feat(vanilla): add testing infrastructure and tests (NK-wjnczv)

1 files changed, 85 insertions, 0 deletions

diff --git a/vanilla/node_modules/nanoid/index.cjs b/vanilla/node_modules/nanoid/index.cjs
new file mode 100644
index 0000000..c20e374
--- /dev/null
+++ b/vanilla/node_modules/nanoid/index.cjs
@@ -0,0 +1,85 @@
+let crypto = require('crypto')
+
+let { urlAlphabet } = require('./url-alphabet/index.cjs')
+
+// It is best to make fewer, larger requests to the crypto module to
+// avoid system call overhead. So, random numbers are generated in a
+// pool. The pool is a Buffer that is larger than the initial random
+// request size by this multiplier. The pool is enlarged if subsequent
+// requests exceed the maximum buffer size.
+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 => {
+  // `|=` convert `bytes` to number to prevent `valueOf` abusing and pool pollution
+  fillPool((bytes |= 0))
+  return pool.subarray(poolOffset - bytes, poolOffset)
+}
+
+let customRandom = (alphabet, defaultSize, getRandom) => {
+  // First, a bitmask is necessary to generate the ID. The bitmask makes bytes
+  // values closer to the alphabet size. The bitmask calculates the closest
+  // `2^31 - 1` number, which exceeds the alphabet size.
+  // For example, the bitmask for the alphabet size 30 is 31 (00011111).
+  let mask = (2 << (31 - Math.clz32((alphabet.length - 1) | 1))) - 1
+  // Though, the bitmask solution is not perfect since the bytes exceeding
+  // the alphabet size are refused. Therefore, to reliably generate the ID,
+  // the random bytes redundancy has to be satisfied.
+
+  // Note: every hardware random generator call is performance expensive,
+  // because the system call for entropy collection takes a lot of time.
+  // So, to avoid additional system calls, extra bytes are requested in advance.
+
+  // Next, a step determines how many random bytes to generate.
+  // The number of random bytes gets decided upon the ID size, mask,
+  // alphabet size, and magic number 1.6 (using 1.6 peaks at performance
+  // according to benchmarks).
+  let step = Math.ceil((1.6 * mask * defaultSize) / alphabet.length)
+
+  return (size = defaultSize) => {
+    let id = ''
+    while (true) {
+      let bytes = getRandom(step)
+      // A compact alternative for `for (let i = 0; i < step; i++)`.
+      let i = step
+      while (i--) {
+        // Adding `|| ''` refuses a random byte that exceeds the alphabet size.
+        id += alphabet[bytes[i] & mask] || ''
+        if (id.length === size) return id
+      }
+    }
+  }
+}
+
+let customAlphabet = (alphabet, size = 21) =>
+  customRandom(alphabet, size, random)
+
+let nanoid = (size = 21) => {
+  // `|=` convert `size` to number to prevent `valueOf` abusing and pool pollution
+  fillPool((size |= 0))
+  let id = ''
+  // We are reading directly from the random pool to avoid creating new array
+  for (let i = poolOffset - size; i < poolOffset; i++) {
+    // It is incorrect to use bytes exceeding the alphabet size.
+    // The following mask reduces the random byte in the 0-255 value
+    // range to the 0-63 value range. Therefore, adding hacks, such
+    // as empty string fallback or magic numbers, is unneccessary because
+    // the bitmask trims bytes down to the alphabet size.
+    id += urlAlphabet[pool[i] & 63]
+  }
+  return id
+}
+
+module.exports = { nanoid, customAlphabet, customRandom, urlAlphabet, random }