LUCENE-1583: SpanOrQuery skipTo() doesn't always move forwards as Spans documentation indicates it should.

git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@794063 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -379,6 +379,9 @@ Bug fixes
 18. LUCENE-1718: Fix termInfosIndexDivisor to carry over to reopened
     readers (Mike McCandless)
     
+19. LUCENE-1583: SpanOrQuery skipTo() doesn't always move forwards as Spans
+	documentation indicates it should.  (Moti Nisenson via Mark Miller)
+
 New features
 
  1. LUCENE-1411: Added expert API to open an IndexWriter on a prior

src/java/org/apache/lucene/search/spans/SpanOrQuery.java

@@ -216,16 +216,21 @@ public class SpanOrQuery extends SpanQuery implements Cloneable {
             return initSpanQueue(target);
           }
   
+          boolean skipCalled = false;
           while (queue.size() != 0 && top().doc() < target) {
             if (top().skipTo(target)) {
               queue.adjustTop();
             } else {
               queue.pop();
             }
+            skipCalled = true;
           }
   
+          if (skipCalled) {
             return queue.size() != 0;
           }
+          return next();
+        }
 
         public int doc() { return top().doc(); }
         public int start() { return top().start(); }

src/test/org/apache/lucene/search/spans/TestSpans.java

@@ -331,6 +331,23 @@ public class TestSpans extends LuceneTestCase {
     assertFalse("final next", spans.next());
   }
   
+  public void testSpanOrMovesForward() throws Exception {
+    Spans spans = orSpans(new String[] {"w1", "xx"});
+
+    spans.next();
+    int doc = spans.doc();
+    assertEquals(0, doc);
+    
+    spans.skipTo(0);
+    doc = spans.doc();
+    
+    // LUCENE-1583:
+    // according to Spans, a skipTo to the same doc or less
+    // should still call next() on the underlying Spans
+    assertEquals(1, doc);
+
+  }
+  
   public void testSpanOrDouble() throws Exception {
     Spans spans = orSpans(new String[] {"w5", "yy"});
     tstNextSpans(spans, 0, 4, 5);