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/*
* COPIED FROM APACHE LUCENE 4.7.2
*
* Git URL: [email protected]:apache/lucene.git, tag: releases/lucene-solr/4.7.2, path: lucene/core/src/java
*
* (see https://issues.apache.org/jira/browse/OAK-10786 for details)
*/
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 java.util.Collection;
import java.util.Collections;
import org.apache.lucene.index.DocsEnum;
/**
* Expert: Common scoring functionality for different types of queries.
*
*
* A Scorer iterates over documents matching a
* query in increasing order of doc Id.
*
*
* Document scores are computed using a given Similarity
* implementation.
*
*
* NOTE: The values Float.Nan,
* Float.NEGATIVE_INFINITY and Float.POSITIVE_INFINITY are
* not valid scores. Certain collectors (eg {@link
* TopScoreDocCollector}) will not properly collect hits
* with these scores.
*/
public abstract class Scorer extends DocsEnum {
/** the Scorer's parent Weight. in some cases this may be null */
// TODO can we clean this up?
protected final Weight weight;
/**
* Constructs a Scorer
* @param weight The scorers Weight.
*/
protected Scorer(Weight weight) {
this.weight = weight;
}
/** Scores and collects all matching documents.
* @param collector The collector to which all matching documents are passed.
*/
public void score(Collector collector) throws IOException {
assert docID() == -1; // not started
collector.setScorer(this);
int doc;
while ((doc = nextDoc()) != NO_MORE_DOCS) {
collector.collect(doc);
}
}
/**
* Expert: Collects matching documents in a range. Hook for optimization.
* Note, firstDocID is added to ensure that {@link #nextDoc()}
* was called before this method.
*
* @param collector
* The collector to which all matching documents are passed.
* @param max
* Do not score documents past this.
* @param firstDocID
* The first document ID (ensures {@link #nextDoc()} is called before
* this method.
* @return true if more matching documents may remain.
*/
public boolean score(Collector collector, int max, int firstDocID) throws IOException {
assert docID() == firstDocID;
collector.setScorer(this);
int doc;
for (doc = firstDocID; doc < max; doc = nextDoc()) {
collector.collect(doc);
}
return doc != NO_MORE_DOCS;
}
/** Returns the score of the current document matching the query.
* Initially invalid, until {@link #nextDoc()} or {@link #advance(int)}
* is called the first time, or when called from within
* {@link Collector#collect}.
*/
public abstract float score() throws IOException;
/** returns parent Weight
* @lucene.experimental
*/
public Weight getWeight() {
return weight;
}
/** Returns child sub-scorers
* @lucene.experimental */
public Collection getChildren() {
return Collections.emptyList();
}
/** A child Scorer and its relationship to its parent.
* the meaning of the relationship depends upon the parent query.
* @lucene.experimental */
public static class ChildScorer {
/**
* Child Scorer. (note this is typically a direct child, and may
* itself also have children).
*/
public final Scorer child;
/**
* An arbitrary string relating this scorer to the parent.
*/
public final String relationship;
/**
* Creates a new ChildScorer node with the specified relationship.
*
* The relationship can be any be any string that makes sense to
* the parent Scorer.
*/
public ChildScorer(Scorer child, String relationship) {
this.child = child;
this.relationship = relationship;
}
}
}