#ifndef __OPERAND_H__
#define __OPERAND_H__
#include "tdafx.h"

struct Operand
{
/*	virtual void Mul(const Operand&){}
	virtual void Div(const Operand&){}
	virtual void Add(const Operand&){}
	virtual void Sub(const Operand&){}
*/
	virtual double GetResult()const{return 1;}
	virtual double GetSingleValue()const=0;
	virtual bool operator<(const Operand&)const{return false;}
    virtual bool IsConst()const{return false;}
	virtual string GetExpression()const{return "";};
     
	//virtual void FillNode(double){}


	virtual ~Operand(){};//不能為純虛

protected:
	Operand(){}//不能為私有？？
};

#endif //__OPERAND_H__