[C++知识库]C++状态模式

定义一个状态基类state，然后继承出来两个状态：company和home，通过stateManger类去管理当前状态，状态切换。这个模式感觉像是把一个过程的状态切开分为很多个小段，各个状态只通过一个管理类去维护。

#include <stdlib.h>
#include <iostream>
#include <string>

using namespace std;

class state {
public:
    virtual state* getState() = 0;
    virtual string getStateName() = 0;
};

class stateHome : public state {
public:
    static stateHome* getInstance() {
        static stateHome* instance = new stateHome();
        return instance;
    }
    virtual string getStateName() { return "Home"; };
    virtual state* getState() {
        return getInstance();
    }
};

class stateCompany : public state {
public:
    static stateCompany* getInstance() {
        static stateCompany* instance = new stateCompany();
        return instance;
    }
    virtual string getStateName() { return "Company"; };
    virtual state *getState() { return getInstance(); }
};

class stateManager {
public:
    state* getState() {  return stateCurent;  }
    void setState(state* st) {  stateCurent = st;  }
private:
    state* stateCurent;
};

int main() {
    stateManager *mstateManager = new stateManager();

    mstateManager->setState(stateCompany::getInstance());
    cout << mstateManager->getState()->getStateName() << endl;

    mstateManager->setState(stateHome::getInstance());
    cout << mstateManager->getState()->getStateName() << endl;
}