Function prepareI18nBlockForHydrationImpl

packages/core/src/hydration/i18n.ts:406–472

(
  lView: LView,
  index: number,
  parentTNode: TNode | null,
  subTemplateIndex: number,
)

}

function prepareI18nBlockForHydrationImpl(
  lView: LView,
  index: number,
  parentTNode: TNode | null,
  subTemplateIndex: number,
) {
  const hydrationInfo = lView[HYDRATION];
  if (!hydrationInfo) {
    return;
  }

  if (
    !isI18nHydrationSupportEnabled() ||
    (parentTNode &&
      (isI18nInSkipHydrationBlock(parentTNode) ||
        isDisconnectedNode(hydrationInfo, parentTNode.index - HEADER_OFFSET)))
  ) {
    return;
  }

  const tView = lView[TVIEW];
  const tI18n = tView.data[index] as TI18n;
  ngDevMode &&
    assertDefined(tI18n, 'Expected i18n data to be present in a given TView slot during hydration');

  function findHydrationRoot() {
    if (isRootTemplateMessage(subTemplateIndex)) {
      // This is the root of an i18n block. In this case, our hydration root will
      // depend on where our parent TNode (i.e. the block with i18n applied) is
      // in the DOM.
      ngDevMode && assertDefined(parentTNode, 'Expected parent TNode while hydrating i18n root');
      const rootNode = locateNextRNode(hydrationInfo!, tView, lView, parentTNode!) as Node;

      // If this i18n block is attached to an <ng-container>, then we want to begin
      // hydrating directly with the RNode. Otherwise, for a TNode with a physical DOM
      // element, we want to recurse into the first child and begin there.
      return parentTNode!.type & TNodeType.ElementContainer ? rootNode : rootNode.firstChild;
    }

    // This is a nested template in an i18n block. In this case, the entire view
    // is translated, and part of a dehydrated view in a container. This means that
    // we can simply begin hydration with the first dehydrated child.
    return hydrationInfo?.firstChild as Node;
  }

  const currentNode = findHydrationRoot();
  ngDevMode && assertDefined(currentNode, 'Expected root i18n node during hydration');

  const disconnectedNodes = initDisconnectedNodes(hydrationInfo) ?? new Set();
  const i18nNodes = (hydrationInfo.i18nNodes ??= new Map<number, RNode | null>());
  const caseQueue = hydrationInfo.data[I18N_DATA]?.[index - HEADER_OFFSET] ?? [];
  const dehydratedIcuData = (hydrationInfo.dehydratedIcuData ??= new Map<
    number,
    DehydratedIcuData
  >());

  collectI18nNodesFromDom(
    {hydrationInfo, lView, i18nNodes, disconnectedNodes, caseQueue, dehydratedIcuData},