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123 lines
4.0 KiB
JavaScript
123 lines
4.0 KiB
JavaScript
/**
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @flow
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*/
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// A pure JS implementation of a string hashing function. We do not use it for
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// security or obfuscation purposes, only to create compact hashes. So we
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// prioritize speed over collision avoidance. For example, we use this to hash
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// the component key path used by useActionState for MPA-style submissions.
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//
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// In environments where built-in hashing functions are available, we prefer
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// those instead. Like Node's crypto module, or Bun.hash. Unfortunately this
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// does not include the web standard crypto API because those methods are all
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// async. For our purposes, we need it to be sync because the cost of context
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// switching is too high to be worth it.
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//
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// The most popular hashing algorithm that meets these requirements in the JS
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// ecosystem is MurmurHash3, and almost all implementations I could find used
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// some version of the implementation by Gary Court inlined below.
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export function createFastHashJS(key: string): number {
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return murmurhash3_32_gc(key, 0);
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}
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/* eslint-disable prefer-const, no-fallthrough */
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/**
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* @license
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*
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* JS Implementation of MurmurHash3 (r136) (as of May 20, 2011)
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*
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* Copyright (c) 2011 Gary Court
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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function murmurhash3_32_gc(key: string, seed: number): number {
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let remainder, bytes, h1, h1b, c1, c2, k1, i;
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remainder = key.length & 3; // key.length % 4
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bytes = key.length - remainder;
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h1 = seed;
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c1 = 0xcc9e2d51;
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c2 = 0x1b873593;
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i = 0;
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while (i < bytes) {
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k1 =
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(key.charCodeAt(i) & 0xff) |
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((key.charCodeAt(++i) & 0xff) << 8) |
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((key.charCodeAt(++i) & 0xff) << 16) |
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((key.charCodeAt(++i) & 0xff) << 24);
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++i;
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k1 =
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((k1 & 0xffff) * c1 + ((((k1 >>> 16) * c1) & 0xffff) << 16)) & 0xffffffff;
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k1 = (k1 << 15) | (k1 >>> 17);
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k1 =
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((k1 & 0xffff) * c2 + ((((k1 >>> 16) * c2) & 0xffff) << 16)) & 0xffffffff;
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h1 ^= k1;
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h1 = (h1 << 13) | (h1 >>> 19);
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h1b =
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((h1 & 0xffff) * 5 + ((((h1 >>> 16) * 5) & 0xffff) << 16)) & 0xffffffff;
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h1 = (h1b & 0xffff) + 0x6b64 + ((((h1b >>> 16) + 0xe654) & 0xffff) << 16);
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}
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k1 = 0;
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switch (remainder) {
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case 3:
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k1 ^= (key.charCodeAt(i + 2) & 0xff) << 16;
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case 2:
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k1 ^= (key.charCodeAt(i + 1) & 0xff) << 8;
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case 1:
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k1 ^= key.charCodeAt(i) & 0xff;
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k1 =
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((k1 & 0xffff) * c1 + ((((k1 >>> 16) * c1) & 0xffff) << 16)) &
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0xffffffff;
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k1 = (k1 << 15) | (k1 >>> 17);
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k1 =
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((k1 & 0xffff) * c2 + ((((k1 >>> 16) * c2) & 0xffff) << 16)) &
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0xffffffff;
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h1 ^= k1;
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}
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h1 ^= key.length;
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h1 ^= h1 >>> 16;
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h1 =
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((h1 & 0xffff) * 0x85ebca6b +
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((((h1 >>> 16) * 0x85ebca6b) & 0xffff) << 16)) &
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0xffffffff;
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h1 ^= h1 >>> 13;
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h1 =
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((h1 & 0xffff) * 0xc2b2ae35 +
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((((h1 >>> 16) * 0xc2b2ae35) & 0xffff) << 16)) &
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0xffffffff;
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h1 ^= h1 >>> 16;
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return h1 >>> 0;
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}
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