// op.h: interface for the op class.
//
//////////////////////////////////////////////////////////////////////

#if !defined(AFX_OP_H__66A78B09_F9D2_4CA6_92CF_7BDD0EA49FC7__INCLUDED_)
#define AFX_OP_H__66A78B09_F9D2_4CA6_92CF_7BDD0EA49FC7__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

class op  
{
public:
	op();
	virtual ~op();

	virtual int evaluate();

};

class unary : public op  
{
public:
	unary();
	~unary();

private:
	op *next;

};


class binary : public op  
{
public:
	binary();
	~binary();

private:
	op *left, *right;
};

class value : public op  
{
	friend ostream &operator<<(ostream &, const value &);
	friend istream &operator>>(istream &, value &)
public:
	value(int x);
	~value();

	int operator==(const op &x);
	int operator=(const value &x);

private:
	int val;
};


class add : public binary  
{
	friend ostream &operator<<(ostream &, const binary &);
	friend istream &operator>>(istream &, binary &)
public:
	value(op &lt, op &rt);
	~value();

	int operator==(const op &x);
	int operator=(const add&x);

};

#endif // !defined(AFX_OP_H__66A78B09_F9D2_4CA6_92CF_7BDD0EA49FC7__INCLUDED_)