insertOrAppend method

Iterable<T> insertOrAppend(int index, T value)

Inserts an element into the iterable at the specified index.

Takes the specified element and inserts it into the iterable at the position index.

If index is less than zero, a RangeError is thrown.

If iteration of the underlying iterable is exausted before the position index is reached, value is added to the end iterable as if calling append.

Implementation

Iterable<T> insertOrAppend(int index, T value) sync* {
  if (index == 0) {
    yield* prepend(value);
    return;
  }
  if (index < 0) {
    throw RangeError.index(
      index,
      this,
      'index',
      'The index must not be negative.',
    );
  }

  final iterator = this.iterator;
  var i = 0;

  while (iterator.moveNext()) {
    if (i == index) {
      yield value;
    }
    yield iterator.current;
    i++;
  }

  if (index >= i) {
    yield value;
  }
}