http://xml.apache.org/xalan-j/: Serializer to write out XML, HTML etc. as a stream of characters from an input DOM or from input SAX events. (The Apache Software Foundation) 
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 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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: Variable.java 468655 2006-10-28 07:12:06Z minchau $
 */
package org.apache.xpath.operations;

import javax.xml.transform.TransformerException;

import org.apache.xalan.res.XSLMessages;
import org.apache.xml.utils.QName;
import org.apache.xpath.Expression;
import org.apache.xpath.ExpressionOwner;
import org.apache.xpath.XPath;
import org.apache.xpath.XPathContext;
import org.apache.xpath.XPathVisitor;
import org.apache.xpath.axes.PathComponent;
import org.apache.xpath.axes.WalkerFactory;
import org.apache.xpath.objects.XNodeSet;
import org.apache.xpath.objects.XObject;
import org.apache.xpath.res.XPATHErrorResources;



The variable reference expression executer.

/**
 * The variable reference expression executer.
 */
public class Variable extends Expression implements PathComponent
{
    static final long serialVersionUID = -4334975375609297049L;
  
Tell if fixupVariables was called.
 @serial   
/** Tell if fixupVariables was called.
   *  @serial   */
  private boolean m_fixUpWasCalled = false;

  
The qualified name of the variable.
 @serial   
/** The qualified name of the variable.
   *  @serial   */
  protected QName m_qname;
  
  
The index of the variable, which is either an absolute index to a 
global, or, if higher than the globals area, must be adjusted by adding 
the offset to the current stack frame.

/**
   * The index of the variable, which is either an absolute index to a 
   * global, or, if higher than the globals area, must be adjusted by adding 
   * the offset to the current stack frame.
   */
  protected int m_index;
  
  
Set the index for the variable into the stack.  For advanced use only. You 
must know what you are doing to use this.

Params:
  • index – a global or local index.
/**
   * Set the index for the variable into the stack.  For advanced use only. You 
   * must know what you are doing to use this.
   * 
   * @param index a global or local index.
   */
  public void setIndex(int index)
  {
  	m_index = index;
  }
  
  
Set the index for the variable into the stack.  For advanced use only.

Returns:index a global or local index.
/**
   * Set the index for the variable into the stack.  For advanced use only.
   * 
   * @return index a global or local index.
   */
  public int getIndex()
  {
  	return m_index;
  }
  
  
Set whether or not this is a global reference.  For advanced use only.

Params:
  • isGlobal – true if this should be a global variable reference.
/**
   * Set whether or not this is a global reference.  For advanced use only.
   * 
   * @param isGlobal true if this should be a global variable reference.
   */
  public void setIsGlobal(boolean isGlobal)
  {
  	m_isGlobal = isGlobal;
  }
  
  
Set the index for the variable into the stack.  For advanced use only.

Returns:true if this should be a global variable reference.
/**
   * Set the index for the variable into the stack.  For advanced use only.
   * 
   * @return true if this should be a global variable reference.
   */
  public boolean getGlobal()
  {
  	return m_isGlobal;
  }

  
  

  
  protected boolean m_isGlobal = false;
  
  
This function is used to fixup variables from QNames to stack frame 
indexes at stylesheet build time.

Params:
  • vars – List of QNames that correspond to variables.  This list 
should be searched backwards for the first qualified name that 
corresponds to the variable reference qname.  The position of the 
QName in the vector from the start of the vector will be its position 
in the stack frame (but variables above the globalsTop value will need 
to be offset to the current stack frame).
/**
   * This function is used to fixup variables from QNames to stack frame 
   * indexes at stylesheet build time.
   * @param vars List of QNames that correspond to variables.  This list 
   * should be searched backwards for the first qualified name that 
   * corresponds to the variable reference qname.  The position of the 
   * QName in the vector from the start of the vector will be its position 
   * in the stack frame (but variables above the globalsTop value will need 
   * to be offset to the current stack frame).
   */
  public void fixupVariables(java.util.Vector vars, int globalsSize)
  {
    m_fixUpWasCalled = true;
    int sz = vars.size();

    for (int i = vars.size()-1; i >= 0; i--) 
    {
      QName qn = (QName)vars.elementAt(i);
      // System.out.println("qn: "+qn);
      if(qn.equals(m_qname))
      {
        
        if(i < globalsSize)
        {
          m_isGlobal = true;
          m_index = i;
        }
        else
        {
          m_index = i-globalsSize;
        }
          
        return;
      }
    }
    
    java.lang.String msg = XSLMessages.createXPATHMessage(XPATHErrorResources.ER_COULD_NOT_FIND_VAR, 
                                             new Object[]{m_qname.toString()});
                                             
    TransformerException te = new TransformerException(msg, this);
                                             
    throw new org.apache.xml.utils.WrappedRuntimeException(te);
    
  }


  
Set the qualified name of the variable.

