Review

finding-17

/mubench/checkouts/lucene/1918/build/src/java/org/apache/lucene/search/FilteredQuery.java

createWeight(Searcher)

class FilteredQuery {
  /**
   * Returns a Weight that applies the filter to the enclosed query's Weight.
   * This is accomplished by overriding the Scorer returned by the Weight.
   */
  public Weight createWeight(final Searcher searcher) throws IOException {
    final Weight weight = query.createWeight (searcher);
    final Similarity similarity = query.getSimilarity(searcher);
    return new Weight() {
      private float value;
        
      // pass these methods through to enclosed query's weight
      public float getValue() { return value; }
      public float sumOfSquaredWeights() throws IOException { 
        return weight.sumOfSquaredWeights() * getBoost() * getBoost(); 
      }
      public void normalize (float v) { 
        weight.normalize(v);
        value = weight.getValue() * getBoost();
      }
      public Explanation explain (IndexReader ir, int i) throws IOException {
        Explanation inner = weight.explain (ir, i);
        if (getBoost()!=1) {
          Explanation preBoost = inner;
          inner = new Explanation(inner.getValue()*getBoost(),"product of:");
          inner.addDetail(new Explanation(getBoost(),"boost"));
          inner.addDetail(preBoost);
        }
        Filter f = FilteredQuery.this.filter;
        DocIdSet docIdSet = f.getDocIdSet(ir);
        DocIdSetIterator docIdSetIterator = docIdSet == null ? DocIdSet.EMPTY_DOCIDSET.iterator() : docIdSet.iterator();
        if (docIdSetIterator == null) {
          docIdSetIterator = DocIdSet.EMPTY_DOCIDSET.iterator();
        }
        if (docIdSetIterator.advance(i) == i) {
          return inner;
        } else {
          Explanation result = new Explanation
            (0.0f, "failure to match filter: " + f.toString());
          result.addDetail(inner);
          return result;
        }
      }

      // return this query
      public Query getQuery() { return FilteredQuery.this; }

      // return a filtering scorer
      public Scorer scorer(IndexReader indexReader, boolean scoreDocsInOrder, boolean topScorer)
          throws IOException {
        final Scorer scorer = weight.scorer(indexReader, true, false);
        if (scorer == null) {
          return null;
        }
        DocIdSet docIdSet = filter.getDocIdSet(indexReader);
        if (docIdSet == null) {
          return null;
        }
        final DocIdSetIterator docIdSetIterator = docIdSet.iterator();
        if (docIdSetIterator == null) {
          return null;
        }

        return new Scorer(similarity) {

          private int doc = -1;
          
          private int advanceToCommon(int scorerDoc, int disiDoc) throws IOException {
            while (scorerDoc != disiDoc) {
              if (scorerDoc < disiDoc) {
                scorerDoc = scorer.advance(disiDoc);
              } else {
                disiDoc = docIdSetIterator.advance(scorerDoc);
              }
            }
            return scorerDoc;
          }

          /** @deprecated use {@link #nextDoc()} instead. */
          public boolean next() throws IOException {
            return nextDoc() != NO_MORE_DOCS;
          }

          public int nextDoc() throws IOException {
            int scorerDoc, disiDoc;
            return doc = (disiDoc = docIdSetIterator.nextDoc()) != NO_MORE_DOCS
                && (scorerDoc = scorer.nextDoc()) != NO_MORE_DOCS
                && advanceToCommon(scorerDoc, disiDoc) != NO_MORE_DOCS ? scorer.docID() : NO_MORE_DOCS;
          }
          
          /** @deprecated use {@link #docID()} instead. */
          public int doc() { return scorer.doc(); }
          public int docID() { return doc; }
          
          /** @deprecated use {@link #advance(int)} instead. */
          public boolean skipTo(int i) throws IOException {
            return advance(i) != NO_MORE_DOCS;
          }
          
          public int advance(int target) throws IOException {
            int disiDoc, scorerDoc;
            return doc = (disiDoc = docIdSetIterator.advance(target)) != NO_MORE_DOCS
                && (scorerDoc = scorer.advance(disiDoc)) != NO_MORE_DOCS 
                && advanceToCommon(scorerDoc, disiDoc) != NO_MORE_DOCS ? scorer.docID() : NO_MORE_DOCS;
          }

          public float score() throws IOException { return getBoost() * scorer.score(); }

          // add an explanation about whether the document was filtered
          public Explanation explain (int i) throws IOException {
            Explanation exp = scorer.explain(i);
            
            if (docIdSetIterator.advance(i) == i) {
              exp.setDescription ("allowed by filter: "+exp.getDescription());
              exp.setValue(getBoost() * exp.getValue());
            } else {
              exp.setDescription ("removed by filter: "+exp.getDescription());
              exp.setValue(0.0f);
            }
            return exp;
          }
        };
      }
    };
  }

}