main.dart

class ThemeMapper<T> {
  ThemeMapper(this.callback);

  final T Function(T value) callback;

  T invoke(T defaultValue) {
    return callback(defaultValue);
  }
}

class ThemeDataMapper {
  final Map<Type, ThemeMapper<Object?>> map_ = {};

  void addAdaptive<T>(T Function(T value) callback) {
    map_[T] = ThemeMapper<T>(callback);
  }

  T makeAdaptive<T>(T defaultValue) {
    var mapper = map_[T];
    if (mapper == null) {
      return defaultValue;
    }
    return (mapper as ThemeMapper<T>).invoke(defaultValue);
  }
}

class SwitchThemeData {
  const SwitchThemeData(this.value);

  final int value;
}

void main() {
  var themeMapper = ThemeDataMapper();
  themeMapper.addAdaptive((SwitchThemeData data) {
    return SwitchThemeData(data.value + 1);
  });

  var switchTheme = SwitchThemeData(0);

  var adaptive = themeMapper.makeAdaptive(switchTheme);
  print(adaptive.value);
}