nodesetdtm.java

java1.6众多例子参考

/*
 * Copyright 1999-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: NodeSetDTM.java,v 1.2.4.2 2005/09/14 20:30:06 jeffsuttor Exp $
 */
package com.sun.org.apache.xpath.internal;

import com.sun.org.apache.xalan.internal.res.XSLMessages;
import com.sun.org.apache.xml.internal.dtm.DTM;
import com.sun.org.apache.xml.internal.dtm.DTMFilter;
import com.sun.org.apache.xml.internal.dtm.DTMIterator;
import com.sun.org.apache.xml.internal.dtm.DTMManager;
import com.sun.org.apache.xml.internal.utils.NodeVector;
import com.sun.org.apache.xpath.internal.res.XPATHErrorResources;

import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.traversal.NodeIterator;


/**
 * <p>The NodeSetDTM class can act as either a NodeVector,
 * NodeList, or NodeIterator.  However, in order for it to
 * act as a NodeVector or NodeList, it's required that
 * setShouldCacheNodes(true) be called before the first
 * nextNode() is called, in order that nodes can be added
 * as they are fetched.  Derived classes that implement iterators
 * must override runTo(int index), in order that they may
 * run the iteration to the given index. </p>
 * 
 * <p>Note that we directly implement the DOM's NodeIterator
 * interface. We do not emulate all the behavior of the
 * standard NodeIterator. In particular, we do not guarantee
 * to present a "live view" of the document ... but in XSLT,
 * the source document should never be mutated, so this should
 * never be an issue.</p>
 * 
 * <p>Thought: Should NodeSetDTM really implement NodeList and NodeIterator,
 * or should there be specific subclasses of it which do so? The
 * advantage of doing it all here is that all NodeSetDTMs will respond
 * to the same calls; the disadvantage is that some of them may return
 * less-than-enlightening results when you do so.</p>
 * @xsl.usage advanced
 */
public class NodeSetDTM extends NodeVector
        implements /* NodeList, NodeIterator, */ DTMIterator, 
        Cloneable
{
    static final long serialVersionUID = 7686480133331317070L;

  /**
   * Create an empty nodelist.
   */
  public NodeSetDTM(DTMManager dtmManager)
  {
    super();
    m_manager = dtmManager;
  }

  /**
   * Create an empty, using the given block size.
   *
   * @param blocksize Size of blocks to allocate 
   * @param dummy pass zero for right now...
   */
  public NodeSetDTM(int blocksize, int dummy, DTMManager dtmManager)
  {
    super(blocksize);
    m_manager = dtmManager;
  }

  // %TBD%
//  /**
//   * Create a NodeSetDTM, and copy the members of the
//   * given nodelist into it.
//   *
//   * @param nodelist List of Nodes to be made members of the new set.
//   */
//  public NodeSetDTM(NodeList nodelist)
//  {
//
//    super();
//
//    addNodes(nodelist);
//  }

  /**
   * Create a NodeSetDTM, and copy the members of the
   * given NodeSetDTM into it.
   *
   * @param nodelist Set of Nodes to be made members of the new set.
   */
  public NodeSetDTM(NodeSetDTM nodelist)
  {

    super();
    m_manager = nodelist.getDTMManager();
    m_root = nodelist.getRoot();

    addNodes((DTMIterator) nodelist);
  }

  /**
   * Create a NodeSetDTM, and copy the members of the
   * given DTMIterator into it.
   *
   * @param ni Iterator which yields Nodes to be made members of the new set.
   */
  public NodeSetDTM(DTMIterator ni)
  {

    super();

    m_manager = ni.getDTMManager();
    m_root = ni.getRoot();
    addNodes(ni);
  }
  
  /**
   * Create a NodeSetDTM, and copy the members of the
   * given DTMIterator into it.
   *
   * @param iterator Iterator which yields Nodes to be made members of the new set.
   */
  public NodeSetDTM(NodeIterator iterator, XPathContext xctxt)
  {

    super();

