org.apache.jackrabbit.commons.visitor.FilteringItemVisitor Maven / Gradle / Ivy
/*
* 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.commons.visitor;
import java.util.LinkedList;
import javax.jcr.Item;
import javax.jcr.ItemVisitor;
import javax.jcr.Node;
import javax.jcr.NodeIterator;
import javax.jcr.Property;
import javax.jcr.PropertyIterator;
import javax.jcr.RepositoryException;
import org.apache.jackrabbit.commons.predicate.Predicate;
public abstract class FilteringItemVisitor implements ItemVisitor {
/**
* Predicate that defines which items are included.
*/
protected Predicate includePredicate = Predicate.TRUE;
/**
* Predicate that defines which items are traversed.
*/
protected Predicate traversalPredicate = Predicate.TRUE;
/**
* Do we want to walk all properties of nodes?
* The default is false.
*/
protected boolean walkProperties = false;
/**
* indicates if traversal should be done in a breadth-first
* manner rather than depth-first (which is the default)
*/
protected boolean breadthFirst = false;
/**
* the 0-based level up to which the hierarchy should be traversed
* (if it's -1, the hierarchy will be traversed until there are no
* more children of the current item)
*/
protected int maxLevel = -1;
/**
* queues used to implement breadth-first traversal
*/
protected LinkedList currentQueue;
protected LinkedList nextQueue;
/**
* used to track hierarchy level of item currently being processed
*/
protected int currentLevel;
public void setMaxLevel(final int ml) {
this.maxLevel = ml;
}
public void setBreadthFirst(final boolean flag) {
if ( this.breadthFirst != flag ) {
this.breadthFirst = flag;
if (breadthFirst) {
this.currentQueue = new LinkedList();
this.nextQueue = new LinkedList();
} else {
this.currentQueue = null;
this.nextQueue = null;
}
}
}
public void setWalkProperties(final boolean flag) {
this.walkProperties = flag;
}
public void setIncludePredicate(final Predicate ip) {
this.includePredicate = ip;
}
public void setTraversalPredicate(final Predicate tp) {
this.traversalPredicate = tp;
}
/**
* Implement this method to add behaviour performed before a
* Property is visited.
*
* @param property the Property that is accepting this visitor.
* @param level hierarchy level of this property (the root node starts at level 0)
* @throws RepositoryException if an error occurrs
*/
protected abstract void entering(Property property, int level)
throws RepositoryException;
/**
* Implement this method to add behaviour performed before a
* Node is visited.
*
* @param node the Node that is accepting this visitor.
* @param level hierarchy level of this node (the root node starts at level 0)
* @throws RepositoryException if an error occurrs
*/
protected abstract void entering(Node node, int level)
throws RepositoryException;
/**
* Implement this method to add behaviour performed after a
* Property is visited.
*
* @param property the Property that is accepting this visitor.
* @param level hierarchy level of this property (the root node starts at level 0)
* @throws RepositoryException if an error occurrs
*/
protected abstract void leaving(Property property, int level)
throws RepositoryException;
/**
* Implement this method to add behaviour performed after a
* Node is visited.
*
* @param node the Node that is accepting this visitor.
* @param level hierarchy level of this node (the root node starts at level 0)
* @throws RepositoryException if an error occurrs
*/
protected abstract void leaving(Node node, int level)
throws RepositoryException;
/**
* Called when the Visitor is passed to a Property.
*
* It calls TraversingItemVisitor.entering(Property, int) followed by
* TraversingItemVisitor.leaving(Property, int). Implement these abstract methods to
* specify behaviour on 'arrival at' and 'after leaving' the Property.
*
*
* If this method throws, the visiting process is aborted.
*
* @param property the Property that is accepting this visitor.
* @throws RepositoryException if an error occurrs
*/
public void visit(Property property) throws RepositoryException {
if ( this.walkProperties && this.includePredicate.evaluate(property) ) {
entering(property, currentLevel);
leaving(property, currentLevel);
}
}
/**
* Called when the Visitor is passed to a Node.
*
* It calls TraversingItemVisitor.entering(Node, int) followed by
* TraversingItemVisitor.leaving(Node, int). Implement these abstract methods to
* specify behaviour on 'arrival at' and 'after leaving' the Node.
*
* If this method throws, the visiting process is aborted.
*
* @param node the Node that is accepting this visitor.
* @throws RepositoryException if an error occurrs
*/
public void visit(Node node)
throws RepositoryException {
if ( this.traversalPredicate.evaluate(node) ) {
if ( this.includePredicate == this.traversalPredicate || this.includePredicate.evaluate(node) ) {
try {
if (!breadthFirst) {
// depth-first traversal
entering(node, currentLevel);
if (maxLevel == -1 || currentLevel < maxLevel) {
currentLevel++;
if ( this.walkProperties ) {
PropertyIterator propIter = node.getProperties();
while (propIter.hasNext()) {
propIter.nextProperty().accept(this);
}
}
NodeIterator nodeIter = node.getNodes();
while (nodeIter.hasNext()) {
nodeIter.nextNode().accept(this);
}
currentLevel--;
}
leaving(node, currentLevel);
} else {
// breadth-first traversal
entering(node, currentLevel);
leaving(node, currentLevel);
if (maxLevel == -1 || currentLevel < maxLevel) {
if ( this.walkProperties ) {
PropertyIterator propIter = node.getProperties();
while (propIter.hasNext()) {
nextQueue.addLast(propIter.nextProperty());
}
}
NodeIterator nodeIter = node.getNodes();
while (nodeIter.hasNext()) {
nextQueue.addLast(nodeIter.nextNode());
}
}
while (!currentQueue.isEmpty() || !nextQueue.isEmpty()) {
if (currentQueue.isEmpty()) {
currentLevel++;
currentQueue = nextQueue;
nextQueue = new LinkedList();
}
Item e = (Item) currentQueue.removeFirst();
e.accept(this);
}
currentLevel = 0;
}
} catch (RepositoryException re) {
currentLevel = 0;
throw re;
}
}
}
}
}