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- let crypto = require('crypto')
- let { urlAlphabet } = require('./url-alphabet/index.cjs')
- const POOL_SIZE_MULTIPLIER = 128
- let pool, poolOffset
- let fillPool = bytes => {
- if (!pool || pool.length < bytes) {
- pool = Buffer.allocUnsafe(bytes * POOL_SIZE_MULTIPLIER)
- crypto.randomFillSync(pool)
- poolOffset = 0
- } else if (poolOffset + bytes > pool.length) {
- crypto.randomFillSync(pool)
- poolOffset = 0
- }
- poolOffset += bytes
- }
- let random = bytes => {
- fillPool((bytes -= 0))
- return pool.subarray(poolOffset - bytes, poolOffset)
- }
- let customRandom = (alphabet, defaultSize, getRandom) => {
- let mask = (2 << (31 - Math.clz32((alphabet.length - 1) | 1))) - 1
- let step = Math.ceil((1.6 * mask * defaultSize) / alphabet.length)
- return (size = defaultSize) => {
- let id = ''
- while (true) {
- let bytes = getRandom(step)
- let i = step
- while (i--) {
- id += alphabet[bytes[i] & mask] || ''
- if (id.length === size) return id
- }
- }
- }
- }
- let customAlphabet = (alphabet, size = 21) =>
- customRandom(alphabet, size, random)
- let nanoid = (size = 21) => {
- fillPool((size -= 0))
- let id = ''
- for (let i = poolOffset - size; i < poolOffset; i++) {
- id += urlAlphabet[pool[i] & 63]
- }
- return id
- }
- module.exports = { nanoid, customAlphabet, customRandom, urlAlphabet, random }
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