/*
* 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.axiom.om.impl.dom;
import org.apache.axiom.om.OMContainer;
import org.apache.axiom.om.OMElement;
import org.apache.axiom.om.OMNode;
/**
* This is exactly the same as org.apache.axiom.om.impl.om.OMNavigator, only the llom specifics are
* changed to dom. Refer to the testClass to find out how to use features like isNavigable,
* isComplete and step.
*/
public class DOMNavigator {
/** Field node */
protected OMNode node;
/** Field visited */
private boolean visited;
/** Field next */
private OMNode next;
// root is the starting element. Once the navigator comes back to the
// root, the traversal is terminated
/** Field root */
private OMNode root;
/** Field backtracked */
private boolean backtracked;
// flags that tell the status of the navigator
/** Field end */
private boolean end = false;
/** Field start */
private boolean start = true;
/** Constructor OMNavigator. */
public DOMNavigator() {
}
/**
* Constructor OMNavigator.
*
* @param node
*/
public DOMNavigator(OMNode node) {
init(node);
}
/**
* Method init.
*
* @param node
*/
public void init(OMNode node) {
next = node;
root = node;
backtracked = false;
}
/**
* Gets the next node.
*
* @return Returns OMNode in the sequence of preorder traversal. Note however that an element
* node is treated slightly differently. Once the element is passed it returns the same
* element in the next encounter as well.
*/
public OMNode next() {
if (next == null) {
return null;
}
node = next;
visited = backtracked;
backtracked = false;
updateNextNode();
// set the starting and ending flags
if (root.equals(node)) {
if (!start) {
end = true;
} else {
start = false;
}
}
return node;
}
/** Private method to encapsulate the searching logic */
private void updateNextNode() {
if ((next instanceof OMElement) && !visited) {
ElementImpl e = (ElementImpl) next;
if (e.firstChild != null) {
next = e.firstChild;
} else if (e.isComplete()) {
backtracked = true;
} else {
next = null;
}
} else {
OMNode nextSibling = ((ChildNode) next).nextSibling;
OMContainer parent = next.getParent();
if (nextSibling != null) {
next = nextSibling;
} else if ((parent != null) && parent.isComplete()) {
next = (NodeImpl) parent;
backtracked = true;
} else {
next = null;
}
}
}
/**
* Method visited.
*
* @return Returns boolean.
*/
public boolean visited() {
return visited;
}
/**
* This is a very special method. This allows the navigator to step once it has reached the
* existing OM. At this point the isNavigable method will return false but the isComplete method
* may return false which means that the navigating the given element is not complete but the
* navigator cannot proceed.
*/
public void step() {
if (!end) {
next = node;
updateNextNode();
}
}
/**
* Returns the navigable status.
*
* @return Returns boolean.
*/
public boolean isNavigable() {
if (end) {
return false;
} else {
return !(next == null);
}
}
/**
* Returns the completed status.
*
* @return Returns boolean.
*/
public boolean isCompleted() {
return end;
}
}