Expression.java

/**
 *  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();

}