DelegateChain

template <typename ... Parameters>
class ACTIONRPG_API DelegateChain
{
protected:
    typedef std::function<bool(Parameters...)> FunctionType;

    struct Delegate {
        Delegate(UObject* Target, int32 Priority, FunctionType Function) {
            this->Target = Target;
            this->Priority = Priority;
            this->Function = Function;
        }
        UObject* Target;
        int32 Priority;
        FunctionType Function;
    };

    std::list<Delegate> Delegates;

    void AddDelegate(Delegate& Delegate) {
        for (auto Iterator = Delegates.begin(); Iterator != Delegates.end(); Iterator++) {
            if (Iterator->Priority < Delegate.Priority) {
                Delegates.insert(Iterator, Delegate);
                return;
            }
        }
        Delegates.insert(Delegates.end(), Delegate);
    }

public:
    template <typename ObjectType, typename MemberType>
    void Register(ObjectType* Object, MemberType Function, int32 Priority) {
        Delegate Delegate(Object, Priority, [=](Parameters... params) -> bool {
            return (Object->*Function)(params...);
        });
        AddDelegate(Delegate);
    }

    void Unregister(UObject* Target) {
        for (auto Iterator = Delegates.begin(); Iterator != Delegates.end();) {
            auto OldIterator = Iterator++;
            if (OldIterator->Target == Target) {
                Delegates.erase(OldIterator);
            }
        }
        return;
    }

    bool Call(Parameters... params) {
        for (auto Iterator = Delegates.begin(); Iterator != Delegates.end(); ) {
            auto Current = Iterator++;
            if (Current->Function(params...)) {
                return true;
            }
        }
        return false;
    }
};