--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/ToolNodeInstrumentListener.java	Tue Mar 31 19:01:07 2015 -0700
@@ -0,0 +1,58 @@
+/*
+ * 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;
+
+/**
+ * Instrument listener for a tool that works by providing an AST to be attached/adopted directly
+ * into the AST.
+ */
+public interface ToolNodeInstrumentListener {
+
+    /**
+     * Receive notification that a probed AST node to which the {@link Instrument} is attached is
+     * about to be executed for the first time. This is a lazy opportunity for the tool to
+     * optionally add the root of a newly created AST fragment that will be attached/adopted
+     * directly into the executing AST. The new AST fragment will immediately begin receiving
+     * {@link InstrumentationNode.TruffleEvents}, beginning with the current execution event.
+     * <p>
+     * AST fragments must be written to Truffle conventions. Some of these conventions are
+     * especially important if the fragment is to be fully optimized along with it's new parent AST.
+     * <p>
+     * If this method returns {@code null} then it will be called again the next time the probed
+     * node is about to be executed.
+     * <p>
+     * In some situations, this method will be called more than once for a particular Probe, and a
+     * new instance must be supplied each time. Each instance will be attached at the equivalent
+     * location in clones of the AST, and so should be behave as if equivalent for most purposes.
+     * <p>
+     * In some situations the AST fragment supplied by this method maybe cloned for attachment to
+     * equivalent locations in cloned AST, so care should be taken about any state local to each
+     * instance of the AST fragment.
+     *
+     * @see Instrument
+     */
+    ToolNode getToolNode(Probe probe);
+
+}