Change hash implementation

packages/emotion-utils/src/hash.js

@@ -1,74 +1,51 @@
 // @flow
-// murmurhash2 via https://gist.github.com/raycmorgan/588423
+/* eslint-disable */
+// murmurhash2 via https://github.com/garycourt/murmurhash-js/blob/master/murmurhash2_gc.js
 
 export function hashString(str: string) {
-  return hash(str, str.length).toString(36)
+  return murmurhash2_32_gc(str, str.length).toString(36)
 }
 
-function hash(str: string, seed: number) {
-  let m = 0x5bd1e995
-  let r = 24
-  let h = seed ^ str.length
-  let length = str.length
-  let currentIndex = 0
-
-  while (length >= 4) {
-    let k = UInt32(str, currentIndex)
-
-    k = Umul32(k, m)
-    k ^= k >>> r
-    k = Umul32(k, m)
-
-    h = Umul32(h, m)
-    h ^= k
-
-    currentIndex += 4
-    length -= 4
+function murmurhash2_32_gc(str: string, seed: number) {
+  var l = str.length,
+    h = seed ^ l,
+    i = 0,
+    k
+
+  while (l >= 4) {
+    k =
+      (str.charCodeAt(i) & 0xff) |
+      ((str.charCodeAt(++i) & 0xff) << 8) |
+      ((str.charCodeAt(++i) & 0xff) << 16) |
+      ((str.charCodeAt(++i) & 0xff) << 24)
+
+    k = (k & 0xffff) * 0x5bd1e995 + ((((k >>> 16) * 0x5bd1e995) & 0xffff) << 16)
+    k ^= k >>> 24
+    k = (k & 0xffff) * 0x5bd1e995 + ((((k >>> 16) * 0x5bd1e995) & 0xffff) << 16)
+
+    h =
+      ((h & 0xffff) * 0x5bd1e995 +
+        ((((h >>> 16) * 0x5bd1e995) & 0xffff) << 16)) ^
+      k
+
+    l -= 4
+    ++i
   }
 
-  switch (length) {
+  switch (l) {
     case 3:
-      h ^= UInt16(str, currentIndex)
-      h ^= str.charCodeAt(currentIndex + 2) << 16
-      h = Umul32(h, m)
-      break
-
+      h ^= (str.charCodeAt(i + 2) & 0xff) << 16
     case 2:
-      h ^= UInt16(str, currentIndex)
-      h = Umul32(h, m)
-      break
-
+      h ^= (str.charCodeAt(i + 1) & 0xff) << 8
     case 1:
-      h ^= str.charCodeAt(currentIndex)
-      h = Umul32(h, m)
-      break
+      h ^= str.charCodeAt(i) & 0xff
+      h =
+        (h & 0xffff) * 0x5bd1e995 + ((((h >>> 16) * 0x5bd1e995) & 0xffff) << 16)
   }
 
   h ^= h >>> 13
-  h = Umul32(h, m)
+  h = (h & 0xffff) * 0x5bd1e995 + ((((h >>> 16) * 0x5bd1e995) & 0xffff) << 16)
   h ^= h >>> 15
 
   return h >>> 0
 }
-
-function UInt32(str, pos) {
-  return (
-    str.charCodeAt(pos++) +
-    (str.charCodeAt(pos++) << 8) +
-    (str.charCodeAt(pos++) << 16) +
-    (str.charCodeAt(pos) << 24)
-  )
-}
-
-function UInt16(str, pos) {
-  return str.charCodeAt(pos++) + (str.charCodeAt(pos++) << 8)
-}
-
-function Umul32(n, m) {
-  n = n | 0
-  m = m | 0
-  let nlo = n & 0xffff
-  let nhi = n >>> 16
-  let res = (nlo * m + (((nhi * m) & 0xffff) << 16)) | 0
-  return res
-}