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 javax.xml.namespace.QName;
29
30/**
31 * <p><code>XPathVariableResolver</code> provides access to the set of user defined XPath variables.</p>
32 *
33 * <p>The <code>XPathVariableResolver</code> and the XPath evaluator must adhere to a contract that
34 * cannot be directly enforced by the API.  Although variables may be mutable,
35 * that is, an application may wish to evaluate the same XPath expression more
36 * than once with different variable values, in the course of evaluating any
37 * single XPath expression, a variable's value <strong><em>must</em></strong>
38 * not change.</p>
39 *
40 * @author  <a href="mailto:Norman.Walsh@Sun.com">Norman Walsh</a>
41 * @author  <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a>
42 * @since 1.5
43 */
44public interface XPathVariableResolver {
45  /**
46   * <p>Find a variable in the set of available variables.</p>
47   *
48   * <p>If <code>variableName</code> is <code>null</code>, then a <code>NullPointerException</code> is thrown.</p>
49   *
50   * @param variableName The <code>QName</code> of the variable name.
51   *
52   * @return The variables value, or <code>null</code> if no variable named <code>variableName</code>
53   *   exists.  The value returned must be of a type appropriate for the underlying object model.
54   *
55   * @throws NullPointerException If <code>variableName</code> is <code>null</code>.
56   */
57  public Object resolveVariable(QName variableName);
58}
59