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//--------------------------------------------------------------------------
//	Copyright (c) 1998-2004, Drew Davidson and Luke Blanshard
//  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 Drew Davidson 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
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//  FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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//  THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
//  DAMAGE.
//--------------------------------------------------------------------------
package com.feilong.lib.ognl;

import java.util.Map;

/**
 * Interface for handling null results from Chains.
 * Object has the opportunity to substitute an object for the
 * null and continue.
 * 
 * @author Luke Blanshard ([email protected])
 * @author Drew Davidson ([email protected])
 */
public interface NullHandler{

    /**
     * Method called on target returned null.
     *
     * @param context
     *            the current execution context.
     * @param target
     *            the Object on which the method was called.
     * @param methodName
     *            the name of the method which was called.
     * @param args
     *            the arguments to the method that was called.
     * @return the result Object containing the state of the method call that returned null.
     */
    public Object nullMethodResult(Map context,Object target,String methodName,Object[] args);

    /**
     * Property in target evaluated to null. Property can be a constant
     * String property name or a DynamicSubscript.
     *
     * @param context
     *            the current execution context.
     * @param target
     *            the Object to which the property belongs.
     * @param property
     *            the property whose value evaluated to null.
     * @return the result Object containing the state of the property that evaluated to null.
     */
    public Object nullPropertyValue(Map context,Object target,Object property);
}