| 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 } | |