From 8e027b3baf77b13bb7108930ce66c87bdc8770ae Mon Sep 17 00:00:00 2001
From: kimchy <kimchy@gmail.com>
Date: Tue, 19 Apr 2011 21:28:08 +0300
Subject: [PATCH] properly handle cases where filter returns null docIdSet with
 and/or/not filters

---
 .../elasticsearch/common/lucene/search/AndFilter.java    | 3 +++
 .../elasticsearch/common/lucene/search/NotFilter.java    | 4 ++++
 .../org/elasticsearch/common/lucene/search/OrFilter.java | 9 +++++++++
 3 files changed, 16 insertions(+)

diff --git a/modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/search/AndFilter.java b/modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/search/AndFilter.java
index 5ee5ee2a064..29d902b79d2 100644
--- a/modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/search/AndFilter.java
+++ b/modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/search/AndFilter.java
@@ -53,6 +53,9 @@ public class AndFilter extends Filter {
         boolean allAreDocSet = true;
         for (Filter filter : filters) {
             DocIdSet set = filter.getDocIdSet(reader);
+            if (set == null) { // none matching for this filter, we AND, so return EMPTY
+                return DocSet.EMPTY_DOC_SET;
+            }
             if (!(set instanceof DocSet)) {
                 allAreDocSet = false;
             }
diff --git a/modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/search/NotFilter.java b/modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/search/NotFilter.java
index 8902d15b4d6..3e5ade23c86 100644
--- a/modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/search/NotFilter.java
+++ b/modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/search/NotFilter.java
@@ -22,6 +22,7 @@ package org.elasticsearch.common.lucene.search;
 import org.apache.lucene.index.IndexReader;
 import org.apache.lucene.search.DocIdSet;
 import org.apache.lucene.search.Filter;
+import org.elasticsearch.common.lucene.docset.AllDocSet;
 import org.elasticsearch.common.lucene.docset.DocSet;
 import org.elasticsearch.common.lucene.docset.NotDocIdSet;
 import org.elasticsearch.common.lucene.docset.NotDocSet;
@@ -45,6 +46,9 @@ public class NotFilter extends Filter {
 
     @Override public DocIdSet getDocIdSet(IndexReader reader) throws IOException {
         DocIdSet set = filter.getDocIdSet(reader);
+        if (set == null) {
+            return new AllDocSet(reader.maxDoc());
+        }
         if (set instanceof DocSet) {
             return new NotDocSet((DocSet) set, reader.maxDoc());
         }
diff --git a/modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/search/OrFilter.java b/modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/search/OrFilter.java
index dbb8937f51a..286d992cb43 100644
--- a/modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/search/OrFilter.java
+++ b/modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/search/OrFilter.java
@@ -53,11 +53,20 @@ public class OrFilter extends Filter {
         boolean allAreDocSet = true;
         for (Filter filter : filters) {
             DocIdSet set = filter.getDocIdSet(reader);
+            if (set == null) { // none matching for this filter, continue
+                continue;
+            }
             if (!(set instanceof DocSet)) {
                 allAreDocSet = false;
             }
             sets.add(set);
         }
+        if (sets.size() == 0) {
+            return DocSet.EMPTY_DOC_SET;
+        }
+        if (sets.size() == 1) {
+            return (DocIdSet) sets.get(0);
+        }
         if (allAreDocSet) {
             return new OrDocSet(sets);
         }