TYPO3 / TYPO3.CMS

        // Evaluate regularly indexed pages based on item_type:

        // External media:

        $connection = GeneralUtility::makeInstance(ConnectionPool::class)->getConnectionForTable('index_grlist');

        if ($row['item_type']) {

            // For external media we will check the access of the parent page on which the media was linked from.

            // "phash_t3" is the phash of the parent TYPO3 page row which initiated the indexing of the documents

            // in this section. So, selecting for the grlist records belonging to the parent phash-row where the

            // current users gr_list exists will help us to know. If this is NOT found, there is still a theoretical

            // possibility that another user accessible page would display a link, so maybe the resume of such a

            // document here may be unjustified hidden. But better safe than sorry.

            if (!$this->isTableUsed('index_grlist')) {

                return false;

            }

            return (bool)$connection->count(

                'phash',

                'index_grlist',

                [

                    'phash' => (int)$row['phash_t3'],

                    'gr_list' => $this->frontendUserGroupList

                ]

            );

        }

        // Ordinary TYPO3 pages:

        if ((string)$row['gr_list'] !== (string)$this->frontendUserGroupList) {

            // Selecting for the grlist records belonging to the phash-row where the current users gr_list exists.

            );

        }

        // Ordinary TYPO3 pages:

        if ((string)$row['gr_list'] !== (string)$this->frontendUserGroupList) {

            // Selecting for the grlist records belonging to the phash-row where the current users gr_list exists.

            // If it is found it is proof that this user has direct access to the phash-rows content although

            // he did not himself initiate the indexing...

            if (!$this->isTableUsed('index_grlist')) {

                return false;

            }

            return (bool)$connection->count(

                    'phash',

                    'index_grlist',

                    [

                        'phash' => (int)$row['phash'],

                        'gr_list' => $this->frontendUserGroupList

                    ]

                );

        }

        return true;

    }