1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 /* 19 * $Id: ExtensionHandler.java 468637 2006-10-28 06:51:02Z minchau $ 20 */ 21 package org.apache.xalan.extensions; 22 23 import java.io.IOException; 24 import java.util.Vector; 25 26 import javax.xml.transform.TransformerException; 27 28 import org.apache.xalan.templates.ElemTemplateElement; 29 import org.apache.xalan.templates.Stylesheet; 30 import org.apache.xalan.transformer.TransformerImpl; 31 import org.apache.xpath.functions.FuncExtFunction; 32 33 /** 34 * Abstract base class for handling an extension namespace for XPath. 35 * Provides functions to test a function's existence and call a function. 36 * Also provides functions for calling an element and testing for 37 * an element's existence. 38 * 39 * @author Sanjiva Weerawarana (sanjiva (at) watson.ibm.com) 40 * @xsl.usage internal 41 */ 42 public abstract class ExtensionHandler 43 { 44 45 /** uri of the extension namespace */ 46 protected String m_namespaceUri; 47 48 /** scripting language of implementation */ 49 protected String m_scriptLang; 50 51 /** 52 * This method loads a class using the context class loader if we're 53 * running under Java2 or higher. 54 * 55 * @param className Name of the class to load 56 */ 57 static Class getClassForName(String className) 58 throws ClassNotFoundException 59 { 60 // Hack for backwards compatibility with XalanJ1 stylesheets 61 if(className.equals("org.apache.xalan.xslt.extensions.Redirect")) { 62 className = "org.apache.xalan.lib.Redirect"; 63 } 64 65 return ObjectFactory.findProviderClass( 66 className, ObjectFactory.findClassLoader(), true); 67 } 68 69 /** 70 * Construct a new extension namespace handler given all the information 71 * needed. 72 * 73 * @param namespaceUri the extension namespace URI that I'm implementing 74 * @param scriptLang language of code implementing the extension 75 */ 76 protected ExtensionHandler(String namespaceUri, String scriptLang) 77 { 78 m_namespaceUri = namespaceUri; 79 m_scriptLang = scriptLang; 80 } 81 82 /** 83 * Tests whether a certain function name is known within this namespace. 84 * @param function name of the function being tested 85 * @return true if its known, false if not. 86 */ 87 public abstract boolean isFunctionAvailable(String function); 88 89 /** 90 * Tests whether a certain element name is known within this namespace. 91 * @param element Name of element to check 92 * @return true if its known, false if not. 93 */ 94 public abstract boolean isElementAvailable(String element); 95 96 /** 97 * Process a call to a function. 98 * 99 * @param funcName Function name. 100 * @param args The arguments of the function call. 101 * @param methodKey A key that uniquely identifies this class and method call. 102 * @param exprContext The context in which this expression is being executed. 103 * 104 * @return the return value of the function evaluation. 105 * 106 * @throws TransformerException if parsing trouble 107 */ 108 public abstract Object callFunction( 109 String funcName, Vector args, Object methodKey, 110 ExpressionContext exprContext) throws TransformerException; 111 112 /** 113 * Process a call to a function. 114 * 115 * @param extFunction The XPath extension function. 116 * @param args The arguments of the function call. 117 * @param exprContext The context in which this expression is being executed. 118 * 119 * @return the return value of the function evaluation. 120 * 121 * @throws TransformerException if parsing trouble 122 */ 123 public abstract Object callFunction( 124 FuncExtFunction extFunction, Vector args, 125 ExpressionContext exprContext) throws TransformerException; 126 127 /** 128 * Process a call to this extension namespace via an element. As a side 129 * effect, the results are sent to the TransformerImpl's result tree. 130 * 131 * @param localPart Element name's local part. 132 * @param element The extension element being processed. 133 * @param transformer Handle to TransformerImpl. 134 * @param stylesheetTree The compiled stylesheet tree. 135 * @param methodKey A key that uniquely identifies this class and method call. 136 * 137 * @throws XSLProcessorException thrown if something goes wrong 138 * while running the extension handler. 139 * @throws MalformedURLException if loading trouble 140 * @throws FileNotFoundException if loading trouble 141 * @throws IOException if loading trouble 142 * @throws TransformerException if parsing trouble 143 */ 144 public abstract void processElement( 145 String localPart, ElemTemplateElement element, TransformerImpl transformer, 146 Stylesheet stylesheetTree, Object methodKey) throws TransformerException, IOException; 147 } 148
