fix(NODE-6552): remove cache and use toStringTag in type helpers (#740)

src/parser/utils.ts

@@ -1,65 +1,44 @@
-const map = new WeakMap<object, string>();
+const TypedArrayPrototypeGetSymbolToStringTag = (() => {
+  // Type check system lovingly referenced from:
+  // https://github.com/nodejs/node/blob/7450332339ed40481f470df2a3014e2ec355d8d8/lib/internal/util/types.js#L13-L15
+  // eslint-disable-next-line @typescript-eslint/unbound-method -- the intention is to call this method with a bound value
+  const g = Object.getOwnPropertyDescriptor(
+    Object.getPrototypeOf(Uint8Array.prototype),
+    Symbol.toStringTag
+  )!.get!;
 
-const TYPES = {
-  ArrayBuffer: '[object ArrayBuffer]',
-  SharedArrayBuffer: '[object SharedArrayBuffer]',
-  Uint8Array: '[object Uint8Array]',
-  BigInt64Array: '[object BigInt64Array]',
-  BigUint64Array: '[object BigUint64Array]',
-  RegExp: '[object RegExp]',
-  Map: '[object Map]',
-  Date: '[object Date]'
-};
-
-/**
- * Retrieves the prototype.toString() of a value.
- * If the value is an object, it will cache the result in a WeakMap for future use.
- */
-function getPrototypeString(value: unknown): string {
-  let str = map.get(value as object);
-
-  if (!str) {
-    str = Object.prototype.toString.call(value);
-    if (value !== null && typeof value === 'object') {
-      map.set(value, str);
-    }
-  }
-  return str;
-}
-
-export function isAnyArrayBuffer(value: unknown): value is ArrayBuffer {
-  const type = getPrototypeString(value);
-  return type === TYPES.ArrayBuffer || type === TYPES.SharedArrayBuffer;
-}
+  return (value: unknown) => g.call(value);
+})();
 
 export function isUint8Array(value: unknown): value is Uint8Array {
-  const type = getPrototypeString(value);
-  return type === TYPES.Uint8Array;
+  return TypedArrayPrototypeGetSymbolToStringTag(value) === 'Uint8Array';
 }
 
-export function isBigInt64Array(value: unknown): value is BigInt64Array {
-  const type = getPrototypeString(value);
-  return type === TYPES.BigInt64Array;
-}
-
-export function isBigUInt64Array(value: unknown): value is BigUint64Array {
-  const type = getPrototypeString(value);
-  return type === TYPES.BigUint64Array;
+export function isAnyArrayBuffer(value: unknown): value is ArrayBuffer {
+  return (
+    typeof value === 'object' &&
+    value != null &&
+    Symbol.toStringTag in value &&
+    (value[Symbol.toStringTag] === 'ArrayBuffer' ||
+      value[Symbol.toStringTag] === 'SharedArrayBuffer')
+  );
 }
 
-export function isRegExp(d: unknown): d is RegExp {
-  const type = getPrototypeString(d);
-  return type === TYPES.RegExp;
+export function isRegExp(regexp: unknown): regexp is RegExp {
+  return regexp instanceof RegExp || Object.prototype.toString.call(regexp) === '[object RegExp]';
 }
 
-export function isMap(d: unknown): d is Map<unknown, unknown> {
-  const type = getPrototypeString(d);
-  return type === TYPES.Map;
+export function isMap(value: unknown): value is Map<unknown, unknown> {
+  return (
+    typeof value === 'object' &&
+    value != null &&
+    Symbol.toStringTag in value &&
+    value[Symbol.toStringTag] === 'Map'
+  );
 }
 
-export function isDate(d: unknown): d is Date {
-  const type = getPrototypeString(d);
-  return type === TYPES.Date;
+export function isDate(date: unknown): date is Date {
+  return date instanceof Date || Object.prototype.toString.call(date) === '[object Date]';
 }
 
 export type InspectFn = (x: unknown, options?: unknown) => string;