Function materializeViewResults

packages/core/src/render3/queries/query.ts:388–416

* A helper function that creates query results for a given view. This function is meant to do the * processing once and only once for a given view instance (a set of results for a given view * doesn't change).

(
  tView: TView,
  lView: LView,
  tQuery: TQuery,
  queryIndex: number,
)

 * doesn't change).
 */
function materializeViewResults<T>(
  tView: TView,
  lView: LView,
  tQuery: TQuery,
  queryIndex: number,
): T[] {
  const lQuery = lView[QUERIES]!.queries![queryIndex];
  if (lQuery.matches === null) {
    const tViewData = tView.data;
    const tQueryMatches = tQuery.matches;
    const result: Array<T | null> = [];
    for (let i = 0; tQueryMatches !== null && i < tQueryMatches.length; i += 2) {
      const matchedNodeIdx = tQueryMatches[i];
      if (matchedNodeIdx < 0) {
        // we at the <ng-template> marker which might have results in views created based on this
        // <ng-template> - those results will be in separate views though, so here we just leave
        // null as a placeholder
        result.push(null);
      } else {
        ngDevMode && assertIndexInRange(tViewData, matchedNodeIdx);
        const tNode = tViewData[matchedNodeIdx] as TNode;
        result.push(createResultForNode(lView, tNode, tQueryMatches[i + 1], tQuery.metadata.read));
      }
    }
    lQuery.matches = result;
  }

  return lQuery.matches;
}

/**
 * A helper function that collects (already materialized) query results from a tree of views,