如何获取角色节点

如何获取"Blog-Autor"-Role和"Kommentar-Manager"-Role的角色节点?

或者是否有一种方法可以更动态地使用角色节点?

我的XML:

<roles>
    <role role="Administrator">
        <role role="Account Manager">
            <role role="Blog-Autor"/>
            <role role="Kommentar-Manager"/>
        </role>
    </role>
</roles>

和我的php代码，我通过从上面的XML:(在output_roles-function中，$roles变量只是第一个子变量，但我需要两个子变量)(->children()没有帮助)

public function User_Roles() {
        $User_Type = $_SESSION["User_Type"];
        $xml_path = "./blog_config/blog_roles.xml";
        $xml_file = simplexml_load_file($xml_path);
        foreach ($xml_file->role as $role) {
            $role_attributes = $role->attributes();
            $user_role = (string) $role_attributes->role;
            if ($user_role == $User_Type) {
                $this->output_roles($role);
            }
        }
    }
private function output_roles($role) {
    foreach ($role as $current_role) {
        $role_ = $current_role->attributes();
        $role_type = (string) $role_->role;
        echo "<tr>";
        echo "<td><b>" . $role_type . "</b></td>";
        echo "</tr>";
        $roles = $role->role;
        $x = is_array($roles);
        if (is_array($current_role->role)) {
            $this->output_roles($current_role->role);
        }
    }
}