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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.
*/
public class Variable extends Expression implements PathComponent
{
static final long serialVersionUID = -4334975375609297049L;
/** Tell if fixupVariables was called.
* @serial */
private boolean m_fixUpWasCalled = false;
/** 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.
*/
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.
*
* @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.
*
* @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.
*
* @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.
*
* @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.
* @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.
*
* @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.
*
* @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.
*
*
* @param xctxt The XPath runtime context.
*
* @return The result of the expression in the form of a XObject.
*
* @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.
*
*
* @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.
* @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.
*
*
* @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.
* @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 org.apache.xpath.XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor)
*/
public void callVisitors(ExpressionOwner owner, XPathVisitor visitor)
{
visitor.visitVariableRef(owner, this);
}
/**
* @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.
*/
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;
}
}
