Simple events with C++11

events.cpp

#include <windows.h>
#include <list>
#include <map>
#include <functional>
#include <string>
#include <iostream>
#include <algorithm>

using namespace std;
typedef function<bool()> pred_f;
typedef function<void()> handler_f;
typedef list<handler_f> handler_list;

class handler_cls;

class event_cls {
    friend handler_cls;
    string name;
    pred_f & predicate;
    handler_list handlers;
public:
    event_cls(string name, pred_f predicate): name(name), predicate(predicate) {}

    void add_handler(handler_f && handler) {
        handlers.push_back(handler);
    }
};


class handler_cls {
    typedef map<string, pair<pred_f, handler_list> > event_map;
private:
    event_map events;
public:
    void add_event(event_cls & event) {
        events[event.name].first = event.predicate;
        events[event.name].second.insert(
            events[event.name].second.end(),
            event.handlers.begin(),
            event.handlers.end()
        );
    }

    void check_events() {
        for(auto & event : events) {
            if(!event.second.first()) {
                continue;
            }
            for(auto & handler : event.second.second) {
                handler();
            }
        }
    }
} ev;


int main() {
    event_cls arrow_up(string("up"), []() -> bool {
        return GetAsyncKeyState(VK_UP);
    });

    arrow_up.add_handler([](){
        cout << "up - first\n";
    });

    arrow_up.add_handler([](){
        cout << "up - second\n";
    });

    event_cls arrow_down(string("down"), []() -> bool {
        return GetAsyncKeyState(VK_DOWN);
    });

    arrow_down.add_handler([](){
        cout << "down\n";
    });

    ev.add_event(arrow_up);
    ev.add_event(arrow_down);

    for(;;) {
        ev.check_events();
        Sleep(1000/60);
    }

    return 0;
}