add method

@override bool add(E e)

Adds the element e to this, and returns whether the element was added or not. If the element already exists in the collection, it isn't added.

Implementation

@override
bool add(E e) {
  final elementPriority = _mappingFunction(e);
  final innerSet = _backingSet.putIfAbsent(elementPriority, () => <E>{});
  final added = innerSet.add(e);
  if (added) {
    _length++;
    _validReverseCache = false;
  }
  return added;
}