class Formula

class Formula extends ArgumentPluginBase {
  public $formula = NULL;
  
  /**
   * {@inheritdoc}
   */
  public function init(ViewExecutable $view, DisplayPluginBase $display, ?array &$options = NULL) {
    parent::init($view, $display, $options);
    if (!empty($this->definition['formula'])) {
      $this->formula = $this->definition['formula'];
    }
  }
  public function getFormula() {
    return str_replace('***table***', $this->tableAlias, $this->formula);
  }
  
  /**
   * Build the summary query based on a formula.
   */
  protected function summaryQuery() {
    $this->ensureMyTable();
    // Now that our table is secure, get our formula.
    $formula = $this->getFormula();
    // Add the field.
    $this->base_alias = $this->name_alias = $this->query
      ->addField(NULL, $formula, $this->field);
    $this->query
      ->setCountField(NULL, $formula, $this->field);
    return $this->summaryBasics(FALSE);
  }
  
  /**
   * Build the query based upon the formula.
   */
  public function query($group_by = FALSE) {
    $this->ensureMyTable();
    // Now that our table is secure, get our formula.
    $placeholder = $this->placeholder();
    $formula = $this->getFormula() . ' = ' . $placeholder;
    $placeholders = [
      $placeholder => $this->argument,
    ];
    $this->query
      ->addWhere(0, $formula, $placeholders, 'formula');
  }

}