EventDelegator.h

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#pragma once
 
#include <container/seadTList.h>
#include <telkin/Print.h>
 
namespace red {
 
    template <typename T> //requires std::derived_from<T, EventBase>
    class EventDelegator {
    public:
        using Callback = void (*)(T& event);
 
    public:
        class Listener {
        public:
            // higher priority = fires earlier
            Listener(Callback callback, s32 priority)
                : mNode(this)
                , mCallback(callback)
                , mPriority(priority)
            { }
 
            [[clang::always_inline]]
            void invoke(T& event) const {
                return mCallback(event);
            }
 
            [[nodiscard]]
            sead::TListNode<Listener*>& getNode() { return mNode; }
 
            [[nodiscard]]
            s32 getPriority() const { return mPriority; }
 
        private:
            sead::TListNode<Listener*> mNode;
            Callback mCallback;
            s32 mPriority;
        };
 
    public:
        void connect(Listener& listener) {
            mListeners.pushBack(&listener.getNode());
            mListeners.sort(&compare);
        }
 
        void fire(T& event) const {
            for (const Listener* listener : mListeners) {
                listener->invoke(event);
 
                if (event.isConsumed()) [[unlikely]]
                    return; // stop propagation
            }
        }
 
    private:
        static s32 compare(Listener* const* a, Listener* const* b) {
            if ((*a)->getPriority() < (*b)->getPriority())
                return 1;
 
            if ((*b)->getPriority() < (*a)->getPriority())
                return -1;
 
            return 0;
        }
 
    private:
        sead::TList<Listener*> mListeners;
    };
 
}