lessc_parser::guard PHP Method

    protected function guard(&$guard)
    {
        $s = $this->seek();
        $negate = $this->literal("not");
        if ($this->literal("(") && $this->expression($exp) && $this->literal(")")) {
            $guard = $exp;
            if ($negate) {
                $guard = array("negate", $guard);
            }
            return true;
        }
        $this->seek($s);
        return false;
    }