underive(clojure.core)

Removes a parent/child relationship between parent and tag. h must be a hierarchy obtained from make-hierarchy, if not supplied defaults to, and modifies, the global hierarchy.

; clojure/core.clj:3372
(defn underive
  ([tag parent] (alter-var-root #'global-hierarchy underive tag parent) nil)
  ([h tag parent]
   (let [tp (:parents h)
         td (:descendants h)
         ta (:ancestors h)
         tf (fn [m source sources target targets]
              (reduce
               (fn [ret k]
                 (assoc ret k
                        (reduce disj (get targets k) (cons target (targets target)))))
               m (cons source (sources source))))]
     (if (contains? (tp tag) parent)
       {:parent (assoc (:parents h) tag (disj (get tp tag) parent))
        :ancestors (tf (:ancestors h) tag td parent ta)
        :descendants (tf (:descendants h) parent ta tag td)}
       h))))

Copyright (c) Rich Hickey. All rights reserved.

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