signature CPP = sig
  type t
  type tkPos
  type tkExpectedValue

  exception TkExpected of tkExpectedValue

  datatype tkExp =
    Tk of Tokenizer.token |
    Id |
    NumConst |
    StrLiteral |
    UnOp |
    BinOp |
    Op

  val create: string -> t
  val getToken: t -> Tokenizer.token * t
  val getLastPos: t -> tkPos

  val prepAndRaise: t -> tkPos -> tkExp list -> 'a
  val tkExpectedPrint: tkExpectedValue -> unit

  val debugPrint: string -> unit
end