1 /*
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8  * particular file as subject to the "Classpath" exception as provided
9  * by Oracle in the LICENSE file that accompanied this code.
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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).
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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  * @since 1.5
43  */
44 public 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    */
resolveVariable(QName variableName)57   public Object resolveVariable(QName variableName);
58 }
59