package org.apache.lucene.search.function;
/**
* 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.index.TermDocs;
import org.apache.lucene.search.*;
import org.apache.lucene.util.ToStringUtils;
import java.io.IOException;
import java.util.Set;
/**
* Expert: A Query that sets the scores of document to the
* values obtained from a {@link org.apache.lucene.search.function.ValueSource ValueSource}.
* <p>
* This query provides a score for <em>each and every</em> undeleted document in the index.
* <p>
* The value source can be based on a (cached) value of an indexed field, but it
* can also be based on an external source, e.g. values read from an external database.
* <p>
* Score is set as: Score(doc,query) = query.getBoost()<sup>2</sup> * valueSource(doc).
*
* <p><font color="#FF0000">
* WARNING: The status of the <b>search.function</b> package is experimental.
* The APIs introduced here might change in the future and will not be
* supported anymore in such a case.</font>
*/
public class ValueSourceQuery extends Query {
ValueSource valSrc;
/**
* Create a value source query
* @param valSrc provides the values defines the function to be used for scoring
*/
public ValueSourceQuery(ValueSource valSrc) {
this.valSrc=valSrc;
}
/*(non-Javadoc) @see org.apache.lucene.search.Query#rewrite(org.apache.lucene.index.IndexReader) */
@Override
public Query rewrite(IndexReader reader) throws IOException {
return this;
}
/*(non-Javadoc) @see org.apache.lucene.search.Query#extractTerms(java.util.Set) */
@Override
public void extractTerms(Set<Term> terms) {
// no terms involved here
}
class ValueSourceWeight extends Weight {
Similarity similarity;
float queryNorm;
float queryWeight;
public ValueSourceWeight(Searcher searcher) {
this.similarity = getSimilarity(searcher);
}
/*(non-Javadoc) @see org.apache.lucene.search.Weight#getQuery() */
@Override
public Query getQuery() {
return ValueSourceQuery.this;
}
/*(non-Javadoc) @see org.apache.lucene.search.Weight#getValue() */
@Override
public float getValue() {
return queryWeight;
}
/*(non-Javadoc) @see org.apache.lucene.search.Weight#sumOfSquaredWeights() */
@Override
public float sumOfSquaredWeights() throws IOException {
queryWeight = getBoost();
return queryWeight * queryWeight;
}
/*(non-Javadoc) @see org.apache.lucene.search.Weight#normalize(float) */
@Override
public void normalize(float norm) {
this.queryNorm = norm;
queryWeight *= this.queryNorm;
}
@Override
public Scorer scorer(IndexReader reader, boolean scoreDocsInOrder, boolean topScorer) throws IOException {
return new ValueSourceScorer(similarity, reader, this);
}
/*(non-Javadoc) @see org.apache.lucene.search.Weight#explain(org.apache.lucene.index.IndexReader, int) */
@Override
public Explanation explain(IndexReader reader, int doc) throws IOException {
DocValues vals = valSrc.getValues(reader);
float sc = queryWeight * vals.floatVal(doc);
Explanation result = new ComplexExplanation(
true, sc, ValueSourceQuery.this.toString() + ", product of:");
result.addDetail(vals.explain(doc));
result.addDetail(new Explanation(getBoost(), "boost"));
result.addDetail(new Explanation(queryNorm,"queryNorm"));
return result;
}
}
/**
* A scorer that (simply) matches all documents, and scores each document with
* the value of the value source in effect. As an example, if the value source
* is a (cached) field source, then value of that field in that document will
* be used. (assuming field is indexed for this doc, with a single token.)
*/
private class ValueSourceScorer extends Scorer {
private final ValueSourceWeight weight;
private final float qWeight;
private final DocValues vals;
private final TermDocs termDocs;
private int doc = -1;
// constructor
private ValueSourceScorer(Similarity similarity, IndexReader reader, ValueSourceWeight w) throws IOException {
super(similarity);
this.weight = w;
this.qWeight = w.getValue();
// this is when/where the values are first created.
vals = valSrc.getValues(reader);
termDocs = reader.termDocs(null);
}
@Override
public int nextDoc() throws IOException {
return doc = termDocs.next() ? termDocs.doc() : NO_MORE_DOCS;
}
@Override
public int docID() {
return doc;
}
@Override
public int advance(int target) throws IOException {
return doc = termDocs.skipTo(target) ? termDocs.doc() : NO_MORE_DOCS;
}
/*(non-Javadoc) @see org.apache.lucene.search.Scorer#score() */
@Override
public float score() throws IOException {
return qWeight * vals.floatVal(termDocs.doc());
}
}
@Override
public Weight createWeight(Searcher searcher) {
return new ValueSourceQuery.ValueSourceWeight(searcher);
}
@Override
public String toString(String field) {
return valSrc.toString() + ToStringUtils.boost(getBoost());
}
/** Returns true if <code>o</code> is equal to this. */
@Override
public boolean equals(Object o) {
if (getClass() != o.getClass()) {
return false;
}
ValueSourceQuery other = (ValueSourceQuery)o;
return this.getBoost() == other.getBoost()
&& this.valSrc.equals(other.valSrc);
}
/** Returns a hash code value for this object. */
@Override
public int hashCode() {
return (getClass().hashCode() + valSrc.hashCode()) ^ Float.floatToIntBits(getBoost());
}
}