设计模式复习-访问者模式

VisitorMode.h

#pragma once
#include<list>
#include<string>
#include<iostream>
using namespace std;

/*
设计模式-访问者模式（Visitor）
表示一个作用于某对象机构中各元素的操作。它使你可以在不改变各元素的类的前提下定义作用于
这些元素的新操作。
*/

class CConcreteElementA;
class CConcreteElementB;

class CVisitor {//为该对象结构中ConcreteElement的每个类声明一个Visit操作。
public:
	virtual void VisitConcreteElementA(CConcreteElementA * pConcreteElementA) = 0;
	virtual void VisitConcreteElementB(CConcreteElementB * pConcreteElementB) = 0;
};

class ConcreteVisitor1 :public CVisitor {//具体访问者类
public:
	void VisitConcreteElementA(CConcreteElementA * pConcreteElementA);
	void VisitConcreteElementB(CConcreteElementB * pConcreteElementB);
};

class ConcreteVisitor2 :public CVisitor {//具体访问者类
public:
	void VisitConcreteElementA(CConcreteElementA * pConcreteElementA);
	void VisitConcreteElementB(CConcreteElementB * pConcreteElementB);
};

class CElement {//定义一个Accept操作,它以一个访问者为参数
public:
	virtual void Accept(CVisitor *pVisitor) = 0;
};

class CConcreteElementA :public CElement {
private:
	string mstrName;
public:
	CConcreteElementA(const string &strName);
	void Accept(CVisitor *pVisitor);
	void OperationA() {}//A的单独方法
	string GetName();
};

class CConcreteElementB :public CElement {
private:
	string mstrName;
public:
	CConcreteElementB(const string &strName);
	void Accept(CVisitor *pVisitor);
	void OperationB() {}//B的单独方法
	string GetName();
};

class CobjuctStructure {//定义一个高层接口，以允许访问者访问它的元素。
private:
	list<CElement*>mlElement;
public:
	CobjuctStructure();
	~CobjuctStructure();
	void Attach(CElement *pElement);
	void Eetach(CElement *pElement);
	void Accept(CVisitor *pVisitor);
};

VisitorMode.cpp
#include "stdafx.h"
#include "VisitorMode.h"



void ConcreteVisitor1::VisitConcreteElementA(CConcreteElementA * pConcreteElementA) {
	cout << "1-A:" << pConcreteElementA->GetName() << endl;
}
void ConcreteVisitor1::VisitConcreteElementB(CConcreteElementB * pConcreteElementB) {
	cout << "1-B:" << pConcreteElementB->GetName() << endl;
}


void ConcreteVisitor2::VisitConcreteElementA(CConcreteElementA * pConcreteElementA) {
	cout << "2-A:" << pConcreteElementA->GetName() << endl;
}
void ConcreteVisitor2::VisitConcreteElementB(CConcreteElementB * pConcreteElementB) {
	cout << "2-B:" << pConcreteElementB->GetName() << endl;
}

CConcreteElementA::CConcreteElementA(const string &strName) {
	mstrName = strName;

}
void CConcreteElementA::Accept(CVisitor *pVisitor) {
	pVisitor->VisitConcreteElementA(this);
}
string CConcreteElementA::GetName() {
	return mstrName;
}

CConcreteElementB::CConcreteElementB(const string &strName) {
	mstrName = strName;

}
void CConcreteElementB::Accept(CVisitor *pVisitor) {
	pVisitor->VisitConcreteElementB(this);
}
string CConcreteElementB::GetName() {
	return mstrName;
}

CobjuctStructure::CobjuctStructure() {
	mlElement.clear();
}
CobjuctStructure::~CobjuctStructure() {
	for each(CElement* index in mlElement) {
		delete index;
	}
}
void CobjuctStructure::Attach(CElement *pElement) {
	mlElement.push_back(pElement);
}
void CobjuctStructure::Eetach(CElement *pElement) {
	mlElement.remove(pElement);
}
void CobjuctStructure::Accept(CVisitor *pVisitor) {
	for each (CElement * index in mlElement) {
		index->Accept(pVisitor);
	}
}

客户端调用

#include<string>
#include<iostream>
#include "VisitorMode.h"
using namespace std;

int main() {

	CobjuctStructure *pO = new CobjuctStructure();
	pO->Attach(new CConcreteElementA("man"));
	pO->Attach(new CConcreteElementB("woman"));

	ConcreteVisitor1 *pV1 = new ConcreteVisitor1();
	ConcreteVisitor2 *pV2 = new ConcreteVisitor2();

	pO->Accept(pV1);
	pO->Accept(pV2);

	delete pO, delete pV1, delete pV2;

	getchar();
	return 0;
}