convertFuelEconomy function

double convertFuelEconomy(FuelEconomy from, FuelEconomy to, double value)

Convert Fuel economy. It may lose some decimals in the proccess.

from, to and value can NOT be null, otherwise an AssertionError is thrown

Basic usage:

main() {
 final fuel = convertFuelEconomy(
   FuelEconomy.kilometerPerLitre, // from
   FuelEconomy.milePerUsGallon, // to
   1, // value
 );
 print(fuel); // 2,35215
}

Read the documentation for more information

Implementation

double convertFuelEconomy(
  FuelEconomy from,
  FuelEconomy to,
  double value,
) {
  verify(from, to, value);
  if (from == to) return value;
  if (from == FuelEconomy.kilometerPerLitre) {
    switch (to) {
      case FuelEconomy.literPer100Kilometres:
        return value * 100;
      case FuelEconomy.milePerUsGallon:
        return value * 2.352;
      case FuelEconomy.milePerImperialGallon:
        return value * 2.825;
      default:
        return value;
    }
  } else {
    // always convert to liter per liter
    // to convert to the needed value
    // may lost a few decimals in the proccess
    final litre = FuelEconomy.kilometerPerLitre;
    switch (from) {
      case FuelEconomy.literPer100Kilometres:
        return convertFuelEconomy(litre, to, value / 100);
      case FuelEconomy.milePerUsGallon:
        return convertFuelEconomy(litre, to, value / 2.352);
      case FuelEconomy.milePerImperialGallon:
        return convertFuelEconomy(litre, to, value / 2.825);
      default:
        return value;
    }
  }
}