1 /*
2 * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/SimpleFunctionContext.java,v 1.14 2006/02/05 21:47:41 elharo Exp $
3 * $Revision: 1.14 $
4 * $Date: 2006/02/05 21:47:41 $
5 *
6 * ====================================================================
7 *
8 * Copyright 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 are
13 * met:
14 *
15 * * Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 *
18 * * Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 *
22 * * Neither the name of the Jaxen Project nor the names of its
23 * contributors may be used to endorse or promote products derived
24 * from this software without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
27 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
29 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
30 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
31 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
32 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
33 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
34 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
35 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
36 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37 *
38 * ====================================================================
39 * This software consists of voluntary contributions made by many
40 * individuals on behalf of the Jaxen Project and was originally
41 * created by bob mcwhirter <bob@werken.com> and
42 * James Strachan <jstrachan@apache.org>. For more information on the
43 * Jaxen Project, please see <http://www.jaxen.org/>.
44 *
45 * $Id: SimpleFunctionContext.java,v 1.14 2006/02/05 21:47:41 elharo Exp $
46 */
47
48
49 package org.jaxen;
50
51 import java.util.HashMap;
52
53 /*** Simple default implementation of <code>FunctionContext</code>.
54 *
55 * <p>
56 * This is a simple table-based key-lookup implementation
57 * for <code>FunctionContext</code> which can be programmatically
58 * extended by registering additional functions.
59 * </p>
60 *
61 * @see XPathFunctionContext
62 *
63 * @author <a href="mailto:bob@werken.com">bob mcwhirter</a>
64 */
65 public class SimpleFunctionContext implements FunctionContext
66 {
67 /*** Table of functions. */
68 private HashMap functions;
69
70 /***
71 * <p>
72 * Construct an empty function context.
73 * </p>
74 */
75 public SimpleFunctionContext()
76 {
77 this.functions = new HashMap();
78 }
79
80 /*** Register a new function.
81 *
82 * <p>
83 * By registering a new function, any XPath expression
84 * that utilizes this <code>FunctionContext</code> may
85 * refer to and use the new function.
86 * </p>
87 *
88 * <p>
89 * Functions may exist either in a namespace or not.
90 * Namespace prefix-to-URI resolution is the responsibility
91 * of a {@link NamespaceContext}. Within this <code>FunctionContext</code>
92 * functions are only referenced using the URI, <strong>not</strong>
93 * the prefix.
94 * </p>
95 *
96 * <p>
97 * The namespace URI of a function may be <code>null</code>
98 * to indicate that it exists without a namespace.
99 * </p>
100 *
101 * @param namespaceURI the namespace URI of the function to
102 * be registered with this context
103 * @param localName the non-prefixed local portion of the
104 * function to be registered with this context
105 * @param function a {@link Function} implementation object
106 * to be used when evaluating the function
107 */
108 public void registerFunction(String namespaceURI,
109 String localName,
110 Function function )
111 {
112 this.functions.put( new QualifiedName(namespaceURI, localName),
113 function );
114 }
115
116 public Function getFunction(String namespaceURI,
117 String prefix,
118 String localName )
119 throws UnresolvableException
120 {
121 QualifiedName key = new QualifiedName( namespaceURI, localName );
122
123 if ( this.functions.containsKey(key) ) {
124 return (Function) this.functions.get( key );
125 }
126 else {
127 throw new UnresolvableException( "No Such Function " + key.getClarkForm() );
128 }
129 }
130 }