Params:
  • qname – Must be a non-null reference to a qualified name.
/**
   * Set the qualified name of the variable.
   *
   * @param qname Must be a non-null reference to a qualified name.
   */
  public void setQName(QName qname)
  {
    m_qname = qname;
  }
  
  
Get the qualified name of the variable.

Returns:A non-null reference to a qualified name.
/**
   * Get the qualified name of the variable.
   *
   * @return A non-null reference to a qualified name.
   */
  public QName getQName()
  {
    return m_qname;
  }
  
  
Execute an expression in the XPath runtime context, and return the
result of the expression.

Params:
  • xctxt – The XPath runtime context.
Throws:
Returns:The result of the expression in the form of a XObject.
/**
   * Execute an expression in the XPath runtime context, and return the
   * result of the expression.
   *
   *
   * @param xctxt The XPath runtime context.
   *
   * @return The result of the expression in the form of a <code>XObject</code>.
   *
   * @throws javax.xml.transform.TransformerException if a runtime exception
   *         occurs.
   */
  public XObject execute(XPathContext xctxt)
    throws javax.xml.transform.TransformerException
  {
  	return execute(xctxt, false);
  }


  
Dereference the variable, and return the reference value.  Note that lazy 
evaluation will occur.  If a variable within scope is not found, a warning 
will be sent to the error listener, and an empty nodeset will be returned.

Params:
  • xctxt – The runtime execution context.
Throws:
Returns:The evaluated variable, or an empty nodeset if not found.
/**
   * Dereference the variable, and return the reference value.  Note that lazy 
   * evaluation will occur.  If a variable within scope is not found, a warning 
   * will be sent to the error listener, and an empty nodeset will be returned.
   *
   *
   * @param xctxt The runtime execution context.
   *
   * @return The evaluated variable, or an empty nodeset if not found.
   *
   * @throws javax.xml.transform.TransformerException
   */
  public XObject execute(XPathContext xctxt, boolean destructiveOK) throws javax.xml.transform.TransformerException
  {
    org.apache.xml.utils.PrefixResolver xprefixResolver = xctxt.getNamespaceContext();

    XObject result;
    // Is the variable fetched always the same?
    // XObject result = xctxt.getVariable(m_qname);
    if(m_fixUpWasCalled)
    {    
      if(m_isGlobal)
        result = xctxt.getVarStack().getGlobalVariable(xctxt, m_index, destructiveOK);
      else
        result = xctxt.getVarStack().getLocalVariable(xctxt, m_index, destructiveOK);
    } 
    else {  
    	result = xctxt.getVarStack().getVariableOrParam(xctxt,m_qname);
    }
  
      if (null == result)
      {
        // This should now never happen...
        warn(xctxt, XPATHErrorResources.WG_ILLEGAL_VARIABLE_REFERENCE,
             new Object[]{ m_qname.getLocalPart() });  //"VariableReference given for variable out "+
  //      (new RuntimeException()).printStackTrace();
  //      error(xctxt, XPATHErrorResources.ER_COULDNOT_GET_VAR_NAMED,
  //            new Object[]{ m_qname.getLocalPart() });  //"Could not get variable named "+varName);
        
        result = new XNodeSet(xctxt.getDTMManager());
      }
  
      return result;
//    }
//    else
//    {
//      // Hack city... big time.  This is needed to evaluate xpaths from extensions, 
//      // pending some bright light going off in my head.  Some sort of callback?
//      synchronized(this)
//      {
//      	org.apache.xalan.templates.ElemVariable vvar= getElemVariable();
//      	if(null != vvar)
//      	{
//          m_index = vvar.getIndex();
//          m_isGlobal = vvar.getIsTopLevel();
//          m_fixUpWasCalled = true;
//          return execute(xctxt);
//      	}
//      }
//      throw new javax.xml.transform.TransformerException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_VAR_NOT_RESOLVABLE, new Object[]{m_qname.toString()})); //"Variable not resolvable: "+m_qname);
//    }
  }
  
  
Get the XSLT ElemVariable that this sub-expression references.  In order for 
this to work, the SourceLocator must be the owning ElemTemplateElement.

