+++ /dev/null
-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 java.io.IOException;
-
-import org.apache.lucene.index.IndexReader;
-
-/**
- * A {@link Collector} implementation that collects the top-scoring hits,
- * returning them as a {@link TopDocs}. This is used by {@link IndexSearcher} to
- * implement {@link TopDocs}-based search. Hits are sorted by score descending
- * and then (when the scores are tied) docID ascending. When you create an
- * instance of this collector you should know in advance whether documents are
- * going to be collected in doc Id order or not.
- *
- * <p><b>NOTE</b>: The values {@link Float#NaN} and
- * {Float#NEGATIVE_INFINITY} are not valid scores. This
- * collector will not properly collect hits with such
- * scores.
- */
-public abstract class TopScoreDocCollector extends TopDocsCollector<ScoreDoc> {
-
- // Assumes docs are scored in order.
- private static class InOrderTopScoreDocCollector extends TopScoreDocCollector {
- private InOrderTopScoreDocCollector(int numHits) {
- super(numHits);
- }
-
- @Override
- public void collect(int doc) throws IOException {
- float score = scorer.score();
-
- // This collector cannot handle these scores:
- assert score != Float.NEGATIVE_INFINITY;
- assert !Float.isNaN(score);
-
- totalHits++;
- if (score <= pqTop.score) {
- // Since docs are returned in-order (i.e., increasing doc Id), a document
- // with equal score to pqTop.score cannot compete since HitQueue favors
- // documents with lower doc Ids. Therefore reject those docs too.
- return;
- }
- pqTop.doc = doc + docBase;
- pqTop.score = score;
- pqTop = pq.updateTop();
- }
-
- @Override
- public boolean acceptsDocsOutOfOrder() {
- return false;
- }
- }
-
- // Assumes docs are scored out of order.
- private static class OutOfOrderTopScoreDocCollector extends TopScoreDocCollector {
- private OutOfOrderTopScoreDocCollector(int numHits) {
- super(numHits);
- }
-
- @Override
- public void collect(int doc) throws IOException {
- float score = scorer.score();
-
- // This collector cannot handle NaN
- assert !Float.isNaN(score);
-
- totalHits++;
- if (score < pqTop.score) {
- // Doesn't compete w/ bottom entry in queue
- return;
- }
- doc += docBase;
- if (score == pqTop.score && doc > pqTop.doc) {
- // Break tie in score by doc ID:
- return;
- }
- pqTop.doc = doc;
- pqTop.score = score;
- pqTop = pq.updateTop();
- }
-
- @Override
- public boolean acceptsDocsOutOfOrder() {
- return true;
- }
- }
-
- /**
- * Creates a new {@link TopScoreDocCollector} given the number of hits to
- * collect and whether documents are scored in order by the input
- * {@link Scorer} to {@link #setScorer(Scorer)}.
- *
- * <p><b>NOTE</b>: The instances returned by this method
- * pre-allocate a full array of length
- * <code>numHits</code>, and fill the array with sentinel
- * objects.
- */
- public static TopScoreDocCollector create(int numHits, boolean docsScoredInOrder) {
-
- if (numHits <= 0) {
- throw new IllegalArgumentException("numHits must be > 0; please use TotalHitCountCollector if you just need the total hit count");
- }
-
- if (docsScoredInOrder) {
- return new InOrderTopScoreDocCollector(numHits);
- } else {
- return new OutOfOrderTopScoreDocCollector(numHits);
- }
-
- }
-
- ScoreDoc pqTop;
- int docBase = 0;
- Scorer scorer;
-
- // prevents instantiation
- private TopScoreDocCollector(int numHits) {
- super(new HitQueue(numHits, true));
- // HitQueue implements getSentinelObject to return a ScoreDoc, so we know
- // that at this point top() is already initialized.
- pqTop = pq.top();
- }
-
- @Override
- protected TopDocs newTopDocs(ScoreDoc[] results, int start) {
- if (results == null) {
- return EMPTY_TOPDOCS;
- }
-
- // We need to compute maxScore in order to set it in TopDocs. If start == 0,
- // it means the largest element is already in results, use its score as
- // maxScore. Otherwise pop everything else, until the largest element is
- // extracted and use its score as maxScore.
- float maxScore = Float.NaN;
- if (start == 0) {
- maxScore = results[0].score;
- } else {
- for (int i = pq.size(); i > 1; i--) { pq.pop(); }
- maxScore = pq.pop().score;
- }
-
- return new TopDocs(totalHits, results, maxScore);
- }
-
- @Override
- public void setNextReader(IndexReader reader, int base) {
- docBase = base;
- }
-
- @Override
- public void setScorer(Scorer scorer) throws IOException {
- this.scorer = scorer;
- }
-}
fnp / pylucene.git / blobdiff