From ae706faf1262537ba4f8a4ec67dd230ca20ee324 Mon Sep 17 00:00:00 2001
From: Daniel Naber <dnaber@apache.org>
Date: Tue, 4 Oct 2005 21:30:37 +0000
Subject: [PATCH] don't let MultiFieldQueryParser create empty clauses for
 stopwords

git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@294924 13f79535-47bb-0310-9956-ffa450edef68
---
 .../queryParser/MultiFieldQueryParser.java    |  2 ++
 .../TestMultiFieldQueryParser.java            | 26 +++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/src/java/org/apache/lucene/queryParser/MultiFieldQueryParser.java b/src/java/org/apache/lucene/queryParser/MultiFieldQueryParser.java
index f47615ee186..a72fdb6387d 100644
--- a/src/java/org/apache/lucene/queryParser/MultiFieldQueryParser.java
+++ b/src/java/org/apache/lucene/queryParser/MultiFieldQueryParser.java
@@ -76,6 +76,8 @@ public class MultiFieldQueryParser extends QueryParser
           clauses.add(new BooleanClause(q, BooleanClause.Occur.SHOULD));
         }
       }
+      if (clauses.size() == 0)  // happens for stopwords
+        return null;
       return getBooleanQuery(clauses, true);
     }
     return super.getFieldQuery(field, queryText);
diff --git a/src/test/org/apache/lucene/queryParser/TestMultiFieldQueryParser.java b/src/test/org/apache/lucene/queryParser/TestMultiFieldQueryParser.java
index 6ab65b4a357..0677926591d 100644
--- a/src/test/org/apache/lucene/queryParser/TestMultiFieldQueryParser.java
+++ b/src/test/org/apache/lucene/queryParser/TestMultiFieldQueryParser.java
@@ -24,7 +24,14 @@ import org.apache.lucene.analysis.Analyzer;
 import org.apache.lucene.analysis.Token;
 import org.apache.lucene.analysis.TokenStream;
 import org.apache.lucene.analysis.standard.StandardAnalyzer;
+import org.apache.lucene.document.Document;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.index.IndexWriter;
+import org.apache.lucene.search.Hits;
+import org.apache.lucene.search.IndexSearcher;
 import org.apache.lucene.search.Query;
+import org.apache.lucene.store.Directory;
+import org.apache.lucene.store.RAMDirectory;
 
 /**
  * Tests QueryParser.
@@ -181,6 +188,25 @@ public class TestMultiFieldQueryParser extends TestCase {
     assertEquals("f1:[a TO c] f2:[a TO c] f3:[a TO c]", q.toString());
   }
 
+  public void testStopWordSearching() throws Exception {
+    Analyzer analyzer = new StandardAnalyzer();
+    Directory ramDir = new RAMDirectory();
+    IndexWriter iw =  new IndexWriter(ramDir, analyzer, true);
+    Document doc = new Document();
+    doc.add(new Field("body", "blah the footest blah", Field.Store.NO, Field.Index.TOKENIZED));
+    iw.addDocument(doc);
+    iw.close();
+    
+    MultiFieldQueryParser mfqp = 
+      new MultiFieldQueryParser(new String[] {"body"}, analyzer);
+    mfqp.setDefaultOperator(QueryParser.Operator.AND);
+    Query q = mfqp.parse("the footest");
+    IndexSearcher is = new IndexSearcher(ramDir);
+    Hits hits = is.search(q);
+    assertEquals(1, hits.length());
+    is.close();
+  }
+  
   /**
    * Return empty tokens for field "f1".
    */