/**
* Copyright (C) 2010 dennis zhuang (killme2008@gmail.com)
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
**/
package com.googlecode.aviator;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
* A expression
*
* @author dennis
*
*/
public interface Expression {
/**
* Execute expression with environment
*
* @param env
* Binding variable environment
* @return
*/
public abstract Object execute(Map<String, Object> env);
/**
* Execute expression with empty environment
*
* @return
*/
public abstract Object execute();
/**
* Returns this expression's all variable names in order when using
* AviatorEvaluator.EVAL mode,else returns empty set
*
* @see com.googlecode.aviator.AviatorEvaluator#EVAL
* @return
*/
public List<String> getVariableNames();
}