设计模式复习-状态模式

#pragma once
#include "stdafx.h"

#include <queue>
#include<iostream>
using namespace std;

//设计模式-状态模式State
/*
当一个对象的内在状态改变时，允许改变其行为，这个对象看起来就是改变了类。
*/

class CContexct;

class CState {//抽象状态类，定义一个接口以封装与Context的一个特定状态相关的行为。
public:
	virtual void Handle(CContexct *pContext) = 0;
};

class CContexct {//维护一个concretestate子类的实例，这个实例定义当前的状态。
private:
	CState *m_pState;
	queue<CState *>m_qHashMemory;
public:
	CContexct(CState *pState) {
		while (!m_qHashMemory.empty()) {
			m_qHashMemory.pop();
		}
		m_pState = pState;
		m_qHashMemory.push(m_pState);
	}
	~CContexct() {
		while (!m_qHashMemory.empty()) {
			delete m_qHashMemory.front();
			m_qHashMemory.pop();
		}
	}
	void SetContext(CState *pState) {
		m_pState = pState;
		m_qHashMemory.push(m_pState);
	}
	void Request() {
		m_pState->Handle(this);
	}
};

class CConcreteStateC :public CState {//具体状态，每一个子类实现一个与Context的一个状态相关的行为。
public:
	void Handle(CContexct *pContext) {
		cout << "over" << endl;
		return;
	}
};

class CConcreteStateB : public CState {
public:
	void Handle(CContexct *pContext) {
		pContext->SetContext(new CConcreteStateC());
		pContext->Request();
	}
};

class CConcreteStateA : public CState {
public:
	void Handle(CContexct *pContext) {
		pContext->SetContext(new CConcreteStateB());
		pContext->Request();
	}
};


int main() {

	CContexct *pContexct = new CContexct(new CConcreteStateA());
	pContexct->Request();
	delete pContexct;

	getchar();
	return 0;
}