convert method

@override String convert(List items)

Converts input and returns the result of the conversion.

Implementation

@override
String convert(List<dynamic> items) {
  final result = StringBuffer();
  for (final dynamic item_ in items) {
    dynamic item = item_;
    if (item is! List) {
      item = item.toCsv();
      if (item is! List) {
        throw Exception(
          'Expecting $item to be a List or have toCsv() function that returns List',
        );
      }
    }
    for (int i = 0; i < item.length; i++) {
      dynamic cell = item[i];
      if (cell is! String) {
        cell = '$cell';
      }
      if (cell.isEmpty) {
        // do nothing
      } else {
        int index = 0;
        bool needsEscaping = cell[0] == '"';
        while (!needsEscaping && index < cell.length) {
          final current = cell[index++];
          needsEscaping = switch (current) {
            ',' => true,
            '\n' => true,
            _ => false,
          };
        }
        if (needsEscaping) {
          result.write('"');
          for (int i = 0; i < cell.length; i++) {
            result.write(switch (cell[i]) {
              '"' => '""',
              final symbol => symbol,
            });
          }
          result.write('"');
        } else {
          result.write(cell);
        }
      }
      if (i == item.length - 1) {
        result.write('\r\n');
      } else {
        result.write(',');
      }
    }
  }
  return result.toString();
}