sketch.cpp

//
//  main.cpp
//  Watchman
//
//  Created by Matheus Mariano on 21/06/17.
//  Copyright © 2017 Matheus Mariano. All rights reserved.
//

#include <iostream>
#include <vector>

class Observer {
public:
    virtual void handle() = 0;
};

class Subject {
    std::vector<class Observer *> observers;
    
public:
    void attach(Observer * observer) {
        observers.push_back(observer);
    }
    
    void detach(int index) {
        observers.erase(observers.begin() + index);
    }
    
    void notify() {
        for (int index = 0; index < observers.size(); index++) {
            observers.at(index)->handle();
        }
    }
};

class Board: public Subject {
};

class Led: public Observer {
    unsigned int pin;
    
public:
    Led(int p) {
        pin = p;
    }
    
    void handle() {
        std::cout << "New LED attached to pin " << pin << ".\n";
    }
    
    void on() {
        std::cout << "Led at pin " << pin << " is on.\n";
    }
    
    void off() {
        std::cout << "Led at pin " << pin << " is off.\n";
    }
};

class AnalogInput: public Observer {
    unsigned int pin;
    
public:
    AnalogInput(int p) {
        pin = p;
    }
    
    void handle() {
        std::cout << "New AnalogPin attached to pin " << pin << ".\n";
    }
    
    int read() {
        return 128;
    }
};

int main() {
    Board * board = new Board();
    AnalogInput * photoCell = new AnalogInput(1);
    Led * led = new Led(9);
    
    // Setup
    board->attach(photoCell);
    board->attach(led);
    board->notify();
    
    // Loop
    while (true) {
        if (photoCell->read() > 50) {
            led->on();
        } else {
            led->off();
        }
    }
    
    return 0;
}

class Subject
{
typedef std::vector<class Observer*>::iterator Offset;

std::vector<class Observer *> observers;
Offset begin;
Offset end;

inline void update ()
{
	begin = observers.begin ();
	end = observers.end ();
}

public:
Subject ()
{
update ();
}

void attach (Observer * observer)
{
	observers.push_back (observer);
	update ();
}

void detach (unsigned int offset)
{
	if (offset >= end - begin)
		return;

	observers.erase (begin + offset);

	update ();
}

void notify ()
{
	for (unsigned int offset = 0; offset < end - begin; ++offset)
		(*(begin + offset))->handle ();
}

};