--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/ASTNodeProber.java	Sun Apr 20 20:37:27 2014 -0700
@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2014, 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.nodes.*;
+
+/**
+ * Implementation of a policy for <em>instrumenting</em> inserting a {@link Probe} at a Truffle AST
+ * node.
+ * <p>
+ * Note that this interface is guest language agnostic, but current extensions are
+ * language-specific. This will be revisited.
+ * <p>
+ * <strong>Disclaimer:</strong> experimental interface under development. Really!
+ */
+public interface ASTNodeProber {
+
+    /**
+     * Optionally applies <em>instrumentation</em> at a Truffle AST node, depending on guest
+     * language characteristics and use-case policy.
+     * <ul>
+     * <li>if no instrumentation is to be applied, returns the AST node unmodified;</li>
+     * <li>if an AST node is to be instrumented, then returns a newly created {@link Wrapper} that
+     * <em>decorates</em> the AST node and notifies an associated {@link Probe} of all
+     * {@link ExecutionEvents} at the wrapped AST node.</li>
+     * <li>if the argument is itself a {@link Wrapper}, i.e. if the AST node at this site has
+     * already been wrapped, then the wrapper is returned (with the possible addition of a
+     * {@linkplain PhylumTag tag}).</li>
+     * </ul>
+     *
+     * @param astNode an AST node to which instrumentation might be applied
+     * @param tag an optional category directing how the node, if instrumented, should be perceived
+     *            by tool users
+     * @param args additional arguments for instrumentation specific to a particular guest language
+     * @return if no instrumentation should be applied or if the node is a {@link Wrapper} then the
+     *         unmodified node; otherwise a newly created {@link Wrapper} (whose child
+     *         {@code astNode}) with an associated {@link Probe} .
+     */
+
+    Node probeAs(Node astNode, PhylumTag tag, Object... args);
+}