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Apache Lucene (module: sandbox)
/*
* 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.
*/
package org.apache.lucene.sandbox.search;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Objects;
import java.util.stream.Collectors;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.Explanation;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.LongValues;
import org.apache.lucene.search.LongValuesSource;
import org.apache.lucene.search.MatchNoDocsQuery;
import org.apache.lucene.search.Matches;
import org.apache.lucene.search.MatchesUtils;
import org.apache.lucene.search.Multiset;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.QueryVisitor;
import org.apache.lucene.search.ScoreMode;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.Weight;
import org.apache.lucene.util.Accountable;
import org.apache.lucene.util.RamUsageEstimator;
/**
* A {@link Query} that allows to have a configurable number or required matches per document. This
* is typically useful in order to build queries whose query terms must all appear in documents.
*
* @lucene.experimental
*/
public final class CoveringQuery extends Query implements Accountable {
private static final long BASE_RAM_BYTES =
RamUsageEstimator.shallowSizeOfInstance(CoveringQuery.class);
private final Collection queries;
private final LongValuesSource minimumNumberMatch;
private final int hashCode;
private final long ramBytesUsed;
/**
* Sole constructor.
*
* @param queries Sub queries to match.
* @param minimumNumberMatch Per-document long value that records how many queries should match.
* Values that are less than 1 are treated like 1: only documents that have at
* least one matching clause will be considered matches. Documents that do not have a value
* for minimumNumberMatch do not match.
*/
public CoveringQuery(Collection queries, LongValuesSource minimumNumberMatch) {
if (queries.size() > IndexSearcher.getMaxClauseCount()) {
throw new IndexSearcher.TooManyClauses();
}
if (minimumNumberMatch.needsScores()) {
throw new IllegalArgumentException(
"The minimum number of matches may not depend on the score.");
}
this.queries = new Multiset<>();
this.queries.addAll(queries);
this.minimumNumberMatch = Objects.requireNonNull(minimumNumberMatch);
this.hashCode = computeHashCode();
this.ramBytesUsed =
BASE_RAM_BYTES
+ RamUsageEstimator.sizeOfObject(
this.queries, RamUsageEstimator.QUERY_DEFAULT_RAM_BYTES_USED);
}
@Override
public String toString(String field) {
String queriesToString =
queries.stream().map(q -> q.toString(field)).sorted().collect(Collectors.joining(", "));
return "CoveringQuery(queries=["
+ queriesToString
+ "], minimumNumberMatch="
+ minimumNumberMatch
+ ")";
}
@Override
public boolean equals(Object obj) {
if (sameClassAs(obj) == false) {
return false;
}
CoveringQuery that = (CoveringQuery) obj;
return hashCode == that.hashCode // not necessary but makes equals faster
&& Objects.equals(queries, that.queries)
&& Objects.equals(minimumNumberMatch, that.minimumNumberMatch);
}
private int computeHashCode() {
int h = classHash();
h = 31 * h + queries.hashCode();
h = 31 * h + minimumNumberMatch.hashCode();
return h;
}
@Override
public int hashCode() {
return hashCode;
}
@Override
public long ramBytesUsed() {
return ramBytesUsed;
}
@Override
public Query rewrite(IndexReader reader) throws IOException {
if (minimumNumberMatch instanceof LongValuesSource.ConstantLongValuesSource) {
final long constantMin =
((LongValuesSource.ConstantLongValuesSource) minimumNumberMatch).getValue();
if (constantMin > queries.size()) {
return new MatchNoDocsQuery(
"More clauses are required to match than the number of clauses");
}
BooleanQuery.Builder builder =
new BooleanQuery.Builder().setMinimumNumberShouldMatch((int) Math.max(constantMin, 1));
for (Query query : queries) {
Query r = query.rewrite(reader);
builder.add(r, BooleanClause.Occur.SHOULD);
}
return builder.build();
}
Multiset rewritten = new Multiset<>();
boolean actuallyRewritten = false;
for (Query query : queries) {
Query r = query.rewrite(reader);
rewritten.add(r);
actuallyRewritten |= query != r;
}
if (actuallyRewritten) {
return new CoveringQuery(rewritten, minimumNumberMatch);
}
return super.rewrite(reader);
}
@Override
public void visit(QueryVisitor visitor) {
QueryVisitor v = visitor.getSubVisitor(BooleanClause.Occur.SHOULD, this);
for (Query query : queries) {
query.visit(v);
}
}
@Override
public Weight createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost)
throws IOException {
final List weights = new ArrayList<>(queries.size());
for (Query query : queries) {
weights.add(searcher.createWeight(query, scoreMode, boost));
}
return new CoveringWeight(this, weights, minimumNumberMatch.rewrite(searcher));
}
private static class CoveringWeight extends Weight {
private final Collection weights;
private final LongValuesSource minimumNumberMatch;
CoveringWeight(Query query, Collection weights, LongValuesSource minimumNumberMatch) {
super(query);
this.weights = weights;
this.minimumNumberMatch = minimumNumberMatch;
}
@Override
public Matches matches(LeafReaderContext context, int doc) throws IOException {
LongValues minMatchValues = minimumNumberMatch.getValues(context, null);
if (minMatchValues.advanceExact(doc) == false) {
return null;
}
final long minimumNumberMatch = Math.max(1, minMatchValues.longValue());
long matchCount = 0;
List subMatches = new ArrayList<>();
for (Weight weight : weights) {
Matches matches = weight.matches(context, doc);
if (matches != null) {
matchCount++;
subMatches.add(matches);
}
}
if (matchCount < minimumNumberMatch) {
return null;
}
return MatchesUtils.fromSubMatches(subMatches);
}
@Override
public Explanation explain(LeafReaderContext context, int doc) throws IOException {
LongValues minMatchValues = minimumNumberMatch.getValues(context, null);
if (minMatchValues.advanceExact(doc) == false) {
return Explanation.noMatch("minimumNumberMatch has no value on the current document");
}
final long minimumNumberMatch = Math.max(1, minMatchValues.longValue());
int freq = 0;
double score = 0;
List subExpls = new ArrayList<>();
for (Weight weight : weights) {
Explanation subExpl = weight.explain(context, doc);
if (subExpl.isMatch()) {
freq++;
score += subExpl.getValue().doubleValue();
}
subExpls.add(subExpl);
}
if (freq >= minimumNumberMatch) {
return Explanation.match(
(float) score,
freq + " matches for " + minimumNumberMatch + " required matches, sum of:",
subExpls);
} else {
return Explanation.noMatch(
freq + " matches for " + minimumNumberMatch + " required matches", subExpls);
}
}
@Override
public Scorer scorer(LeafReaderContext context) throws IOException {
Collection scorers = new ArrayList<>();
for (Weight w : weights) {
Scorer s = w.scorer(context);
if (s != null) {
scorers.add(s);
}
}
if (scorers.isEmpty()) {
return null;
}
return new CoveringScorer(
this, scorers, minimumNumberMatch.getValues(context, null), context.reader().maxDoc());
}
@Override
public boolean isCacheable(LeafReaderContext ctx) {
return minimumNumberMatch.isCacheable(ctx);
}
}
}