Decorator

Decorator2.cpp

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

class Interface
{
public:
    virtual ~Interface(){}
    virtual void write(string &) = 0;
    virtual void read(string &) = 0;
};

class Core: public Interface
{
public:
    ~Core()
    {
        cout << "dtor-Core\n";
    }
    /*virtual*/void write(string &b)
    {
        b += "MESSAGE|";
    }
    /*virtual*/void read(string &)
    {
        ;
    }
};

class Decorator: public Interface
{
    Interface *inner;
public:
    Decorator(Interface *c)
    {
        inner = c;
    }
    ~Decorator()
    {
        delete inner;
    }
    /*virtual*/void write(string &b)
    {
        inner->write(b);
    }
    /*virtual*/void read(string &b)
    {
        inner->read(b);
    }
};

class Wrapper: public Decorator
{
    string forward, backward;
public:
    Wrapper(Interface *c, string str): Decorator(c)
    {
        forward = str;
        string::reverse_iterator it;
        it = str.rbegin();
        for (; it != str.rend(); ++it)
            backward +=  *it;
    }
    ~Wrapper()
    {
        cout << "dtor-" << forward << "  ";
    }
    void write(string &);
    void read(string &);
};

void Wrapper::write(string & s)
{
    s += forward;
    Decorator::write(s);
}
void Wrapper::read(string & s)
{
    //Decorator::read(forward);    
    std::cout<<"Wrapper:"<<forward<<std::endl;
}

int main()
{
    Interface *object = new Wrapper(new Wrapper(new Wrapper(new Core(), "123"), "abc"), "987");
    string buf;
    object->write(buf);
    cout << "main: " << buf << endl;
    object->read(buf);
    delete object;
}