/* Flyweight类
 * 它是所有具体享元类的超类或接口，通过这个接口，
 * Flyweight可以接受并作用于外部状态。
 */
class Flyweight
{
public:
	virtual void Operation( int extrinsicstate ) = 0;
};

/* ConcreteFlyweight类
 * ConcreteFlyweight是继承Flyweight超类或实现Flyweight接口，并为内部状态增加存储空间。
 */
class ConcreteFlyweight : Flyweight
{
public:
	virtual void Operation( int extrinsicstate )
	{
		printf("具体Flyweight:%d\n",extrinsicstate);
	}
}; 

/* UnsharedConcreteFlyweight类
 * 是指那些不需要共享的Flyweight子类。因为Flyweight接口共享成为可能，但并不强制共享。
 */
class UnsharedConcreteFlyweight : public Flyweight
{
public:
	virtual void Operation( int extrinsicstate )
	{
		printf("不共享的具体Flyweight:%d\n",extrinsicstate);
	}
};

/* FlyweightFactory类
 * 是一个享元工厂，用来创建并管理Flyweight对象。它主要是用来确保合理地共享Flyweight，
 * 当用户请求一个Flyweight时，FlyweightFactory对象提供一个已创建的实例或创建一个
 * （如果不存在的话）
 */
class FlyweightFactory
{
private:
	Hashtable flyweights = new Hashtable();
	
public:
	Flyweight GetFlyweight(string key)
	{
		if( !flyweights.ContainKey(key) )
			flyweights.add( key, new ConcreteFlyweight() );
		return (Flyweight)flyweights[key];
	}
};

// 客户端
int main()
{
	int extrinsicstate;		// 代码外部状态
	
	FlyweightFactory f = new FlyweightFactory();
	
	Flyweight fx = f.GetFlyweight("X");
	fx.Operation(--extrinsicstate);
	
	Flyweight fy = f.GetFlyweight("Y");
	fy.Operation(--extrinsicstate);
	
	Flyweight uf = new UnsharedConcreteFlyweight();
	uf.Operation(--extrinsicstate);
}