protected function processValue($value)
 {
     if ($value === 'true()') {
         $this->pushToken(Token::T_TRUE, $value);
         $this->moveCursor($value);
     } elseif ($value === 'false()') {
         $this->pushToken(Token::T_FALSE, $value);
         $this->moveCursor($value);
     } elseif ($value === 'null()') {
         $this->pushToken(Token::T_NULL, $value);
         $this->moveCursor($value);
     } elseif ($value === 'empty()') {
         $this->pushToken(Token::T_EMPTY, $value);
         $this->moveCursor($value);
     } elseif ($value === 'true' || $value === 'false' || $value === 'null') {
         $this->pushToken(Token::T_STRING, $value);
         $this->moveCursor($value);
     } else {
         parent::processValue($value);
     }
 }