transform method

Implementation

@override
ResultWithVariables transform(value) {
  // _log.fine("group transfer $value");
  // _log.fine("group transfers $_transformers");
  if (value is List && mapList) {
    final results =
        value.map((v) => Transformer.transformMultiple(transformers, v));
    return ResultWithVariables(
        result: results
            .where((v) => v.result != null)
            .map((v) => v.result)
            .toList(),
        variables: results
            .map((v) => v.variables)
            .toList()
            .fold({}, (prev, next) => {...prev, ...next}));
  } else {
    return Transformer.transformMultiple(transformers, value);
  }
}