--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.ruby.nodes/src/com/oracle/truffle/ruby/nodes/objects/DefineOrGetClassNode.java	Mon Jan 06 17:12:09 2014 +0000
@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2013 Oracle and/or its affiliates. All rights reserved. This
+ * code is released under a tri EPL/GPL/LGPL license. You can use it,
+ * redistribute it and/or modify it under the terms of the:
+ *
+ * Eclipse Public License version 1.0
+ * GNU General Public License version 2
+ * GNU Lesser General Public License version 2.1
+ */
+package com.oracle.truffle.ruby.nodes.objects;
+
+import com.oracle.truffle.api.*;
+import com.oracle.truffle.api.frame.*;
+import com.oracle.truffle.ruby.nodes.*;
+import com.oracle.truffle.ruby.runtime.*;
+import com.oracle.truffle.ruby.runtime.control.*;
+import com.oracle.truffle.ruby.runtime.core.*;
+
+/**
+ * Define a new class, or get the existing one of the same name.
+ */
+public class DefineOrGetClassNode extends RubyNode {
+
+    private final String name;
+    @Child protected RubyNode moduleDefinedIn;
+    @Child protected RubyNode superClass;
+
+    public DefineOrGetClassNode(RubyContext context, SourceSection sourceSection, String name, RubyNode moduleDefinedIn, RubyNode superClass) {
+        super(context, sourceSection);
+        this.name = name;
+        this.moduleDefinedIn = adoptChild(moduleDefinedIn);
+        this.superClass = adoptChild(superClass);
+    }
+
+    @Override
+    public Object execute(VirtualFrame frame) {
+        CompilerAsserts.neverPartOfCompilation();
+
+        final RubyContext context = getContext();
+
+        final RubyModule moduleDefinedInObject = (RubyModule) moduleDefinedIn.execute(frame);
+
+        // Look for a current definition of the class, or create a new one
+
+        final Object constantValue = moduleDefinedInObject.lookupConstant(name);
+
+        RubyClass definingClass;
+
+        if (constantValue == null) {
+            final Object self = frame.getArguments(RubyArguments.class).getSelf();
+
+            RubyModule parentModule;
+
+            if (self instanceof RubyModule) {
+                parentModule = (RubyModule) self;
+            } else {
+                // Because it's top level, and so self is the magic main object
+                parentModule = null;
+            }
+
+            final RubyClass superClassObject = (RubyClass) superClass.execute(frame);
+
+            if (superClassObject instanceof RubyException.RubyExceptionClass) {
+                definingClass = new RubyException.RubyExceptionClass(superClassObject, name);
+            } else {
+                definingClass = new RubyClass(parentModule, superClassObject, name);
+            }
+
+            moduleDefinedInObject.setConstant(name, definingClass);
+            moduleDefinedInObject.getSingletonClass().setConstant(name, definingClass);
+
+            definingClass.getRubyClass().include(moduleDefinedInObject);
+        } else {
+            if (constantValue instanceof RubyClass) {
+                definingClass = (RubyClass) constantValue;
+            } else {
+                throw new RaiseException(context.getCoreLibrary().typeErrorIsNotA(constantValue.toString(), "class"));
+            }
+        }
+
+        return definingClass;
+    }
+}