1 /* 2 * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/SimpleFunctionContext.java,v 1.9 2005/03/23 13:12:54 elharo Exp $ 3 * $Revision: 1.9 $ 4 * $Date: 2005/03/23 13:12:54 $ 5 * 6 * ==================================================================== 7 * 8 * Copyright (C) 2000-2002 bob mcwhirter & James Strachan. 9 * All rights reserved. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions, and the following disclaimer. 17 * 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions, and the disclaimer that follows 20 * these conditions in the documentation and/or other materials 21 * provided with the distribution. 22 * 23 * 3. The name "Jaxen" must not be used to endorse or promote products 24 * derived from this software without prior written permission. For 25 * written permission, please contact license@jaxen.org. 26 * 27 * 4. Products derived from this software may not be called "Jaxen", nor 28 * may "Jaxen" appear in their name, without prior written permission 29 * from the Jaxen Project Management (pm@jaxen.org). 30 * 31 * In addition, we request (but do not require) that you include in the 32 * end-user documentation provided with the redistribution and/or in the 33 * software itself an acknowledgement equivalent to the following: 34 * "This product includes software developed by the 35 * Jaxen Project (http://www.jaxen.org/)." 36 * Alternatively, the acknowledgment may be graphical using the logos 37 * available at http://www.jaxen.org/ 38 * 39 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED 40 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 41 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 42 * DISCLAIMED. IN NO EVENT SHALL THE Jaxen AUTHORS OR THE PROJECT 43 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 45 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 46 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 47 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 48 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 49 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 50 * SUCH DAMAGE. 51 * 52 * ==================================================================== 53 * This software consists of voluntary contributions made by many 54 * individuals on behalf of the Jaxen Project and was originally 55 * created by bob mcwhirter <bob@werken.com> and 56 * James Strachan <jstrachan@apache.org>. For more information on the 57 * Jaxen Project, please see <http://www.jaxen.org/>. 58 * 59 * $Id: SimpleFunctionContext.java,v 1.9 2005/03/23 13:12:54 elharo Exp $ 60 */ 61 62 63 package org.jaxen; 64 65 import java.util.HashMap; 66 67 /*** Simple default implementation of <code>FunctionContext</code>. 68 * 69 * <p> 70 * This is a simple table-based key-lookup implementation 71 * for <code>FunctionContext</code> which can be programmatically 72 * extended by registering additional functions. 73 * </p> 74 * 75 * @see XPathFunctionContext 76 * 77 * @author <a href="mailto:bob@werken.com">bob mcwhirter</a> 78 */ 79 public class SimpleFunctionContext implements FunctionContext 80 { 81 /*** Table of functions. */ 82 private HashMap functions; 83 84 /*** Construct. 85 * 86 * <p> 87 * Construct with an empty function lookup table. 88 * </p> 89 */ 90 public SimpleFunctionContext() 91 { 92 this.functions = new HashMap(); 93 } 94 95 /*** Register a new function. 96 * 97 * <p> 98 * By registering a new function, any XPath expression 99 * that utilizes this <code>FunctionContext</code> may 100 * refer to and use the new function. 101 * </p> 102 * 103 * <p> 104 * Functions may exist either in an namespace or not. 105 * Namespace prefix-to-URI resolution is the responsibility 106 * of a {@link NamespaceContext}. Within this <code>FunctionContext</code> 107 * functions are only referenced using the URI, <b>not</b> 108 * the prefix. 109 * </p> 110 * 111 * <p> 112 * The namespace URI of a function may be <code>null</code> 113 * to indicate that it exists without a namespace. 114 * </p> 115 * 116 * @param namespaceURI the namespace URI of the function to 117 * be registered with this context 118 * @param localName the non-prefixed local portion of the 119 * function to be registered with this context 120 * @param function a {@link Function} implementation object 121 * to be used when evaluating the function 122 */ 123 public void registerFunction(String namespaceURI, 124 String localName, 125 Function function ) 126 { 127 this.functions.put( new QualifiedName(namespaceURI, localName), 128 function ); 129 } 130 131 public Function getFunction(String namespaceURI, 132 String prefix, 133 String localName ) 134 throws UnresolvableException 135 { 136 Object key = new QualifiedName( namespaceURI, localName ); 137 138 if ( this.functions.containsKey(key) ) { 139 return (Function) this.functions.get( key ); 140 } 141 else { 142 throw new UnresolvableException( "Function " + 143 prefix + ":" + localName ); 144 } 145 } 146 }