/*
* 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.exoplatform.services.jcr.impl.core.query.lucene;
import java.io.IOException;
import java.util.ArrayList;
import java.util.BitSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermDocs;
import org.apache.lucene.search.Explanation;
import org.apache.lucene.search.HitCollector;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.Searcher;
import org.apache.lucene.search.Similarity;
import org.apache.lucene.search.TermQuery;
import org.apache.lucene.search.Weight;
/**
* Implements a lucene <code>Query</code> which returns the nodes selected by a reference property
* of the context node.
*/
class DerefQuery
extends Query
{
/**
* The context query
*/
private final Query contextQuery;
/**
* The name of the reference property.
*/
private final String refProperty;
/**
* The nameTest to apply on target node, or <code>null</code> if all target nodes should be
* selected.
*/
private final String nameTest;
/**
* The scorer of the context query
*/
private Scorer contextScorer;
/**
* The scorer of the name test query
*/
private Scorer nameTestScorer;
/**
* Creates a new <code>DerefQuery</code> based on a <code>context</code> query.
*
* @param context
* the context for this query.
* @param refProperty
* the name of the reference property.
* @param nameTest
* a name test or <code>null</code> if any node is selected.
*/
DerefQuery(Query context, String refProperty, String nameTest)
{
this.contextQuery = context;
this.refProperty = refProperty;
this.nameTest = nameTest;
}
/**
* Creates a <code>Weight</code> instance for this query.
*
* @param searcher
* the <code>Searcher</code> instance to use.
* @return a <code>DerefWeight</code>.
*/
protected Weight createWeight(Searcher searcher)
{
return new DerefWeight(searcher);
}
/**
* Always returns 'DerefQuery'.
*
* @param field
* the name of a field.
* @return 'DerefQuery'.
*/
public String toString(String field)
{
return "DerefQuery";
}
/**
* {@inheritDoc}
*/
public void extractTerms(Set terms)
{
// no terms to extract
}
/**
* {@inheritDoc}
*/
public Query rewrite(IndexReader reader) throws IOException
{
Query cQuery = contextQuery.rewrite(reader);
if (cQuery == contextQuery)
{
return this;
}
else
{
return new DerefQuery(cQuery, refProperty, nameTest);
}
}
// -------------------< DerefWeight >------------------------------------
/**
* The <code>Weight</code> implementation for this <code>DerefQuery</code>.
*/
private class DerefWeight
implements Weight
{
/**
* The searcher in use
*/
private final Searcher searcher;
/**
* Creates a new <code>DerefWeight</code> instance using <code>searcher</code>.
*
* @param searcher
* a <code>Searcher</code> instance.
*/
private DerefWeight(Searcher searcher)
{
this.searcher = searcher;
}
/**
* Returns this <code>DerefQuery</code>.
*
* @return this <code>DerefQuery</code>.
*/
public Query getQuery()
{
return DerefQuery.this;
}
/**
* {@inheritDoc}
*/
public float getValue()
{
return 1.0f;
}
/**
* {@inheritDoc}
*/
public float sumOfSquaredWeights() throws IOException
{
return 1.0f;
}
/**
* {@inheritDoc}
*/
public void normalize(float norm)
{
}
/**
* Creates a scorer for this <code>DerefQuery</code>.
*
* @param reader
* a reader for accessing the index.
* @return a <code>DerefScorer</code>.
* @throws IOException
* if an error occurs while reading from the index.
*/
public Scorer scorer(IndexReader reader) throws IOException
{
contextScorer = contextQuery.weight(searcher).scorer(reader);
if (nameTest != null)
{
nameTestScorer = new TermQuery(new Term(FieldNames.LABEL, nameTest)).weight(searcher).scorer(reader);
}
return new DerefScorer(searcher.getSimilarity(), reader);
}
/**
* {@inheritDoc}
*/
public Explanation explain(IndexReader reader, int doc) throws IOException
{
return new Explanation();
}
}
// ----------------------< DerefScorer >---------------------------------
/**
* Implements a <code>Scorer</code> for this <code>DerefQuery</code>.
*/
private class DerefScorer
extends Scorer
{
/**
* An <code>IndexReader</code> to access the index.
*/
private final IndexReader reader;
/**
* BitSet storing the id's of selected documents
*/
private final BitSet hits;
/**
* List of UUIDs of selected nodes
*/
private List uuids = null;
/**
* The next document id to return
*/
private int nextDoc = -1;
/**
* Creates a new <code>DerefScorer</code>.
*
* @param similarity
* the <code>Similarity</code> instance to use.
* @param reader
* for index access.
*/
protected DerefScorer(Similarity similarity, IndexReader reader)
{
super(similarity);
this.reader = reader;
this.hits = new BitSet(reader.maxDoc());
}
/**
* {@inheritDoc}
*/
public boolean next() throws IOException
{
calculateChildren();
nextDoc = hits.nextSetBit(nextDoc + 1);
return nextDoc > -1;
}
/**
* {@inheritDoc}
*/
public int doc()
{
return nextDoc;
}
/**
* {@inheritDoc}
*/
public float score() throws IOException
{
return 1.0f;
}
/**
* {@inheritDoc}
*/
public boolean skipTo(int target) throws IOException
{
calculateChildren();
nextDoc = hits.nextSetBit(target);
return nextDoc > -1;
}
/**
* {@inheritDoc}
*
* @throws UnsupportedOperationException
* this implementation always throws an <code>UnsupportedOperationException</code>.
*/
public Explanation explain(int doc) throws IOException
{
throw new UnsupportedOperationException();
}
private void calculateChildren() throws IOException
{
if (uuids == null)
{
uuids = new ArrayList();
contextScorer.score(new HitCollector()
{
public void collect(int doc, float score)
{
hits.set(doc);
}
});
// collect nameTest hits
final BitSet nameTestHits = new BitSet();
if (nameTestScorer != null)
{
nameTestScorer.score(new HitCollector()
{
public void collect(int doc, float score)
{
nameTestHits.set(doc);
}
});
}
// retrieve uuids of target nodes
String prefix = FieldNames.createNamedValue(refProperty, "");
for (int i = hits.nextSetBit(0); i >= 0; i = hits.nextSetBit(i + 1))
{
String[] values = reader.document(i).getValues(FieldNames.PROPERTIES);
if (values == null)
{
// no reference properties at all on this node
continue;
}
for (int v = 0; v < values.length; v++)
{
if (values[v].startsWith(prefix))
{
uuids.add(values[v].substring(prefix.length()));
}
}
}
// collect the doc ids of all target nodes. we reuse the existing
// bitset.
hits.clear();
for (Iterator it = uuids.iterator(); it.hasNext();)
{
TermDocs node = reader.termDocs(new Term(FieldNames.UUID, (String) it.next()));
try
{
while (node.next())
{
hits.set(node.doc());
}
}
finally
{
node.close();
}
}
// filter out the target nodes that do not match the name test
// if there is any name test at all.
if (nameTestScorer != null)
{
hits.and(nameTestHits);
}
}
}
}
}