xpathcontext.java

java1.6众多例子参考

  /**
   * Get the current namespace context for the xpath.
   *
   * @return the current prefix resolver for resolving prefixes to 
   *         namespace URLs.
   */
  public final PrefixResolver getNamespaceContext()
  {
    return (PrefixResolver) m_prefixResolvers.peek();
  }

  /**
   * Get the current namespace context for the xpath.
   *
   * @param pr the prefix resolver to be used for resolving prefixes to 
   *         namespace URLs.
   */
  public final void setNamespaceContext(PrefixResolver pr)
  {
    m_prefixResolvers.setTop(pr);
  }

  /**
   * Push a current namespace context for the xpath.
   *
   * @param pr the prefix resolver to be used for resolving prefixes to 
   *         namespace URLs.
   */
  public final void pushNamespaceContext(PrefixResolver pr)
  {
    m_prefixResolvers.push(pr);
  }
  
  /**
   * Just increment the namespace contest stack, so that setNamespaceContext
   * can be used on the slot.
   */
  public final void pushNamespaceContextNull()
  {
    m_prefixResolvers.push(null);
  }

  /**
   * Pop the current namespace context for the xpath.
   */
  public final void popNamespaceContext()
  {
    m_prefixResolvers.pop();
  }

  //==========================================================
  // SECTION: Current TreeWalker contexts (for internal use)
  //==========================================================

  /**
   * Stack of AxesIterators.
   */
  private Stack m_axesIteratorStack = new Stack();
  
  public Stack getAxesIteratorStackStacks() { return m_axesIteratorStack; }
  public void setAxesIteratorStackStacks(Stack s) { m_axesIteratorStack = s; }

  /**
   * Push a TreeWalker on the stack.
   *
   * @param iter A sub-context AxesWalker.
   * @xsl.usage internal
   */
  public final void pushSubContextList(SubContextList iter)
  {
    m_axesIteratorStack.push(iter);
  }

  /**
   * Pop the last pushed axes iterator.
   * @xsl.usage internal
   */
  public final void popSubContextList()
  {
    m_axesIteratorStack.pop();
  }

  /**
   * Get the current axes iterator, or return null if none.
   *
   * @return the sub-context node list.
   * @xsl.usage internal
   */
  public SubContextList getSubContextList()
  {
    return m_axesIteratorStack.isEmpty()
           ? null : (SubContextList) m_axesIteratorStack.peek();
  }
  
  /**
   * Get the <a href="http://www.w3.org/TR/xslt#dt-current-node-list">current node list</a> 
   * as defined by the XSLT spec.
   *
   * @return the <a href="http://www.w3.org/TR/xslt#dt-current-node-list">current node list</a>.
   * @xsl.usage internal
   */

  public com.sun.org.apache.xpath.internal.axes.SubContextList getCurrentNodeList()
  {
    return m_axesIteratorStack.isEmpty()
           ? null : (SubContextList) m_axesIteratorStack.elementAt(0);
  }
  //==========================================================
  // SECTION: Implementation of ExpressionContext interface
  //==========================================================

  /**
   * Get the current context node.
   * @return The current context node.
   */
  public final int getContextNode()
  {
    return this.getCurrentNode();
  }

  /**
   * Get the current context node list.
   * @return An iterator for the current context list, as
   * defined in XSLT.
   */
  public final DTMIterator getContextNodes()
  {

    try
    {
      DTMIterator cnl = getContextNodeList();

      if (null != cnl)
        return cnl.cloneWithReset();
      else
        return null;  // for now... this might ought to be an empty iterator.
    }
    catch (CloneNotSupportedException cnse)
    {
      return null;  // error reporting?
    }
  }
  
  XPathExpressionContext expressionContext = new XPathExpressionContext();
  
  /**
   * The the expression context for extensions for this context.
   * 
   * @return An object that implements the ExpressionContext.
   */
  public ExpressionContext getExpressionContext()
  {
    return expressionContext;
  }
  
  public class XPathExpressionContext implements ExpressionContext
  {
    /**
     * Return the XPathContext associated with this XPathExpressionContext.
     * Extensions should use this judiciously and only when special processing
     * requirements cannot be met another way.  Consider requesting an enhancement
     * to the ExpressionContext interface to avoid having to call this method.
     * @return the XPathContext associated with this XPathExpressionContext.
     */
     public XPathContext getXPathContext()
     {
       return XPathContext.this;
     }

    /**
     * Return the DTMManager object.  Though XPathContext context extends 
     * the DTMManager, it really is a proxy for the real DTMManager.  If a 
     * caller needs to make a lot of calls to the DTMManager, it is faster 
     * if it gets the real one from this function.
     */
     public DTMManager getDTMManager()
     {
       return m_dtmManager;
     }
    
