event.h

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#pragma once
 
#include <algorithm>
#include <functional>
#include <vector>
 
#include "contur/core/types.h"
 
namespace contur {

    template <typename... Args> class Event
    {
        public:
        using Callback = std::function<void(Args...)>;
 
        Event() = default;
        ~Event() = default;
 
        // Non-copyable (subscriptions are identity-bound)
        Event(const Event &) = delete;
        Event &operator=(const Event &) = delete;
 
        // Movable
        Event(Event &&) noexcept = default;
        Event &operator=(Event &&) noexcept = default;

        [[nodiscard]] SubscriptionId subscribe(Callback callback)
        {
            auto id = nextId_++;
            subscribers_.push_back({id, std::move(callback)});
            return id;
        }

        bool unsubscribe(SubscriptionId id)
        {
            auto it = std::find_if(subscribers_.begin(), subscribers_.end(), [id](const Subscriber &s) {
                return s.id == id;
            });
            if (it != subscribers_.end())
            {
                subscribers_.erase(it);
                return true;
            }
            return false;
        }

        void emit(Args... args) const
        {
            for (const auto &sub : subscribers_)
            {
                sub.callback(args...);
            }
        }

        [[nodiscard]] std::size_t subscriberCount() const noexcept
        {
            return subscribers_.size();
        }

        void clear()
        {
            subscribers_.clear();
        }
 
        private:
        struct Subscriber
        {
            SubscriptionId id;
            Callback callback;
        };
 
        std::vector<Subscriber> subscribers_;
        SubscriptionId nextId_ = 1;
    };
 
} // namespace contur