reorderRoots method

void reorderRoots(List<TKey> orderedKeys)

Reorders the root nodes to match orderedKeys.

orderedKeys must contain exactly the current live (non-pending-deletion) root keys. Expansion state, animation state, and measured extents are preserved. Pending-deletion roots are appended after the live roots.

Implementation

void reorderRoots(List<TKey> orderedKeys) {
  final pendingRoots = <TKey>[];
  final liveRootSet = <TKey>{};
  for (final k in _roots) {
    if (_isPendingDeletion(k)) {
      pendingRoots.add(k);
    } else {
      liveRootSet.add(k);
    }
  }
  // Validate in all build modes: an `assert` here would be stripped in
  // release and silently corrupt `_roots` (duplicated entries, lost subtrees,
  // references to unknown keys).
  if (orderedKeys.length != liveRootSet.length ||
      orderedKeys.toSet().length != orderedKeys.length ||
      !liveRootSet.containsAll(orderedKeys)) {
    throw ArgumentError.value(
      orderedKeys,
      "orderedKeys",
      "must contain exactly the current live root keys with no duplicates",
    );
  }

  _roots
    ..clear()
    ..addAll(orderedKeys)
    ..addAll(pendingRoots);
  _markVisibleOrderDirty();
  // Pure reorder: positions change but no row's builder output does
  // (nodeBuilder signature takes (context, key, depth) — no index). The
  // sliver's layout repositions elements in place.
  _notifyStructural(affectedKeys: const {});
}