    /**
     * Get the current context node.
     * @return The current context node.
     */
    public org.w3c.dom.Node getContextNode()
    {
      int context = getCurrentNode();
      
      return getDTM(context).getNode(context);
    }
  
    /**
     * Get the current context node list.
     * @return An iterator for the current context list, as
     * defined in XSLT.
     */
    public org.w3c.dom.traversal.NodeIterator getContextNodes()
    {
      return new com.sun.org.apache.xml.internal.dtm.ref.DTMNodeIterator(getContextNodeList());
    }

    /**
     * Get the error listener.
     * @return The registered error listener.
     */
    public ErrorListener getErrorListener()
    {
      return XPathContext.this.getErrorListener();
    }
  
    /**
     * Get the value of a node as a number.
     * @param n Node to be converted to a number.  May be null.
     * @return value of n as a number.
     */
    public double toNumber(org.w3c.dom.Node n)
    {
      // %REVIEW% You can't get much uglier than this...
      int nodeHandle = getDTMHandleFromNode(n);
      DTM dtm = getDTM(nodeHandle);
      XString xobj = (XString)dtm.getStringValue(nodeHandle);
      return xobj.num();
    }
  
    /**
     * Get the value of a node as a string.
     * @param n Node to be converted to a string.  May be null.
     * @return value of n as a string, or an empty string if n is null.
     */
    public String toString(org.w3c.dom.Node n)
    {
      // %REVIEW% You can't get much uglier than this...
      int nodeHandle = getDTMHandleFromNode(n);
      DTM dtm = getDTM(nodeHandle);
      XMLString strVal = dtm.getStringValue(nodeHandle);
      return strVal.toString();
    }

    /**
     * Get a variable based on it's qualified name.
     * @param qname The qualified name of the variable.
     * @return The evaluated value of the variable.
     * @throws javax.xml.transform.TransformerException
     */

    public final XObject getVariableOrParam(com.sun.org.apache.xml.internal.utils.QName qname)
              throws javax.xml.transform.TransformerException
    {
      return m_variableStacks.getVariableOrParam(XPathContext.this, qname);
    }

  }

 /**
   * Get a DTM to be used as a container for a global Result Tree
   * Fragment. This will always be an instance of (derived from? equivalent to?) 
   * SAX2DTM, since each RTF is constructed by temporarily redirecting our SAX 
   * output to it. It may be a single DTM containing for multiple fragments, 
   * if the implementation supports that.
   * 
   * Note: The distinction between this method and getRTFDTM() is that the latter
   * allocates space from the dynamic variable stack (m_rtfdtm_stack), which may
   * be pruned away again as the templates which defined those variables are exited.
   * Global variables may be bound late (see XUnresolvedVariable), and never want to
   * be discarded, hence we need to allocate them separately and don't actually need
   * a stack to track them.
   * 
   * @return a non-null DTM reference.
   */
  public DTM getGlobalRTFDTM()
  {
  	// We probably should _NOT_ be applying whitespace filtering at this stage!
  	//
  	// Some magic has been applied in DTMManagerDefault to recognize this set of options
  	// and generate an instance of DTM which can contain multiple documents
  	// (SAX2RTFDTM). Perhaps not the optimal way of achieving that result, but
  	// I didn't want to change the manager API at this time, or expose 
  	// too many dependencies on its internals. (Ideally, I'd like to move
  	// isTreeIncomplete all the way up to DTM, so we wouldn't need to explicitly
  	// specify the subclass here.)

	// If it doesn't exist, or if the one already existing is in the middle of
	// being constructed, we need to obtain a new DTM to write into. I'm not sure
	// the latter will ever arise, but I'd rather be just a bit paranoid..
	if( m_global_rtfdtm==null || m_global_rtfdtm.isTreeIncomplete() )
	{
  		m_global_rtfdtm=(SAX2RTFDTM)m_dtmManager.getDTM(null,true,null,false,false);
	}
    return m_global_rtfdtm;
  }
  



  /**
   * Get a DTM to be used as a container for a dynamic Result Tree
   * Fragment. This will always be an instance of (derived from? equivalent to?) 
   * SAX2DTM, since each RTF is constructed by temporarily redirecting our SAX 
   * output to it. It may be a single DTM containing for multiple fragments, 
   * if the implementation supports that.
   * 
   * @return a non-null DTM reference.
   */
  public DTM getRTFDTM()
  {
  	SAX2RTFDTM rtfdtm;

  	// We probably should _NOT_ be applying whitespace filtering at this stage!
  	//
  	// Some magic has been applied in DTMManagerDefault to recognize this set of options
  	// and generate an instance of DTM which can contain multiple documents
  	// (SAX2RTFDTM). Perhaps not the optimal way of achieving that result, but
  	// I didn't want to change the manager API at this time, or expose 
  	// too many dependencies on its internals. (Ideally, I'd like to move
  	// isTreeIncomplete all the way up to DTM, so we wouldn't need to explicitly
  	// specify the subclass here.)

