Improved [Protocol -isEqual:], now more correct and faster

From-SVN: r82619

libobjc/ChangeLog

+2004-06-03  Nicola Pero  <n.pero@mi.flashnet.it>
+
+	* Protocol.m ([-isEqual:]): Small optimizations returning
+	immediately if the argument is equal to self, and accessing
+	the argument's name directly if it's a protocol.
+
+2004-06-03  David Ayers  <d.ayers@inode.at>
+
+	* Protocol.m ([-isEqual:]): Test the class of the argument.
+
 2004-05-25  Andrew Pinski  <pinskia@physics.uc.edu>
 
 	* configure.ac (includedir): Rename to ...

libobjc/Protocol.m

@@ -150,11 +150,33 @@ struct objc_method_description_list {
   return hash;
 }
 
+/*
+ * Equality between formal protocols is only formal (nothing to do
+ * with actually checking the list of methods they have!).  Two formal
+ * Protocols are equal if and only if they have the same name.
+ *
+ * Please note (for comparisons with other implementations) that
+ * checking the names is equivalent to checking that Protocol A
+ * conforms to Protocol B and Protocol B conforms to Protocol A,
+ * because this happens iff they have the same name.  If they have
+ * different names, A conforms to B if and only if A includes B, but
+ * the situation where A includes B and B includes A is a circular
+ * dependency between Protocols which is forbidden by the compiler, so
+ * A conforms to B and B conforms to A with A and B having different
+ * names is an impossible case.
+ */
 - (BOOL) isEqual: (id)obj
 {
-  if (strcmp (protocol_name, [obj name]) == 0)
+  if (obj == self)
+    return YES;
+
+  if ([obj isKindOf: [Protocol class]])
+    {
+      if (strcmp (protocol_name, ((Protocol *)obj)->protocol_name) == 0)
 	return YES;
+    }
 
   return NO;
 }
 @end
+