mbt.cljc

(ns replicate.tree
   [clojure.walk
    :refer [postwalk]]))

(defprotocol NodeStore
  (persist [store node])
  (fetch   [store node-hash]))

(defprotocol Node
  (insert [node k store])
  (search [node k store]))

(extend-protocol Node
  nil
  (insert [_ k _] [k nil nil])
  (search [_ _ _] nil)

  #?(:clj  clojure.lang.IPersistentVector
     :cljs PersistentVector)
  (insert [[k :as node] k' store]
    (cond (< k' k) (update node 1 insert k' store)
          (> k' k) (update node 2 insert k' store)
          :else    node))
  (search [[k l r :as node] k' store]
    (cond (< k' k) (search l k' store)
          (> k' k) (search r k' store)
          :else    node))

  #?(:clj  java.lang.String
     :cljs string)
  (insert [n-hash k store]
    (-> (fetch store n-hash) (insert k store)))
  (search [n-hash k store]
    (-> (fetch store n-hash) (search k store))))

(defn persist-tree [node store]
  (postwalk
   #(cond->> % (vector? %) (persist store))
   node))