package org.apache.maven.shared.dependency.tree;

 /*

  * 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.

  */

 import java.util.Iterator;

 import java.util.List;

 import java.util.NoSuchElementException;

 import java.util.Stack;

 /**

  * {@link Iterator} for {@link DependencyNode} implementing a preoder traversal.

  * 

  * @author <a href="mailto:carlos@apache.org">Carlos Sanchez</a>

  * @version $Id: DependencyTreePreorderIterator.java 1100703 2011-05-08 08:27:33Z hboutemy $

  */

 public class DependencyTreePreorderIterator

     implements Iterator<DependencyNode>

 {

     private Stack<DependencyNode> nodesToProcess = new Stack<DependencyNode>();

     public DependencyTreePreorderIterator( DependencyNode rootNode )

     {

         nodesToProcess.push( rootNode );

     }

     public boolean hasNext()

     {

         return !nodesToProcess.isEmpty();

     }

     public DependencyNode next()

     {

         if ( !hasNext() )

         {

             throw new NoSuchElementException();

         }

         DependencyNode currentNode = nodesToProcess.pop();

         List<DependencyNode> children = currentNode.getChildren();

         if ( children != null )

         {

             for ( int i = children.size() - 1; i >= 0; i-- )

             {

                 nodesToProcess.push( children.get( i ) );

             }

         }

         return currentNode;

     }

     /**

      * @throws UnsupportedOperationException

      */

     public void remove()

     {

         throw new UnsupportedOperationException();

     }

 }