nested-sets-clj

It helps to use Nested Sets Model with Clojure and ClojureScript.

Usage

Make a vector tree from nested sets which is sometimes gotton from DB.

(require '[nested-sets.core :as nested])

;; A-----B-----C
;; |
;; |-----D-----E----F
;; |     |     |
;; |     |     -----G---H
;; |      -----I
(let [a {:id :a :lft 1 :rgt 18}
      b {:id :b :lft 2 :rgt 5}
      c {:id :c :lft 3 :rgt 4}
      d {:id :d :lft 6 :rgt 17}
      e {:id :e :lft 7 :rgt 14}
      f {:id :f :lft 8 :rgt 9}
      g {:id :g :lft 10 :rgt 13}
      h {:id :h :lft 11 :rgt 12}
      i {:id :i :lft 15 :rgt 16}]
  (= [a
      [b [c]]
      [d
       [e
        [f]
        [g [h]]]
       [i]]]
     (nested/nested-sets->vec-tree [a b c d e f g h i])))
;=> true

nested-sets->vec-tree can also take a function which controls how to make a node in the tree.

(let [a {:id :a :lft 1 :rgt 18}
      b {:id :b :lft 2 :rgt 5}
      c {:id :c :lft 3 :rgt 4}
      d {:id :d :lft 6 :rgt 17}
      e {:id :e :lft 7 :rgt 14}
      f {:id :f :lft 8 :rgt 9}
      g {:id :g :lft 10 :rgt 13}
      h {:id :h :lft 11 :rgt 12}
      i {:id :i :lft 15 :rgt 16}]
  (= [:Node a
      [:Node b [:Node c]]
      [:Node d
       [:Node e
        [:Node f]
        [:Node g [:Node h]]]
       [:Node i]]]
     (nested/nested-sets->vec-tree [a b c d e f g h i]
                                   {:make-node (fn [node] [:Node node])})))
;=> true

On the contary, it enable to make nested sets form a vector tree.

(require '[nested-sets.core :as nested])

;; A-----B-----C
;; |
;; |-----D-----E----F
;; |     |     |
;; |     |     -----G---H
;; |      -----I
(let [a {:id :a}
      b {:id :b}
      c {:id :c}
      d {:id :d}
      e {:id :e}
      f {:id :f}
      g {:id :g}
      h {:id :h}
      i {:id :i}]
  (= [{:id :a :lft 1 :rgt 18}
      {:id :b :lft 2 :rgt 5}
      {:id :c :lft 3 :rgt 4}
      {:id :d :lft 6 :rgt 17}
      {:id :e :lft 7 :rgt 14}
      {:id :f :lft 8 :rgt 9}
      {:id :g :lft 10 :rgt 13}
      {:id :h :lft 11 :rgt 12}
      {:id :i :lft 15 :rgt 16}]
     (nested/vec-tree->nested-sets [a
                                    [b [c]]
                                    [d
                                     [e
                                      [f]
                                      [g [h]]]
                                     [i]]])))
;=> true

It also provides a function to make a vector tree from adjacency list.

(require '[nested-sets.core :as nested])

;; A-----B-----C
;; |
;; |-----D-----E----F
;; |     |     |
;; |     |     -----G---H
;; |      -----I
(let [a {:id :a :parent-id nil}
      b {:id :b :parent-id :a}
      c {:id :c :parent-id :b}
      d {:id :d :parent-id :a}
      e {:id :e :parent-id :d}
      f {:id :f :parent-id :e}
      g {:id :g :parent-id :e}
      h {:id :h :parent-id :g}
      i {:id :i :parent-id :d}]
  (= [a
      [b [c]]
      [d
       [e
        [f]
        [g [h]]]
       [i]]]
     (nested/adjacency-list->vec-tree :id :parent-id [a b c d e f g h i])))

adjacency-list->vec-tree can also take a function which controls how to make a node in the tree.

(let [a {:id :a :parent-id nil}
      b {:id :b :parent-id :a}
      c {:id :c :parent-id :b}
      d {:id :d :parent-id :a}
      e {:id :e :parent-id :d}
      f {:id :f :parent-id :e}
      g {:id :g :parent-id :e}
      h {:id :h :parent-id :g}
      i {:id :i :parent-id :d}]
  (= [:Node a
      [:Node b [:Node c]]
      [:Node d
       [:Node e
        [:Node f]
        [:Node g [:Node h]]]
       [:Node i]]]
     (nested/adjacency-list->vec-tree :id
                                      :parent-id
                                      [a b c d e f g h i]
                                      {:make-node (fn [node] [:Node node])})))

License

Copyright 2020 TOYOKUMO,Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.