/*
* 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;
import org.apache.commons.collections.iterators.IteratorChain;
import org.apache.jackrabbit.core.NodeImpl;
import javax.jcr.Node;
import javax.jcr.NodeIterator;
import javax.jcr.RepositoryException;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;
import java.util.ArrayList;
import java.util.Collections;
/**
* <code>NodeTraversingQueryHits</code> implements query hits that traverse
* a node hierarchy.
*/
public class NodeTraversingQueryHits extends AbstractQueryHits {
/**
* The nodes to traverse.
*/
private final Iterator nodes;
/**
* Creates query hits that consist of the nodes that are traversed from a
* given <code>start</code> node.
*
* @param start the start node of the traversal.
* @param includeStart whether to include the start node in the result.
*/
public NodeTraversingQueryHits(Node start, boolean includeStart) {
this(start, includeStart, Integer.MAX_VALUE);
}
/**
* Creates query hits that consist of the nodes that are traversed from a
* given <code>start</code> node.
*
* @param start the start node of the traversal.
* @param includeStart whether to include the start node in the result.
* @param maxDepth the maximum depth of nodes to traverse.
*/
public NodeTraversingQueryHits(Node start,
boolean includeStart,
int maxDepth) {
this.nodes = new TraversingNodeIterator(start, maxDepth);
if (!includeStart) {
nodes.next();
}
}
/**
* {@inheritDoc}
*/
public ScoreNode nextScoreNode() throws IOException {
if (nodes.hasNext()) {
NodeImpl n = (NodeImpl) nodes.next();
return new ScoreNode(n.getNodeId(), 1.0f);
} else {
return null;
}
}
/**
* Implements a node iterator that traverses a node tree in document
* order.
*/
private class TraversingNodeIterator implements Iterator {
/**
* The current <code>Node</code>, which acts as the starting point for
* the traversal.
*/
private final Node currentNode;
/**
* The maximum depth of the traversal.
*/
private final int maxDepth;
/**
* The chain of iterators which includes the iterators of the children
* of the current node.
*/
private Iterator selfAndChildren;
/**
* Creates a <code>TraversingNodeIterator</code>.
*
* @param start the node from where to start the traversal.
* @param maxDepth the maximum depth of nodes to traverse.
*/
TraversingNodeIterator(Node start, int maxDepth) {
if (maxDepth < 0) {
throw new IllegalArgumentException("maxDepth must be >= 0");
}
currentNode = start;
this.maxDepth = maxDepth;
}
/**
* @exception UnsupportedOperationException always.
*/
public void remove() {
throw new UnsupportedOperationException("remove");
}
/**
* @inheritDoc
*/
public boolean hasNext() {
init();
return selfAndChildren.hasNext();
}
/**
* @inheritDoc
*/
public Object next() {
init();
NodeImpl n = (NodeImpl) selfAndChildren.next();
return n;
}
/**
* Initializes the iterator chain once.
*/
private void init() {
if (selfAndChildren == null) {
List allIterators = new ArrayList();
Iterator current = Collections.singletonList(currentNode).iterator();
allIterators.add(current);
if (maxDepth == 0) {
// only current node
} else if (maxDepth == 1) {
try {
allIterators.add(currentNode.getNodes());
} catch (RepositoryException e) {
// currentNode is probably stale
}
} else {
// create new TraversingNodeIterator for each child
try {
NodeIterator children = currentNode.getNodes();
while (children.hasNext()) {
allIterators.add(new TraversingNodeIterator(children.nextNode(), maxDepth - 1));
}
} catch (RepositoryException e) {
// currentNode is probably stale
}
}
selfAndChildren = new IteratorChain(allIterators);
}
}
}
}