/*
* Copyright (c) 2003, 2005, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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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;
}