php匹配指定标签的内容

/*** 匹配任意id的html标签内容* */function getWebTag($tag_id,$tag='div',$data=false){             $charset_pos = stripos($data,'charset');        if($charset_pos) {            if(stripos($data,'utf-8',$charset_pos)) {                $data = iconv('utf-8','utf-8',$data);            }else if(stripos($data,'gb2312',$charset_pos)) {                $data = iconv('gb2312','utf-8',$data);            }else if(stripos($data,'gbk',$charset_pos)) {                $data = iconv('gbk','utf-8',$data);            }        }               preg_match_all('/<'.$tag.'/i',$data,$pre_matches,PREG_OFFSET_CAPTURE);    //获取所有div前缀        preg_match_all('/<\/'.$tag.'/i',$data,$suf_matches,PREG_OFFSET_CAPTURE); //获取所有div后缀        $hit = strpos($data,$tag_id);        if($hit == -1) return false;    //未命中        $divs = array();    //合并所有div        foreach($pre_matches[0] as $index=>$pre_div){            $divs[(int)$pre_div[1]] = 'p';            $divs[(int)$suf_matches[0][$index][1]] = 's';           }               //对div进行排序        $sort = array_keys($divs);        asort($sort);               $count = count($pre_matches[0]);        foreach($pre_matches[0] as $index=>$pre_div){            //<div $hit <div+1    时div被命中            if(($pre_matches[0][$index][1] < $hit) && ($hit < $pre_matches[0][$index+1][1])){                $deeper = 0;                //弹出被命中div前的div                while(array_shift($sort) != $pre_matches[0][$index][1] && ($count--)) continue;                //对剩余div进行匹配，若下一个为前缀，则向下一层，$deeper加1，                //否则后退一层，$deeper减1，$deeper为0则命中匹配，计算div长度                foreach($sort as $key){                    if($divs[$key] == 'p') $deeper++;                    else if($deeper == 0) {                        $length = $key-$pre_matches[0][$index][1];                        break;                    }else {                        $deeper--;                    }                }                $hitDivString = substr($data,$pre_matches[0][$index][1],$length).'</'.$tag.'>';                break;            }        }        return $hitDivString;}