resolve method

Resolvable<T> resolve(Resolvable<T> resolvable)

Safely resolves the completer with the outcome of a Resolvable.

If the completer is already completed or is in the process of completing, this method will return an Err and have no effect.

Implementation

Resolvable<T> resolve(Resolvable<T> resolvable) {
  if (_isCompleting) {
    return Sync.err(Err('SafeCompleter<$T> is already resolving!'));
  }
  _isCompleting = true;

  if (isCompleted) {
    _isCompleting = false;
    return Sync.err(Err('SafeCompleter<$T> is already completed!'));
  }

  // `ifOk` and `ifErr` are used to handle the two possible outcomes of the
  // resolvable, ensuring the completer is correctly handled in both cases.
  return resolvable
      .ifOk((_, ok) {
        final okValue = ok.unwrap();
        _value = Some(okValue);
        _completer.complete(okValue);
      })
      .ifErr((_, err) {
        _completer.completeError(err);
      })
      .whenComplete((_) {
        // Ensure the lock is always released.
        _isCompleting = false;
        return resolvable;
      });
}