/*
* $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/Function.java,v 1.8 2006/02/05 21:47:41 elharo Exp $
* $Revision: 1.8 $
* $Date: 2006/02/05 21:47:41 $
*
* ====================================================================
*
* Copyright 2000-2002 bob mcwhirter & James Strachan.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* * Neither the name of the Jaxen Project nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* ====================================================================
* This software consists of voluntary contributions made by many
* individuals on behalf of the Jaxen Project and was originally
* created by bob mcwhirter <bob@werken.com> and
* James Strachan <jstrachan@apache.org>. For more information on the
* Jaxen Project, please see <http://www.jaxen.org/>.
*
* $Id: Function.java,v 1.8 2006/02/05 21:47:41 elharo Exp $
*/
package org.orbeon.jaxen;
import java.util.List;
/** Interface for the extensible function framework.
*
* <p>
* <strong>NOTE:</strong> This class is not typically used directly,
* but is exposed for writers of extended XPath packages.
* </p>
*
* <p>
* Implementations of <code>Function</code> are functors
* which are used to evaluate a function-call within an
* XPath expression.
* </p>
*
* @see FunctionContext
*
* @author <a href="mailto:bob@werken.com">bob mcwhirter</a>
*/
public interface Function
{
/** Evaluate this function.
*
* @param context the context at the point in the
* expression when the function is called
* @param args arguments provided to the function
*
* @return the result of evaluating the function; a <code>List</code>
* (node-set), <code>Double</code>, <code>Boolean</code>, or
* <code>String</code>
*
* @throws FunctionCallException if an XPath error occurs during evaluation;
* for instance, if the number or type of the arguments is incorrect
*/
Object call(Context context,
List args) throws FunctionCallException;
}