设计模式复习-迭代器模式
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设计模式复习-迭代器模式
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Iterator.H
#pragma once
#include <list>
#include <windows.h>
using namespace std;/*
设计模式-迭代器模式（Iterator）
提供一种方法顺序访问一个聚合对象中的各个元素，而不暴露该对象内部表示。
(现在好多语言都已经内置实现了这个功能了，所以实际用途不大，
但是建议写一下，实现过程价值远远大于使用价值。)
*/class Iterator{//迭代器抽象类public:virtual void * First() = 0;virtual void * Next() = 0;virtual BOOL IsDone() = 0;virtual void * CurrentItem() = 0;
};class CAggregate {//聚集抽象类public:virtual Iterator * CreateIterator() = 0;virtual void Insert(void * const pNode) = 0;virtual void Remove(void * const pNode) = 0;
};class CConcreteAggregate :public CAggregate {//具体聚集类public:list<void*>mpItems;CConcreteAggregate();void Clear();Iterator * CreateIterator();void Insert(void * const pNode);void Remove(void * const pNode);
};class CConcreteIterator : public Iterator {//具体的迭代器类private:CConcreteAggregate *mpAggregate = NULL;int mnCurrent = 0;
public:CConcreteIterator(CConcreteAggregate * pAggregate);void * First();void * Next();BOOL IsDone();void * CurrentItem();
};Iterator.CPP
#include "stdafx.h"
#include "Iterator.h"CConcreteAggregate::CConcreteAggregate() {mpItems.clear();
}void CConcreteAggregate::Clear() {for each(auto i in mpItems) {delete i;}
}Iterator * CConcreteAggregate::CreateIterator() {return new CConcreteIterator(this);
}void CConcreteAggregate::Insert(void * const pNode) {mpItems.push_back(pNode);
}
void CConcreteAggregate::Remove(void * const pNode) {mpItems.remove(pNode);
}CConcreteIterator::CConcreteIterator(CConcreteAggregate * pAggregate) {mpAggregate = pAggregate;mnCurrent = 0;
}void * CConcreteIterator::First() {return mpAggregate->mpItems.size() == 0 ? NULL :*(mpAggregate->mpItems.begin());
}
void * CConcreteIterator::Next() {if (IsDone()) return NULL;int nSubscript = 0;mnCurrent++;for each(auto i in mpAggregate->mpItems) {if (nSubscript++ == mnCurrent + 1) {return i;}}
}
BOOL CConcreteIterator::IsDone() {return mnCurrent >= mpAggregate->mpItems.size();
}
void * CConcreteIterator::CurrentItem() {int nSubscript = 0;for each(auto i in mpAggregate->mpItems) {if (nSubscript++ == mnCurrent) {return i;}}return NULL;
}#pragma once
#include "stdafx.h"
#include "Iterator.h"
#include<string>
#include<iostream>
using namespace std;int main() {CConcreteAggregate *pA = new CConcreteAggregate();pA->Insert(new string("node-1"));pA->Insert(new string("node-2"));string * pStr = new string("node-3");pA->Insert(pStr);Iterator *pIteratorA = new CConcreteIterator(pA);while (!pIteratorA->IsDone()) {cout << *((string*)pIteratorA->CurrentItem()) << endl;pIteratorA->Next();}pA->Remove(pStr);Iterator *pIteratorB = pA->CreateIterator();while (!pIteratorB->IsDone()) {cout << *((string*)pIteratorB->CurrentItem()) << endl;pIteratorB->Next();}pA->Clear();delete pIteratorA;delete pIteratorB;delete pA;delete pStr;getchar();return 0;
}
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