Function CreateOrNullptr

library/cpp/json/ordered_maps/json_value_ordered.cpp:883–885

    namespace {
        template <class TPtr, class T>
        TPtr* CreateOrNullptr(TPtr* p, T key, std::true_type /*create*/) {
            return &(*p)[key];
        }

        template <class TPtr, class T>
        TPtr* CreateOrNullptr(const TPtr* p, T key, std::false_type /*create*/) noexcept {