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.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.util.ToStringUtils;
import java.io.IOException;
import java.util.Set;
/**
* A query that wraps another query or a filter and simply returns a constant score equal to the
* query boost for every document that matches the filter or query.
* For queries it therefore simply strips of all scores and returns a constant one.
*
* <p><b>NOTE</b>: if the wrapped filter is an instance of
* {@link CachingWrapperFilter}, you'll likely want to
* enforce deletions in the filter (using either {@link
* CachingWrapperFilter.DeletesMode#RECACHE} or {@link
* CachingWrapperFilter.DeletesMode#DYNAMIC}).
*/
public class ConstantScoreQuery extends Query {
protected final Filter filter;
protected final Query query;
/** Strips off scores from the passed in Query. The hits will get a constant score
* dependent on the boost factor of this query. */
public ConstantScoreQuery(Query query) {
if (query == null)
throw new NullPointerException("Query may not be null");
this.filter = null;
this.query = query;
}
/** Wraps a Filter as a Query. The hits will get a constant score
* dependent on the boost factor of this query.
* If you simply want to strip off scores from a Query, no longer use
* {@code new ConstantScoreQuery(new QueryWrapperFilter(query))}, instead
* use {@link #ConstantScoreQuery(Query)}!
*/
public ConstantScoreQuery(Filter filter) {
if (filter == null)
throw new NullPointerException("Filter may not be null");
this.filter = filter;
this.query = null;
}
/** Returns the encapsulated filter, returns {@code null} if a query is wrapped. */
public Filter getFilter() {
return filter;
}
/** Returns the encapsulated query, returns {@code null} if a filter is wrapped. */
public Query getQuery() {
return query;
}
@Override
public Query rewrite(IndexReader reader) throws IOException {
if (query != null) {
Query rewritten = query.rewrite(reader);
if (rewritten != query) {
rewritten = new ConstantScoreQuery(rewritten);
rewritten.setBoost(this.getBoost());
return rewritten;
}
}
return this;
}
@Override
public void extractTerms(Set<Term> terms) {
// TODO: OK to not add any terms when wrapped a filter
// and used with MultiSearcher, but may not be OK for
// highlighting.
// If a query was wrapped, we delegate to query.
if (query != null)
query.extractTerms(terms);
}
protected class ConstantWeight extends Weight {
private final Weight innerWeight;
private final Similarity similarity;
private float queryNorm;
private float queryWeight;
public ConstantWeight(Searcher searcher) throws IOException {
this.similarity = getSimilarity(searcher);
this.innerWeight = (query == null) ? null : query.createWeight(searcher);
}
@Override
public Query getQuery() {
return ConstantScoreQuery.this;
}
@Override
public float getValue() {
return queryWeight;
}
@Override
public float sumOfSquaredWeights() throws IOException {
// we calculate sumOfSquaredWeights of the inner weight, but ignore it (just to initialize everything)
if (innerWeight != null) innerWeight.sumOfSquaredWeights();
queryWeight = getBoost();
return queryWeight * queryWeight;
}
@Override
public void normalize(float norm) {
this.queryNorm = norm;
queryWeight *= this.queryNorm;
// we normalize the inner weight, but ignore it (just to initialize everything)
if (innerWeight != null) innerWeight.normalize(norm);
}
@Override
public Scorer scorer(IndexReader reader, boolean scoreDocsInOrder, boolean topScorer) throws IOException {
final DocIdSetIterator disi;
if (filter != null) {
assert query == null;
final DocIdSet dis = filter.getDocIdSet(reader);
if (dis == null)
return null;
disi = dis.iterator();
} else {
assert query != null && innerWeight != null;
disi =
innerWeight.scorer(reader, scoreDocsInOrder, topScorer);
}
if (disi == null)
return null;
return new ConstantScorer(similarity, disi, this);
}
@Override
public boolean scoresDocsOutOfOrder() {
return (innerWeight != null) ? innerWeight.scoresDocsOutOfOrder() : false;
}
@Override
public Explanation explain(IndexReader reader, int doc) throws IOException {
final Scorer cs = scorer(reader, true, false);
final boolean exists = (cs != null && cs.advance(doc) == doc);
final ComplexExplanation result = new ComplexExplanation();
if (exists) {
result.setDescription(ConstantScoreQuery.this.toString() + ", product of:");
result.setValue(queryWeight);
result.setMatch(Boolean.TRUE);
result.addDetail(new Explanation(getBoost(), "boost"));
result.addDetail(new Explanation(queryNorm, "queryNorm"));
} else {
result.setDescription(ConstantScoreQuery.this.toString() + " doesn't match id " + doc);
result.setValue(0);
result.setMatch(Boolean.FALSE);
}
return result;
}
}
protected class ConstantScorer extends Scorer {
final DocIdSetIterator docIdSetIterator;
final float theScore;
public ConstantScorer(Similarity similarity, DocIdSetIterator docIdSetIterator, Weight w) throws IOException {
super(similarity,w);
theScore = w.getValue();
this.docIdSetIterator = docIdSetIterator;
}
@Override
public int nextDoc() throws IOException {
return docIdSetIterator.nextDoc();
}
@Override
public int docID() {
return docIdSetIterator.docID();
}
@Override
public float score() throws IOException {
return theScore;
}
@Override
public int advance(int target) throws IOException {
return docIdSetIterator.advance(target);
}
private Collector wrapCollector(final Collector collector) {
return new Collector() {
@Override
public void setScorer(Scorer scorer) throws IOException {
// we must wrap again here, but using the scorer passed in as parameter:
collector.setScorer(new ConstantScorer(ConstantScorer.this.getSimilarity(),
scorer, ConstantScorer.this.weight));
}
@Override
public void collect(int doc) throws IOException {
collector.collect(doc);
}
@Override
public void setNextReader(IndexReader reader, int docBase) throws IOException {
collector.setNextReader(reader, docBase);
}
@Override
public boolean acceptsDocsOutOfOrder() {
return collector.acceptsDocsOutOfOrder();
}
};
}
// this optimization allows out of order scoring as top scorer!
@Override
public void score(Collector collector) throws IOException {
if (docIdSetIterator instanceof Scorer) {
((Scorer) docIdSetIterator).score(wrapCollector(collector));
} else {
super.score(collector);
}
}
// this optimization allows out of order scoring as top scorer,
// TODO: theoretically this method should not be called because its protected and
// this class does not use it, it should be public in Scorer!
@Override
protected boolean score(Collector collector, int max, int firstDocID) throws IOException {
if (docIdSetIterator instanceof Scorer) {
return ((Scorer) docIdSetIterator).score(wrapCollector(collector), max, firstDocID);
} else {
return super.score(collector, max, firstDocID);
}
}
}
@Override
public Weight createWeight(Searcher searcher) throws IOException {
return new ConstantScoreQuery.ConstantWeight(searcher);
}
@Override
public String toString(String field) {
return new StringBuilder("ConstantScore(")
.append((query == null) ? filter.toString() : query.toString(field))
.append(')')
.append(ToStringUtils.boost(getBoost()))
.toString();
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (!super.equals(o))
return false;
if (o instanceof ConstantScoreQuery) {
final ConstantScoreQuery other = (ConstantScoreQuery) o;
return
((this.filter == null) ? other.filter == null : this.filter.equals(other.filter)) &&
((this.query == null) ? other.query == null : this.query.equals(other.query));
}
return false;
}
@Override
public int hashCode() {
return 31 * super.hashCode() +
((query == null) ? filter : query).hashCode();
}
}