1 /*
2 * $Header$
3 * $Revision$
4 * $Date$
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 * $Id$
46 */
47
48
49 package org.jaxen;
50
51 /** Implemented by classes that know how to resolve XPath function names and
52 * namespaces to implementations of these functions.
53 *
54 * <p>
55 * By using a custom <code>FunctionContext</code>, new or different
56 * functions may be installed and available to XPath expression writers.
57 * </p>
58 *
59 * @see XPathFunctionContext
60 *
61 * @author <a href="mailto:bob@werken.com">bob mcwhirter</a>
62 */
63 public interface FunctionContext
64 {
65 /** An implementation should return a <code>Function</code> implementation object
66 * based on the namespace URI and local name of the function-call
67 * expression.
68 *
69 * <p>
70 * It must not use the prefix parameter to select an implementation,
71 * because a prefix could be bound to any namespace; the prefix parameter
72 * could be used in debugging output or other generated information.
73 * The prefix may otherwise be completely ignored.
74 * </p>
75 *
76 * @param namespaceURI the namespace URI to which the prefix parameter
77 * is bound in the XPath expression. If the function
78 * call expression had no prefix, the namespace URI
79 * is <code>null</code>.
80 * @param prefix the prefix that was used in the function call
81 * expression
82 * @param localName the local name of the function-call expression.
83 * If there is no prefix, then this is the whole
84 * name of the function.
85 *
86 * @return a Function implementation object.
87 * @throws UnresolvableException when the function cannot be resolved
88 */
89 Function getFunction( String namespaceURI,
90 String prefix,
91 String localName ) throws UnresolvableException;
92 }