Function replaceLViewInTree

packages/core/src/render3/hmr.ts:355–389

* Replaces one LView in the tree with another one. * @param parentLView Parent of the LView being replaced. * @param oldLView LView being replaced. * @param newLView Replacement LView to be inserted. * @param index Index at which the LView should be inserted.

(
  parentLView: LView,
  oldLView: LView,
  newLView: LView,
  index: number,
)

 * @param index Index at which the LView should be inserted.
 */
function replaceLViewInTree(
  parentLView: LView,
  oldLView: LView,
  newLView: LView,
  index: number,
): void {
  // Update the sibling whose `NEXT` pointer refers to the old view.
  for (let i = HEADER_OFFSET; i < parentLView[TVIEW].bindingStartIndex; i++) {
    const current = parentLView[i];

    if ((isLView(current) || isLContainer(current)) && current[NEXT] === oldLView) {
      current[NEXT] = newLView;
      break;
    }
  }

  // Set the new view as the head, if the old view was first.
  if (parentLView[CHILD_HEAD] === oldLView) {
    parentLView[CHILD_HEAD] = newLView;
  }

  // Set the new view as the tail, if the old view was last.
  if (parentLView[CHILD_TAIL] === oldLView) {
    parentLView[CHILD_TAIL] = newLView;
  }

  // Update the `NEXT` pointer to the same as the old view.
  newLView[NEXT] = oldLView[NEXT];

  // Clear out the `NEXT` of the old view.
  oldLView[NEXT] = null;

  // Insert the new LView at the correct index.
  parentLView[index] = newLView;
}

/**
 * Child nodes mutate the `projection` state of their parent node as they're being projected.