treewalker.java

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/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * 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 the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xalan" and "Apache Software Foundation" 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 "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * 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 THE APACHE SOFTWARE FOUNDATION 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 the Apache Software Foundation and was
 * originally based on software copyright (c) 1999, Lotus
 * Development Corporation., http://www.lotus.com.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
package org.apache.xml.utils;

import org.w3c.dom.*;

import org.xml.sax.*;
import org.xml.sax.ext.LexicalHandler;
import org.xml.sax.helpers.LocatorImpl;

import org.apache.xpath.DOM2Helper;
import org.apache.xpath.DOMHelper;
import org.apache.xml.utils.NodeConsumer;

/**
 * <meta name="usage" content="advanced"/>
 * This class does a pre-order walk of the DOM tree, calling a ContentHandler
 * interface as it goes.
 */

public class TreeWalker
{

  /** Local reference to a ContentHandler          */
  private ContentHandler m_contentHandler = null;

  // ARGHH!!  JAXP Uses Xerces without setting the namespace processing to ON!
  // DOM2Helper m_dh = new DOM2Helper();

  /** DomHelper for this TreeWalker          */
  protected DOMHelper m_dh;
        
        /** Locator object for this TreeWalker          */
        private LocatorImpl m_locator = new LocatorImpl();

  /**
   * Get the ContentHandler used for the tree walk.
   *
   * @return the ContentHandler used for the tree walk
   */
  public ContentHandler getContentHandler()
  {
    return m_contentHandler;
  }

  /**
   * Get the ContentHandler used for the tree walk.
   *
   * @return the ContentHandler used for the tree walk
   */
  public void setContentHandler(ContentHandler ch)
  {
    m_contentHandler = ch;
  }
        
        /**
   * Constructor.
   * @param   contentHandler The implemention of the
   * @param   systemId System identifier for the document.
   * contentHandler operation (toXMLString, digest, ...)
   */
  public TreeWalker(ContentHandler contentHandler, DOMHelper dh, String systemId)
  {
    this.m_contentHandler = contentHandler;
                m_contentHandler.setDocumentLocator(m_locator);
                if (systemId != null)
                  m_locator.setSystemId(systemId);
                else {
                  try {
                    m_locator.setSystemId(System.getProperty("user.dir"));
                  }
                  catch (SecurityException se) {// user.dir not accessible from applet
                    m_locator.setSystemId("");
                  }
                }
    m_dh = dh;
  }

  /**
   * Constructor.
   * @param   contentHandler The implemention of the
   * contentHandler operation (toXMLString, digest, ...)
   */
  public TreeWalker(ContentHandler contentHandler, DOMHelper dh)
  {
    this.m_contentHandler = contentHandler;
    m_contentHandler.setDocumentLocator(m_locator);
    try {
      m_locator.setSystemId(System.getProperty("user.dir"));
    } 
    catch (SecurityException se){// user.dir not accessible from applet
      m_locator.setSystemId("");
    }
    m_dh = dh;
  }
  
  /**
   * Constructor.
   * @param   contentHandler The implemention of the
   * contentHandler operation (toXMLString, digest, ...)
   */
  public TreeWalker(ContentHandler contentHandler)
  {
    this.m_contentHandler = contentHandler;
                if (m_contentHandler != null)
                        m_contentHandler.setDocumentLocator(m_locator);
                try {
                  m_locator.setSystemId(System.getProperty("user.dir"));
                } 
                catch (SecurityException se){// user.dir not accessible from applet
                  m_locator.setSystemId("");
    }
    m_dh = new org.apache.xpath.DOM2Helper();
  }

  /**
   * Perform a pre-order traversal non-recursive style.  
   *
   * Note that TreeWalker assumes that the subtree is intended to represent 
   * a complete (though not necessarily well-formed) document and, during a 
   * traversal, startDocument and endDocument will always be issued to the 
   * SAX listener.
   *  
   * @param pos Node in the tree where to start traversal
   *
   * @throws TransformerException
   */
  public void traverse(Node pos) throws org.xml.sax.SAXException
  {

   	this.m_contentHandler.startDocument();

    Node top = pos;

    while (null != pos)
    {
      startNode(pos);

      Node nextNode = pos.getFirstChild();

      while (null == nextNode)
      {
        endNode(pos);

        if (top.equals(pos))
          break;

        nextNode = pos.getNextSibling();

        if (null == nextNode)
        {
          pos = pos.getParentNode();

          if ((null == pos) || (top.equals(pos)))
          {
            if (null != pos)
              endNode(pos);

            nextNode = null;

            break;
          }
        }
      }

      pos = nextNode;
    }
    this.m_contentHandler.endDocument();
  }

  /**
   * Perform a pre-order traversal non-recursive style.

   * Note that TreeWalker assumes that the subtree is intended to represent 
   * a complete (though not necessarily well-formed) document and, during a 
   * traversal, startDocument and endDocument will always be issued to the 
   * SAX listener.
   *
   * @param pos Node in the tree where to start traversal
   * @param top Node in the tree where to end traversal
   *
   * @throws TransformerException
   */
  public void traverse(Node pos, Node top) throws org.xml.sax.SAXException
  {

	this.m_contentHandler.startDocument();
	
    while (null != pos)
    {
      startNode(pos);

      Node nextNode = pos.getFirstChild();

      while (null == nextNode)
      {
        endNode(pos);

        if ((null != top) && top.equals(pos))
          break;

        nextNode = pos.getNextSibling();

        if (null == nextNode)
        {
          pos = pos.getParentNode();

          if ((null == pos) || ((null != top) && top.equals(pos)))