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1   package org.apache.maven.shared.dependency.tree;
2   
3   /*
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *   http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.
20   */
21  
22  import java.util.Iterator;
23  import java.util.NoSuchElementException;
24  import java.util.Stack;
25  
26  /**
27   * {@link Iterator} for {@link DependencyNode} implementing a traversal from leaves to root.
28   * 
29   * TODO {@link #DependencyTreeInverseIterator(DependencyNode)} is costly,
30   * a better implementation would move the cost to {@link #next()}
31   * 
32   * @author <a href="mailto:carlos@apache.org">Carlos Sanchez</a>
33   * @version $Id: DependencyTreeInverseIterator.java 661727 2008-05-30 14:21:49Z bentmann $
34   */
35  public class DependencyTreeInverseIterator
36      implements Iterator
37  {
38      private Stack nodesToProcess = new Stack();
39  
40      public DependencyTreeInverseIterator( DependencyNode rootNode )
41      {
42          DependencyTreePreorderIterator it = new DependencyTreePreorderIterator( rootNode );
43          while ( it.hasNext() )
44          {
45              nodesToProcess.push( it.next() );
46          }
47      }
48  
49      public boolean hasNext()
50      {
51          return !nodesToProcess.isEmpty();
52      }
53  
54      public Object next()
55      {
56          if ( !hasNext() )
57          {
58              throw new NoSuchElementException();
59          }
60          return nodesToProcess.pop();
61      }
62  
63      /**
64       * @throws UnsupportedOperationException
65       */
66      public void remove()
67      {
68          throw new UnsupportedOperationException();
69      }
70  }