01 /*
02 * Copyright 2003-2005 Sun Microsystems, Inc. All Rights Reserved.
03 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
04 *
05 * This code is free software; you can redistribute it and/or modify it
06 * under the terms of the GNU General Public License version 2 only, as
07 * published by the Free Software Foundation. Sun designates this
08 * particular file as subject to the "Classpath" exception as provided
09 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package javax.xml.xpath;
27
28 import 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 * @version $Revision: 1.3 $, $Date: 2005/07/25 14:46:33 $
43 * @since 1.5
44 */
45 public interface XPathVariableResolver {
46 /**
47 * <p>Find a variable in the set of available variables.</p>
48 *
49 * <p>If <code>variableName</code> is <code>null</code>, then a <code>NullPointerException</code> is thrown.</p>
50 *
51 * @param variableName The <code>QName</code> of the variable name.
52 *
53 * @return The variables value, or <code>null</code> if no variable named <code>variableName</code>
54 * exists. The value returned must be of a type appropriate for the underlying object model.
55 *
56 * @throws NullPointerException If <code>variableName</code> is <code>null</code>.
57 */
58 public Object resolveVariable(QName variableName);
59 }
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