/*
* Copyright (c) 2003, 2005, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*/
package javax.xml.xpath;
import javax.xml.namespace.QName;
/**
* <p><code>XPathVariableResolver</code> provides access to the set of user defined XPath variables.</p>
*
* <p>The <code>XPathVariableResolver</code> and the XPath evaluator must adhere to a contract that
* cannot be directly enforced by the API. Although variables may be mutable,
* that is, an application may wish to evaluate the same XPath expression more
* than once with different variable values, in the course of evaluating any
* single XPath expression, a variable's value <strong><em>must</em></strong>
* not change.</p>
*
* @author <a href="mailto:Norman.Walsh@Sun.com">Norman Walsh</a>
* @author <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a>
* @since 1.5
*/
public interface XPathVariableResolver {
/**
* <p>Find a variable in the set of available variables.</p>
*
* <p>If <code>variableName</code> is <code>null</code>, then a <code>NullPointerException</code> is thrown.</p>
*
* @param variableName The <code>QName</code> of the variable name.
*
* @return The variables value, or <code>null</code> if no variable named <code>variableName</code>
* exists. The value returned must be of a type appropriate for the underlying object model.
*
* @throws NullPointerException If <code>variableName</code> is <code>null</code>.
*/
public Object resolveVariable(QName variableName);
}