/* TreeNode.java --
   Copyright (C) 2002, 2006, Free Software Foundation, Inc.

This file is part of GNU Classpath.

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package javax.swing.tree;

import java.util.Enumeration;

/**
 * A tree node.
 * 
 * @author Andrew Selkirk
 */
public interface TreeNode 
{

  /**
   * Returns the parent node for this tree node, or <code>null</code> if this
   * node has no parent.
   * 
   * @return The parent node (possibly <code>null</code>).
   */
  TreeNode getParent();

  /**
   * Returns the index of the specified child node, or -1 if the node is not
   * in fact a child of this node.
   * 
   * @param node  the node (<code>null</code> not permitted).
   * 
   * @return The index of the specified child node, or -1.
   * 
   * @throws IllegalArgumentException if <code>node</code> is <code>null</code>.
   */
  int getIndex(TreeNode node);

  /**
   * Returns the child node at the given index.
   * 
   * @param index  the index (in the range <code>0</code> to 
   *     <code>getChildCount() - 1</code>).
   *     
   * @return The child node at the given index.
   */
  TreeNode getChildAt(int index);

  /**
   * Returns the number of children for this node.
   * 
   * @return The number of children for this node.
   */
  int getChildCount();

  /**
   * Returns <code>true</code> if this node allows children, and 
   * <code>false</code> otherwise.
   * 
   * @return A boolean.
   */
  boolean getAllowsChildren();

  /**
   * Returns <code>true</code> if this node is a leaf node, and 
   * <code>false</code> otherwise.
   * 
   * @return A boolean.
   */
  boolean isLeaf();

  /**
   * Returns an enumeration of the children of this node, or an empty 
   * enumeration if this node has no children.
   * 
   * @return An enumeration of the children of this node.
   */
  Enumeration children();

}