--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/impl/SimpleASTInstrumentListener.java	Thu Mar 12 18:04:30 2015 -0700
@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 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.impl;
+
+import com.oracle.truffle.api.frame.*;
+import com.oracle.truffle.api.instrument.*;
+import com.oracle.truffle.api.nodes.*;
+
+/**
+ * An abstract listener for AST {@linkplain ASTInstrumentListener execution events} that ignores
+ * return values and supports handling all events by overriding only two methods:
+ * <ul>
+ * <li>{@link #enter(Probe, Node, VirtualFrame)}, and</li>
+ * <li>{@link #returnAny(Probe, Node, VirtualFrame)}.</li>
+ * </ul>
+ */
+public abstract class SimpleASTInstrumentListener implements ASTInstrumentListener {
+
+    public void enter(Probe probe, Node node, VirtualFrame vFrame) {
+    }
+
+    /**
+     * Receive notification that one of an AST Node's execute methods has just returned by any
+     * means: with or without a return value (ignored) or via exception (ignored).
+     *
+     * @param probe where the event originated
+     * @param node specific node of the event
+     * @param vFrame
+     */
+    protected void returnAny(Probe probe, Node node, VirtualFrame vFrame) {
+    }
+
+    public final void returnVoid(Probe probe, Node node, VirtualFrame vFrame) {
+        returnAny(probe, node, vFrame);
+    }
+
+    public final void returnValue(Probe probe, Node node, VirtualFrame vFrame, Object result) {
+        returnAny(probe, node, vFrame);
+    }
+
+    public final void returnExceptional(Probe probe, Node node, VirtualFrame vFrame, Exception e) {
+        returnAny(probe, node, vFrame);
+    }
+
+}