Function getFirstNativeNodeForI18nNode

packages/core/src/hydration/i18n.ts:296–316

* Helper function to get the first native node to begin hydrating * the given i18n node.

(lView: LView, node: I18nNode)

 * the given i18n node.
 */
function getFirstNativeNodeForI18nNode(lView: LView, node: I18nNode) {
  const tView = lView[TVIEW];
  const maybeTNode = tView.data[node.index];

  if (isTNodeShape(maybeTNode)) {
    // If the node is backed by an actual TNode, we can simply delegate.
    return getFirstNativeNode(lView, maybeTNode);
  } else if (node.kind === I18nNodeKind.ICU) {
    // A nested ICU container won't have an actual TNode. In that case, we can use
    // an iterator to find the first child.
    const icuIterator = createIcuIterator(maybeTNode as TIcu, lView);
    let rNode: RNode | null = icuIterator();

    // If the ICU container has no nodes, then we use the ICU anchor as the node.
    return rNode ?? unwrapRNode(lView[node.index]);
  } else {
    // Otherwise, the node is a text or trivial element in an ICU container,
    // and we can just use the RNode directly.
    return unwrapRNode(lView[node.index]) ?? null;
  }
}

/**
 * Describes shared data available during the hydration process.