iterator模式
类似于stl里面的迭代器
iterator.h
#ifndef _ITERATOR_H
#define _ITERATOR_H
#include <iostream>
#include <vector>
using namespace std;
template <class item>
class Iterator
{
public:
virtual ~Iterator() {}
virtual void first()=0;
virtual void next()=0;
virtual item* currentItem()=0;
virtual bool isDone()=0;
};
template <class item>
{
public:
virtual ~Aggregate() {}
virtual Iterator*<item> createIterator()=0;
virtual void pushData(item)=0;
};
template <class item>
class ConcreteIterator;
template<class item>
class ConcreteAggregate : public Aggregate<item>
{
public: ConcreteAggregate() { }
int getLen() { return data.size(); }
void pushData(item a) { data.push_back(a); }
item& operator[](int index) { return data[index]; }
Iterator<item>* createIterator() { return new ConcreteIterator<item>(this); }
private:
vector<item> data;
};
template<class item>
class ConcreteIterator : public Iterator<item>
{
public:
ConcreteIterator(ConcreteAggregate<item>* a) : aggr_(a), cur_(0) {}
void first() { cur_ = 0; }
void next() { if (cur_ < aggr_->getLen()) { cur_ ++; } }
bool isDone() { return (cur_ >= aggr_->getLen()); }
item* currentItem() { if (cur_ < aggr_->getLen()) { return &(*aggr_)[cur_]; } else { return NULL; } }
private:
int cur_;
ConcreteAggregate<item>* aggr_;
}
#endif // _ITERATOR_H
iterator.cpp
#include "iterator.h"
int main()
{
Aggregate<int>* aggr = new ConcreteAggregate<int>();
aggr->pushData(1);
aggr->pushData(2);
aggr->pushData(3);
Iterator<int>* it = aggr->createIterator();
for (it->first(); !it->isDone(); it->next()) {
cout << *(it->currentItem()) << endl;
}
return 0;
}
编译:make iterator
