Iterator模式

Iterator模式

一.意图

提供一种方法顺序访问一个聚合对象中各个元素，而又不需暴露该对象的内部表示。

二.适用性

1.  访问一个聚合对象的内容而无需暴露它的内部表示

2.  支持对聚合对象的多种遍历

3.  为遍历不同聚合结构提供一个统一的接口(即支持多态迭代)。

三.结构

四.代码

Iterator类

H文件

#ifndef ITERATOR_H#define ITERATOR_H//迭代器接口类class CIterator{public:    virtual void First(){}    virtual void Next(){}    virtual bool IsDone(){}    virtual void* CurrentItem(){}};#endif // ITERATOR_H

ConcreteIteator类

H文件

#ifndef CONCRETEITEATOR_H#define CONCRETEITEATOR_H#include "ConcreteAggregate.h"class CConcreteAggregate;//迭代器接口实现类class CConcreteIterator : public CIterator{public:    //将容器实现类传入    CConcreteIterator(CConcreteAggregate* conAgg);    //设置第一个    void First();    //判断是否最后一个    bool IsDone();    //下一个    void Next();    //获取容器index的实例    void* CurrentItem();private:    CConcreteAggregate* m_concreteAggregate;    int m_index = 0;};#endif // CONCRETEITEATOR_H

CPP文件

#include "ConcreteIteator.h"CConcreteIterator::CConcreteIterator(CConcreteAggregate* conAgg){    m_concreteAggregate = conAgg;}void CConcreteIterator::First(){    m_index = 0;}bool CConcreteIterator::IsDone(){    if(m_index < m_concreteAggregate->GetLength())    {        return true;    }    else    {        return false;    }}void CConcreteIterator::Next(){    if(m_index < m_concreteAggregate->GetLength())    {        m_index++;    }}void* CConcreteIterator::CurrentItem(){    if(m_index < m_concreteAggregate->GetLength())    {        return m_concreteAggregate->GetIndex(m_index);    }    else    {        return NULL;    }}

ConcreteAggregate类

H文件

#ifndef CONCRETEAGGREGATE_H#define CONCRETEAGGREGATE_H#include "Iterator.h"#include "ConcreteIteator.h"#include <vector>#include <string>using namespace std;//容器接口class CAggregate{public:    virtual CIterator* CreateIterator(){}};//容器存放数据class CBook{public:    CBook(string name)    {        this->m_name = name;    }    string GetName()    {        return m_name;    }private:    string m_name="";};//容器接口实现类class CConcreteAggregate : public CAggregate{public:    CConcreteAggregate();    //根据index获取数据    CBook* GetIndex(int index);    //添加数据    void AppandBook(CBook* book);    //获取容器中数据个数    int GetLength();    //获取迭代器对象    virtual CIterator* CreateIterator();private:    vector<CBook*> m_pBook;};#endif // CONCRETEAGGREGATE_H

CPP文件

#include "ConcreteAggregate.h"CConcreteAggregate::CConcreteAggregate(){}CBook* CConcreteAggregate::GetIndex(int index){    if(index >= m_pBook.size())    {        return NULL;    }    else    {        return m_pBook[index];    }}void CConcreteAggregate::AppandBook(CBook* book){    m_pBook.push_back(book);}int CConcreteAggregate::GetLength(){    return m_pBook.size();}CIterator* CConcreteAggregate::CreateIterator(){    return new CConcreteIterator(this);}

Main文件

#include <iostream>#include <stdio.h>#include <stdlib.h>#include <vector>#include <math.h>#include "ConcreteAggregate.h"#include "ConcreteIteator.h"using namespace std;//Iterator mode//迭代器设计模式的总体思想就是“在容器实现类中实现对实体的增删改查操作，而在迭代器实现类中实现遍历操作int main(){    cout << "Hello World!" << endl;    //容器类    CConcreteAggregate* aggregate = new CConcreteAggregate();    aggregate->AppandBook(new CBook("Book 1"));    aggregate->AppandBook(new CBook("Book 2"));    aggregate->AppandBook(new CBook("Book 3"));    aggregate->AppandBook(new CBook("Book 4"));    aggregate->AppandBook(new CBook("Book 5"));    //获取迭代器    CIterator* it = aggregate->CreateIterator();    for(it->First(); it->IsDone(); it->Next())    {        CBook* book = (CBook*)it->CurrentItem();        cout << book->GetName() << endl;    }    if(it != NULL)    {        delete it;        it = NULL;    }    if(aggregate != NULL)    {        delete aggregate;        aggregate = NULL;    }    return 0;}