Function sortedChanges

src/compat/firestore/collection/changes.ts:53–62

(
  query: Query,
  events: DocumentChangeType[],
  scheduler?: SchedulerLike)

 * Return a stream of document changes on a query. These results are in sort order.
 */
export function sortedChanges<T>(
  query: Query,
  events: DocumentChangeType[],
  scheduler?: SchedulerLike): Observable<DocumentChangeAction<T>[]> {
  return docChanges<T>(query, scheduler)
    .pipe(
      scan((current, changes) => combineChanges<T>(current, changes.map(it => it.payload), events), []),
      distinctUntilChanged(), // cut down on unneed change cycles
      map(changes => changes.map(c => ({ type: c.type, payload: c } as DocumentChangeAction<T>))));
}

/**
 * Combines the total result set from the current set of changes from an incoming set