概念

 

角色和职责

 

Context

　　解释器上下文环境类。用来存储解释器的上下文环境，比如需要解释的文法等。

AbstractExpression   

 　　解释器抽象类。

ConcreteExpression

　　解释器具体实现类。

适用于:

 　　解释器根据中介结果实现对应的运算。

 

案例

//加号、减号解释器，根据上下文储存内容再加载到解释器中，进行对应的运算

#include 
     
      using namespace std;#include "string" //保存中间结果class Context{public:	Context(int num)	{		m_num = num;	}public:	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;};//加号解释器class Expression{public:	virtual void interpreter(Context *context) = 0;};class PlusExpression : public Expression{public:	virtual void interpreter(Context *context)	{		int num = context->getNum();		num ++ ;		context->setNum(num);		context->setRes(num);	}};//减法解释器class MinusExpression : public Expression{public:	virtual void interpreter(Context *context)	{		int num = context->getNum();		num -- ;		context->setNum(num);		context->setRes(num);	}};void main(){	Context *pcxt = new Context(10);	Expression *e1 = new PlusExpression;	e1->interpreter(pcxt);	cout << "PlusExpression:" << pcxt->getRes() << endl;	Expression *e2 = new MinusExpression;	e2->interpreter(pcxt);	cout << "MinusExpression:" << pcxt->getRes() << endl;	delete e2;	delete e1;	system("pause");	return ;}