getPositionDelta function

int getPositionDelta(Delta user, Delta actual)

Implementation

int getPositionDelta(Delta user, Delta actual) {
  if (actual.isEmpty) {
    return 0;
  }

  final userItr = DeltaIterator(user);
  final actualItr = DeltaIterator(actual);
  var diff = 0;
  while (userItr.hasNext || actualItr.hasNext) {
    final length = math.min(userItr.peekLength(), actualItr.peekLength());
    final userOperation = userItr.next(length);
    final actualOperation = actualItr.next(length);
    if (userOperation.length != actualOperation.length) {
      throw 'userOp ${userOperation.length} does not match actualOp '
          '${actualOperation.length}';
    }
    if (userOperation.key == actualOperation.key) {
      continue;
    } else if (userOperation.isInsert && actualOperation.isRetain) {
      diff -= userOperation.length!;
    } else if (userOperation.isDelete && actualOperation.isRetain) {
      diff += userOperation.length!;
    } else if (userOperation.isRetain && actualOperation.isInsert) {
      String? operationTxt = '';
      if (actualOperation.data is String) {
        operationTxt = actualOperation.data as String?;
      }
      if (operationTxt!.startsWith('\n')) {
        continue;
      }
      diff += actualOperation.length!;
    }
  }
  return diff;
}