signature PPC = sig

  structure T: TOKENIZER

  type t
  type tkErrorVal
  type tkErrorExpVal
  type tkPos

  exception TkError of tkErrorVal
  exception TkErrorExp of tkErrorExpVal

  datatype expTk =
    ExpTk of T.token |
    ExpId |
    ExpConst |
    ExpUnop |
    ExpBinop |
    ExpOp


  val create: { fname: string, incDirs: string list } -> t
  val debugPrint: string -> string list -> unit


  val raiseTkError: string -> tkPos -> 'a
  val tkErrorPrint: tkErrorVal -> unit

  val raiseTkErrorExp: tkPos -> expTk list -> 'a
  val tkErrorExpPrint: tkErrorExpVal -> unit
end