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(*
* Abstract interface for GC types.
*)
functor GCType(ObjType : OBJ_TYPE) : GC_TYPE =
struct
structure O = ObjType
type ty = int
datatype gctype =
CONST of int (* integer constant *)
| NONREF of O.objtype ref (* non-reference value *)
| REF of O.objtype ref (* a reference, pointer to a gc object *)
| ADD of ty * gctype * gctype (* address arithmetic + *)
| SUB of ty * gctype * gctype (* address arithmetic - *)
| BOT
| TOP
type gcmap = gctype Intmap.intmap
exception GCTYPE
fun int i = if i >= 0 then Int.toString i else "-"^Int.toString(~i)
fun toString BOT = "bot"
| toString TOP = "top"
| toString (CONST i) = int i
| toString (NONREF(ref obj)) = "nonref "^O.toString obj
| toString (REF(ref obj)) = "ref "^O.toString obj
| toString (ADD(ty,a,b)) = "("^toString a^"+"^toString b^")"
| toString (SUB(ty,a,b)) = "("^toString a^"-"^toString b^")"
fun mapToString gcmap =
let val lookup = Intmap.map gcmap
fun f r = "{"^toString(lookup r)^"}" handle _ => "{?}"
in f end
val GCMAP = Annotations.new NONE : gcmap Annotations.property
val GCSAFEPOINT = Annotations.newFlag ""
end
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