private function beginBracket($op) {
        $this->currentWhere[] = [$op => []];
        $this->whereStack[] = &$this->currentWhere;
        end($this->currentWhere);
        $this->currentWhere = &$this->currentWhere[key($this->currentWhere)][$op];

        return $this;
    }
private function beginBracket($op) {
        $this->currentWhere[] = [$op => []];
        $this->whereStack[] = &$this->currentWhere;
        end($this->currentWhere);
        $this->currentWhere = &$this->currentWhere[key($this->currentWhere)][$op];

        return $this;
    }
private function beginBracket ( $ op ) { $ this -> currentWhere [ ] = [ $ op => [ ] ] ; $ this -> whereStack [ ] = & $ this -> currentWhere ; end ( $ this -> currentWhere ) ; $ this -> currentWhere = & $ this -> currentWhere [ key ( $ this -> currentWhere ) ] [ $ op ] ; return $ this ; }
Begin a bracket group in the WHERE clause.

@param string $op One of the **DB::OP_*** constants.
@return $this
Begin a bracket group in the WHERE clause .