--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.ruby.nodes/src/com/oracle/truffle/ruby/nodes/instrument/MinimalRubyNodeInstrumenter.java	Sun Feb 23 17:00:35 2014 -0800
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2014 Oracle and/or its affiliates. All rights reserved. This
+ * code is released under a tri EPL/GPL/LGPL license. You can use it,
+ * redistribute it and/or modify it under the terms of the:
+ *
+ * Eclipse Public License version 1.0
+ * GNU General Public License version 2
+ * GNU Lesser General Public License version 2.1
+ */
+package com.oracle.truffle.ruby.nodes.instrument;
+
+import com.oracle.truffle.api.nodes.instrument.*;
+import com.oracle.truffle.ruby.nodes.*;
+import com.oracle.truffle.ruby.runtime.*;
+import com.oracle.truffle.ruby.runtime.debug.*;
+import com.oracle.truffle.ruby.runtime.methods.*;
+
+/**
+ * Utility for instrumenting Ruby AST nodes to support the language's built-in <A
+ * href="http://www.ruby-doc.org/core-2.0.0/Kernel.html#method-i-set_trace_func">tracing
+ * facility</A>. It ignores nodes other than {@linkplain NodePhylum#STATEMENT statements}.
+ */
+public final class MinimalRubyNodeInstrumenter extends DefaultNodeInstrumenter implements RubyNodeInstrumenter {
+
+    // TODO (mlvdv) convert methods to the general interface? will help with dependencies
+
+    public RubyNode instrumentAsStatement(RubyNode rubyNode) {
+        assert rubyNode != null;
+        assert !(rubyNode instanceof RubyProxyNode);
+        final RubyContext context = rubyNode.getContext();
+        if (context.getConfiguration().getTrace()) {
+            final RubyProxyNode proxy = new RubyProxyNode(context, rubyNode);
+            proxy.markAs(NodePhylum.STATEMENT);
+            proxy.getProbeChain().appendProbe(new RubyTraceProbe(context));
+            return proxy;
+        }
+        return rubyNode;
+    }
+
+    public RubyNode instrumentAsCall(RubyNode node, String callName) {
+        return node;
+    }
+
+    public RubyNode instrumentAsLocalAssignment(RubyNode node, UniqueMethodIdentifier methodIdentifier, String localName) {
+        return node;
+    }
+
+}