/**
  * 获得树状数据
  * @param $data 数据
  * @param $title    数据库中字段名
  * @param string $fieldPri  数据库中主键id
  * @param string $fieldPid  数据库中父id
  * @return array
  */
 static public function tree($data, $title, $fieldPri = 'cid', $fieldPid = 'pid')
 {
  if (!is_array($data) || empty($data))
   return array();
  $arr = Data::channelList($data);
  foreach ($arr as $k => $v) {
   $str = "";
   if ($v['_level'] > 2) {
    for ($i = 1; $i < $v['_level'] - 1; $i++) {
     $str .= "│ ";
    }
   }
   if ($v['_level'] != 1) {
    $t = $title ? $v[$title] : "";
    if (isset($arr[$k + 1]) && $arr[$k + 1]['_level'] >= $arr[$k]['_level']) {
     $arr[$k]['_name'] = $str . "├─ " . $v['_html'] . $t;
    } else {
     $arr[$k]['_name'] = $str . "└─ " . $v['_html'] . $t;
    }
   } else {
    $arr[$k]['_name'] = $v[$title];
   }
  }
  //设置主键为$fieldPri
  $data = array();
  foreach ($arr as $d) {
   $data[$d[$fieldPri]] = $d;
  }
  return $data;
 }

/**
  * 获得所有子栏目
  * @param $data 栏目数据
  * @param int $pid 操作的栏目
  * @param string $html 栏目名前字符
  * @param string $fieldPri 表主键
  * @param string $fieldPid 父id
  * @param int $level 等级
  * @return array
  */
 static public function channelList($data, $pid = 0, $html = " ", $fieldPri = 'cid', $fieldPid = 'pid', $level = 1)
 {
  $data = self::_channelList($data, $pid, $html, $fieldPri, $fieldPid, $level);
  if (empty($data))
   return $data;
 
  foreach ($data as $n => $m) {
   if ($m['_level'] == 1)
    continue;//结束单次循环
   $data[$n]['_first'] = false;
   $data[$n]['_end'] = false;
   if (!isset($data[$n - 1]) || $data[$n - 1]['_level'] != $m['_level']) {
    $data[$n]['_first'] = true; 
   }
   if (isset($data[$n + 1]) && $data[$n]['_level'] > $data[$n + 1]['_level']) {
    $data[$n]['_end'] = true;
   }
  }
  //更新key为栏目主键
  $category=array();
  foreach($data as $d){
   $category[$d[$fieldPri]]=$d;
  }
  return $category;
 }

//只供channelList方法使用
 
 /**
  * 获得所有子栏目
  * @param $data 栏目数据
  * @param int $pid 操作的栏目
  * @param string $html 栏目名前字符
  * @param string $fieldPri 表主键
  * @param string $fieldPid 父id
  * @param int $level 等级
  * @return array
  */
 static private function _channelList($data, $pid = 0, $html = " ", $fieldPri = 'cid', $fieldPid = 'pid', $level = 1)
 {
  if (empty($data))
   return array();
  $arr = array();
 
  foreach ($data as $v) {
   $id = $v[$fieldPri];
   if ($v[$fieldPid] == $pid) {
    $v['_level'] = $level;
    $v['_html'] = str_repeat($html, $level - 1);
    $arr[] = $v;
 
    $tmp = self::_channelList($data, $id, $html, $fieldPri, $fieldPid, $level + 1);
    $arr = array_merge($arr, $tmp);//array_merge把两个数组整合为一个数组
   }
  }
  return $arr;
 }