Function getOrCreateTNode

packages/core/src/render3/tnode_manipulation.ts:102–147

(
  tView: TView,
  index: number,
  type: TNodeType,
  name: string | null,
  attrs: TAttributes | null,
)

  | TIcuContainerNode
  | TLetDeclarationNode;
export function getOrCreateTNode(
  tView: TView,
  index: number,
  type: TNodeType,
  name: string | null,
  attrs: TAttributes | null,
):
  | TElementNode
  | TContainerNode
  | TElementContainerNode
  | TProjectionNode
  | TIcuContainerNode
  | TLetDeclarationNode {
  ngDevMode &&
    index !== 0 && // 0 are bogus nodes and they are OK. See `createContainerRef` in
    // `view_engine_compatibility` for additional context.
    assertGreaterThanOrEqual(index, HEADER_OFFSET, "TNodes can't be in the LView header.");
  // Keep this function short, so that the VM will inline it.
  ngDevMode && assertPureTNodeType(type);
  let tNode = tView.data[index] as TNode;
  if (tNode === null) {
    tNode = createTNodeAtIndex(tView, index, type, name, attrs);
    if (isInI18nBlock()) {
      // If we are in i18n block then all elements should be pre declared through `Placeholder`
      // See `TNodeType.Placeholder` and `LFrame.inI18n` for more context.
      // If the `TNode` was not pre-declared than it means it was not mentioned which means it was
      // removed, so we mark it as detached.
      tNode.flags |= TNodeFlags.isDetached;
    }
  } else if (tNode.type & TNodeType.Placeholder) {
    tNode.type = type;
    tNode.value = name;
    tNode.attrs = attrs;
    const parent = getCurrentParentTNode();
    tNode.injectorIndex = parent === null ? -1 : parent.injectorIndex;
    ngDevMode && assertTNodeForTView(tNode, tView);
    ngDevMode && assertEqual(index, tNode.index, 'Expecting same index');
  }
  setCurrentTNode(tNode, true);
  return tNode as
    | TElementNode
    | TContainerNode
    | TElementContainerNode
    | TProjectionNode
    | TIcuContainerNode;
}

export function createTNodeAtIndex(
  tView: TView,