at method

@override TreeNode? at(int index)

Implementation

@override
TreeNode? at(int index) {
  final f = _filter;
  if (f == null) return null;

  var j = 0;
  for (var i = 0; i < _data.length; i++) {
    if (f(i)) {
      if (j == index) return _data.at(i);
      j++;
    }
  }
  return null;
}