PHP学习：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;
}