/*
* 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.jackrabbit.core.query.lucene.join;
import java.io.IOException;
import java.util.List;
import java.util.ArrayList;
import org.apache.jackrabbit.core.query.lucene.MultiColumnQueryHits;
import org.apache.jackrabbit.core.query.lucene.ScoreNode;
import org.apache.jackrabbit.core.query.lucene.HierarchyResolver;
import org.apache.jackrabbit.spi.Name;
import org.apache.lucene.index.IndexReader;
/**
* <code>DescendantNodeJoin</code> implements a descendant node join condition.
*/
public class DescendantNodeJoin extends AbstractCondition {
/**
* A score node map with the score nodes from the inner query hits, indexed
* by the document number.
*/
private final ScoreNodeMap contextIndex = new ScoreNodeMap();
/**
* The index reader.
*/
private final IndexReader reader;
/**
* The hierarchy resolver.
*/
private final HierarchyResolver resolver;
/**
* Reusable array of document numbers.
*/
private int[] docNums = new int[1];
/**
* Reusable list of document number.
*/
private final List<Integer> ancestors = new ArrayList<Integer>();
/**
* Reusable list of score nodes.
*/
private final List<ScoreNode[]> scoreNodes = new ArrayList<ScoreNode[]>();
/**
* Creates a new descendant node join condition.
*
* @param context the inner query hits.
* @param contextSelectorName the selector name for the inner query hits.
* @param reader the index reader.
* @param resolver the hierarchy resolver.
* @throws IOException if an error occurs while reading fromt the index.
*/
public DescendantNodeJoin(MultiColumnQueryHits context,
Name contextSelectorName,
IndexReader reader,
HierarchyResolver resolver) throws IOException {
super(context);
this.reader = reader;
this.resolver = resolver;
int idx = getIndex(context, contextSelectorName);
ScoreNode[] nodes;
while ((nodes = context.nextScoreNodes()) != null) {
Integer docNum = nodes[idx].getDoc(reader);
contextIndex.addScoreNodes(docNum, nodes);
}
}
/**
* {@inheritDoc}
* <p>
* The outer query hits loop contains the descendant nodes.
*/
public ScoreNode[][] getMatchingScoreNodes(ScoreNode descendant)
throws IOException {
ancestors.clear();
collectAncestors(descendant.getDoc(reader));
scoreNodes.clear();
for (Integer ancestor : ancestors) {
ScoreNode[][] sn = contextIndex.getScoreNodes(ancestor);
if (sn != null) {
for (ScoreNode[] aSn : sn) {
scoreNodes.add(aSn);
}
}
}
if (scoreNodes.isEmpty()) {
return null;
} else {
return scoreNodes.toArray(new ScoreNode[scoreNodes.size()][]);
}
}
/**
* Collects the ancestors of the given <code>doc</code> number into
* {@link #ancestors}.
*
* @param doc the current document number.
* @throws IOException if an error occurs while reading from the index.
*/
private void collectAncestors(int doc) throws IOException {
docNums = resolver.getParents(doc, docNums);
if (docNums.length == 1) {
ancestors.add(docNums[0]);
collectAncestors(docNums[0]);
} else if (docNums.length > 1) {
// clone because recursion uses docNums again
for (int docNum : docNums.clone()) {
ancestors.add(docNum);
collectAncestors(docNum);
}
}
}
}