takeAfterPrefix method

Uint8List takeAfterPrefix(int prefix, int count)

Returns count bytes after a consumed leading prefix without moving the returned payload. Only bytes after the returned range are copied into the next accumulator backing.

Streaming multi-result frames use this to discard their five-byte header while preserving the payload as a view of the previous backing store.

Implementation

Uint8List takeAfterPrefix(int prefix, int count) {
  if (prefix < 0 || count < 0 || prefix + count > _length) {
    throw RangeError.range(prefix + count, 0, _length, 'prefix + count');
  }
  final old = _data;
  final consumed = prefix + count;
  final payload = Uint8List.sublistView(old, prefix, consumed);

  if (consumed == _length) {
    _data = _acquireBacking(_defaultInitialCapacity);
    _length = 0;
    if (consumed == old.length) {
      _recycleFinalizer.attach(payload, old);
    }
    return payload;
  }

  final remaining = _length - consumed;
  final nextCapacity = remaining < _defaultInitialCapacity
      ? _defaultInitialCapacity
      : remaining;
  final next = _acquireBacking(nextCapacity)
    ..setRange(0, remaining, old, consumed);
  _data = next;
  _length = remaining;
  return payload;
}