--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.api.codegen/src/com/oracle/truffle/api/codegen/TypeSystem.java	Fri Dec 21 10:44:31 2012 -0800
@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2012, 2012, 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.oracle.truffle.api.codegen;
+
+import java.lang.annotation.*;
+
+import com.oracle.truffle.api.nodes.*;
+
+/**
+ * <p>
+ * Annotates a type system class that represents type information for a node. Generates code for converting and managing
+ * types. Methods contained in the type system may be annotated with {@link TypeCast}, {@link TypeCheck} or
+ * {@link GuardCheck}. These methods alter the default behavior of the type system.
+ * </p>
+ *
+ *
+ * <b>Example:</b>
+ * <p>
+ * Shows a <code>@TypeSystem</code> definition with three types. In this example BigIntegers can be also treated as
+ * integers if their bit width is less than 32.
+ * </p>
+ *
+ * <pre>
+ *
+ * &#064;TypeSystem(types = {int.class, BigInteger.class, String.class}, nodeBaseClass = TypedNode.class)
+ * public abstract class Types {
+ *
+ *     &#064;TypeCheck
+ *     public boolean isInteger(Object value) {
+ *         return value instanceof Integer || (value instanceof BigInteger &amp;&amp; ((BigInteger) value).bitLength() &lt; Integer.SIZE);
+ *     }
+ *
+ *     &#064;TypeCast
+ *     public int asInteger(Object value) {
+ *         if (value instanceof Integer) {
+ *             return (int) value;
+ *         } else {
+ *             return ((BigInteger) value).intValue();
+ *         }
+ *     }
+ * }
+ * </pre>
+ *
+ * @see TypeCast
+ * @see TypeCheck
+ * @see GuardCheck
+ */
+@Retention(RetentionPolicy.CLASS)
+@Target({ElementType.TYPE})
+public @interface TypeSystem {
+
+    /**
+     * Sets the types contained by this type system. The order of types also determines the order of specialization.
+     */
+    Class[] types();
+
+    /**
+     * Specifies whether the node base class has an executeVoid method or not. Operations derived from this type system
+     * will automatically implement executeVoid for all generated nodes. Defaults to false.
+     */
+    boolean hasVoid() default false;
+
+    /**
+     * Specifies the node base class used for generated code that uses this type system. The node base class must extend
+     * {@link Node} and provide a public non-final method <code>${type} execute${typeName}(VirtualFrame)</code> for all
+     * types specified in the types attribute.
+     */
+    Class< ? extends Node> nodeBaseClass();
+
+}