设计模式-Interpreter(行为模式) 使用解释器给用户提供一个一门定义语言的语法表示的解释器，通过该解释器解释语言中的句子。

//以下代码来源： 设计模式精解－GoF 23种设计模式解析附C++实现源码

//Context.h

#pragma once

class Context
{
public:
    Context();
    ~Context();
protected:
private:
};

//Context.cpp

#include"Context.h"
Context::Context(){}
Context::~Context(){}

//Interpret.h

#include"Context.h"
#include<string>

class AbstractExpression{
public:
    virtual ~AbstractExpression();
    virtual void Interpret(const Context& c);
protected:
    AbstractExpression();
private:
};

class TerminalExpression :public AbstractExpression
{
public:
    TerminalExpression(const std::string& statement);
    ~TerminalExpression();
    void Interpret(const Context&c);
protected:
private:
    std::string _statement;
};

class NonterminalExpression :public AbstractExpression
{
public:
    NonterminalExpression(AbstractExpression* expression, int times);
    ~NonterminalExpression();
    void Interpret(const Context& c);
protected:
private:
    AbstractExpression* _expression;
    int _times;
};

//Interpret.cpp

#include"Interpret.h"
#include"Context.h"
#include<iostream>

AbstractExpression::AbstractExpression(){}
AbstractExpression::~AbstractExpression(){}
void AbstractExpression::Interpret(const Context&c)
{

}
TerminalExpression::TerminalExpression(const std::string &statement)
{
    this->_statement = statement;
}
TerminalExpression::~TerminalExpression(){}

void TerminalExpression::Interpret(const Context& c)
{
    std::cout << this->_statement << "TerminalExpression" << std::endl;
}

NonterminalExpression::NonterminalExpression(AbstractExpression* expression, int times)
{
    this->_expression = expression;
    this->_times = times;
}

NonterminalExpression::~NonterminalExpression(){}

void NonterminalExpression::Interpret(const Context& c)
{
    for (int i = 0; i < _times; ++i)
    {
        this->_expression->Interpret(c);
    }
}

//main.cpp

#include"Context.h"
#include"Interpret.h"
#include<iostream>
#include<string>
int main(int args, char* argv)
{
    Context* c = new Context();
    AbstractExpression* te = new TerminalExpression("Hello");
    AbstractExpression* nte = new NonterminalExpression(te, 2);
    nte->Interpret(*c);
    getchar();
    return 0;
}