/**************************************************************************************
* Copyright (C) 2008 EsperTech, Inc. All rights reserved. *
* http://esper.codehaus.org *
* http://www.espertech.com *
* ---------------------------------------------------------------------------------- *
* The software in this package is published under the terms of the GPL license *
* a copy of which has been included with this distribution in the license.txt file. *
**************************************************************************************/
package com.espertech.esper.pattern;
/**
* Interface for visiting each element in the evaluation node tree for an event expression (see Visitor pattern).
*/
public interface EvalStateNodeVisitor
{
/**
* Invoked by each child node as part of accepting this visitor.
* @param node is the node in the composite tree accepting the visitor
* @param data is any additional useful to implementations
* @return any additional data useful to implementations or null
*/
public Object visit(EvalStateNode node, Object data);
}