retainWhere method

@override void retainWhere(bool test(T value))

Removes all elements of this set that fail to satisfy test.

final characters = <String>{'A', 'B', 'C'};
characters.retainWhere(
    (element) => element.startsWith('B') || element.startsWith('C'));
print(characters); // {B, C}

Implementation

@override
void retainWhere(bool Function(T element) test) {
  final copy = {..._internalSet};
  final initialLength = copy.length;
  copy.retainWhere(test);
  if (copy.length != initialLength) {
    _emitSet(copy);
  }
}