From 9251a63e01293f39243cd3fc7af3d22fbb9bdad0 Mon Sep 17 00:00:00 2001
From: Mark Harwood <mharwood@apache.org>
Date: Wed, 24 Jan 2007 22:19:05 +0000
Subject: [PATCH] Fixed bug when BooleanFilter class is used in conjunction
 with cached filters - the anding of filters' bitsets was changing the
 original rather than taking a copy of the contents. Changed to use
 BitSet.clone before performing any destructive operation

git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@499592 13f79535-47bb-0310-9956-ffa450edef68
---
 .../apache/lucene/search/BooleanFilter.java    | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/contrib/queries/src/java/org/apache/lucene/search/BooleanFilter.java b/contrib/queries/src/java/org/apache/lucene/search/BooleanFilter.java
index fe213fa5201..6f3c838b11e 100644
--- a/contrib/queries/src/java/org/apache/lucene/search/BooleanFilter.java
+++ b/contrib/queries/src/java/org/apache/lucene/search/BooleanFilter.java
@@ -41,9 +41,10 @@ public class BooleanFilter extends Filter
 		if (shouldFilters!=null)
 		{
 			returnBits = ((Filter)shouldFilters.get(0)).bits(reader);
+//			avoid changing the original bitset - it may be cached
+			returnBits=(BitSet) returnBits.clone(); 
 			if (shouldFilters.size() > 1)
 			{
-				
 				for (int i = 1; i < shouldFilters.size(); i++)
 				{
 					returnBits.or(((Filter)shouldFilters.get(i)).bits(reader));
@@ -59,7 +60,7 @@ public class BooleanFilter extends Filter
 				BitSet notBits=((Filter)notFilters.get(i)).bits(reader);
 				if(returnBits==null)
 				{
-					returnBits=notBits;
+					returnBits=(BitSet) notBits.clone();					
 					returnBits.flip(0,reader.maxDoc());
 				}
 				else
@@ -77,7 +78,16 @@ public class BooleanFilter extends Filter
 				BitSet mustBits=((Filter)mustFilters.get(i)).bits(reader);
 				if(returnBits==null)
 				{
-					returnBits=mustBits;
+					if(mustFilters.size()==1)
+					{
+						returnBits=mustBits;
+						
+					}
+					else
+					{
+						//don't mangle the bitset
+						returnBits=(BitSet) mustBits.clone();						
+					}
 				}
 				else
 				{
@@ -124,4 +134,4 @@ public class BooleanFilter extends Filter
 			notFilters.add(filterClause.getFilter());
 		}
 	}
-}
+}
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