whetstone_DSL/editor/src/DAPEventBroadcaster.h

#pragma once
#include <nlohmann/json.hpp>
#include <functional>
#include <map>
#include <string>
#include <vector>

namespace whetstone {

class DAPEventBroadcaster {
public:
    using EventHandler = std::function<void(const nlohmann::json&)>;

    // Subscribe to events of eventType. Returns a subscription id.
    int subscribe(const std::string& eventType, EventHandler handler) {
        int id = nextId_++;
        subs_.push_back({id, eventType, std::move(handler)});
        return id;
    }

    // Remove the subscription with the given id.
    void unsubscribe(int id) {
        subs_.erase(
            std::remove_if(subs_.begin(), subs_.end(),
                           [id](const Sub& s){ return s.id == id; }),
            subs_.end());
    }

    // Call all handlers registered for eventType, passing body.
    void broadcast(const std::string& eventType, const nlohmann::json& body) const {
        for (const auto& s : subs_)
            if (s.eventType == eventType) s.handler(body);
    }

    // Broadcast using event["event"] as the type, event itself as the body.
    void broadcastAll(const nlohmann::json& event) const {
        if (!event.contains("event") || !event["event"].is_string()) return;
        broadcast(event["event"].get<std::string>(), event);
    }

    int subscriberCount(const std::string& eventType) const {
        int n = 0;
        for (const auto& s : subs_)
            if (s.eventType == eventType) ++n;
        return n;
    }

private:
    struct Sub {
        int          id;
        std::string  eventType;
        EventHandler handler;
    };

    std::vector<Sub> subs_;
    int              nextId_ = 1;
};

} // namespace whetstone