dedup

main.dart

void dedup<T>(List<T> list, {removeLast: true}) {
  int shift = removeLast ? 1 : 0;
  T compareItem;
  for (int i = list.length - 1; i >= 0; i--) {
    if (compareItem == (compareItem = list[i])) {
      list.removeAt(i + shift);
    }
  }
}

void dedupBy<T, I>(List<T> list, I Function(T) compare, {removeLast: true}) {
  int shift = removeLast ? 1 : 0;
  I compareItem;
  for (int i = list.length - 1; i >= 0; i--) {
    if (compareItem == (compareItem = compare(list[i]))) {
      list.removeAt(i + shift);
    }
  }
}

void main() {
  List<List<int>> list = [[1], [1], [2, 1], [2, 2]];
  print('$list');
  dedupBy(list, (innerList) => innerList[0]);
  print('$list');

  print('\n removeLast: false \n');

  List<List<int>> list2 = [[1], [1], [2, 1], [2, 2]];
  print('$list2');
  dedupBy(list2, (innerList) => innerList[0], removeLast: false);
  print('$list2');
}