--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.max.base/src/com/sun/max/collect/HashEquality.java	Sat Dec 17 19:59:18 2011 +0100
@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2007, 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package com.sun.max.collect;
+
+import com.sun.max.*;
+
+/**
+ * Defines the semantics of key comparison in a {@linkplain HashMapping hash based data structure} that delegate to
+ * {@link Object#equals(Object)} and {@link Object#hashCode()}. There is a {@linkplain #instance(Class) singleton}
+ * instance of this class.
+ */
+public final class HashEquality<T> implements HashEquivalence<T> {
+
+    private HashEquality() {
+    }
+
+    public boolean equivalent(T object1, T object2) {
+        if (object1 == null) {
+            return object2 == null;
+        }
+        return object1.equals(object2);
+    }
+
+    public int hashCode(T object) {
+        if (object == null) {
+            return 0;
+        }
+        return object.hashCode();
+    }
+
+    private static final HashEquality equality = new HashEquality<Object>();
+
+    public static <T> HashEquality<T> instance(Class<HashEquality<T>> type) {
+        return Utils.cast(type, equality);
+    }
+}