EventBus/event_bus.hpp at main · Sebight/EventBus · GitHub

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#pragma once

#include <unordered_map>
#include <vector>
#include <typeindex>
#include <functional>

class EventBus
{
public:
	template <typename EventType>
	void Subscribe(const std::function<void(const EventType& event)>& callback, void* subscriber)
	{
		Subscription s = {};
		s.handle = reinterpret_cast<uintptr_t>(subscriber);
		s.callback = [callback](const void* event) {
			callback(*static_cast<const EventType*>(event));
			};

		m_subscriptions[typeid(EventType)].emplace_back(s);
	}

	template <typename EventType>
	void Publish(const EventType& event)
	{
		std::type_index typeIdx = typeid(EventType);

		auto it = m_subscriptions.find(typeIdx);
		if (it == m_subscriptions.end()) return;

		for (Subscription& subscription : it->second)
		{
			subscription.callback(&event);
		}
	}

	template <typename EventType>
	void Unsubscribe(void* self)
	{
		uintptr_t subscriberId = reinterpret_cast<uintptr_t>(self);
		std::type_index typeIdx = typeid(EventType);

		auto it = m_subscriptions.find(typeIdx);
		if (it == m_subscriptions.end()) return;

		std::vector<Subscription>& subscriptions = it->second;

		subscriptions.erase(
			std::remove_if(subscriptions.begin(),
				subscriptions.end(),
				[this, subscriberId](const Subscription& data) { return data.handle == subscriberId; }),
			subscriptions.end());
	}

private:
	struct Subscription
	{
		uintptr_t handle;
		std::function<void(const void*)> callback;
	};

	std::unordered_map<std::type_index, std::vector<Subscription>> m_subscriptions;
};