next method

Operation? next([ num length = double.infinity ])

Consumes and returns next operation.

Optional length specifies maximum length of operation to return. Note that actual length of returned operation may be less than specified value.

Implementation

Operation? next([num length = double.infinity]) {
  assert(length != null);

  if (_modificationCount != delta._modificationCount) {
    throw new ConcurrentModificationError(delta);
  }

  if (_index < delta.length) {
    final op = delta.elementAt(_index);
    final opKey = op.key;
    final opAttributes = op.attributes;
    final _currentOffset = _offset;
    num actualLength = math.min(op.length! - _currentOffset, length);
    if (actualLength == op.length! - _currentOffset) {
      _index++;
      _offset = 0;
    } else {
      _offset += actualLength;
    }
    final String opData = op.isInsert
        ? op.data.substring(_currentOffset as int, _currentOffset + (actualLength as int))
        : '';
    final int opLength = (opData.isNotEmpty) ? opData.length : actualLength as int;
    return Operation._(opKey, opLength, opData, opAttributes);
  }
  return Operation.retain(length as int?);
}