//
// Created by andrew on 2020年11月29日.
//
#include <iostream>

using namespace std;

class Context {
public:
 explicit Context(int num) {
 this->m_num = num;
 }

 int getNum() const {
 return m_num;
 }

 int getRes() const {
 return m_res;
 }

 void setNum(int num) {
 this->m_num = num;
 }

 void setRes(int res) {
 this->m_res = res;
 }

private:
 int m_num;
 int m_res{};
};

class Expression {
public:
 virtual void interpreter(Context *context) = 0;

private:
 Context *m_context{};
};

//加法
class PlusExpression : public Expression {
public:
 PlusExpression() {
 this->context = nullptr;
 }

 void interpreter(Context *context) override {
 int num = context->getNum();
 num ++;
 context->setNum(num);
 context->setRes(num);
 }

private:
 Context *context;
};
// 减法
class MinusExpression : public Expression {
public:
 MinusExpression() {
 this->context = nullptr;
 }

 void interpreter(Context * context) override{
 int num = context->getNum();
 num --;
 context->setNum(num);
 context->setRes(num);
 }

private:
 Context * context;
};

int main(int argc, char *argv[]) {
 Expression *expression = nullptr;
 Context *context = nullptr;

 Expression * expression2 = nullptr;

 context = new Context(10);
 cout << context->getNum() << endl;

 expression = new PlusExpression;
 expression->interpreter(context);

 cout << context->getRes() << endl;

 //// -----------------------------------------------

 expression2 = new MinusExpression;
 expression2->interpreter(context);
 cout << context->getRes() << endl;

 cout << "interpreter demo" << endl;
 return 0;
}