/***********************************************************************************************************************
* Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
*
* 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 eu.stratosphere.nephele.topology;
import java.util.Iterator;
import java.util.Stack;
public class NetworkTopologyIterator implements Iterator<NetworkNode> {
private static class TraversalEntry {
private NetworkNode networkNode;
private int childrenVisited = 0;
public TraversalEntry(final NetworkNode networkNode) {
this.networkNode = networkNode;
}
public NetworkNode getNetworkNode() {
return this.networkNode;
}
public int getChildrenVisited() {
return this.childrenVisited;
}
public void increaseChildrenVisited() {
++this.childrenVisited;
}
}
private Stack<TraversalEntry> traversalStack = new Stack<TraversalEntry>();
NetworkTopologyIterator(final NetworkTopology networkTopology) {
traversalStack.add(new TraversalEntry(networkTopology.getRootNode()));
refillStack();
}
private void refillStack() {
while (true) {
final TraversalEntry traversalEntry = this.traversalStack.peek();
final NetworkNode networkNode = traversalEntry.getNetworkNode();
if (networkNode.isLeafNode()) {
break;
}
final NetworkNode childNode = networkNode.getChildNode(traversalEntry.getChildrenVisited());
this.traversalStack.add(new TraversalEntry(childNode));
}
}
@Override
public boolean hasNext() {
if (this.traversalStack.isEmpty()) {
return false;
}
return true;
}
@Override
public NetworkNode next() {
final TraversalEntry traversalEntry = this.traversalStack.pop();
final NetworkNode networkNode = traversalEntry.networkNode;
if (!this.traversalStack.isEmpty()) {
final TraversalEntry parentTraversalEntry = this.traversalStack.peek();
parentTraversalEntry.increaseChildrenVisited();
if (parentTraversalEntry.getChildrenVisited() < parentTraversalEntry.getNetworkNode()
.getNumberOfChildNodes()) {
refillStack();
}
}
return networkNode;
}
@Override
public void remove() {
// Optional operation
}
}