treewalker.java

来自「Jive 是一个系统工程」· Java 代码 · 共 116 行

/**
 * $RCSfile: TreeWalker.java,v $
 * $Revision: 1.2 $
 * $Date: 2000/12/21 17:46:53 $
 *
 * Copyright (C) 2000 CoolServlets.com. All rights reserved.
 *
 * ===================================================================
 * The Apache Software License, Version 1.1
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by
 *        CoolServlets.com (http://www.coolservlets.com)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Jive" and "CoolServlets.com" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please
 *    contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Jive",
 *    nor may "Jive" appear in their name, without prior written
 *    permission of CoolServlets.com.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL COOLSERVLETS.COM OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of CoolServlets.com. For more information
 * on CoolServlets.com, please see <http://www.coolservlets.com>.
 */

package com.coolservlets.forum;

/**
 * Allows hierarchical navigation of a Thread. It closely follows the
 * TreeModel interface in Swing in the hopes of being easier to use.
 *
 * @see ForumThread
 */
public interface TreeWalker {

    /**
     * Returns the root of the tree. Returns null only if the tree has no nodes.
     *
     * @returns the root of the tree
     */
    public ForumMessage getRoot();

    /**
     * Returns the child of parent at index index in the parent's child array.
     * This should not return null if index is a valid index for parent (that
     * is index >= 0 && index < getChildCount(parent)).
     *
     * @param parent the parent message.
     * @param index the index of the child.
     * @returns the child of parent at index.
     */
    public ForumMessage getChild(ForumMessage parent, int index);

    /**
     * Returns the number of children of parent. Returns 0 if the node is a
     * leaf or if it has no children.
     *
     * @param parent a node in the tree, obtained from this data source.
     * @returns the number of children of the node parent.
     */
    public int getChildCount(ForumMessage parent);

    /**
     * Returns the total number of recursive children of a parent. Returns 0
     * if there are no children. This method is not intended to aid in
     * navigation of a Thread but is included as an added utility.
     */
    public int getRecursiveChildCount(ForumMessage parent);

    /**
     * Returns the index of child in parent.
     */
    public int getIndexOfChild(ForumMessage parent, ForumMessage child);

    /**
     * Returns true if node is a leaf. A node is a leaf when it has no children
     * messages.
     *
     * @param node a node in the tree, obtained from this data source
     * @returns true if node is a leaf
     */
    public boolean isLeaf(ForumMessage node);
}