+static int
+instantiator_eq_equal (Lisp_Object obj1, Lisp_Object obj2)
+{
+ if (EQ (obj1, obj2))
+ return 1;
+
+ else if (CONSP (obj1) && CONSP (obj2))
+ {
+ return instantiator_eq_equal (XCAR (obj1), XCAR (obj2))
+ &&
+ instantiator_eq_equal (XCDR (obj1), XCDR (obj2));
+ }
+ return 0;
+}
+
+static hashcode_t
+instantiator_eq_hash (Lisp_Object obj)
+{
+ if (CONSP (obj))
+ {
+ /* no point in worrying about tail recursion, since we're not
+ going very deep */
+ return HASH2 (instantiator_eq_hash (XCAR (obj)),
+ instantiator_eq_hash (XCDR (obj)));
+ }
+ return LISP_HASH (obj);
+}
+
+/* We need a special hash table for storing image instances. */
+Lisp_Object
+make_image_instance_cache_hash_table (void)
+{
+ return make_general_lisp_hash_table
+ (instantiator_eq_hash, instantiator_eq_equal,
+ 30, -1.0, -1.0,
+ HASH_TABLE_KEY_CAR_VALUE_WEAK);
+}
+