1
package org.apache.lucene.search;
4
* Licensed to the Apache Software Foundation (ASF) under one or more
5
* contributor license agreements. See the NOTICE file distributed with
6
* this work for additional information regarding copyright ownership.
7
* The ASF licenses this file to You under the Apache License, Version 2.0
8
* (the "License"); you may not use this file except in compliance with
9
* the License. You may obtain a copy of the License at
11
* http://www.apache.org/licenses/LICENSE-2.0
13
* Unless required by applicable law or agreed to in writing, software
14
* distributed under the License is distributed on an "AS IS" BASIS,
15
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16
* See the License for the specific language governing permissions and
17
* limitations under the License.
20
import java.io.IOException;
21
import org.apache.lucene.index.IndexReader;
22
import org.apache.lucene.index.Term;
23
import org.apache.lucene.search.MultiTermQuery.RewriteMethod;
25
/** @lucene.internal Only public to be accessible by spans package. */
26
public abstract class ScoringRewrite<Q extends Query> extends TermCollectingRewrite<Q> {
28
/** A rewrite method that first translates each term into
29
* {@link BooleanClause.Occur#SHOULD} clause in a
30
* BooleanQuery, and keeps the scores as computed by the
31
* query. Note that typically such scores are
32
* meaningless to the user, and require non-trivial CPU
33
* to compute, so it's almost always better to use {@link
34
* MultiTermQuery#CONSTANT_SCORE_AUTO_REWRITE_DEFAULT} instead.
36
* <p><b>NOTE</b>: This rewrite method will hit {@link
37
* BooleanQuery.TooManyClauses} if the number of terms
38
* exceeds {@link BooleanQuery#getMaxClauseCount}.
40
* @see #setRewriteMethod */
41
public final static ScoringRewrite<BooleanQuery> SCORING_BOOLEAN_QUERY_REWRITE = new ScoringRewrite<BooleanQuery>() {
43
protected BooleanQuery getTopLevelQuery() {
44
return new BooleanQuery(true);
48
protected void addClause(BooleanQuery topLevel, Term term, float boost) {
49
final TermQuery tq = new TermQuery(term);
51
topLevel.add(tq, BooleanClause.Occur.SHOULD);
54
// Make sure we are still a singleton even after deserializing
55
protected Object readResolve() {
56
return SCORING_BOOLEAN_QUERY_REWRITE;
60
/** Like {@link #SCORING_BOOLEAN_QUERY_REWRITE} except
61
* scores are not computed. Instead, each matching
62
* document receives a constant score equal to the
65
* <p><b>NOTE</b>: This rewrite method will hit {@link
66
* BooleanQuery.TooManyClauses} if the number of terms
67
* exceeds {@link BooleanQuery#getMaxClauseCount}.
69
* @see #setRewriteMethod */
70
public final static RewriteMethod CONSTANT_SCORE_BOOLEAN_QUERY_REWRITE = new RewriteMethod() {
72
public Query rewrite(IndexReader reader, MultiTermQuery query) throws IOException {
73
final BooleanQuery bq = SCORING_BOOLEAN_QUERY_REWRITE.rewrite(reader, query);
74
// TODO: if empty boolean query return NullQuery?
75
if (bq.clauses().isEmpty())
77
// strip the scores off
78
final Query result = new ConstantScoreQuery(bq);
79
result.setBoost(query.getBoost());
83
// Make sure we are still a singleton even after deserializing
84
protected Object readResolve() {
85
return CONSTANT_SCORE_BOOLEAN_QUERY_REWRITE;
90
public Q rewrite(final IndexReader reader, final MultiTermQuery query) throws IOException {
91
final Q result = getTopLevelQuery();
92
final int[] size = new int[1]; // "trick" to be able to make it final
93
collectTerms(reader, query, new TermCollector() {
94
public boolean collect(Term t, float boost) throws IOException {
95
addClause(result, t, query.getBoost() * boost);
100
query.incTotalNumberOfTerms(size[0]);