runningReduceIndexed<S> method

KtList<S> runningReduceIndexed<S>(
  1. S operation(
    1. int index,
    2. S acc,
    3. T
    )
)

Returns a list containing successive accumulation values generated by applying operation from left to right to each element, its index in the original collection and current accumulator value that starts with the first element of this collection.

Implementation

KtList<S> runningReduceIndexed<S>(S Function(int index, S acc, T) operation) {
  final i = iterator();
  if (!i.hasNext()) {
    return emptyList();
  }
  S accumulator = i.next() as S;
  final result = mutableListOf<S>()..add(accumulator);
  int index = 1;
  while (i.hasNext()) {
    accumulator = operation(index++, accumulator, i.next());
    result.add(accumulator);
  }
  return result;
}