/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// $Id: XPathVariableResolver.java 446598 2006-09-15 12:55:40Z jeremias $
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> be immutable.</p>
*
* @author <a href="mailto:Norman.Walsh@Sun.com">Norman Walsh</a>
* @author <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a>
* @version $Revision: 446598 $, $Date: 2006-09-15 05:55:40 -0700 (Fri, 15 Sep 2006) $
* @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);
}