hooks

hooks react native

(def db (atom {:counter 0}))

(defmulti query (fn [db query-v] query-v))

(defmethod query :default
  [db query-v]
  (cond
    (keyword? query-v) (get db query-v)
    (vector? query-v) (get-in db query-v)
    (set? query-v) (select-keys db (into [] query-v))
    (map? query-v) (persistent! (reduce-kv (fn [m k v]
                                             (assoc! m k (query (get db k) v)))
                                           (transient {})
                                           query-v))))

(defn <-query
  [query-v]
  (let [result (<-state (query @db query-v))]
    (<-effect
      (fn []
        (let [id (random-uuid)]
          (add-watch db id
                     (fn [_ _ _ new-db]
                       (reset! result (query new-db query-v))))
          (fn []
            (remove-watch db id))))
      #js [query-v])
    result))

(defmulti handle-event (fn [db event-v] (first event-v)))

(defmethod handle-event :default
  [db event-v]
  (let [[e1 e2 & more] event-v]
    (cond
      (and (keyword? e1) (fn? e2)) (apply update db e1 e2 more)
      (and (vector? e1) (fn? e2)) (apply update-in db e1 e2 more)
      (keyword? e1) (assoc db e1 e1)
      (vector? e1) (assoc-in db e1 e2)
      :else db)))

(defn dispatch!
  [event-v]
  (swap! db handle-event event-v))