Hi,
On 21 Feb., 08:17, Damien <[email protected]> wrote:
> Not sure if I should talk about flattening but basically I'm trying to
> achieve the following transformation:
>
> user=>(flatten-tree {1 {2 {3 4 5 6} 7 {8 9}}})
> ((1 2 3 4) (1 2 5 6) (1 7 8 9))
Using protocols seems overkill:
(defprotocol TreeFlattener (flatten-tree [this]))
(extend-protocol TreeFlattener
clojure.lang.IPersistentMap
(flatten-tree
[this]
(mapcat (fn [[k v]] (map #(cons k %) (flatten-tree v))) this))
Object
(flatten-tree
[this]
(list (list this)))
nil
(flatten-tree [_] (list (list nil))))
user=> (flatten-tree {1 {2 {3 [4 nil] 5 6} 7 {8 9}}})
((1 2 3 [4 nil]) (1 2 5 6) (1 7 8 9))
... but it also allows to add other data structures later on:
(extend-type clojure.lang.IPersistentVector
TreeFlattener
(flatten-tree
[this]
(mapcat (fn [idx x] (map #(cons idx %) (flatten-tree x))) (range)
this)))
user=> (flatten-tree {1 {2 {3 [4 nil] 5 6} 7 {8 9}}})
((1 2 3 0 4) (1 2 3 1 nil) (1 2 5 6) (1 7 8 9))
Beware structure depths and stack overflows, though.
Hope that helps.
Sincerely
Meikel
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