/*
* Copyright (c) 2003, 2005, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
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package javax.xml.xpath;
import java.util.List;
/**
* <p><code>XPathFunction</code> provides access to XPath functions.</p>
*
* <p>Functions are identified by QName and arity in XPath.</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 XPathFunction {
/**
* <p>Evaluate the function with the specified arguments.</p>
*
* <p>To the greatest extent possible, side-effects should be avoided in the
* definition of extension functions. The implementation evaluating an
* XPath expression is under no obligation to call extension functions in
* any particular order or any particular number of times.</p>
*
* @param args The arguments, <code>null</code> is a valid value.
*
* @return The result of evaluating the <code>XPath</code> function as an <code>Object</code>.
*
* @throws XPathFunctionException If <code>args</code> cannot be evaluated with this <code>XPath</code> function.
*/
public Object evaluate(List args)
throws XPathFunctionException;
}