Event.h

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#pragma once

#include <functional>
#include <vector>
#include <algorithm>
#include <iostream>

namespace Treehopper {
    using namespace std;

    template<class Sender, class EventArgs>
    class Event {
        friend Sender;
    public:
        Event<Sender, EventArgs>(Sender &sender) : sender(sender), handlers() {
        }

        size_t getAddress(std::function<void(Sender &, EventArgs &)> f) {
            typedef void (fnType)(Sender &, EventArgs &);
            fnType **fnPointer = f.template target<fnType *>();
            if (fnPointer == NULL) return 0;
            return (size_t) *fnPointer;
        }

        void operator+=(function<void(Sender &sender, EventArgs &e)> handler) {
            handlers.push_back(handler);
        }

        void operator-=(function<void(Sender &sender, EventArgs &e)> handler) {
            int handlerAddress = getAddress(handler);
            if (handlerAddress == 0) // we can't get the function's address
            {
                return;
            }

            int idx = -1;
            for (int i = 0; i < handlers.size(); i++) {
                if (handlerAddress == getAddress(handlers[i])) {
                    idx = i;
                }
            }

            if (idx >= 0)
                handlers.erase(handlers.begin() + idx);
            else
                cerr << "Couldn't find an event handler to remove. Check your method's signature.";
        }

    protected:
        vector<function<void(Sender &sender, EventArgs &e)>> handlers;

        void invoke(EventArgs arg) {
            for (auto pin1inputHandler : handlers) {
                pin1inputHandler(sender, arg);
            }
        }

        Sender &sender;
    };
}