php截取html字符串及自动补全html标签的方法

/** 
 * 截取HTML,并自动补全闭合 
 * @param $html 
 * @param $length 
 * @param $end 
 */ 
function subHtml($html,$length) { 
 $result = ''; 
 $tagStack = array(); 
 $len = 0; 
 
 $contents = preg_split("~(<[^>]+?>)~si",$html, -1,PREG_SPLIT_NO_EMPTY| PREG_SPLIT_DELIM_CAPTURE); 
 foreach($contents as $tag) 
 { 
 if (trim($tag)=="")  continue; 
 if(preg_match("~<([a-z0-9]+)[^/>]*?/>~si",$tag)){ 
 $result .= $tag; 
 }else if(preg_match("~</([a-z0-9]+)[^/>]*?>~si",$tag,$match)){ 
 if($tagStack[count($tagStack)-1] == $match[1]){ 
 array_pop($tagStack); 
 $result .= $tag; 
 } 
 }else if(preg_match("~<([a-z0-9]+)[^/>]*?>~si",$tag,$match)){ 
 array_push($tagStack,$match[1]); 
 $result .= $tag; 
 }else if(preg_match("~<!--.*?-->~si",$tag)){ 
 $result .= $tag; 
 }else{ 
 if($len + mstrlen($tag) < $length){ 
 $result .= $tag; 
 $len += mstrlen($tag);  
 }else { 
 $str = msubstr($tag,0,$length-$len+1); 
 $result .= $str; 
 break; 
 } 
 
 } 
 } 
 while(!emptyempty($tagStack)){ 
 $result .= '</'.array_pop($tagStack).'>'; 
 } 
 return  $result; 
} 
 
/** 
 * 截取中文字符串 
 * @param $string 字符串 
 * @param $start 起始位 
 * @param $length 长度 
 * @param $charset  编码 
 * @param $dot 附加字串 
 */ 
function msubstr($string, $start, $length,$dot='',$charset = 'UTF-8') { 
 $string = str_replace(array('&', '"', '<', '>',' '), array('&', '"', '<', '>',' '), $string); 
 if(strlen($string) <= $length) { 
 return $string; 
 } 
 
 if(strtolower($charset) == 'utf-8') { 
 $n = $tn = $noc = 0; 
 while($n < strlen($string)) { 
 $t = ord($string[$n]); 
 if($t == 9 || $t == 10 || (32 <= $t && $t <= 126)) { 
 $tn = 1; $n++; 
 } elseif(194 <= $t && $t <= 223) { 
 $tn = 2; $n += 2; 
 } elseif(224 <= $t && $t <= 239) { 
 $tn = 3; $n += 3; 
 } elseif(240 <= $t && $t <= 247) { 
 $tn = 4; $n += 4; 
 } elseif(248 <= $t && $t <= 251) { 
 $tn = 5; $n += 5; 
 } elseif($t == 252 || $t == 253) { 
 $tn = 6; $n += 6; 
 } else { 
 $n++; 
 } 
 $noc++; 
 if($noc >= $length) { 
 break; 
 } 
 } 
 if($noc > $length) { 
 $n -= $tn; 
 } 
 $strcut = substr($string, 0, $n); 
 } else { 
 for($i = 0; $i < $length; $i++) { 
 $strcut .= ord($string[$i]) > 127 ? $string[$i].$string[++$i] : $string[$i]; 
 } 
 } 
 
 return $strcut.$dot; 
} 
 
/** 
 * 取得字符串的长度，包括中英文。 
 */ 
function mstrlen($str,$charset = 'UTF-8'){ 
 if (function_exists('mb_substr')) { 
 $length=mb_strlen($str,$charset); 
 } elseif (function_exists('iconv_substr')) { 
 $length=iconv_strlen($str,$charset); 
 } else {
 preg_match_all("/[x01-x7f]|[xc2-xdf][x80-xbf]|xe0[xa0-xbf][x80-xbf]|[xe1-xef][x80-xbf][x80-xbf]|xf0[x90-xbf][x80-xbf][x80-xbf]|[xf1-xf7][x80-xbf][x80-xbf][x80-xbf]/", $text, $ar);   
 $length=count($ar[0]); 
 } 
 return $length; 
}

