--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.dsl.processor/src/com/oracle/truffle/dsl/processor/util/Filterator.java	Tue Jan 07 12:22:47 2014 +0100
@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) 2012, 2012, 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.
+ *
+ * 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.dsl.processor.util;
+
+import java.util.*;
+
+public class Filterator<T> implements Iterator<T> {
+
+    private final Predicate<T> includePredicate;
+    private final Iterator<T> elements;
+
+    private boolean hasCached;
+    private T cached;
+
+    public Filterator(Iterator<T> elements, Predicate<T> includePredicate) {
+        this.elements = elements;
+        this.includePredicate = includePredicate;
+    }
+
+    public boolean hasNext() {
+        if (hasCached) {
+            return true;
+        }
+        nextValue();
+        return hasCached;
+    }
+
+    private void nextValue() {
+        while (!hasCached && elements.hasNext()) {
+            T element = elements.next();
+            if (includePredicate.evaluate(element)) {
+                cached = element;
+                hasCached = true;
+            }
+        }
+    }
+
+    public T next() {
+        T foundCached = getCached();
+        if (foundCached != null) {
+            return foundCached;
+        } else {
+            nextValue();
+            if (!hasCached) {
+                throw new NoSuchElementException();
+            }
+            return getCached();
+        }
+    }
+
+    private T getCached() {
+        if (hasCached) {
+            hasCached = false;
+            T value = cached;
+            cached = null;
+            return value;
+        }
+        return null;
+    }
+
+    public void remove() {
+        elements.remove();
+    }
+
+}