1 /*
2 * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/SimpleFunctionContext.java,v 1.12 2005/09/25 11:39:21 elharo Exp $
3 * $Revision: 1.12 $
4 * $Date: 2005/09/25 11:39:21 $
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 1.12 2005/09/25 11:39:21 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 /***
85 * <p>
86 * Construct an empty function context.
87 * </p>
88 */
89 public SimpleFunctionContext()
90 {
91 this.functions = new HashMap();
92 }
93
94 /*** Register a new function.
95 *
96 * <p>
97 * By registering a new function, any XPath expression
98 * that utilizes this <code>FunctionContext</code> may
99 * refer to and use the new function.
100 * </p>
101 *
102 * <p>
103 * Functions may exist either in a namespace or not.
104 * Namespace prefix-to-URI resolution is the responsibility
105 * of a {@link NamespaceContext}. Within this <code>FunctionContext</code>
106 * functions are only referenced using the URI, <strong>not</strong>
107 * the prefix.
108 * </p>
109 *
110 * <p>
111 * The namespace URI of a function may be <code>null</code>
112 * to indicate that it exists without a namespace.
113 * </p>
114 *
115 * @param namespaceURI the namespace URI of the function to
116 * be registered with this context
117 * @param localName the non-prefixed local portion of the
118 * function to be registered with this context
119 * @param function a {@link Function} implementation object
120 * to be used when evaluating the function
121 */
122 public void registerFunction(String namespaceURI,
123 String localName,
124 Function function )
125 {
126 this.functions.put( new QualifiedName(namespaceURI, null, localName),
127 function );
128 }
129
130 public Function getFunction(String namespaceURI,
131 String prefix,
132 String localName )
133 throws UnresolvableException
134 {
135 QualifiedName key = new QualifiedName( namespaceURI, prefix, localName );
136
137 if ( this.functions.containsKey(key) ) {
138 return (Function) this.functions.get( key );
139 }
140 else {
141 throw new UnresolvableException( "No Such Function " + key.getClarkForm() );
142 }
143 }
144 }