package org.apache.lucene.search;
/**
* 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.
*/
import org.apache.lucene.util.PriorityQueue;
/** A {@link HitCollector} implementation that collects the top-scoring
* documents, returning them as a {@link TopDocs}. This is used by {@link
* IndexSearcher} to implement {@link TopDocs}-based search.
*
* <p>This may be extended, overriding the collect method to, e.g.,
* conditionally invoke <code>super()</code> in order to filter which
* documents are collected.
*
* @deprecated Please use {@link TopScoreDocCollector}
* instead, which has better performance.
**/
public class TopDocCollector extends HitCollector {
private ScoreDoc reusableSD;
/** The total number of hits the collector encountered. */
protected int totalHits;
/** The priority queue which holds the top-scoring documents. */
protected PriorityQueue hq;
/** Construct to collect a given number of hits.
* @param numHits the maximum number of hits to collect
*/
public TopDocCollector(int numHits) {
this(new HitQueue(numHits, false));
}
/** @deprecated use TopDocCollector(hq) instead. numHits is not used by this
* constructor. It will be removed in a future release.
*/
TopDocCollector(int numHits, PriorityQueue hq) {
this.hq = hq;
}
/** Constructor to collect the top-scoring documents by using the given PQ.
* @param hq the PQ to use by this instance.
*/
protected TopDocCollector(PriorityQueue hq) {
this.hq = hq;
}
// javadoc inherited
public void collect(int doc, float score, int[] sorts) {
if (score > 0.0f) {
totalHits++;
if (reusableSD == null) {
reusableSD = new ScoreDoc(doc, score, sorts);
} else if (score >= reusableSD.score) {
// reusableSD holds the last "rejected" entry, so, if
// this new score is not better than that, there's no
// need to try inserting it
reusableSD.doc = doc;
reusableSD.score = score;
} else {
return;
}
reusableSD = (ScoreDoc) hq.insertWithOverflow(reusableSD);
}
}
/** The total number of documents that matched this query. */
public int getTotalHits() { return totalHits; }
/** The top-scoring hits. */
public TopDocs topDocs() {
ScoreDoc[] scoreDocs = new ScoreDoc[hq.size()];
for (int i = hq.size()-1; i >= 0; i--) // put docs in array
scoreDocs[i] = (ScoreDoc)hq.pop();
float maxScore = (totalHits==0)
? Float.NEGATIVE_INFINITY
: scoreDocs[0].score;
return new TopDocs(totalHits, scoreDocs, maxScore);
}
}