Skip to content

CLJS-3410: JavaScript double values should not hash to the same result #220

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 4 commits into from
Jan 22, 2024
Merged

CLJS-3410: JavaScript double values should not hash to the same result #220

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
53a57b6
* add hash-long
swannodette Jan 22, 2024
107eb74
* typos
swannodette Jan 22, 2024
e0d5458
* switch to isSafeInteger
swannodette Jan 22, 2024
bff567f
* more test assertions
swannodette Jan 22, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
14 changes: 13 additions & 1 deletion src/main/cljs/cljs/core.cljs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -960,6 +960,16 @@
h1 (m3-mix-H1 m3-seed k1)]
(m3-fmix h1 4))))

(defn hash-long [high low]
(bit-xor high low))

(defn hash-double [f]
(let [arr (doto (js/Float64Array. 1) (aset 0 f))
buf (.-buffer arr)
high (.getInt32 (js/DataView. buf 0 4))
low (.getInt32 (js/DataView. buf 4 4))]
(hash-long high low)))

(defn ^number m3-hash-unencoded-chars [in]
(let [h1 (loop [i 1 h1 m3-seed]
(if (< i (.-length in))
Expand Down Expand Up @@ -1021,7 +1031,9 @@

(number? o)
(if ^boolean (js/isFinite o)
(js-mod (Math/floor o) 2147483647)
(if-not ^boolean (.isSafeInteger js/Number o)
(hash-double o)
(js-mod (Math/floor o) 2147483647))
(case o
##Inf
2146435072
Expand Down
9 changes: 9 additions & 0 deletions src/test/cljs/cljs/hashing_test.cljs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -93,3 +93,12 @@
(deftest test-cljs-1818
(is (= (hash true) 1231))
(is (= (hash false) 1237)))

(deftest test-cljs-3410
(testing "Small doubles should not hash the same"
(is (not= (hash-double -0.32553251) (hash-double -0.0000032553251)))
(is (not= (hash -0.32553251) (hash -0.0000032553251))))
(testing "Same double hashes the same"
(is (= (hash 0.5) (hash 0.5)))
(is (= (hash -0.32553251) (hash -0.32553251)))
(is (= (hash -0.0000032553251) (hash -0.0000032553251)))))