/*
* Copyright 2004,2005 The Apache Software Foundation.
*
* Licensed 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.llom;
import org.apache.axiom.om.OMContainer;
import org.apache.axiom.om.OMElement;
import org.apache.axiom.om.OMNode;
/**
* Refer to the testClass to find out how to use
* features like isNavigable, isComplete and step.
*/
public class OMNavigator {
/**
* 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 OMNavigator() {
}
/**
* Constructor OMNavigator.
*
* @param node
*/
public OMNavigator(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) {
OMElementImpl e = (OMElementImpl) next;
if (e.firstChild != null) {
next = e.firstChild;
} else if (e.isComplete()) {
backtracked = true;
} else {
next = null;
}
} else {
OMNode nextSibling = ((OMNodeImpl) next).nextSibling;
//OMNode parent = next.getParent();
OMContainer parent = next.getParent();
if (nextSibling != null) {
next = nextSibling;
} else if ((parent != null) && parent.isComplete()) {
next = (OMNodeImpl) 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 and
* 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;
}
}