/*
* 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: ExtensionHandlerExsltFunction.java,v 1.9 2005/01/23 00:10:05 mcnamara Exp $
*/
package org.apache.xalan.extensions;
import java.io.IOException;
import java.util.Vector;
import javax.xml.transform.TransformerException;
import org.apache.xalan.res.XSLMessages;
import org.apache.xalan.res.XSLTErrorResources;
import org.apache.xalan.templates.Constants;
import org.apache.xalan.templates.ElemExsltFuncResult;
import org.apache.xalan.templates.ElemExsltFunction;
import org.apache.xalan.templates.ElemTemplate;
import org.apache.xalan.templates.ElemTemplateElement;
import org.apache.xalan.templates.Stylesheet;
import org.apache.xalan.templates.StylesheetRoot;
import org.apache.xalan.transformer.TransformerImpl;
import org.apache.xml.utils.QName;
import org.apache.xpath.ExpressionNode;
import org.apache.xpath.XPathContext;
import org.apache.xpath.functions.FuncExtFunction;
import org.apache.xpath.objects.XObject;
import org.apache.xpath.objects.XString;
/**
* Execute EXSLT functions, determine the availability of EXSLT functions, and the
* availability of an EXSLT result element.
*/
public class ExtensionHandlerExsltFunction extends ExtensionHandler
{
private String m_namespace;
private StylesheetRoot m_stylesheet;
private static final QName RESULTQNAME =
new QName(Constants.S_EXSLT_FUNCTIONS_URL,
Constants.EXSLT_ELEMNAME_FUNCRESULT_STRING);
/**
* Constructor called from ElemExsltFunction runtimeInit().
*/
public ExtensionHandlerExsltFunction(String ns, StylesheetRoot stylesheet)
{
super(ns, "xml"); // required by ExtensionHandler interface.
m_namespace = ns;
m_stylesheet = stylesheet;
}
/**
* Required by ExtensionHandler (an abstract method). No-op.
*/
public void processElement(
String localPart, ElemTemplateElement element, TransformerImpl transformer,
Stylesheet stylesheetTree, Object methodKey) throws TransformerException, IOException
{}
/**
* Get the ElemExsltFunction element associated with the
* function.
*
* @param funcName Local name of the function.
* @return the ElemExsltFunction element associated with
* the function, null if none exists.
*/
public ElemExsltFunction getFunction(String funcName)
{
QName qname = new QName(m_namespace, funcName);
ElemTemplate templ = m_stylesheet.getTemplateComposed(qname);
if (templ != null && templ instanceof ElemExsltFunction)
return (ElemExsltFunction) templ;
else
return null;
}
/**
* Does the EXSLT function exist?
*
* @param funcName Local name of the function.
* @return true if the function exists.
*/
public boolean isFunctionAvailable(String funcName)
{
return getFunction(funcName)!= null;
}
/** If an element-available() call applies to an EXSLT result element within
* an EXSLT function element, return true.
*
* Note: The EXSLT function element is a template-level element, and
* element-available() returns false for it.
*
* @param elemName name of the element.
* @return true if the function is available.
*/
public boolean isElementAvailable(String elemName)
{
if (!(new QName(m_namespace, elemName).equals(RESULTQNAME)))
{
return false;
}
else
{
ElemTemplateElement elem = m_stylesheet.getFirstChildElem();
while (elem != null && elem != m_stylesheet)
{
if (elem instanceof ElemExsltFuncResult && ancestorIsFunction(elem))
return true;
ElemTemplateElement nextElem = elem.getFirstChildElem();
if (nextElem == null)
nextElem = elem.getNextSiblingElem();
if (nextElem == null)
nextElem = elem.getParentElem();
elem = nextElem;
}
}
return false;
}
/**
* Determine whether the func:result element is within a func:function element.
* If not, it is illegal.
*/
private boolean ancestorIsFunction(ElemTemplateElement child)
{
while (child.getParentElem() != null
&& !(child.getParentElem() instanceof StylesheetRoot))
{
if (child.getParentElem() instanceof ElemExsltFunction)
return true;
child = child.getParentElem();
}
return false;
}
/**
* Execute the EXSLT function and return the result value.
*
* @param funcName Name of the EXSLT function.
* @param args The arguments of the function call.
* @param methodKey Not used.
* @param exprContext Used to get the XPathContext.
* @return the return value of the function evaluation.
* @throws javax.xml.transform.TransformerException
*/
public Object callFunction(
String funcName, Vector args, Object methodKey,
ExpressionContext exprContext) throws TransformerException
{
throw new TransformerException("This method should not be called.");
}
/**
* Execute the EXSLT function and return the result value.
*
* @param extFunction The XPath extension function
* @param args The arguments of the function call.
* @param exprContext The context in which this expression is being executed.
* @return the return value of the function evaluation.
* @throws javax.xml.transform.TransformerException
*/
public Object callFunction(FuncExtFunction extFunction,
Vector args,
ExpressionContext exprContext)
throws TransformerException
{
// Find the template which invokes this EXSLT function.
ExpressionNode parent = extFunction.exprGetParent();
while (parent != null && !(parent instanceof ElemTemplate))
{
parent = parent.exprGetParent();
}
ElemTemplate callerTemplate = (parent != null) ? (ElemTemplate)parent: null;
XObject[] methodArgs;
methodArgs = new XObject[args.size()];
try
{
for (int i = 0; i < methodArgs.length; i++)
{
methodArgs[i] = XObject.create(args.elementAt(i));
}
ElemExsltFunction elemFunc = getFunction(extFunction.getFunctionName());
if (null != elemFunc) {
XPathContext context = exprContext.getXPathContext();
TransformerImpl transformer = (TransformerImpl)context.getOwnerObject();
transformer.pushCurrentFuncResult(null);
elemFunc.execute(transformer, methodArgs);
XObject val = (XObject)transformer.popCurrentFuncResult();
return (val == null) ? new XString("") // value if no result element.
: val;
}
else {
throw new TransformerException(XSLMessages.createMessage(XSLTErrorResources.ER_FUNCTION_NOT_FOUND, new Object[] {extFunction.getFunctionName()}));
}
}
catch (TransformerException e)
{
throw e;
}
catch (Exception e)
{
throw new TransformerException(e);
}
}
}