    Node node;
    m_manager = xctxt.getDTMManager();

    while (null != (node = iterator.nextNode()))
    {
      int handle = xctxt.getDTMHandleFromNode(node);
      addNodeInDocOrder(handle, xctxt);
    }
  }
  
  /**
   * Create a NodeSetDTM, and copy the members of the
   * given DTMIterator into it.
   *
   */
  public NodeSetDTM(NodeList nodeList, XPathContext xctxt)
  {

    super();

    m_manager = xctxt.getDTMManager();

    int n = nodeList.getLength();
    for (int i = 0; i < n; i++) 
    {
      Node node = nodeList.item(i);
      int handle = xctxt.getDTMHandleFromNode(node);
      // Do not reorder or strip duplicate nodes from the given DOM nodelist
      addNode(handle); // addNodeInDocOrder(handle, xctxt);  
    } 
  }


  /**
   * Create a NodeSetDTM which contains the given Node.
   *
   * @param node Single node to be added to the new set.
   */
  public NodeSetDTM(int node, DTMManager dtmManager)
  {

    super();
    m_manager = dtmManager;

    addNode(node);
  }
  
  /**
   * Set the environment in which this iterator operates, which should provide:
   * a node (the context node... same value as "root" defined below) 
   * a pair of non-zero positive integers (the context position and the context size) 
   * a set of variable bindings 
   * a function library 
   * the set of namespace declarations in scope for the expression.
   * 
   * <p>At this time the exact implementation of this environment is application 
   * dependent.  Probably a proper interface will be created fairly soon.</p>
   * 
   * @param environment The environment object.
   */
  public void setEnvironment(Object environment)
  {
    // no-op
  }


  /**
   * @return The root node of the Iterator, as specified when it was created.
   * For non-Iterator NodeSetDTMs, this will be null.
   */
  public int getRoot()
  {
    if(DTM.NULL == m_root)
    {
      if(size() > 0)
        return item(0);
      else
        return DTM.NULL;
    }
    else
      return m_root;
  }
  
  /**
   * Initialize the context values for this expression
   * after it is cloned.
   *
   * @param context The XPath runtime context for this
   * transformation.
   */
  public void setRoot(int context, Object environment)
  {
    // no-op, I guess...  (-sb)
  }

  /**
   * Clone this NodeSetDTM.
   * At this time, we only expect this to be used with LocPathIterators;
   * it may not work with other kinds of NodeSetDTMs.
   *
   * @return a new NodeSetDTM of the same type, having the same state...
   * though unless overridden in the subclasses, it may not copy all
   * the state information.
   *
   * @throws CloneNotSupportedException if this subclass of NodeSetDTM
   * does not support the clone() operation.
   */
  public Object clone() throws CloneNotSupportedException
  {

    NodeSetDTM clone = (NodeSetDTM) super.clone();

    return clone;
  }

  /**
   * Get a cloned Iterator, and reset its state to the beginning of the
   * iteration.
   *
   * @return a new NodeSetDTM of the same type, having the same state...
   * except that the reset() operation has been called.
   *
   * @throws CloneNotSupportedException if this subclass of NodeSetDTM
   * does not support the clone() operation.
   */
  public DTMIterator cloneWithReset() throws CloneNotSupportedException
  {

    NodeSetDTM clone = (NodeSetDTM) clone();

    clone.reset();

    return clone;
  }

  /**
   * Reset the iterator. May have no effect on non-iterator Nodesets.
   */
  public void reset()
  {
    m_next = 0;
  }

  /**
   *  This attribute determines which node types are presented via the
   * iterator. The available set of constants is defined in the
   * <code>DTMFilter</code> interface. For NodeSetDTMs, the mask has been
   * hardcoded to show all nodes except EntityReference nodes, which have
   * no equivalent in the XPath data model.
   *
   * @return integer used as a bit-array, containing flags defined in
   * the DOM's DTMFilter class. The value will be 
   * <code>SHOW_ALL & ~SHOW_ENTITY_REFERENCE</code>, meaning that
   * only entity references are suppressed.
   */
  public int getWhatToShow()
  {
    return DTMFilter.SHOW_ALL & ~DTMFilter.SHOW_ENTITY_REFERENCE;
  }

