--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/utilities/CyclicAssumption.java	Fri Dec 13 15:53:30 2013 +0000
@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2013, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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.oracle.truffle.api.utilities;
+
+import com.oracle.truffle.api.*;
+
+/**
+ * Holds an {@link Assumption}, and knows how to recreate it with the same properties on
+ * invalidation. Used so that mutability is isolated in this class, and all other classes that need
+ * an assumption that may be recreated can have a final reference to an object of this class. Note
+ * that you should be careful that repeated invalidations do not cause a deoptimization loop in that
+ * same way that you would with any other assumption.
+ */
+public class CyclicAssumption {
+
+    private final String name;
+    private Assumption assumption;
+
+    public CyclicAssumption(String name) {
+        this.name = name;
+        invalidate();
+    }
+
+    public void invalidate() {
+        if (assumption != null) {
+            assumption.invalidate();
+        }
+
+        assumption = Truffle.getRuntime().createAssumption(name);
+    }
+
+    public Assumption getAssumption() {
+        return assumption;
+    }
+
+}