Current.php

<?php

/**
 * @file
 * Definition of views_handler_filter_user_current.
 */

namespace Drupal\user\Plugin\views\filter;

use Drupal\views\Plugin\views\display\DisplayPluginBase;
use Drupal\views\ViewExecutable;
use Drupal\views\Plugin\views\filter\BooleanOperator;

/**
 * Filter handler for the current user.
 *
 * @ingroup views_filter_handlers
 *
 * @PluginID("user_current")
 */
class Current extends BooleanOperator {

  /**
   * Overrides Drupal\views\Plugin\views\filter\BooleanOperator::init().
   */
  public function init(ViewExecutable $view, DisplayPluginBase $display, array &$options = NULL) {
    parent::init($view, $display, $options);

    $this->value_value = t('Is the logged in user');
  }

  public function query() {
    $this->ensureMyTable();

    $field = $this->tableAlias . '.' . $this->realField . ' ';
    $or = db_or();

    if (empty($this->value)) {
      $or->condition($field, '***CURRENT_USER***', '<>');
      if ($this->accept_null) {
        $or->isNull($field);
      }
    }
    else {
      $or->condition($field, '***CURRENT_USER***', '=');
    }
    $this->query->addWhere($this->options['group'], $or);
  }

}