Index: src/java/org/apache/lucene/util/OpenBitSetDISI.java
===================================================================
--- src/java/org/apache/lucene/util/OpenBitSetDISI.java	(revision 0)
+++ src/java/org/apache/lucene/util/OpenBitSetDISI.java	(revision 0)
@@ -0,0 +1,52 @@
+package org.apache.lucene.util;
+
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import org.apache.lucene.search.DocIdSetIterator;
+ 
+public class OpenBitSetDISI extends OpenBitSet {
+  public OpenBitSetDISI(DocIdSetIterator disi) {
+    or(disi);
+  }
+  
+  public void or(DocIdSetIterator disi) {
+    while (disi.next()) {
+      set(disi.doc());
+    }
+  }
+
+  public void and(DocIdSetIterator disi) {
+    int index = nextSetBit(0);
+    while ((index != -1) && disi.skipTo(index)) {
+      while ((index != -1) && (index < disi.doc())) {
+        fastClear(index);
+        index = nextSetBit(index + 1);
+      }
+      if (index == disi.doc()) {
+        index++;
+      }
+      assert (index == -1) || (index > disi.doc());
+    }
+  }
+
+  public void not(DocIdSetIterator disi) {
+    while (disi.next() && (disi.doc() < size())) {
+      fastClear(disi.doc());
+    }
+  }
+}
\ No newline at end of file