callback_slot.hpp

#pragma once
 
#include <vector>
#include <algorithm>
#include <functional>
 
template <typename Func>
class CallbackSlot {
public:
  CallbackSlot() {}
  ~CallbackSlot() {}
 
  int add(const std::function<Func>& callback) {
    callbacks.push_back(callback);
    return callbacks.size() - 1;
  }
 
  void remove(int callback_id) { callbacks[callback_id] = nullptr; }
 
  operator bool() const {
    return !callbacks.empty() && std::any_of(callbacks.begin(), callbacks.end(), [](const std::function<Func>& f) { return f; });
  }
 
  template <class... Args>
  void call(Args&&... args) const {
    if (callbacks.empty()) {
      return;
    }
 
    for (const auto& callback : callbacks) {
      if (callback) {
        callback(args...);
      }
    }
  }
 
  template <class... Args>
  void operator()(Args&&... args) const {
    return call(args...);
  }
 
private:
  std::vector<std::function<Func>> callbacks;
};