/*
* 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.traverse;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.NoSuchElementException;
import org.apache.axiom.om.OMContainer;
import org.apache.axiom.om.OMNode;
/**
* Abstract base class for iterators over sets of OM nodes.
*/
public abstract class OMAbstractIterator implements Iterator {
private OMNode currentNode;
/**
* The parent of the current node. This is used to detect concurrent modifications.
*/
private OMContainer currentParent;
private OMNode nextNode;
private boolean noMoreNodes;
private boolean nextCalled;
public OMAbstractIterator(OMNode firstNode) {
if (firstNode == null) {
noMoreNodes = true;
} else {
nextNode = firstNode;
}
}
/**
* Get the next node.
*
* @param currentNode the predecessor of the node to retrieve
* @return the next node
*/
protected abstract OMNode getNextNode(OMNode currentNode);
public boolean hasNext() {
if (noMoreNodes) {
return false;
} else if (nextNode != null) {
return true;
} else {
if (currentNode.getParent() != currentParent) {
throw new ConcurrentModificationException("The current node has been removed using a method other than Iterator#remove()");
}
nextNode = getNextNode(currentNode);
noMoreNodes = nextNode == null;
return !noMoreNodes;
}
}
public Object next() {
if (hasNext()) {
currentNode = nextNode;
currentParent = currentNode.getParent();
nextNode = null;
nextCalled = true;
return currentNode;
} else {
throw new NoSuchElementException();
}
}
public void remove() {
if (!nextCalled) {
throw new IllegalStateException("next() has not yet been called");
}
// Make sure that we know the next node before removing the current one
hasNext();
currentNode.detach();
nextCalled = false;
}
}