(*
 * Internal data structure representing a CM dependency graph.
 *
 * (C) 1999 Lucent Technologies, Bell Laboratories
 *
 * Author: Matthias Blume (blume@kurims.kyoto-u.ac.jp)
 *)
structure DependencyGraph = struct

    type symbol = Symbol.symbol
    type groupinfo = Dummy.t
    type primitive = Primitive.primitive

    type filter = SymbolSet.set option

    datatype node =
	NODE of { smlinfo: SmlInfo.info,
		  localimports: node list,
		  globalimports: farnode list }

    and farnode =
	FARNODE of filter * node
      | PNODE of primitive

    (* environments used for dependency analysis *)
    datatype env =
	EMPTY
      | FCTENV of { looker: symbol -> value option,
		    domain: unit -> SymbolSet.set }
      | BINDING of symbol * value
      | LAYER of env * env

    withtype value = env

    fun describeFarNode (FARNODE (f, NODE { smlinfo = i, ... })) =
	SmlInfo.fullName i
      | describeFarNode (PNODE p) = Primitive.toString p
end