replaceRange method

Iterable<T> replaceRange(Iterable<T> source, { required int start, required int count, })

Replaces the elements in the range start (inclusive) to start + count (exclusive) with the elements from source. If the range is longer than the length of source, the elements will be repeated until the end of the range is reached.

If start is greater than the length of the iterable, or if count is zero, the iterable is unchanged. If start + count is greater than the length of the iterable, the elements from start to the end of the iterable will be replaced.

If start or count is less than zero, an RangeError is thrown.

Implementation

Iterable<T> replaceRange(
  Iterable<T> source, {
  required int start,
  required int count,
}) sync* {
  if (start < 0) {
    throw RangeError.index(
      start,
      this,
      'start',
      'The value of "start" must be greater than or equal to zero.',
    );
  }
  if (count < 0) {
    throw RangeError.index(
      count,
      this,
      'count',
      'The value of "count" must be greater than or equal to zero.',
    );
  }

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

  while (iterator.moveNext()) {
    if (i >= start && i < start + count) {
      if (!srcIterator.moveNext()) {
        srcIterator = source.iterator;
        if (!srcIterator.moveNext()) {
          throw ArgumentError('"srcIterator" must not be empty.');
        }
      }
      yield srcIterator.current;
    } else {
      yield iterator.current;
    }

    i++;
  }
}