【设计模式】策略模式

来源：爱编程的大丙

策略模式定义一系列的算法，并且将每种算法都放入到独立的类中，在实际操作中使这些算法对象可以互相替换。

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

class AbstractStrategy {
public:
	virtual void fight(bool isfar = false) = 0;
	virtual ~AbstractStrategy() {}
};

class YiDang :public AbstractStrategy {
public:
	void fight(bool isfar = false)override {
		cout << "***现在是使用的一档：";
		if (isfar) {
			cout << "橡胶机关枪" << endl;
		}
		else {
			cout << "橡胶·攻城炮" << endl;
		}
	}
};

class ErDang :public AbstractStrategy {
public:
	void fight(bool isfar = false)override {
		cout << "***切换二档：";
		if (isfar) {
			cout << "橡胶Jet火箭" << endl;
		}
		else {
			cout <<"橡胶Jet·铳乱打" << endl;
		}
	}
};

class SanDang :public AbstractStrategy {
public:
	void fight(bool isfar = false)override {
		cout << "***切换三档：";
		if (isfar) {
			cout << "橡胶巨人回旋弹" << endl;
		}
		else {
			cout << "橡胶巨人战斧"  << endl;
		}
	}
};

class SiDang :public AbstractStrategy {
public:
	void fight(bool isfar = false)override {
		cout << "***切换四档：";
		if (isfar) {
			cout << "橡胶狮子火箭炮" << endl;
		}
		else {
			cout << "橡胶犀牛榴弹炮" << endl;
		}
	}
};

class WuDang :public AbstractStrategy {
public:
	void fight(bool isfar = false)override {
		cout << "*** 切换成五挡: 变成尼卡形态可以把物体变成橡胶, 并任意改变物体的形态对其进行攻击!!!"<<endl;
	}
};
//难度级别
enum class Level :char {Easy,Normal,Hard,Experts,Professional};
//路飞
class Luffy {
public:
	void fight(Level level, bool isfar = false) {
		if (m_strategy) {
			delete m_strategy;
			m_strategy = nullptr;
		}
		switch (level)
		{
		case Level::Easy:
			m_strategy = new YiDang;
			break;
		case Level::Normal:
			m_strategy = new ErDang;
			break;
		case Level::Hard:
			m_strategy = new SanDang;
			break;
		case Level::Experts:
			m_strategy = new SiDang;
			break;
		case Level::Professional:
			m_strategy = new WuDang;
			break;
		default:
			break;
		}
		m_strategy->fight(isfar);
	}
	~Luffy() {
		delete m_strategy;
	}

private:
	AbstractStrategy* m_strategy = nullptr;
};

int main() {
	Luffy* luffy = new Luffy;
	cout << "--- 在香波地群岛遇到了海军士兵: " << endl;
	luffy->fight(Level::Easy);
	cout << "--- 在魔谷镇遇到了贝拉米: " << endl;
	luffy->fight(Level::Normal);
	cout << "--- 在司法岛遇到了罗布·路奇: " << endl;
	luffy->fight(Level::Hard);
	cout << "--- 在德雷斯罗萨遇到了多弗朗明哥: " << endl;
	luffy->fight(Level::Experts);
	cout << "--- 在鬼岛遇到了凯多: " << endl;
	luffy->fight(Level::Professional);
	delete luffy;

	return 0;
}