nodesequence.java

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/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 2002 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.xpath.axes;

import java.io.Serializable;

import java.util.Vector;
import javax.xml.transform.TransformerException;
import org.apache.xml.dtm.DTM;
import org.apache.xml.dtm.DTMIterator;
import org.apache.xml.dtm.DTMManager;
import org.apache.xml.dtm.DTMFilter;
import org.apache.xml.utils.NodeVector;
import org.apache.xpath.Expression;
import org.apache.xpath.NodeSetDTM;
import org.apache.xpath.XPathContext;
import org.apache.xpath.objects.XObject;

/**
 * This class is the dynamic wrapper for a Xalan DTMIterator instance, and 
 * provides random access capabilities.
 */
public class NodeSequence extends XObject
  implements DTMIterator, Cloneable, PathComponent
{
  /** The index of the last node in the iteration. */
  protected int m_last = -1;
  
  /**
   * The index of the next node to be fetched.  Useful if this
   * is a cached iterator, and is being used as random access
   * NodeList.
   */
  protected int m_next = 0;
    
  /**
   * If this iterator needs to cache nodes that are fetched, they
   * are stored in the Vector in the generic object.
   */
  protected NodeVector getVector()
  {
  	return (NodeVector)m_obj;
  }
  
  /**
   * Set the vector where nodes will be stored.
   */
  protected void SetVector(NodeVector v)
  {
  	m_obj = v;
  }

  
  /**
   * If this iterator needs to cache nodes that are fetched, they
   * are stored here.
   */
  public boolean hasCache()
  {
  	return (m_obj != null);
  }


  /**
   * The functional iterator that fetches nodes.
   */
  protected DTMIterator m_iter;
  
  /**
   * Set the functional iterator that fetches nodes.
   * @param iter The iterator that is to be contained.
   */
  public final void setIter(DTMIterator iter)
  {
  	m_iter = iter;
  }
  
  /**
   * Get the functional iterator that fetches nodes.
   * @return The contained iterator.
   */
  public final DTMIterator getContainedIter()
  {
  	return m_iter;
  }
  
  /**
   * The DTMManager to use if we're using a NodeVector only.
   * We may well want to do away with this, and store it in the NodeVector.
   */
  protected DTMManager m_dtmMgr;
  
  // ==== Constructors ====
  
  /**
   * Create a new NodeSequence from a (already cloned) iterator.
   * 
   * @param iter Cloned (not static) DTMIterator.
   * @param context The initial context node.
   * @param xctxt The execution context.
   * @param shouldCacheNodes True if this sequence can random access.
   */
  public NodeSequence(DTMIterator iter, int context, XPathContext xctxt, boolean shouldCacheNodes)
  {
  	setIter(iter);
  	setRoot(context, xctxt);
  	setShouldCacheNodes(shouldCacheNodes);
  }
  
  /**
   * Create a new NodeSequence from a (already cloned) iterator.
   * 
   * @param iter Cloned (not static) DTMIterator.
   */
  public NodeSequence(Object nodeVector)
  {
  	super(nodeVector);
  	if(null != nodeVector)
  	{
  		assertion(nodeVector instanceof NodeVector, 
  			"Must have a NodeVector as the object for NodeSequence!");
  		if(nodeVector instanceof DTMIterator)
  		{
  			setIter((DTMIterator)nodeVector);
  			m_last = ((DTMIterator)nodeVector).getLength();
  		}
  		
  	}
  }
  
  /**
   * Construct an empty XNodeSet object.  This is used to create a mutable 
   * nodeset to which random nodes may be added.
   */
  public NodeSequence(DTMManager dtmMgr)
  {
    super(new NodeVector());
    m_last = 0;
    m_dtmMgr = dtmMgr;
  }

  
  /**
   * Create a new NodeSequence in an invalid (null) state.
   */
  public NodeSequence()
  {
  }


  /**
   * @see DTMIterator#getDTM(int)
   */
  public DTM getDTM(int nodeHandle)
  {
  	DTMManager mgr = getDTMManager();
  	if(null != mgr)
    	return getDTMManager().getDTM(nodeHandle);
    else
    {
    	assertion(false, "Can not get a DTM Unless a DTMManager has been set!");
    	return null;
    }
  }

  /**
   * @see DTMIterator#getDTMManager()
   */
  public DTMManager getDTMManager()
  {
    return m_dtmMgr;
  }

  /**
   * @see DTMIterator#getRoot()
   */
  public int getRoot()
  {
  	if(null != m_iter)
    	return m_iter.getRoot();
  	else
  	{
  		// NodeSetDTM will call this, and so it's not a good thing to throw 
  		// an assertion here.
  		// assertion(false, "Can not get the root from a non-iterated NodeSequence!");
  		return DTM.NULL;
  	}
  }

  /**
   * @see DTMIterator#setRoot(int, Object)
   */
  public void setRoot(int nodeHandle, Object environment)
  {
  	if(null != m_iter)
  	{
  		XPathContext xctxt = (XPathContext)environment;
  		m_dtmMgr = xctxt.getDTMManager();
  		m_iter.setRoot(nodeHandle, environment);
  		if(!m_iter.isDocOrdered())
  		{
  			if(!hasCache())
  				setShouldCacheNodes(true);
  			runTo(-1);
  			m_next=0;
  		}
  	}
  	else
  		assertion(false, "Can not setRoot on a non-iterated NodeSequence!");
  }

  /**
   * @see DTMIterator#reset()
   */
  public void reset()
  {
  	m_next = 0;
  	// not resetting the iterator on purpose!!!
  }

  /**
   * @see DTMIterator#getWhatToShow()
   */
  public int getWhatToShow()
  {
    return hasCache() ? (DTMFilter.SHOW_ALL & ~DTMFilter.SHOW_ENTITY_REFERENCE) 
    	: m_iter.getWhatToShow();
  }

  /**
   * @see DTMIterator#getExpandEntityReferences()
   */
  public boolean getExpandEntityReferences()
  {
  	if(null != m_iter)
  		return m_iter.getExpandEntityReferences();
  	else
    	return true;
  }

  /**
   * @see DTMIterator#nextNode()
   */
  public int nextNode()
  {
    // If the cache is on, and the node has already been found, then 
    // just return from the list.
    NodeVector vec = getVector();
    if (null != vec)
    {	
    	if(m_next < vec.size())
    	{
			int next = vec.elementAt(m_next);
	    	m_next++;
	    	return next;
    	}
    	else if((-1 != m_last) || (null == m_iter))
    	{
    		m_next++;
    		return DTM.NULL;
    	}
    }
    
  if (null == m_iter)
    return DTM.NULL;
  
 	int next = m_iter.nextNode();
    if(DTM.NULL != next)
    {
    	if(hasCache())
    	{
    		if(m_iter.isDocOrdered())
    	    {
    			getVector().addElement(next);
    			m_next++;
    		}
    		else
    		{
    			int insertIndex = addNodeInDocOrder(next);
    			if(insertIndex >= 0)
    				m_next++;
    		}
    	}
    	else
    		m_next++;
    }
    else
    {
    	m_last = m_next;