* @param supertypeBearer {@code non-null;} the supertype
* @param subtypeBearer {@code non-null;} the subtype
*/
public static boolean isPossiblyAssignableFrom(TypeBearer supertypeBearer,
TypeBearer subtypeBearer) {
Type supertype = supertypeBearer.getType();
Type subtype = subtypeBearer.getType();
if (supertype.equals(subtype)) {
// Easy out.
return true;
}
int superBt = supertype.getBasicType();
int subBt = subtype.getBasicType();
// Treat return types as Object for the purposes of this method.
if (superBt == Type.BT_ADDR) {
supertype = Type.OBJECT;
superBt = Type.BT_OBJECT;
}
if (subBt == Type.BT_ADDR) {
subtype = Type.OBJECT;
subBt = Type.BT_OBJECT;
}
if ((superBt != Type.BT_OBJECT) || (subBt != Type.BT_OBJECT)) {
/*
* No two distinct primitive types are assignable in this sense,
* unless they are both int-like.
*/
return supertype.isIntlike() && subtype.isIntlike();
}
// At this point, we know both types are reference types.
if (supertype == Type.KNOWN_NULL) {
/*
* A known-null supertype is only assignable from another
* known-null (handled in the easy out at the top of the
* method).
*/
return false;
} else if (subtype == Type.KNOWN_NULL) {
/*
* A known-null subtype is in fact assignable to any
* reference type.
*/
return true;
} else if (supertype == Type.OBJECT) {
/*
* Object is assignable from any reference type.
*/
return true;
} else if (supertype.isArray()) {
// The supertype is an array type.
if (! subtype.isArray()) {
// The subtype isn't an array, and so can't be assignable.
return false;
}
/*
* Strip off as many matched component types from both
* types as possible, and check the assignability of the
* results.
*/
do {
supertype = supertype.getComponentType();
subtype = subtype.getComponentType();
} while (supertype.isArray() && subtype.isArray());
return isPossiblyAssignableFrom(supertype, subtype);
} else if (subtype.isArray()) {
/*
* Other than Object (handled above), array types are
* assignable only to Serializable and Cloneable.
*/
return (supertype == Type.SERIALIZABLE) ||