php树状结构数组

public function permissionStructure($Permissions,$Pid){
        $child=[];
        foreach ($Permissions as $key => $Permission) {
            if ($Permission['Pid']==$Pid) {
                $Permission['Child'] = $this->permissionStructure($Permissions,$Permission['ID']);
                $child[$Permission['Pid']][] = $Permission;
            }
        }
        return  $child;
    }