Method _emitExpansionChanges

src/cdk/tree/tree.ts:443–457

(expansionChanges: SelectionChange<K> | null)

  }

  private _emitExpansionChanges(expansionChanges: SelectionChange<K> | null) {
    if (!expansionChanges) {
      return;
    }

    const nodes = this._nodes.value;
    for (const added of expansionChanges.added) {
      const node = nodes.get(added);
      node?._emitExpansionState(true);
    }
    for (const removed of expansionChanges.removed) {
      const node = nodes.get(removed);
      node?._emitExpansionState(false);
    }
  }

  private _initializeKeyManager() {
    const items = combineLatest([this._keyManagerNodes, this._nodes]).pipe(