replaceRange method Null safety

  1. @override
void replaceRange(
  1. int start,
  2. int end,
  3. Iterable<T> newContents
)
override

Replaces a range of elements with the elements of replacements.

Removes the objects in the range from start to end, then inserts the elements of replacements at start.

final numbers = <int>[1, 2, 3, 4, 5];
final replacements = [6, 7];
numbers.replaceRange(1, 4, replacements);
print(numbers); // [1, 6, 7, 5]

The provided range, given by start and end, must be valid. A range from start to end is valid if 0 ≤ startendlength. An empty range (with end == start) is valid.

The operation list.replaceRange(start, end, replacements) is roughly equivalent to:

final numbers = <int>[1, 2, 3, 4, 5];
numbers.removeRange(1, 4);
final replacements = [6, 7];
numbers.insertAll(1, replacements);
print(numbers); // [1, 6, 7, 5]

but may be more efficient.

The list must be growable. This method does not work on fixed-length lists, even when replacements has the same number of elements as the replaced range. In that case use setRange instead.

Implementation

@override
void replaceRange(int start, int end, Iterable<T> newContents) {
  _context.conditionallyRunInAction(() {
    if (end > start || newContents.isNotEmpty) {
      final oldContents = _list.sublist(start, end);
      _list.replaceRange(start, end, newContents);
      _notifyRangeUpdate(
          start, newContents.toList(growable: false), oldContents);
    }
  }, _atom);
}