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Convert MurmurHash3_64 to an ES6 class

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Notable changes:
 - Remove the `return this;` from the `MurmurHash3_64.update` method, since it's completely unused and doesn't make a lot of sense.
 - Remove the loop(s) from the `MurmurHash3_64.hexdigest` method, since creating a temporary array and then looping over it is wasteful given how simple this can be written with modern JavaScript.
This commit is contained in:
Jonas Jenwald 2019-03-09 16:50:50 +01:00
parent e41c4aece4
commit 6b1ac44aea
1 changed files with 85 additions and 100 deletions
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63
src/core/murmurhash3.js
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@ -16,28 +16,28 @@
* Based on https://code.google.com/p/smhasher/wiki/MurmurHash3. * Based on https://code.google.com/p/smhasher/wiki/MurmurHash3.
* Hashes roughly 100 KB per millisecond on i7 3.4 GHz. * Hashes roughly 100 KB per millisecond on i7 3.4 GHz.
*/ */
/* eslint no-var: error */
import { isArrayBuffer, isString } from '../shared/util'; import { isArrayBuffer, isString } from '../shared/util';
var MurmurHash3_64 = (function MurmurHash3_64Closure(seed) { const SEED = 0xc3d2e1f0;
// Workaround for missing math precision in JS. // Workaround for missing math precision in JS.
var MASK_HIGH = 0xffff0000; const MASK_HIGH = 0xffff0000;
var MASK_LOW = 0xffff; const MASK_LOW = 0xffff;
function MurmurHash3_64(seed) { class MurmurHash3_64 {
var SEED = 0xc3d2e1f0; constructor(seed) {
this.h1 = seed ? seed & 0xffffffff : SEED; this.h1 = seed ? seed & 0xffffffff : SEED;
this.h2 = seed ? seed & 0xffffffff : SEED; this.h2 = seed ? seed & 0xffffffff : SEED;
} }
MurmurHash3_64.prototype = { update(input) {
update: function MurmurHash3_64_update(input) {
let data, length; let data, length;
if (isString(input)) { if (isString(input)) {
data = new Uint8Array(input.length * 2); data = new Uint8Array(input.length * 2);
length = 0; length = 0;
for (let i = 0, ii = input.length; i < ii; i++) { for (let i = 0, ii = input.length; i < ii; i++) {
var code = input.charCodeAt(i); const code = input.charCodeAt(i);
if (code <= 0xff) { if (code <= 0xff) {
data[length++] = code; data[length++] = code;
} else { } else {
@ -53,18 +53,14 @@ var MurmurHash3_64 = (function MurmurHash3_64Closure(seed) {
'Input must be a string or array.'); 'Input must be a string or array.');
} }
var blockCounts = length >> 2; const blockCounts = length >> 2;
var tailLength = length - blockCounts * 4; const tailLength = length - blockCounts * 4;
// we don't care about endianness here // We don't care about endianness here.
var dataUint32 = new Uint32Array(data.buffer, 0, blockCounts); const dataUint32 = new Uint32Array(data.buffer, 0, blockCounts);
var k1 = 0; let k1 = 0, k2 = 0;
var k2 = 0; let h1 = this.h1, h2 = this.h2;
var h1 = this.h1; const C1 = 0xcc9e2d51, C2 = 0x1b873593;
var h2 = this.h2; const C1_LOW = C1 & MASK_LOW, C2_LOW = C2 & MASK_LOW;
var C1 = 0xcc9e2d51;
var C2 = 0x1b873593;
var C1_LOW = C1 & MASK_LOW;
var C2_LOW = C2 & MASK_LOW;
for (let i = 0; i < blockCounts; i++) { for (let i = 0; i < blockCounts; i++) {
if (i & 1) { if (i & 1) {
@ -98,6 +94,7 @@ var MurmurHash3_64 = (function MurmurHash3_64Closure(seed) {
case 1: case 1:
k1 ^= data[blockCounts * 4]; k1 ^= data[blockCounts * 4];
/* falls through */ /* falls through */
k1 = (k1 * C1 & MASK_HIGH) | (k1 * C1_LOW & MASK_LOW); k1 = (k1 * C1 & MASK_HIGH) | (k1 * C1_LOW & MASK_LOW);
k1 = k1 << 15 | k1 >>> 17; k1 = k1 << 15 | k1 >>> 17;
k1 = (k1 * C2 & MASK_HIGH) | (k1 * C2_LOW & MASK_LOW); k1 = (k1 * C2 & MASK_HIGH) | (k1 * C2_LOW & MASK_LOW);
@ -110,12 +107,10 @@ var MurmurHash3_64 = (function MurmurHash3_64Closure(seed) {
this.h1 = h1; this.h1 = h1;
this.h2 = h2; this.h2 = h2;
return this; }
},
hexdigest: function MurmurHash3_64_hexdigest() { hexdigest() {
var h1 = this.h1; let h1 = this.h1, h2 = this.h2;
var h2 = this.h2;
h1 ^= h2 >>> 1; h1 ^= h2 >>> 1;
h1 = (h1 * 0xed558ccd & MASK_HIGH) | (h1 * 0x8ccd & MASK_LOW); h1 = (h1 * 0xed558ccd & MASK_HIGH) | (h1 * 0x8ccd & MASK_LOW);
@ -127,20 +122,10 @@ var MurmurHash3_64 = (function MurmurHash3_64Closure(seed) {
(((h2 << 16 | h1 >>> 16) * 0xb9fe1a85 & MASK_HIGH) >>> 16); (((h2 << 16 | h1 >>> 16) * 0xb9fe1a85 & MASK_HIGH) >>> 16);
h1 ^= h2 >>> 1; h1 ^= h2 >>> 1;
for (var i = 0, arr = [h1, h2], str = ''; i < arr.length; i++) { const hex1 = (h1 >>> 0).toString(16), hex2 = (h2 >>> 0).toString(16);
var hex = (arr[i] >>> 0).toString(16); return hex1.padStart(8, '0') + hex2.padStart(8, '0');
while (hex.length < 8) {
hex = '0' + hex;
} }
str += hex; }
}
return str;
},
};
return MurmurHash3_64;
})();
export { export {
MurmurHash3_64, MurmurHash3_64,