implemented nullable type notation

src/lib/objects/objects.c

@@ -33,14 +33,21 @@
 #include "../common/defs.h"
 
 static _Bool op_eql(Object *self, Object *other);
+static bool istypeof(Object *self, Object *other);
 
 TypeObject t_type = {
 	.base = (Object) { .type = &t_type, .flags = Object_STATIC },
 	.name = TYPENAME_TYPE,
 	.size = sizeof(TypeObject),
+	.istypeof = istypeof,
 	.op_eql = op_eql,
 };
 
+static bool istypeof(Object *self, Object *other)
+{
+    return other->type == (TypeObject*) self;
+}
+
 TypeObject *Object_GetTypeType()
 {
 	return &t_type;
@@ -71,6 +78,13 @@ const TypeObject *Object_GetType(const Object *obj)
 	return obj->type;
 }
 
+bool Object_IsTypeOf(Object *typ, Object *obj)
+{
+	if (typ->type->istypeof == NULL)
+		return false;
+	return typ->type->istypeof(typ, obj);
+}
+
 int Object_Hash(Object *obj)
 {
 	ASSERT(obj != NULL);