From 7cccacbcfaeab9cdf16229b7c72469c4efcf72f9 Mon Sep 17 00:00:00 2001
From: kimchy <kimchy@gmail.com>
Date: Fri, 6 May 2011 23:10:21 +0300
Subject: [PATCH] guard in boolean filter from null doc id sets and iterators

---
 .../common/lucene/search/XBooleanFilter.java           | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/search/XBooleanFilter.java b/modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/search/XBooleanFilter.java
index 5023b5e7bb8..e490e869bd1 100644
--- a/modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/search/XBooleanFilter.java
+++ b/modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/search/XBooleanFilter.java
@@ -41,7 +41,15 @@ public class XBooleanFilter extends Filter {
 
     private DocIdSetIterator getDISI(ArrayList<Filter> filters, int index, IndexReader reader)
             throws IOException {
-        return filters.get(index).getDocIdSet(reader).iterator();
+        DocIdSet docIdSet = filters.get(index).getDocIdSet(reader);
+        if (docIdSet == null) {
+            return DocIdSet.EMPTY_DOCIDSET.iterator();
+        }
+        DocIdSetIterator iterator = docIdSet.iterator();
+        if (iterator == null) {
+            return DocIdSet.EMPTY_DOCIDSET.iterator();
+        }
+        return iterator;
     }
 
     public List<Filter> getShouldFilters() {