org.apache.xalan.extensions.ExtensionHandler Maven / Gradle / Ivy
/*
* 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: ExtensionHandler.java 468637 2006-10-28 06:51:02Z minchau $
*/
package org.apache.xalan.extensions;
import java.io.IOException;
import java.util.Vector;
import javax.xml.transform.TransformerException;
import org.apache.xalan.templates.ElemTemplateElement;
import org.apache.xalan.templates.Stylesheet;
import org.apache.xalan.transformer.TransformerImpl;
import org.apache.xpath.functions.FuncExtFunction;
/**
* Abstract base class for handling an extension namespace for XPath.
* Provides functions to test a function's existence and call a function.
* Also provides functions for calling an element and testing for
* an element's existence.
*
* @author Sanjiva Weerawarana ([email protected])
* @xsl.usage internal
*/
public abstract class ExtensionHandler
{
/** uri of the extension namespace */
protected String m_namespaceUri;
/** scripting language of implementation */
protected String m_scriptLang;
/**
* This method loads a class using the context class loader if we're
* running under Java2 or higher.
*
* @param className Name of the class to load
*/
static Class getClassForName(String className)
throws ClassNotFoundException
{
// Hack for backwards compatibility with XalanJ1 stylesheets
if(className.equals("org.apache.xalan.xslt.extensions.Redirect")) {
className = "org.apache.xalan.lib.Redirect";
}
return ObjectFactory.findProviderClass(
className, ObjectFactory.findClassLoader(), true);
}
/**
* Construct a new extension namespace handler given all the information
* needed.
*
* @param namespaceUri the extension namespace URI that I'm implementing
* @param scriptLang language of code implementing the extension
*/
protected ExtensionHandler(String namespaceUri, String scriptLang)
{
m_namespaceUri = namespaceUri;
m_scriptLang = scriptLang;
}
/**
* Tests whether a certain function name is known within this namespace.
* @param function name of the function being tested
* @return true if its known, false if not.
*/
public abstract boolean isFunctionAvailable(String function);
/**
* Tests whether a certain element name is known within this namespace.
* @param element Name of element to check
* @return true if its known, false if not.
*/
public abstract boolean isElementAvailable(String element);
/**
* Process a call to a function.
*
* @param funcName Function name.
* @param args The arguments of the function call.
* @param methodKey A key that uniquely identifies this class and method call.
* @param exprContext The context in which this expression is being executed.
*
* @return the return value of the function evaluation.
*
* @throws TransformerException if parsing trouble
*/
public abstract Object callFunction(
String funcName, Vector args, Object methodKey,
ExpressionContext exprContext) throws TransformerException;
/**
* Process a call to a function.
*
* @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 TransformerException if parsing trouble
*/
public abstract Object callFunction(
FuncExtFunction extFunction, Vector args,
ExpressionContext exprContext) throws TransformerException;
/**
* Process a call to this extension namespace via an element. As a side
* effect, the results are sent to the TransformerImpl's result tree.
*
* @param localPart Element name's local part.
* @param element The extension element being processed.
* @param transformer Handle to TransformerImpl.
* @param stylesheetTree The compiled stylesheet tree.
* @param methodKey A key that uniquely identifies this class and method call.
*
* @throws XSLProcessorException thrown if something goes wrong
* while running the extension handler.
* @throws MalformedURLException if loading trouble
* @throws FileNotFoundException if loading trouble
* @throws IOException if loading trouble
* @throws TransformerException if parsing trouble
*/
public abstract void processElement(
String localPart, ElemTemplateElement element, TransformerImpl transformer,
Stylesheet stylesheetTree, Object methodKey) throws TransformerException, IOException;
}