Returns:The dereference to the ElemVariable, or null if not found.
/**
   * Get the XSLT ElemVariable that this sub-expression references.  In order for 
   * this to work, the SourceLocator must be the owning ElemTemplateElement.
   * @return The dereference to the ElemVariable, or null if not found.
   */
  public org.apache.xalan.templates.ElemVariable getElemVariable()
  {
  	
    // Get the current ElemTemplateElement, and then walk backwards in 
    // document order, searching 
    // for an xsl:param element or xsl:variable element that matches our 
    // qname.  If we reach the top level, use the StylesheetRoot's composed
    // list of top level variables and parameters.
    
    org.apache.xalan.templates.ElemVariable vvar = null;	
    org.apache.xpath.ExpressionNode owner = getExpressionOwner();

    if (null != owner && owner instanceof org.apache.xalan.templates.ElemTemplateElement)
    {

      org.apache.xalan.templates.ElemTemplateElement prev = 
        (org.apache.xalan.templates.ElemTemplateElement) owner;

      if (!(prev instanceof org.apache.xalan.templates.Stylesheet))
      {            
        while ( prev != null && !(prev.getParentNode() instanceof org.apache.xalan.templates.Stylesheet) )
        {
          org.apache.xalan.templates.ElemTemplateElement savedprev = prev;

          while (null != (prev = prev.getPreviousSiblingElem()))
          {
            if(prev instanceof org.apache.xalan.templates.ElemVariable)
            {
              vvar = (org.apache.xalan.templates.ElemVariable) prev;
            
              if (vvar.getName().equals(m_qname))
              {
                return vvar;
              }
              vvar = null; 	 	
            }
          }
          prev = savedprev.getParentElem();
        }
      }
      if (prev != null)
        vvar = prev.getStylesheetRoot().getVariableOrParamComposed(m_qname);
    }
    return vvar;

  }
  
  
Tell if this expression returns a stable number that will not change during 
iterations within the expression.  This is used to determine if a proximity 
position predicate can indicate that no more searching has to occur.

Returns:true if the expression represents a stable number.
/**
   * Tell if this expression returns a stable number that will not change during 
   * iterations within the expression.  This is used to determine if a proximity 
   * position predicate can indicate that no more searching has to occur.
   * 
   *
   * @return true if the expression represents a stable number.
   */
  public boolean isStableNumber()
  {
    return true;
  }
  
  
Get the analysis bits for this walker, as defined in the WalkerFactory.

Returns:One of WalkerFactory#BIT_DESCENDANT, etc.
/** 
   * Get the analysis bits for this walker, as defined in the WalkerFactory.
   * @return One of WalkerFactory#BIT_DESCENDANT, etc.
   */
  public int getAnalysisBits()
  {
  	org.apache.xalan.templates.ElemVariable vvar = getElemVariable();
  	if(null != vvar)
  	{
  		XPath xpath = vvar.getSelect();
  		if(null != xpath)
  		{
	  		Expression expr = xpath.getExpression();
	  		if(null != expr && expr instanceof PathComponent)
	  		{
	  			return ((PathComponent)expr).getAnalysisBits();
	  		}
  		}
  	}
    return WalkerFactory.BIT_FILTER;
  }


  
See Also:
  • callVisitors.callVisitors(ExpressionOwner, XPathVisitor)
/**
   * @see org.apache.xpath.XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor)
   */
  public void callVisitors(ExpressionOwner owner, XPathVisitor visitor)
  {
  	visitor.visitVariableRef(owner, this);
  }
  
See Also:
  • deepEquals.deepEquals(Expression)
/**
   * @see Expression#deepEquals(Expression)
   */
  public boolean deepEquals(Expression expr)
  {
  	if(!isSameClass(expr))
  		return false;
  		
  	if(!m_qname.equals(((Variable)expr).m_qname))
  		return false;
  		
  	// We have to make sure that the qname really references 
  	// the same variable element.
    if(getElemVariable() != ((Variable)expr).getElemVariable())
    	return false;
  		
  	return true;
  }
  
  static final java.lang.String PSUEDOVARNAMESPACE = "http://xml.apache.org/xalan/psuedovar";
  
  
Tell if this is a psuedo variable reference, declared by Xalan instead 
of by the user.

/**
   * Tell if this is a psuedo variable reference, declared by Xalan instead 
   * of by the user.
   */
  public boolean isPsuedoVarRef()
  {
  	java.lang.String ns = m_qname.getNamespaceURI();
  	if((null != ns) && ns.equals(PSUEDOVARNAMESPACE))
  	{
  		if(m_qname.getLocalName().startsWith("#"))
  			return true;
  	}
  	return false;
  }
  

}