Function getParentBlockHydrationQueue

packages/core/src/hydration/utils.ts:600–631

(
  deferBlockId: string,
  injector: Injector,
)

 * Note: This is utilizing serialized information to navigate up the tree
 */
export function getParentBlockHydrationQueue(
  deferBlockId: string,
  injector: Injector,
): {parentBlockPromise: Promise<void> | null; hydrationQueue: string[]} {
  const dehydratedBlockRegistry = injector.get(DEHYDRATED_BLOCK_REGISTRY);
  const transferState = injector.get(TransferState);
  const deferBlockParents = transferState.get(NGH_DEFER_BLOCKS_KEY, {});

  let isTopMostDeferBlock = false;
  let currentBlockId: string | undefined = deferBlockId;
  let parentBlockPromise: Promise<void> | null = null;
  const hydrationQueue: string[] = [];

  while (!isTopMostDeferBlock && currentBlockId) {
    ngDevMode &&
      assertEqual(
        hydrationQueue.indexOf(currentBlockId),
        -1,
        'Internal error: defer block hierarchy has a cycle.',
      );

    isTopMostDeferBlock = dehydratedBlockRegistry.has(currentBlockId);
    const hydratingParentBlock = dehydratedBlockRegistry.hydrating.get(currentBlockId);
    if (parentBlockPromise === null && hydratingParentBlock != null) {
      parentBlockPromise = hydratingParentBlock.promise;
      break;
    }
    hydrationQueue.unshift(currentBlockId);
    currentBlockId = deferBlockParents[currentBlockId][DEFER_PARENT_BLOCK_ID];
  }
  return {parentBlockPromise, hydrationQueue};
}

function gatherDeferBlocksByJSActionAttribute(doc: Document): Set<HTMLElement> {
  const jsactionNodes = doc.body.querySelectorAll('[jsaction]');