Add tree-leafs function

src/potpuri/core.cljc

@@ -412,3 +412,18 @@
   (let [g (group-by parent-fn items)]
     ;; Start with items which have no parent => root items
     (build-tree' opts g (get g nil))))
+
+(defn tree-leafs
+  "Given a tree, branch? predicate and child-fn returns list of found
+  tree leafs.
+
+  If only single function is provided, it is used as both branch? predicate and child-fn."
+  {:added "0.5.2"}
+  ([tree child-fn]
+   (tree-leafs tree child-fn child-fn))
+  ([tree branch? child-fn]
+   (mapcat (fn [node]
+             (if (branch? node)
+               (tree-leafs (child-fn node) branch? child-fn)
+               [node]))
+           tree)))

test/potpuri/benchmark.clj

@@ -1,7 +1,17 @@
 (ns potpuri.benchmark
   (:require [potpuri.core :as p]
-            [criterium.core :as criterium]))
+            [criterium.core :refer [quick-bench]]))
 
 (comment
   (quick-bench (into [1] [2 3 4]))
   (quick-bench (apply vector 1 [ 2 3 4])))
+
+
+(comment
+  (def tree [{:id "top"
+              :lapset [{:id "c1"
+                        :lapset [{:id "c11" :lapset [{:id "c12"}]}
+                                 {:id "c13"}]}
+                       {:id "c2"}]}])
+
+  (quick-bench (p/leafs tree :lapset)))

test/potpuri/core_test.cljc

@@ -271,3 +271,24 @@
                       {:id 3 :parents [1 2]}
                       {:id 4 :parents [1 2]}])))))
   )
+
+(deftest tree-leafs-test
+  (is (= [{:id 2} {:id 3} {:id 4}]
+         (p/tree-leafs [{:id 1
+                         :children [{:id 2}
+                                    {:id 3}]}
+                        {:id 4}]
+                       :children)))
+
+   (testing "branch with empty children list"
+     (is (= [{:id 1 :children nil}]
+            (p/tree-leafs [{:id 1
+                            :children nil}]
+                          :children)))
+
+     (is (= []
+            (p/tree-leafs [{:id 1
+                            :children nil}]
+                          #(contains? % :children)
+                          :children))
+         "Separate branch predicate")))