item.h

一个在linux下的shell的计算器

/*
 *
 *
 *
 */

#ifndef __ITEM_H
#define __ITEM_H

#include <iostream>
#include <string>

enum itemtype
{
 EMPTY,
 INTEGER,
 LOGICAL,
 REAL,
 STRING,
 OPERATION,
 LIST
};

std::string TypeName(itemtype t);

class Item
{
 private:

  std::string name;

 protected:

  itemtype type;

 public:

  Item *prev, *next;

  // 

  Item();

  virtual ~Item();

  itemtype GetType() const;

  // Virtual Methods

  virtual Item *Clone() = 0;

  virtual long ToInteger() const;
  
  virtual bool ToBoolean() const;
  
  virtual double ToDouble() const;

  virtual std::string ToString() const;

  // 
  void SetName(std::string s);

  std::string GetName() const;

};

std::ostream & operator<<(std::ostream & stream, Item const & x);

#endif