Function flatten

tfjs-core/src/util.ts:165–193

(
    arr: T|RecursiveArray<T>, result: T[] = [], skipTypedArray = false)

 * @doc {heading: 'Util', namespace: 'util'}
 */
export function
flatten<T extends number|boolean|string|Promise<number>|TypedArray>(
    arr: T|RecursiveArray<T>, result: T[] = [], skipTypedArray = false): T[] {
  if (result == null) {
    result = [];
  }
  if (typeof arr === 'boolean' || typeof arr === 'number' ||
    typeof arr === 'string' || base.isPromise(arr) || arr == null ||
      isTypedArray(arr) && skipTypedArray) {
    result.push(arr as T);
  } else if (Array.isArray(arr) || isTypedArray(arr)) {
    for (let i = 0; i < arr.length; ++i) {
      flatten(arr[i], result, skipTypedArray);
    }
  } else {
    let maxIndex = -1;
    for (const key of Object.keys(arr)) {
      // 0 or positive integer.
      if (/^([1-9]+[0-9]*|0)$/.test(key)) {
        maxIndex = Math.max(maxIndex, Number(key));
      }
    }
    for (let i = 0; i <= maxIndex; i++) {
      // tslint:disable-next-line: no-unnecessary-type-assertion
      flatten((arr as RecursiveArray<T>)[i], result, skipTypedArray);
    }
  }
  return result;
}