An RTVal.T represents a JunoValue.T. RTVals are used in the Juno machine while it is running. The procedure Dispose reclaims the space for all RTVals.

INTERFACE RTVal;

IMPORT JunoValue;

TYPE T = ROOT BRANDED "RTVal" OBJECT END;

TYPE Real = JunoValue.Real;

TYPE
  Null = T BRANDED "Null" OBJECT END;
  Number <: NumberPublic; NumberPublic = T OBJECT val: Real END;
  Text <: TextPublic; TextPublic = T OBJECT val: TEXT END;
  Pair <: PairPublic; PairPublic = T OBJECT car, cdr: T END;

VAR (* READONLY *) nil: Null;

PROCEDURE FromReal(r: Real): Number;

Returns a new Number with value r.

PROCEDURE FromInt(i: INTEGER): Number;

Returns a new Number with value FLOAT(i).

PROCEDURE FromText(txt: TEXT): Text;

Returns a new Text with value txt. Requires txt # NIL.

PROCEDURE FromPair(car, cdr: T): Pair;

Returns a new Pair with elements car and cdr. Requires both car and cdr to be non-NIL.

PROCEDURE FromJV(jv: JunoValue.T): T;

Returns the run-time value equivalent to jv. If jv = NIL, returns NIL. If jv has type Null, returns JunoValue.Nil.

PROCEDURE ToJV(v: T): JunoValue.T;

Returns the JunoValue.T equivalent to the run-time value v. If v = NIL, returns NIL. If v has type JunoValue.Null, returns nil.

PROCEDURE Equal(v, w: T): BOOLEAN;

Return TRUE iff v and w are equal.

PROCEDURE Mark();

Mark all T's allocated prior to this call so they will not be collected on the next call to Dispose.

PROCEDURE Dispose();

Invalidate and reclaim all Ts allocated since the last call to Mark, and undo the effect of that Mark. If there is no previous Mark, invalidate and reclaim all T's allocated since the last call to Dispose. This never invalidates nil.

END RTVal.