行为型模型 解释模型

行为型模型 解释模型

/**
 * 行为型模型 解释模型
 * 给定一个语言，定义它的文法表示，并定义一个解释器，这个解释器使用该标识来解释语言中的句子。
 *
 */

#define _CRT_SECURE_NO_WARNINGS

#include <iostream>
#include <string>

class Context
{
public:
    Context(int num)
    {
        m_num = num;
    }
    void setNum(int num)
    {
        m_num = num;
    }
    int getNum()
    {
        return m_num;
    }
    void setRes(int res)
    {
        m_res = res;
    }
    int getRes()
    {
        return m_res;
    }

private:
    int m_num;
    int m_res;
};

class Expression
{
public:
    virtual void interpreter(Context * contex) = 0;
    virtual ~Expression() {}
};

class PlusExpression: public Expression
{
    virtual void interpreter(Context * contex) override
    {
        int num = contex->getNum();
        num++;
        contex->setNum(num);
        contex->setRes(num);
    }
};

class MinusExpression: public Expression
{
public:
    virtual void interpreter(Context * contex) override
    {
        int num = contex->getNum();
        num--;
        contex->setNum(num);
        contex->setRes(num);
    }
};


void mytest()
{
    Context *pcxt = new Context(10);
    Expression *e1 = new PlusExpression();
    e1->interpreter(pcxt);
    std::cout << "PlusExpression: " << pcxt->getRes() << std::endl;
    Expression *e2 = new MinusExpression();
    e2->interpreter(pcxt);
    std::cout << "MinusExpression: " << pcxt->getRes() << std::endl;

    delete e2;
    e2 = nullptr;
    delete e1;
    e1 = nullptr;
    delete pcxt;
    pcxt = nullptr;

    return;
}

int main()
{
    mytest();

    system("pause");
    return 0;
}