迭代器模式-c++实现

最喜欢的一个设计模式终于实现了

// IteratorPattern.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <iostream>
#include <vector>
using namespace std;

template<class Iter>
class Iterator
{
public:
virtual void first() = 0;
virtual void next() = 0;
virtual Iter* currentItem() = 0;
virtual bool isDone() = 0;
virtual ~Iterator(){}
};

template<class Item>
class ConcreteAggregate;

template<class Item>
class ConcreteIterator :public Iterator<Item>
{

private:
ConcreteAggregate<Item> *aggr;
int cur;

public:
ConcreteIterator(ConcreteAggregate<Item> *a):aggr(a),cur(0){}
virtual void first()
{
cur = 0;
}

virtual void next()
{
if (cur < aggr->getLen())
cur++;
}

virtual Item* currentItem()
{
if (cur < aggr->getLen())
return &(*aggr)[cur];
else
return NULL;
}

virtual bool isDone()
{
return (cur >= aggr->getLen());
}

};

template<class Item>
class Aggregate
{
public:
virtual Iterator<Item>* createIterator() = 0;
virtual ~Aggregate(){};
};

template<class Item>
class ConcreteAggregate :public Aggregate<Item>
{
vector<Item> data;
public:
ConcreteAggregate()
{
data.push_back(1);
data.push_back(2);
data.push_back(3);
}

virtual Iterator<Item>* createIterator()
{
return new ConcreteIterator<Item>(this);
}

Item& operator[](int index)
{
return data[index];
}

int getLen()
{
return data.size();
}

};

int main()
{
Aggregate<int> *aggr = new ConcreteAggregate<int>();
Iterator<int> *it = aggr->createIterator();

for (it->first(); !it->isDone(); it->next())
{
cout << *(it->currentItem()) << endl;
}

delete it;
delete aggr;
return 0;
}