Flyweight (C++实现）

// Flyweight.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <iostream>
#include <list>
#include <string>

using namespace std;

typedef string STATE;

class Flyweight
{
public:
 STATE GetIntrinsicState()
 {
  return m_state;
 }

 virtual void Operation(STATE& Extrinsic)=0;

protected:
 Flyweight(const STATE& s):m_state(s)
 {
 }

private:
STATE m_state;

};

class ConcreteFlyweight:public Flyweight
{
public:
 ConcreteFlyweight(const STATE& s):Flyweight(s)
 {
 }
 virtual ~ConcreteFlyweight()
 {
 }

 virtual void Operation(STATE& Extrinsic)
 {
  cout<<"Operation of  ConcreteFlyweight"<<endl;
 }
};

class FlyweightFactory
{
public:
 FlyweightFactory()
 {
 }
 virtual ~FlyweightFactory()
 {
  list<Flyweight*>::iterator iter,temp;
  for(iter= m_listFlyweight.begin();iter!= m_listFlyweight.end();iter++)
  {
   temp=iter;
   ++iter;
   delete (*temp);
  }
 }

 Flyweight* GetFlyweight(const STATE& key)
 {
  list<Flyweight*>::iterator iter;
  for(iter= m_listFlyweight.begin();iter!= m_listFlyweight.end();iter++)
  {
   if((*iter)->GetIntrinsicState()==key)
    {
     cout<<"The Flyweight:  /""<<key<<"/" already exists" <<endl;
     return (*iter);
      }
  }
        
  cout<<"Create new instance of ConcreteFlyweight"<<endl;
  Flyweight* pFlyweight=new ConcreteFlyweight(key);
  m_listFlyweight.push_back(pFlyweight);
  return pFlyweight;

 }

private:
 list<Flyweight*> m_listFlyweight;

};

int _tmain(int argc, _TCHAR* argv[])
{
 FlyweightFactory  f;
 Flyweight* fHello=f.GetFlyweight("Hello");
 fHello->Operation(string("%%%%%%"));
 Flyweight* fWorld=f.GetFlyweight("World");
 fWorld->Operation(string("######"));
 Flyweight* p=f.GetFlyweight("Hello");
 p->Operation(string("@@@@@@"));

 return 0;
}