protected function compileExpression(Node $node)
    {

        $code = $node->escaped ? 'htmlentities(%s, \\ENT_QUOTES, \''.$this->options['escape_charset'].'\')' : '%s';

        $value = rtrim(trim($node->value), ';');

        if ($this->isVariable($value) && !$node->unchecked)
            $value = "isset({$value}) ? {$value} : ''";

        return $this->createShortCode(sprintf($code, $value));
    }