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checksums.cljc
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checksums.cljc
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(ns fulcro.checksums
(:require [clojure.string :as str]))
;; ===================================================================
;; Checksums (data-react-checksum)
(def MOD 65521)
;; Adapted from https://github.com/tonsky/rum
(defn adler32 [^StringBuilder sb]
(let [l (.length sb)
m (bit-and l -4)]
(loop [a (int 1)
b (int 0)
i 0
n (min (+ i 4096) m)]
(cond
(< i n)
(let [c0 (int (.charAt sb i))
c1 (int (.charAt sb (+ i 1)))
c2 (int (.charAt sb (+ i 2)))
c3 (int (.charAt sb (+ i 3)))
b (+ b a c0
a c0 c1
a c0 c1 c2
a c0 c1 c2 c3)
a (+ a c0 c1 c2 c3)]
(recur (rem a MOD) (rem b MOD) (+ i 4) n))
(< i m)
(recur a b i (min (+ i 4096) m))
(< i l)
(let [c0 (int (.charAt sb i))]
(recur (+ a c0) (+ b a c0) (+ i 1) n))
:else
(let [a (rem a MOD)
b (rem b MOD)]
(bit-or (int a) (unchecked-int (bit-shift-left b 16))))))))
(defn assign-react-checksum [^StringBuilder sb]
(.insert sb (.indexOf sb ">") (str " data-react-checksum=\"" (adler32 sb) "\"")))