--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.ruby.runtime/src/com/oracle/truffle/ruby/runtime/lookup/LookupFork.java	Mon Jan 06 17:12:09 2014 +0000
@@ -0,0 +1,97 @@
+/*
+ * 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.runtime.lookup;
+
+import java.util.*;
+
+import com.oracle.truffle.api.*;
+import com.oracle.truffle.api.utilities.*;
+import com.oracle.truffle.ruby.runtime.methods.*;
+
+/**
+ * A fork in the lookup graph. Look at first and then look at second.
+ */
+public class LookupFork implements LookupNode {
+
+    private LookupNode first;
+    private LookupNode second;
+
+    public LookupFork(LookupNode first, LookupNode second) {
+        this.first = first;
+        this.second = second;
+    }
+
+    public boolean setClassVariableIfAlreadySet(String variableName, Object value) {
+        if (first.setClassVariableIfAlreadySet(variableName, value)) {
+            return true;
+        }
+
+        return second.setClassVariableIfAlreadySet(variableName, value);
+    }
+
+    @Override
+    public Object lookupConstant(String constantName) {
+        final Object firstResult = first.lookupConstant(constantName);
+
+        if (firstResult != null) {
+            return firstResult;
+        }
+
+        return second.lookupConstant(constantName);
+    }
+
+    @Override
+    public Object lookupClassVariable(String classVariable) {
+        final Object firstResult = first.lookupClassVariable(classVariable);
+
+        if (firstResult != null) {
+            return firstResult;
+        }
+
+        return second.lookupClassVariable(classVariable);
+    }
+
+    @Override
+    public RubyMethod lookupMethod(String methodName) {
+        final RubyMethod firstResult = first.lookupMethod(methodName);
+
+        if (firstResult != null) {
+            return firstResult;
+        }
+
+        return second.lookupMethod(methodName);
+    }
+
+    @Override
+    public Assumption getUnmodifiedAssumption() {
+        return new UnionAssumption(first.getUnmodifiedAssumption(), second.getUnmodifiedAssumption());
+    }
+
+    public LookupNode getFirst() {
+        return first;
+    }
+
+    public LookupNode getSecond() {
+        return second;
+    }
+
+    public Set<String> getClassVariables() {
+        final Set<String> classVariables = new HashSet<>();
+        classVariables.addAll(first.getClassVariables());
+        classVariables.addAll(second.getClassVariables());
+        return classVariables;
+    }
+
+    public void getMethods(Map<String, RubyMethod> methods) {
+        second.getMethods(methods);
+        first.getMethods(methods);
+    }
+
+}