LUCENE-6256: Change PostingsEnum.nextPosition() to consistently return -1 when positions are not available

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1661061 13f79535-47bb-0310-9956-ffa450edef68

lucene/CHANGES.txt

@@ -127,6 +127,10 @@ API Changes
 * LUCENE-6245: Force Filter subclasses to implement toString API from Query.
   (Ryan Ernst)
 
+* LUCENE-6256: Change PostingsEnum.nextPosition() to consistently return -1 when
+  positions are not available.
+  (Ryan Ernst)
+
 Other
 
 * LUCENE-6248: Remove unused odd constants from StandardSyntaxParser.jj

lucene/codecs/src/java/org/apache/lucene/codecs/memory/DirectPostingsFormat.java

@@ -1566,7 +1566,6 @@ public final class DirectPostingsFormat extends PostingsFormat {
 
     @Override
     public int nextPosition() throws IOException {
-      assert false : "Shouldn't be calling nextPosition() if you haven't asked for positions";
       return -1;
     }
 
@@ -1655,7 +1654,6 @@ public final class DirectPostingsFormat extends PostingsFormat {
 
     @Override
     public int nextPosition() throws IOException {
-      assert false : "Shouldn't be calling nextPosition() if you haven't asked for positions";
       return -1;
     }
 
@@ -1760,7 +1758,6 @@ public final class DirectPostingsFormat extends PostingsFormat {
 
     @Override
     public int nextPosition() throws IOException {
-      assert false : "should be using LowFreqDocsAndPositionsEnum";
       return -1;
     }
 

lucene/codecs/src/java/org/apache/lucene/codecs/simpletext/SimpleTextFieldsReader.java

@@ -278,7 +278,6 @@ class SimpleTextFieldsReader extends FieldsProducer {
 
     @Override
     public int nextPosition() throws IOException {
-      assert false : "Shouldn't be calling nextPosition() if you haven't asked for positions";
       return -1;
     }
 

lucene/codecs/src/java/org/apache/lucene/codecs/simpletext/SimpleTextTermVectorsReader.java

@@ -423,7 +423,6 @@ public class SimpleTextTermVectorsReader extends TermVectorsReader {
 
     @Override
     public int nextPosition() throws IOException {
-      assert false;
       return -1;
     }
 

lucene/core/src/java/org/apache/lucene/codecs/lucene50/Lucene50PostingsReader.java

@@ -336,7 +336,6 @@ public final class Lucene50PostingsReader extends PostingsReaderBase {
 
     @Override
     public int nextPosition() throws IOException {
-      assert false;   // shouldn't be calling nextPosition() on this
       return -1;
     }
 

lucene/core/src/java/org/apache/lucene/index/FreqProxFields.java

@@ -345,7 +345,6 @@ class FreqProxFields extends Fields {
 
     @Override
     public int nextPosition() throws IOException {
-      assert false : "Shouldn't be calling nextPositions on DocsEnum";
       return -1;
     }
 

lucene/core/src/java/org/apache/lucene/index/PostingsEnum.java

@@ -92,9 +92,9 @@ public abstract class PostingsEnum extends DocIdSetIterator {
   }
 
   /**
-   * Returns the next position.  If there are no more
-   * positions, or the iterator does not support positions,
-   * this will return DocsEnum.NO_MORE_POSITIONS */
+   * Returns the next position, or -1 if positions were not indexed.
+   * Calling this more than {@link #freq()} times is undefined.
+   */
   public abstract int nextPosition() throws IOException;
 
   /** Returns start offset for the current position, or -1

lucene/test-framework/src/java/org/apache/lucene/index/BasePostingsFormatTestCase.java

@@ -231,7 +231,7 @@ public abstract class BasePostingsFormatTestCase extends BaseIndexFileFormatTest
     public int nextPosition() {
       if (!doPositions) {
         posUpto = freq;
-        return 0;
+        return -1;
       }
       assert posUpto < freq;