PHP递归生成树形数组

public function tree($table,$p_id='00000000-0000-0000-0000-000000000000') {
        $tree = array();
        foreach($table as $row){
            if($row['parent_id']==$p_id){
                $tmp = $this->tree($table,$row['id']);
                if($tmp){
                    $row['children']=$tmp;
                }else{
                    $row['leaf'] = true;
                }
                $tree[]=$row;                
            }
        }
        Return $tree;        
    }