Future<T>.sync constructor Null safety

Future<T>.sync(
  1. FutureOr<T> computation(
      )
    )

    Returns a future containing the result of immediately calling computation.

    If calling computation throws, the returned future is completed with the error.

    If calling computation returns a Future<T>, that future is returned.

    If calling computation returns a non-future value, a future is returned which has been completed with that value.

    Example:

    final result = await Future<int>.sync(() => 12);

    Implementation

    factory Future.sync(FutureOr<T> computation()) {
  try {
    var result = computation();
    if (result is Future<T>) {
      return result;
    } else {
      // TODO(40014): Remove cast when type promotion works.
      return new _Future<T>.value(result as dynamic);
    }
  } catch (error, stackTrace) {
    var future = new _Future<T>();
    AsyncError? replacement = Zone.current.errorCallback(error, stackTrace);
    if (replacement != null) {
      future._asyncCompleteError(replacement.error, replacement.stackTrace);
    } else {
      future._asyncCompleteError(error, stackTrace);
    }
    return future;
  }
}