1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements.  See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License.  You may obtain a copy of the License at
8  *
9  *     http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17 // $Id: XPathVariableResolver.java 446598 2006-09-15 12:55:40Z jeremias $
18 
19 package javax.xml.xpath;
20 
21 import javax.xml.namespace.QName;
22 
23 /**
24  * <p><code>XPathVariableResolver</code> provides access to the set of user defined XPath variables.</p>
25  *
26  * <p>The <code>XPathVariableResolver</code> and the XPath evaluator must adhere to a contract that
27  * cannot be directly enforced by the API.  Although variables may be mutable,
28  * that is, an application may wish to evaluate the same XPath expression more
29  * than once with different variable values, in the course of evaluating any
30  * single XPath expression, a variable's value <strong><em>must</em></strong> be immutable.</p>
31  *
32  * @author  <a href="mailto:Norman.Walsh@Sun.com">Norman Walsh</a>
33  * @author  <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a>
34  * @version $Revision: 446598 $, $Date: 2006-09-15 05:55:40 -0700 (Fri, 15 Sep 2006) $
35  * @since 1.5
36  */
37 public interface XPathVariableResolver {
38   /**
39    * <p>Find a variable in the set of available variables.</p>
40    *
41    * <p>If <code>variableName</code> is <code>null</code>, then a <code>NullPointerException</code> is thrown.</p>
42    *
43    * @param variableName The <code>QName</code> of the variable name.
44    *
45    * @return The variables value, or <code>null</code> if no variable named <code>variableName</code>
46    *   exists.  The value returned must be of a type appropriate for the underlying object model.
47    *
48    * @throws NullPointerException If <code>variableName</code> is <code>null</code>.
49    */
resolveVariable(QName variableName)50   public Object resolveVariable(QName variableName);
51 }
52