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import { webcrypto as crypto } from 'node:crypto'
import { urlAlphabet as scopedUrlAlphabet } from './url-alphabet/index.js'
export { urlAlphabet } from './url-alphabet/index.js'
const POOL_SIZE_MULTIPLIER = 128
let pool, poolOffset
function fillPool(bytes) {
if (!pool || pool.length < bytes) {
pool = Buffer.allocUnsafe(bytes * POOL_SIZE_MULTIPLIER)
crypto.getRandomValues(pool)
poolOffset = 0
} else if (poolOffset + bytes > pool.length) {
crypto.getRandomValues(pool)
poolOffset = 0
}
poolOffset += bytes
}
export function random(bytes) {
fillPool((bytes |= 0))
return pool.subarray(poolOffset - bytes, poolOffset)
}
export function 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
}
}
}
}
export function customAlphabet(alphabet, size = 21) {
return customRandom(alphabet, size, random)
}
export function nanoid(size = 21) {
fillPool((size |= 0))
let id = ''
for (let i = poolOffset - size; i < poolOffset; i++) {
id += scopedUrlAlphabet[pool[i] & 63]
}
return id
}
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