  /**
   * The filter object used to screen nodes. Filters are applied to
   * further reduce (and restructure) the DTMIterator's view of the
   * document. In our case, we will be using hardcoded filters built
   * into our iterators... but getFilter() is part of the DOM's 
   * DTMIterator interface, so we have to support it.
   *
   * @return null, which is slightly misleading. True, there is no
   * user-written filter object, but in fact we are doing some very
   * sophisticated custom filtering. A DOM purist might suggest
   * returning a placeholder object just to indicate that this is
   * not going to return all nodes selected by whatToShow.
   */
  public DTMFilter getFilter()
  {
    return null;
  }

  /**
   *  The value of this flag determines whether the children of entity
   * reference nodes are visible to the iterator. If false, they will be
   * skipped over.
   * <br> To produce a view of the document that has entity references
   * expanded and does not expose the entity reference node itself, use the
   * whatToShow flags to hide the entity reference node and set
   * expandEntityReferences to true when creating the iterator. To produce
   * a view of the document that has entity reference nodes but no entity
   * expansion, use the whatToShow flags to show the entity reference node
   * and set expandEntityReferences to false.
   *
   * @return true for all iterators based on NodeSetDTM, meaning that the
   * contents of EntityRefrence nodes may be returned (though whatToShow
   * says that the EntityReferences themselves are not shown.)
   */
  public boolean getExpandEntityReferences()
  {
    return true;
  }
  
  /**
   * Get an instance of a DTM that "owns" a node handle.  Since a node 
   * iterator may be passed without a DTMManager, this allows the 
   * caller to easily get the DTM using just the iterator.
   *
   * @param nodeHandle the nodeHandle.
   *
   * @return a non-null DTM reference.
   */
  public DTM getDTM(int nodeHandle)
  {
    
    return m_manager.getDTM(nodeHandle);
  }
  
  /* An instance of the DTMManager. */
  DTMManager m_manager;
  
  /**
   * Get an instance of the DTMManager.  Since a node 
   * iterator may be passed without a DTMManager, this allows the 
   * caller to easily get the DTMManager using just the iterator.
   *
   * @return a non-null DTMManager reference.
   */
  public DTMManager getDTMManager()
  {
    
    return m_manager;
  }

  /**
   *  Returns the next node in the set and advances the position of the
   * iterator in the set. After a DTMIterator is created, the first call
   * to nextNode() returns the first node in the set.
   * @return  The next <code>Node</code> in the set being iterated over, or
   *   <code>DTM.NULL</code> if there are no more members in that set.
   * @throws DOMException
   *    INVALID_STATE_ERR: Raised if this method is called after the
   *   <code>detach</code> method was invoked.
   */
  public int nextNode()
  {

    if ((m_next) < this.size())
    {
      int next = this.elementAt(m_next);

      m_next++;

      return next;
    }
    else
      return DTM.NULL;
  }

  /**
   *  Returns the previous node in the set and moves the position of the
   * iterator backwards in the set.
   * @return  The previous <code>Node</code> in the set being iterated over,
   *   or<code>DTM.NULL</code> if there are no more members in that set.
   * @throws DOMException
   *    INVALID_STATE_ERR: Raised if this method is called after the
   *   <code>detach</code> method was invoked.
   * @throws RuntimeException thrown if this NodeSetDTM is not of 
   * a cached type, and hence doesn't know what the previous node was.
   */
  public int previousNode()
  {

    if (!m_cacheNodes)
      throw new RuntimeException(
        XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESETDTM_CANNOT_ITERATE, null)); //"This NodeSetDTM can not iterate to a previous node!");

    if ((m_next - 1) > 0)