collapseAllInRegistry method

List<TKey>? collapseAllInRegistry(int? maxDepth, List<TKey> roots, { bool collectFlipped = false, })

Clears the expanded flag for every registered node whose depth is less than maxDepth (or for every node when maxDepth is null), then rebuilds the ancestors-expanded cache from roots.

When collectFlipped is true, returns the keys whose flag actually went from expanded to collapsed; otherwise returns null. The flag exists for the expansion-listener channel: this is the ONLY site that clears expansion in bulk, so it is the only place those keys can be observed, but the maxDepth == null case is otherwise a single fillRange and must stay that way when nobody is subscribed.

The returned set is wider than the caller's own "collapse these roots" list: it includes interior nodes and expansion recorded under collapsed ancestors, which is exactly what a listener persisting expansion state needs to hear about.

Implementation

List<TKey>? collapseAllInRegistry(
  int? maxDepth,
  List<TKey> roots, {
  bool collectFlipped = false,
}) {
  final List<TKey>? flipped = collectFlipped ? <TKey>[] : null;
  if (maxDepth == null) {
    if (flipped != null) {
      final n = nids.length;
      for (int nid = 0; nid < n; nid++) {
        if (nids.isFree(nid)) continue;
        if (_expandedByNid[nid] == 0) continue;
        flipped.add(nids.keyOfUnchecked(nid));
      }
    }
    _expandedByNid.fillRange(0, _expandedByNid.length, 0);
  } else {
    final n = nids.length;
    for (int nid = 0; nid < n; nid++) {
      if (nids.isFree(nid)) continue;
      if (_expandedByNid[nid] == 0) continue;
      if (_depthByNid[nid] < maxDepth) {
        _expandedByNid[nid] = 0;
        flipped?.add(nids.keyOfUnchecked(nid));
      }
    }
  }
  rebuildAllAncestorsExpanded(roots);
  return flipped;
}