Function deferBlockFinder

packages/core/src/render3/util/control_flow.ts:68–158

({
  node,
  lView,
  tView,
  slotIdx,
}: ControlFlowBlockViewFinderConfig)

 * @returns
 */
const deferBlockFinder: ControlFlowBlockViewFinder = ({
  node,
  lView,
  tView,
  slotIdx,
}: ControlFlowBlockViewFinderConfig) => {
  const slot = lView[slotIdx];
  if (!isLContainer(slot)) {
    return null;
  }

  const lContainer = slot;

  // An LContainer may represent an instance of a defer block, in which case
  // we store it as a result. Otherwise, keep iterating over LContainer views and
  // look for defer blocks.
  const isLast = slotIdx === tView.bindingStartIndex - 1;

  if (!isLast) {
    const tNode = tView.data[slotIdx] as TNode;
    const tDetails = getTDeferBlockDetails(tView, tNode);

    if (isTDeferBlockDetails(tDetails)) {
      const native = getNativeByTNode(tNode, lView);
      const lDetails = getLDeferBlockDetails(lView, tNode);

      // The LView from `getLContext` might be the view the element is placed in.
      // Filter out defer blocks that aren't inside the specified root node.
      if (!node.contains(native as Node)) {
        return null;
      }

      const viewInjector = lView[INJECTOR];
      const registry = viewInjector.get(DEHYDRATED_BLOCK_REGISTRY, null, {optional: true});

      const renderedLView = getRendererLView(lContainer);
      const rootNodes: Node[] = [];
      const hydrationState = inferHydrationState(tDetails, lDetails, registry);

      if (renderedLView !== null) {
        collectNativeNodes(
          renderedLView[TVIEW],
          renderedLView,
          renderedLView[TVIEW].firstChild,
          rootNodes,
        );
      } else if (hydrationState === 'dehydrated') {
        // We'll find the number of root nodes in the transfer state and
        // collect that number of elements that precede the defer block comment node.

        const transferState = viewInjector.get(TransferState);
        const deferBlockParents = transferState.get(NGH_DEFER_BLOCKS_KEY, {});

        const deferId = lDetails[SSR_UNIQUE_ID]!;
        const deferData = deferBlockParents[deferId];
        const numberOfRootNodes = deferData[NUM_ROOT_NODES];

        let collectedNodeCount = 0;