decodeOptions function

List<int> decodeOptions(int sum)

Decodes a summed classifier value back into individual flag values.

Returns the constituent powers-of-two in descending order.

decodeOptions(577); // → [512, 64, 1]  (October, July, January)

Implementation

List<int> decodeOptions(int sum) {
  if (sum == 0) return const [];

  final classifiers = <int>[];
  final totalOptions = sum.bitLength; // position of highest set bit

  for (int i = 1; i <= totalOptions; i++) {
    final next = 1 << (totalOptions - i);
    if (next <= sum) {
      sum -= next;
      classifiers.add(next);
    }
  }

  return classifiers;
}