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hash function seems to be stable now

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This commit is contained in:
Christian Mueller
2012-06-02 13:08:55 +02:00
parent 3893ca44b9
commit d4d2cc244b
1 changed files with 6 additions and 7 deletions
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src/NoteHub/crossover/lib.clj
+6 -7
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@@ -5,13 +5,12 @@
; (doesn't work for UTF-16!) ; (doesn't work for UTF-16!)
(defn hash [f s] (defn hash [f s]
(let [short-mod #(mod % 32767) (let [short-mod #(mod % 32767)
; we cannot use Math/pow because it's imprecise char-codes (map f
; and differs on JVM and JS (filter #(not (contains? #{"\n" "\r"} %)) (map str s)))]
pow (fn [n e]
(reduce #(short-mod (* % %2)) 1
(repeat e n)))
char-codes (map #(f (str %)) s)]
(reduce (reduce
#(short-mod (+ % #(short-mod (+ %
(short-mod (* (first %2) (pow 31 (second %2)))))) (short-mod (* (first %2)
((if (odd? %)
bit-xor
bit-and) 16381 (second %2))))))
0 (map list char-codes (range))))) 0 (map list char-codes (range)))))