1/*
2 * Copyright (c) 2003, 2005, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package javax.xml.xpath;
27
28import java.util.List;
29
30/**
31 * <p><code>XPathFunction</code> provides access to XPath functions.</p>
32 *
33 * <p>Functions are identified by QName and arity in XPath.</p>
34 *
35 * @author  <a href="mailto:Norman.Walsh@Sun.com">Norman Walsh</a>
36 * @author  <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a>
37 * @since 1.5
38 */
39public interface XPathFunction {
40  /**
41   * <p>Evaluate the function with the specified arguments.</p>
42   *
43   * <p>To the greatest extent possible, side-effects should be avoided in the
44   * definition of extension functions. The implementation evaluating an
45   * XPath expression is under no obligation to call extension functions in
46   * any particular order or any particular number of times.</p>
47   *
48   * @param args The arguments, <code>null</code> is a valid value.
49   *
50   * @return The result of evaluating the <code>XPath</code> function as an <code>Object</code>.
51   *
52   * @throws XPathFunctionException If <code>args</code> cannot be evaluated with this <code>XPath</code> function.
53   */
54  public Object evaluate(List args)
55    throws XPathFunctionException;
56}
57