Function getTriggerLView

packages/core/src/defer/dom_triggers.ts:66–99

(
  deferredHostLView: LView,
  deferredTNode: TNode,
  walkUpTimes: number | undefined | null,
)

 *   value means that the trigger is in the same LView as the deferred block.
 */
export function getTriggerLView(
  deferredHostLView: LView,
  deferredTNode: TNode,
  walkUpTimes: number | undefined | null,
): LView | null {
  // The trigger is in the same view, we don't need to traverse.
  if (walkUpTimes == null) {
    return deferredHostLView;
  }

  // A positive value or zero means that the trigger is in a parent view.
  if (walkUpTimes >= 0) {
    return walkUpViews(walkUpTimes, deferredHostLView);
  }

  // If the value is negative, it means that the trigger is inside the placeholder.
  const deferredContainer = deferredHostLView[deferredTNode.index];
  ngDevMode && assertLContainer(deferredContainer);
  const triggerLView = deferredContainer[CONTAINER_HEADER_OFFSET] ?? null;

  // We need to null check, because the placeholder might not have been rendered yet.
  if (ngDevMode && triggerLView !== null) {
    const lDetails = getLDeferBlockDetails(deferredHostLView, deferredTNode);
    const renderedState = lDetails[DEFER_BLOCK_STATE];
    assertEqual(
      renderedState,
      DeferBlockState.Placeholder,
      'Expected a placeholder to be rendered in this defer block.',
    );
    assertLView(triggerLView);
  }

  return triggerLView;
}

/**
 * Gets the element that a deferred block's trigger is pointing to.