src/utils/hash.js
/*
* BSD 3-Clause License
*
* Copyright (c) 2020, Mapcreator
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
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*
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* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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import stringify from 'json-stable-stringify';
const FNV1_32A_INIT = 0x811c9dc5;
/**
* Fast hash function for non-cryptographic use
* @param {string} str - Input to be hashed
* @returns {string} - String representation of the hash
* @private
*/
export function fnv32b (str) {
let hash = str
.split('')
.map(x => x.charCodeAt(0))
.reduce((sum, val) => {
sum ^= val;
return sum + (sum << 1) + (sum << 4) + (sum << 7) + (sum << 8) + (sum << 24);
}, FNV1_32A_INIT);
// Avalanche
hash ^= hash << 3;
hash += hash >> 5;
hash ^= hash << 4;
hash += hash >> 17;
hash ^= hash << 25;
hash += hash >> 6;
return `0000000${(hash >>> 0).toString(16)}`.substr(-8);
}
/**
* Fast object hashing for non-cryptographic use
* @param {object} data - input data
* @returns {string} - String reprisentation of the hash
* @private
*/
export function hashObject (data) {
return fnv32b(stringify(data));
}