splitBeforeIndexed method

Iterable<List<T>> splitBeforeIndexed(
  1. bool test(
    1. int index,
    2. T element
    )
)

Splits the elements into chunks before some elements and indices.

Each element and index except the first is checked using test for whether it should start a new chunk. If so, the elements since the previous chunk-starting element are emitted as a list. Any remaining elements are emitted at the end.

Example:

var parts = [1, 0, 2, 1, 5, 7, 6, 8, 9]
    .splitBeforeIndexed((i, v) => i < v);
print(parts); // ([1], [0, 2], [1, 5, 7], [6, 8, 9])

Implementation

Iterable<List<T>> splitBeforeIndexed(
    bool Function(int index, T element) test) sync* {
  var iterator = this.iterator;
  if (!iterator.moveNext()) {
    return;
  }
  var index = 1;
  var chunk = [iterator.current];
  while (iterator.moveNext()) {
    var element = iterator.current;
    if (test(index++, element)) {
      yield chunk;
      chunk = [];
    }
    chunk.add(element);
  }
  yield chunk;
}