/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.lucene.search;
import java.io.IOException;
import java.util.List;
/**
* The Scorer for DisjunctionMaxQuery. The union of all documents generated by the the subquery scorers
* is generated in document number order. The score for each document is the maximum of the scores computed
* by the subquery scorers that generate that document, plus tieBreakerMultiplier times the sum of the scores
* for the other subqueries that generate the document.
*/
final class DisjunctionMaxScorer extends DisjunctionScorer {
/* Multiplier applied to non-maximum-scoring subqueries for a document as they are summed into the result. */
private final float tieBreakerMultiplier;
/**
* Creates a new instance of DisjunctionMaxScorer
*
* @param weight
* The Weight to be used.
* @param tieBreakerMultiplier
* Multiplier applied to non-maximum-scoring subqueries for a
* document as they are summed into the result.
* @param subScorers
* The sub scorers this Scorer should iterate on
*/
DisjunctionMaxScorer(Weight weight, float tieBreakerMultiplier, List<Scorer> subScorers, boolean needsScores) {
super(weight, subScorers, needsScores);
this.tieBreakerMultiplier = tieBreakerMultiplier;
}
@Override
protected float score(DisiWrapper topList) throws IOException {
float scoreSum = 0;
float scoreMax = Float.NEGATIVE_INFINITY;
for (DisiWrapper w = topList; w != null; w = w.next) {
final float subScore = w.scorer.score();
scoreSum += subScore;
if (subScore > scoreMax) {
scoreMax = subScore;
}
}
return scoreMax + (scoreSum - scoreMax) * tieBreakerMultiplier;
}
}