parentOf method
TKey?
parentOf(
- TKey key
Parent key for key, or null for roots / unregistered keys.
The parent nid slot can be null when the parent has already been freed ahead of this node in a removal sweep, so the reverse lookup must tolerate a null result.
Implementation
TKey? parentOf(TKey key) {
final pNid = parentNidOf(key);
return pNid == kNoParentNid ? null : nids.keyOf(pNid);
}