LUCENE-4567: avoid NPE if no suggestions were built

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1411796 13f79535-47bb-0310-9956-ffa450edef68

lucene/CHANGES.txt

@@ -147,6 +147,10 @@ Bug Fixes
   allow 1+maxMergeCount merges threads to be created, instead of just
   maxMergeCount (Radim Kolar, Mike McCandless)
 
+* LUCENE-4567: Fixed NullPointerException in analzying, fuzzy, and
+  WFST suggesters when no suggestions were added (selckin via Mike
+  McCandless)
+
 Optimizations
 
 * LUCENE-2221: oal.util.BitUtil was modified to use Long.bitCount and

lucene/suggest/src/java/org/apache/lucene/search/suggest/analyzing/AnalyzingSuggester.java

@@ -23,6 +23,7 @@ import java.io.InputStream;
 import java.io.OutputStream;
 import java.io.StringReader;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashSet;
 import java.util.List;
@@ -530,6 +531,10 @@ public class AnalyzingSuggester extends Lookup {
   public boolean store(OutputStream output) throws IOException {
     DataOutput dataOut = new OutputStreamDataOutput(output);
     try {
+      if (fst == null) {
+        return false;
+      }
+
       fst.save(dataOut);
       dataOut.writeVInt(maxAnalyzedPathsForOneInput);
     } finally {
@@ -557,6 +562,9 @@ public class AnalyzingSuggester extends Lookup {
     if (onlyMorePopular) {
       throw new IllegalArgumentException("this suggester only works with onlyMorePopular=false");
     }
+    if (fst == null) {
+      return Collections.emptyList();
+    }
 
     //System.out.println("lookup key=" + key + " num=" + num);
     final BytesRef utf8Key = new BytesRef(key);

lucene/suggest/src/java/org/apache/lucene/search/suggest/fst/WFSTCompletionLookup.java

@@ -147,6 +147,10 @@ public class WFSTCompletionLookup extends Lookup {
       throw new IllegalArgumentException("this suggester only works with onlyMorePopular=false");
     }
 
+    if (fst == null) {
+      return Collections.emptyList();
+    }
+
     BytesRef scratch = new BytesRef(key);
     int prefixLength = scratch.length;
     Arc<Long> arc = new Arc<Long>();
@@ -219,6 +223,9 @@ public class WFSTCompletionLookup extends Lookup {
    * or null if it does not exist.
    */
   public Object get(CharSequence key) {
+    if (fst == null) {
+      return null;
+    }
     Arc<Long> arc = new Arc<Long>();
     Long result = null;
     try {

lucene/suggest/src/test/org/apache/lucene/search/suggest/analyzing/AnalyzingSuggesterTest.java

@@ -134,6 +134,15 @@ public class AnalyzingSuggesterTest extends LuceneTestCase {
     assertEquals(50, results.get(0).value, 0.01F);
   }
 
+  public void testEmpty() throws Exception {
+    Analyzer standard = new MockAnalyzer(random(), MockTokenizer.WHITESPACE, true, MockTokenFilter.ENGLISH_STOPSET, false);
+    AnalyzingSuggester suggester = new AnalyzingSuggester(standard);
+    suggester.build(new TermFreqArrayIterator(new TermFreq[0]));
+
+    List<LookupResult> result = suggester.lookup("a", false, 20);
+    assertTrue(result.isEmpty());
+  }
+
   public void testNoSeps() throws Exception {
     TermFreq[] keys = new TermFreq[] {
       new TermFreq("ab cd", 0),

lucene/suggest/src/test/org/apache/lucene/search/suggest/analyzing/FuzzySuggesterTest.java

@@ -264,7 +264,13 @@ public class FuzzySuggesterTest extends LuceneTestCase {
     assertEquals(10, results.get(1).value);
   }
 
+  public void testEmpty() throws Exception {
+    FuzzySuggester suggester = new FuzzySuggester(new MockAnalyzer(random(), MockTokenizer.KEYWORD, false));
+    suggester.build(new TermFreqArrayIterator(new TermFreq[0]));
 
+    List<LookupResult> result = suggester.lookup("a", false, 20);
+    assertTrue(result.isEmpty());
+  }
 
   public void testInputPathRequired() throws Exception {
 

lucene/suggest/src/test/org/apache/lucene/search/suggest/fst/WFSTCompletionTest.java

@@ -209,4 +209,12 @@ public class WFSTCompletionTest extends LuceneTestCase {
           new TermFreq(key2, 50),
         }));
   }
+
+  public void testEmpty() throws Exception {
+    WFSTCompletionLookup suggester = new WFSTCompletionLookup(false);
+
+    suggester.build(new TermFreqArrayIterator(new TermFreq[0]));
+    List<LookupResult> result = suggester.lookup("a", false, 20);
+    assertTrue(result.isEmpty());
+  }
 }