Method _getRenderData

src/cdk/tree/tree.ts:402–428

Given an Observable containing a stream of the raw data, returns an Observable containing the RenderingData

(dataStream: Observable<readonly T[]>)

  /** Given an Observable containing a stream of the raw data, returns an Observable containing the RenderingData */
  private _getRenderData(dataStream: Observable<readonly T[]>): Observable<RenderingData<T>> {
    const expansionModel = this._getExpansionModel();
    return combineLatest([
      dataStream,
      this._nodeType,
      // We don't use the expansion data directly, however we add it here to essentially
      // trigger data rendering when expansion changes occur.
      expansionModel.changed.pipe(
        startWith(null),
        tap(expansionChanges => {
          this._emitExpansionChanges(expansionChanges);
        }),
      ),
    ]).pipe(
      switchMap(([data, nodeType]) => {
        if (nodeType === null) {
          return observableOf({renderNodes: data, flattenedNodes: null, nodeType} as const);
        }

        // If we're here, then we know what our node type is, and therefore can
        // perform our usual rendering pipeline, which necessitates converting the data
        return this._computeRenderingData(data, nodeType).pipe(
          map(convertedData => ({...convertedData, nodeType}) as const),
        );
      }),
    );
  }

  private _renderDataChanges(data: RenderingData<T>) {
    if (data.nodeType === null) {