001    /*
002     *  This file is part of the Jikes RVM project (http://jikesrvm.org).
003     *
004     *  This file is licensed to You under the Eclipse Public License (EPL);
005     *  You may not use this file except in compliance with the License. You
006     *  may obtain a copy of the License at
007     *
008     *      http://www.opensource.org/licenses/eclipse-1.0.php
009     *
010     *  See the COPYRIGHT.txt file distributed with this work for information
011     *  regarding copyright ownership.
012     */
013    package org.jikesrvm.compilers.opt.util;
014    
015    import java.util.Enumeration;
016    
017    
018    /**
019     *  This class is a node in a tree.  Both up and down pointers are used.
020     */
021    public class TreeNode {
022    
023      /**
024       *  The parent of this node
025       */
026      private TreeNode parent;
027    
028      /**
029       *  The first (leftmost) child
030       */
031      private TreeNode leftChild;
032    
033      /**
034       *  The next node on the child list that I am on
035       */
036      private TreeNode rightSibling;
037    
038      /**
039       * Constructor
040       */
041      public TreeNode() {
042        parent = null;
043        leftChild = null;
044        rightSibling = null;
045      }
046    
047      /**
048       * return the parent of this node
049       * @return my parent
050       */
051      public TreeNode getParent() {
052        return parent;
053      }
054    
055      /**
056       * returns the first child of this node
057       * @return the first child of this node
058       */
059      public TreeNode getLeftChild() {
060        return leftChild;
061      }
062    
063      /**
064       * returns the next node with the same parent as me
065       * @return the next node with the same parent as me
066       */
067      public TreeNode getRightSibling() {
068        return rightSibling;
069      }
070    
071      /**
072       *  adds a child to this node
073       *  @param node the new child
074       */
075      public void addChild(TreeNode node) {
076        if (leftChild == null) {
077          leftChild = node;
078        } else {
079          // get to the last sibling
080          TreeNode siblingNode = leftChild;
081          while (siblingNode.rightSibling != null) {
082            siblingNode = siblingNode.rightSibling;
083          }
084          siblingNode.rightSibling = node;
085        }
086        node.parent = this;
087      }
088    
089      /**
090       *  Sets all tree pointers to null
091       */
092      public void clear() {
093        leftChild = null;
094        rightSibling = null;
095        parent = null;
096      }
097    
098      public Enumeration<TreeNode> getChildren() {
099        return new TreeNodeChildrenEnumerator(this);
100      }
101    
102    }
103    
104    
105