--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/TruffleEventListener.java	Tue Feb 10 16:44:11 2015 -0800
@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2013, 2015, 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.instrument;
+
+import com.oracle.truffle.api.frame.*;
+import com.oracle.truffle.api.nodes.*;
+
+/**
+ * A listener of Truffle AST runtime execution events that can collect information and possibly
+ * intervene on behalf of an external tool.
+ */
+public interface TruffleEventListener {
+
+    /**
+     * Receive notification that an AST node's execute method is about to be called.
+     */
+    void enter(Node node, VirtualFrame frame);
+
+    /**
+     * Receive notification that an AST Node's {@code void}-valued execute method has just returned.
+     */
+    void returnVoid(Node node, VirtualFrame frame);
+
+    /**
+     * Receive notification that an AST Node'sexecute method has just returned a value (boxed if
+     * primitive).
+     */
+    void returnValue(Node node, VirtualFrame frame, Object result);
+
+    /**
+     * Receive notification that an AST Node's execute method has just thrown an exception.
+     */
+    void returnExceptional(Node node, VirtualFrame frame, Exception exception);
+
+}