* @param 要截取的HTML $str 
* @param 截取的数量 $num 
* @param 是否需要加上更多 $more 
* @return 截取串 
*/ 
function phpos_chsubstr_ahtml($str,$num,$more=false) 
{ 
    $leng=strlen($str); 
      if($num>=$leng)
      return $str; 
    $word=0; 
    $i=0;                        /** 字符串指针 **/ 
    $stag=array(array());        /** 存放开始HTML的标志 **/ 
    $etag=array(array());        /** 存放结束HTML的标志 **/ 
    $sp = 0; 
    $ep = 0; 
      while($word!=$num) 
      { 
          if(ord($str[$i])>128) 
          { 
            //$re.=substr($str,$i,3); 
            $i+=3; 
            $word++; 
          } 
          else if ($str[$i]=='<') 
          { 
              if ($str[$i+1] == '!') 
              { 
                $i++; 
                  continue; 
              } 
 
              if ($str[$i+1]=='/')     
              { 
                $ptag=&$etag ; 
                $k=&$ep; 
                $i+=2; 
              } 
              else                     
              { 
                $ptag=&$stag; 
                $i+=1; 
                $k=&$sp; 
              } 
 
              for(;$i<$leng;$i++)         
              { 
                  if ($str[$i] == ' ') 
                  { 
                    $ptag[$k] = implode('',$ptag[$k]); 
                    $k++; 
                      break; 
                  } 
                  if ($str[$i] != '>')  
                  { 
                    $ptag[$k][]=$str[$i]; 
                      continue; 
                  } 
                  else                 
                  { 
                    $ptag[$k] = implode('',$ptag[$k]); 
                    $k++; 
                      break; 
                  } 
              } 
            $i++; 
              continue; 
          } 
          else 
          { 
            //$re.=substr($str,$i,1); 
            $word++; 
            $i++; 
          } 
      } 
      foreach ($etag as $val) 
      { 
        $key1=array_search($val,$stag); 
          if ($key1 !== false)          unset($stag[$key]); 
      } 
      foreach ($stag as $key => $val) 
      { 
          if (in_array($val,array('br','img'))) unset($stag[$key1]); 
      } 
    array_reverse($stag); 
    $ends = '</'.implode('></',$stag).'>'; 
    $re = substr($str,0,$i).$ends; 
      if($more)    $re.='...'; 
      return $re; 
}

function text_zhaiyao($text,$length){ //文章摘要生成函数  $test:内容 $length:摘要长度 
    global $Briefing_Length; 
    mb_regex_encoding("UTF-8"); 
    if(mb_strlen($text) <= $length ) return $text; 
    $Foremost = mb_substr($text, 0, $length); 
    $re = "<(/?) 
    (P|DIV|H1|H2|H3|H4|H5|H6|ADDRESS|PRE|TABLE|TR|TD|TH|INPUT|SELECT|TEXTAREA|OBJECT|A|UL|OL|LI| 
    BASE|META|LINK|HR|BR|PARAM|IMG|AREA|INPUT|SPAN)[^>]*(>?)"; 
    $Single = "/BASE|META|LINK|HR|BR|PARAM|IMG|AREA|INPUT|BR/i"; 
      
    $Stack = array(); $posStack = array(); 
      
    mb_ereg_search_init($Foremost, $re, 'i'); 
      
    while($pos = mb_ereg_search_pos()){ 
    $match = mb_ereg_search_getregs(); 
    /* [Child-matching Formulation]: 
      
    $matche[1] : A "/" charactor indicating whether current "<...>" Friction is 
    Closing Part 
    $matche[2] : Element Name. 
    $matche[3] : Right > of a "<...>" Friction 
    */ 
    if($match[1]==""){ 
    $Elem = $match[2]; 
    if(mb_eregi($Single, $Elem) && $match[3] !=""){ 
    continue; 
}