current top-level property Null safety

Implementation

String get current {
  // If the current working directory gets deleted out from under the program,
  // accessing it will throw an IO exception. In order to avoid transient
  // errors, if we already have a cached working directory, catch the error and
  // use that.
  Uri uri;
  try {
    uri = Uri.base;
  } on Exception {
    if (_current != null) return _current!;
    rethrow;
  }

  // Converting the base URI to a file path is pretty slow, and the base URI
  // rarely changes in practice, so we cache the result here.
  if (uri == _currentUriBase) return _current!;
  _currentUriBase = uri;

  if (Style.platform == Style.url) {
    _current = uri.resolve('.').toString();
  } else {
    final path = uri.toFilePath();
    // Remove trailing '/' or '\' unless it is the only thing left
    // (for instance the root on Linux).
    final lastIndex = path.length - 1;
    assert(path[lastIndex] == '/' || path[lastIndex] == '\\');
    _current = lastIndex == 0 ? path : path.substring(0, lastIndex);
  }
  return _current!;
}