sliver_tree/_bulk_animator library

Internal: bulk animation source for TreeController.

Owns the single shared AnimationGroup used by expandAll / collapseAll. One AnimationController drives every member proportionally — bulk semantics, not per-node.

Maintains a per-nid mirror _isMemberByNid so render-layer hot paths can do O(1) membership checks via isMemberNid without HashMap probes. Generation counter _generation bumps on every membership change so downstream caches (the render-layer prefix sums, the coordinator's BulkAnimationData snapshot) can validate freshness in O(1).

Classes

BulkAnimator<TKey>