/*
* ModeShape (http://www.modeshape.org)
*
* Licensed 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.modeshape.jcr.index.lucene.query;
import java.io.IOException;
import org.apache.lucene.index.LeafReader;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.index.PostingsEnum;
import org.apache.lucene.index.Terms;
import org.apache.lucene.index.TermsEnum;
import org.apache.lucene.search.ConstantScoreScorer;
import org.apache.lucene.search.ConstantScoreWeight;
import org.apache.lucene.search.DocIdSetIterator;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.Weight;
import org.apache.lucene.util.BitSetIterator;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.FixedBitSet;
import org.modeshape.common.annotation.Immutable;
import org.modeshape.common.util.CheckArg;
/**
* Base class for ModeShape-specific Lucene queries, which always use a constant weight and score of 1.0f for the documents.
*
* @author Horia Chiorean (hchiorea@redhat.com)
* @since 4.5
*/
@Immutable
public abstract class ConstantScoreWeightQuery extends Query {
protected static final float SCORE = 1.0f;
private final String field;
protected ConstantScoreWeightQuery(String field) {
CheckArg.isNotNull(field, "field");
this.field = field;
}
protected String field() {
return field;
}
@Override
public Weight createWeight(IndexSearcher searcher, boolean needsScores) throws IOException {
return new ConstantScoreWeight(this) {
@Override
public Scorer scorer(LeafReaderContext context) throws IOException {
LeafReader leafReader = context.reader();
Terms terms = leafReader.terms(field);
if (terms == null) {
return new ConstantScoreScorer(this, SCORE, DocIdSetIterator.empty());
}
TermsEnum termsEnum = terms.iterator();
FixedBitSet result = new FixedBitSet(leafReader.maxDoc());
BytesRef bytesRef;
PostingsEnum postingsEnum = null;
while ((bytesRef = termsEnum.next()) != null) {
String value = bytesRef.utf8ToString();
if (accepts(value)) {
postingsEnum = termsEnum.postings(postingsEnum);
int docId;
while ((docId = postingsEnum.nextDoc()) != DocIdSetIterator.NO_MORE_DOCS) {
result.set(docId);
}
}
}
return new ConstantScoreScorer(this, SCORE, new BitSetIterator(result, result.cardinality()));
}
};
}
/**
* Checks if the given fields are valid for the document matched by a particular query or not.
*
* @param value a {@code String} representing a stored index value; never {@code null}
* @return {@code true} if the value is valid, {@code false} if not.
*/
protected abstract boolean accepts(String value);
@Override
public boolean equals(Object obj) {
return sameClassAs(obj) && field.equals(((ConstantScoreWeightQuery)obj).field);
}
@Override
public int hashCode() {
final int prime = 31;
int result = classHash();
result = prime * result + field.hashCode();
return result;
}
}