Add strings to the IR

[snipe.git] / trans / stringref.sml

(* L3 Compiler
 * Stringreforaries
 * Like temporaries, except more different
 * Author: Joshua Wise <jwise@cs.cmu.edu>
 *)

signature STRINGREF = 
sig
  type stringref

  val reset : unit -> unit	(* resets stringref numbering *)
  val new : string -> stringref	(* returns a unique new stringref *)
  val name : stringref -> string	(* returns the name of a stringref *)
  val compare : stringref * stringref -> order (* comparison function *)
end

structure Stringref :> STRINGREF = 
struct
  type stringref = int

  local
    val counter = ref 1
    val strings = ref []
  in
    (* warning: calling reset() may jeopardize uniqueness of stringrefs! *)
    fun reset () = ( counter := 1 ; strings := [] )
    fun new (s : string) = !counter before ( strings := (!counter, s) :: !strings ; counter := !counter + 1 )
  end

  fun name t = "S" ^ Int.toString t
		      
  fun compare (t1,t2) = Int.compare (t1,t2)
end