     6       yield head

     7 

     8   def || (right : => Parser[I, T]) : Parser[I, T] = 

     9       new AltParser(this, right)

    10   def ==>[S] (f: => T => S) : Parser [I, S] = 

    11       new FunParser(this, f)

    12    def ~[S] (right : => Parser[I, S]) : Parser[I, (T, S)] = 

    13       new SeqParser(this, right)

    14 }

    15 

    16