replaceRange method

  1. @override
void replaceRange(
  1. int start,
  2. int end,
  3. Iterable<E> replacements
)
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 ≤ start ≤ end ≤ length. 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<E> replacements) {
  final oldLength = end - start;

  final iter = replacements.iterator;

  bool needNotify = false;
  int i = 0;

  while (i < oldLength && iter.moveNext()) {
    if (peek[start + i] != iter.current) {
      needNotify = true;
      break;
    }
    i++;
  }

  if (!needNotify && i < oldLength) {
    needNotify = true;
  }

  if (!needNotify && iter.moveNext()) {
    needNotify = true;
  }

  peek.replaceRange(start, end, replacements);

  if (needNotify) notify(true);
}