mapIndexed<U> method

Iterable<U> mapIndexed<U>(
  1. U toElement(
    1. int index,
    2. E element
    )
)

类似 map，但是有当前元素的索引。

举例：

[1, 2, 3].mapIndexed((index, number) => number * 2); // [2, 4, 6]

Implementation

Iterable<U> mapIndexed<U>(U Function(int index, E element) toElement) sync* {
  final it = iterator;
  var index = 0;
  while (it.moveNext()) {
    yield toElement(index++, it.current);
  }
}