1. // $Id: XPathVariableResolver.java,v 1.6 2003/12/08 04:40:47 jsuttor Exp $

  2. 

  3. /*

  4.  * @(#)XPathVariableResolver.java	1.5 04/07/26

  5.  * 

  6.  * Copyright 2004 Sun Microsystems, Inc. All rights reserved.

  7.  * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.

  8.  */

  9. 

  10. package javax.xml.xpath;

  11. 

  12. import javax.xml.namespace.QName;

  13. 

  14. /**

  15.  * <p><code>XPathVariableResolver</code> provides access to the set of user defined XPath variables.</p>

  16.  *

  17.  * <p>The <code>XPathVariableResolver</code> and the XPath evaluator must adhere to a contract that

  18.  * cannot be directly enforced by the API.  Although variables may be mutable,

  19.  * that is, an application may wish to evaluate the same XPath expression more

  20.  * than once with different variable values, in the course of evaluating any

  21.  * single XPath expression, a variable's value <strong><em>must</em></strong> be immutable.</p>

  22.  *

  23.  * @author  <a href="mailto:Norman.Walsh@Sun.com">Norman Walsh</a>

  24.  * @author  <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a>

  25.  * @version $Revision: 1.6 $, $Date: 2003/12/08 04:40:47 $

  26.  * @since 1.5

  27.  */

  28. public interface XPathVariableResolver {

  29.   /** 

  30.    * <p>Find a variable in the set of available variables.</p>

  31.    * 

  32.    * <p>If <code>variableName</code> is <code>null</code>, then a <code>NullPointerException</code> is thrown.</p>

  33.    * 

  34.    * @param variableName The <code>QName</code> of the variable name.

  35.    * 

  36.    * @return The variables value, or <code>null</code> if no variable named <code>variableName</code>

  37.    *   exists.  The value returned must be of a type appropriate for the underlying object model.

  38.    * 

  39.    * @throws NullPointerException If <code>variableName</code> is <code>null</code>.

  40.    */

  41.   public Object resolveVariable(QName variableName);

  42. }