BlockOrdScoreCollector

gistfile1.txt

 /*
  * Collapses groups that have been block indexed.
  */
  private static class BlockOrdScoreCollector extends DelegatingCollector {
    private int currentGroup = -1;
    private float topScore = Float.MIN_VALUE;
    private int topDoc = -1;
    private ScoreAndDoc dummy = new ScoreAndDoc();
    private String collapseField;
    private SortedDocValues segmentValues;
    
    public BlockOrdScoreCollector(String collapseField) throws IOException {
      this.collapseField = collapseField;
    }
    
    @Override public ScoreMode scoreMode() { return ScoreMode.COMPLETE; }
    
    @Override
    protected void doSetNextReader(LeafReaderContext context) throws IOException {
      
      if(topDoc > -1) {
        //Collect the topDoc in the last group of previous segment
        dummy.docId = topDoc;
        dummy.score = topScore;
        leafDelegate.collect(topDoc);
      }
      
      //Now setup for the next segment.
      leafDelegate = delegate.getLeafCollector(context);
      leafDelegate.setScorer(dummy);
      this.segmentValues = DocValues.getSorted(context.reader(), collapseField);
      //Reset the grouping values
      topDoc = -1;
      topScore = Float.MIN_VALUE;
      currentGroup = -1;
    }
    
    @Override
    public void collect(int contextDoc) throws IOException {
      int ord = -1;
      if (segmentValues.advanceExact(contextDoc)) {
        ord = segmentValues.ordValue();
      } else {
        ord = -1;
      }
      
      if(ord > -1) {
        float score = scorer.score();
        if(ord == currentGroup) {
          //We have a document within the current group
          if (score > topScore) {
            //We have a higher scoring document so set the topScore and topDoc
            topScore = score;
            topDoc = contextDoc;
          }
        } else {
          //We have a document that starts a new group
          if(topDoc > -1) {
            //Collect the topDoc in the previous group
            dummy.docId = topDoc;
            dummy.score = topScore;
            leafDelegate.collect(topDoc);
          }
          //Set new doc, score and group
          topDoc = contextDoc;
          topScore = score;
          currentGroup = ord;
        }
      }
    }
    
    @Override
    public void finish() throws IOException {
      //Collect the last document
      dummy.score = topScore;
      dummy.docId = topDoc;
      leafDelegate.collect(topDoc);
      if(delegate instanceof DelegatingCollector) {
        ((DelegatingCollector) delegate).finish();
      }
    }
  }