nav function

Implementation

dynamic nav(dynamic root, List items, {bool nullIfAbsent = false}) {
  if (root == null) return null;
  try {
    dynamic current = root;
    for (final k in items) {
      if (current is JsonMap) {
        current = current[k];
      } else if (current is List) {
        if (k is int && k < 0) {
          current = current.last;
        } else if (k is int && k < current.length) {
          current = current[k];
        } else {
          throw Exception('Invalid index $k for list');
        }
      } else {
        throw Exception('Invalid navigation at key $k on $current');
      }
    }
    return current;
  } catch (e) {
    if (nullIfAbsent) return null;
    throw Exception(
      'Unable to find using path $items on ${json.encode(root)}, exception: $e',
    );
  }
}