functionexpression.java

来自「mysql集群」· Java 代码 · 共 87 行

/*
 * 	This program is free software; you can redistribute it and/or modify it under the terms of 
 * the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, 
 * or (at your option) any later version. 
 * 
 * 	This program 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 General Public License for more details. 
 * 	You should have received a copy of the GNU General Public License along with this program; 
 * if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
package com.meidusa.amoeba.parser.expression;

import java.util.ArrayList;
import java.util.List;

import com.meidusa.amoeba.parser.function.Function;
import com.meidusa.amoeba.parser.function.RealtimeCalculator;
import com.meidusa.amoeba.sqljep.ParseException;

/**
 * 函数表达式
 * @author <a href=mailto:[e-mail]>Struct chen</a>
 *
 */
public class FunctionExpression extends Expression{

	private Function function;
	private List<Expression> argList = new ArrayList<Expression>();

	public List<Expression> getArgList() {
		return argList;
	}

	public void setArgList(List<Expression> argList) {
		this.argList = argList;
	}
	
	/**
	 * 往函数表达式 增加 表达式参数
	 * @param expression 
	 */
	public void addArgExpression(Expression expression){
		argList.add(expression);
	}

	public Function getFunction() {
		return function;
	}

	public void setFunction(Function function) {
		this.function = function;
	}

	public boolean isRealtime(){
		boolean isRealTime = (function instanceof RealtimeCalculator) ;
		if(isRealTime) return true;
		for(Expression e:argList){
			if(e.isRealtime()){
				return true;
			}
		}
		return false;
	}
	
	@SuppressWarnings("unchecked")
	@Override
	public Comparable evaluate(Object[] parameters) {
		try {
			return function.evaluate(argList,parameters);
		} catch (ParseException e) {
			e.printStackTrace();
			return null;
		}
	}

	@Override
	public Expression reverse() {
		return this;
	}
	
	@Override
	protected void toString(StringBuilder builder) {
		function.toString(argList,builder);
	}
}