77 lines
1.9 KiB
JavaScript
77 lines
1.9 KiB
JavaScript
/**
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* @module uuids
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*/
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/**
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* A string or number representing a start state for a random generator
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* @typedef {(Number|String)} Seed
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*/
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/**
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* A UUIDv4 string in the format <code>Hex{8}-Hex{4}-4Hex{3}-[89ab]Hex{3}-Hex{12}</code>
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* @typedef {String} UUIDv4
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*/
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import { MersenneTwister } from 'fast-mersenne-twister';
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import { isString } from 'lodash';
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import stringHash from 'string-hash';
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import { v4 } from 'uuid';
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function getSeed(seeds) {
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return seeds.reduce((seedling, seed, i) => {
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let thisSeed = 0;
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if (Number.isInteger(seed)) {
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thisSeed = seed;
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} else if (isString(seed)) {
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thisSeed = stringHash(seed);
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}
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return seedling + (seeds.length - i) * thisSeed;
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}, 0);
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}
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function getPseudoRandomNumberGenerator(...seeds) {
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let seedNumber;
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if (seeds.length) {
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seedNumber = getSeed(seeds);
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} else {
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seedNumber = Math.floor(Math.random() * 10 ** 15);
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}
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return new MersenneTwister(seedNumber);
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}
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function randomValuesForUuid(prng) {
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const randomValues = [];
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for (let i = 0; i <= 3; i += 1) {
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const buffer = new ArrayBuffer(4);
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const view = new DataView(buffer);
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view.setUint32(0, prng.randomNumber());
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randomValues.push(view.getUint8(0), view.getUint8(1), view.getUint8(2), view.getUint8(3));
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}
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return randomValues;
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}
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/**
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* Get an array of UUIDv4s
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* @param {Object} [options={}]
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* @param {Seed[]} [options.seeds=[]] - A list of mixed strings or numbers to seed the UUIDv4 generator
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* @param {Number} [options.count=1] - A total number of UUIDv4s to generate
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* @returns {UUIDv4[]} An array of UUIDv4s
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*/
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export function uuids({ seeds = [], count = 1 } = {}) {
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const rng = getPseudoRandomNumberGenerator(...seeds);
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return (
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// Create an array the same size as the number of UUIDs requested
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Array(count)
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.fill(0)
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// Replace each slot in the array with a UUID which needs 16 (pseudo)random values to generate
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.map(() => v4({ random: randomValuesForUuid(rng) }))
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);
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}
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