1 /* 2 * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/VariableContext.java,v 1.6 2002/05/20 08:34:10 jstrachan Exp $ 3 * $Revision: 1.6 $ 4 * $Date: 2002/05/20 08:34:10 $ 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: VariableContext.java,v 1.6 2002/05/20 08:34:10 jstrachan Exp $ 60 */ 61 62 63 package org.jaxen; 64 65 /*** Resolves variable bindings within an XPath expression. 66 * 67 * <p> 68 * Variables within an XPath expression are denoted using 69 * notation such as $varName or $nsPrefix:varName, and may 70 * refer to primitive types (Boolean, Number or String), 71 * <code>node-sets</code> or individual XML nodes. 72 * </p> 73 * 74 * <p> 75 * When a variable is bound to a <code>node-set</code>, the 76 * actual Java object returned should be a <code>java.util.List</code> 77 * containing XML nodes from the object-model (dom4j, JDOM, DOM, EXML) 78 * being used with the XPath. 79 * </p> 80 * 81 * <p> 82 * A variable may validly be assigned the <code>null</code> value, 83 * but an unbound variable (one that this context does not know about) 84 * should cause an {@link UnresolvableException} to be thrown. 85 * </p> 86 * 87 * @see SimpleVariableContext 88 * @see NamespaceContext 89 * 90 * @author <a href="mailto:bob@werken.com">bob mcwhirter</a> 91 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a> 92 */ 93 public interface VariableContext 94 { 95 /*** An implementation should return the value of an xpath variable 96 * based on the namespace uri and local name of the variable-reference 97 * expression. 98 * 99 * <p> 100 * It must not use the prefix parameter to select a variable, 101 * because a prefix could be bound to any namespace; the prefix parameter 102 * could be used in debugging output or other generated information. 103 * The prefix may otherwise be ignored. 104 * </p> 105 * 106 * @param namespaceURI the namespace uri to which the prefix parameter 107 * is bound in the xpath expression. If the variable 108 * reference expression had no prefix, the namespace 109 * uri is <code>null</code>. 110 * @param prefix the prefix that was used in the variable reference 111 * expression. 112 * @param localName the local name of the variable-reference 113 * expression; if there is no prefix, then this is 114 * the whole name of the variable. 115 * 116 * @return the variable's value (which can be <code>null</code>) 117 * @throws UnresolvableException when the variable cannot be resolved. 118 */ 119 public Object getVariableValue( String namespaceURI, 120 String prefix, 121 String localName ) 122 throws UnresolvableException; 123 }