	if(m_rtfdtm_stack==null)
	{
		m_rtfdtm_stack=new Vector();
  		rtfdtm=(SAX2RTFDTM)m_dtmManager.getDTM(null,true,null,false,false);
    m_rtfdtm_stack.addElement(rtfdtm);
		++m_which_rtfdtm;
	}
	else if(m_which_rtfdtm<0)
	{
		rtfdtm=(SAX2RTFDTM)m_rtfdtm_stack.elementAt(++m_which_rtfdtm);
	}
	else
	{
		rtfdtm=(SAX2RTFDTM)m_rtfdtm_stack.elementAt(m_which_rtfdtm);
  		
	  	// It might already be under construction -- the classic example would be
 	 	// an xsl:variable which uses xsl:call-template as part of its value. To
  		// handle this recursion, we have to start a new RTF DTM, pushing the old
  		// one onto a stack so we can return to it. This is not as uncommon a case
  		// as we might wish, unfortunately, as some folks insist on coding XSLT
  		// as if it were a procedural language...
  		if(rtfdtm.isTreeIncomplete())
	  	{
	  		if(++m_which_rtfdtm < m_rtfdtm_stack.size())
				rtfdtm=(SAX2RTFDTM)m_rtfdtm_stack.elementAt(m_which_rtfdtm);
	  		else
	  		{
		  		rtfdtm=(SAX2RTFDTM)m_dtmManager.getDTM(null,true,null,false,false);
          m_rtfdtm_stack.addElement(rtfdtm); 	
	  		}
 	 	}
	}
		
    return rtfdtm;
  }
  
  /** Push the RTFDTM's context mark, to allows discarding RTFs added after this
   * point. (If it doesn't exist we don't push, since we might still be able to 
   * get away with not creating it. That requires that excessive pops be harmless.)
   * */
  public void pushRTFContext()
  {
  	m_last_pushed_rtfdtm.push(m_which_rtfdtm);
  	if(null!=m_rtfdtm_stack)
	  	((SAX2RTFDTM)(getRTFDTM())).pushRewindMark();
  }
  
  /** Pop the RTFDTM's context mark. This discards any RTFs added after the last
   * mark was set. 
   * 
   * If there is no RTF DTM, there's nothing to pop so this
   * becomes a no-op. If pushes were issued before this was called, we count on
   * the fact that popRewindMark is defined such that overpopping just resets
   * to empty.
   * 
   * Complicating factor: We need to handle the case of popping back to a previous
   * RTF DTM, if one of the weird produce-an-RTF-to-build-an-RTF cases arose.
   * Basically: If pop says this DTM is now empty, then return to the previous
   * if one exists, in whatever state we left it in. UGLY, but hopefully the
   * situation which forces us to consider this will arise exceedingly rarely.
   * */
  public void popRTFContext()
  {
  	int previous=m_last_pushed_rtfdtm.pop();
  	if(null==m_rtfdtm_stack)
  		return;
  
  	if(m_which_rtfdtm==previous)
  	{
  		if(previous>=0) // guard against none-active
  		{
	  		boolean isEmpty=((SAX2RTFDTM)(m_rtfdtm_stack.elementAt(previous))).popRewindMark();
  		}
  	}
  	else while(m_which_rtfdtm!=previous)
  	{
  		// Empty each DTM before popping, so it's ready for reuse
  		// _DON'T_ pop the previous, since it's still open (which is why we
  		// stacked up more of these) and did not receive a mark.
  		boolean isEmpty=((SAX2RTFDTM)(m_rtfdtm_stack.elementAt(m_which_rtfdtm))).popRewindMark();
  		--m_which_rtfdtm; 
  	}
  }
  
  /**
   * Gets DTMXRTreeFrag object if one has already been created.
   * Creates new DTMXRTreeFrag object and adds to m_DTMXRTreeFrags  HashMap,
   * otherwise.  
   * @param dtmIdentity
   * @return DTMXRTreeFrag
   */
  public DTMXRTreeFrag getDTMXRTreeFrag(int dtmIdentity){
    if(m_DTMXRTreeFrags == null){
      m_DTMXRTreeFrags = new HashMap();     
    }
    
    if(m_DTMXRTreeFrags.containsKey(new Integer(dtmIdentity))){
       return (DTMXRTreeFrag)m_DTMXRTreeFrags.get(new Integer(dtmIdentity));
    }else{
      final DTMXRTreeFrag frag = new DTMXRTreeFrag(dtmIdentity,this);
      m_DTMXRTreeFrags.put(new Integer(dtmIdentity),frag);
      return frag ;
    }   
  }
 
  /**
   * Cleans DTMXRTreeFrag objects by removing references 
   * to DTM and XPathContext objects.   
   */
  private final void releaseDTMXRTreeFrags(){
    if(m_DTMXRTreeFrags == null){
      return;
    }
    final Iterator iter = (m_DTMXRTreeFrags.values()).iterator();
    while(iter.hasNext()){
      DTMXRTreeFrag frag = (DTMXRTreeFrag)iter.next();
      frag.destruct();
      iter.remove();
    }
    m_DTMXRTreeFrags = null;
 }
}