convert method

@override Iterable<bool> convert(String data)

Implementation

@override
Iterable<bool> convert(String data) sync* {
  if (data.length <= 8) {
    data = upceToUpca(data);
  }

  data = checkLength(data, maxLength);
  final int first = data.codeUnitAt(0);
  final int last = data.codeUnitAt(11);

  try {
    data = upcaToUpce(data);
  } on BarcodeException {
    if (fallback) {
      yield* const BarcodeUpcA().convert(data);
      return;
    }
    rethrow;
  }

  yield* add(BarcodeMaps.eanStartEnd, 3);

  final int? parityRow = BarcodeMaps.upce[last];
  final int? parity = first == 0x30 ? parityRow : parityRow! ^ 0x3f;

  int index = 0;
  for (final int code in data.codeUnits) {
    final List<int>? codes = BarcodeMaps.ean[code];

    if (codes == null) {
      throw BarcodeException('Unable to encode "${String.fromCharCode(code)}" to $name Barcode');
    }

    yield* add(codes[(parity! >> index) & 1 == 0 ? 1 : 0], 7);
    index++;
  }

  yield* add(BarcodeMaps.eanEndUpcE, 6);
}