PHP makes HTML tags automatically complete closing function codes

Brief explanation of some codes:
The first ~(<[^>]+?>)~si
This regular expression matches the content in <…………>. Simply put, all .
The second ~<([a-z0-9]+)[^/>]*?/>~si
This regular expression matches the content in <……/>. It is a single closed tag such as

The third ~]*?>~si
This regular expression matches . That is, the end tag such as
The fourth~<([a-z0-9]+)[^/>]*?>~si
matches<......> ; the content in . This is different from the first one. This one is a real html tag, because html tags only have numbers and letters, such as:

The fifth one~~si
No need to explain, HTMl comments
The rest can be seen in the source code, php source code attachment:
Copy code The code is as follows:
/**
* Take HTML and automatically complete and close it
*
* param $html
*
* param $length
*
* param $end
*/
function subHtml($html, $length=50) {
$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 .= $str;
break ;
}
}
} while (!empty($tagStack)) {
$result .= '';
}
return $result;
}
/ **
* Get Chinese string
*
* param $string string
*
* param $start starting bit
*
* param $length length
*
* param $charset encoding
*
* param $dot additional word String
*/
function msubstr($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 . $dot;
}
/**
* Get the length of the string, including Chinese and English.
*/
function mstrlen($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-f][x80-xbf]|[xf1-xf7][x80-xbf][x80-xbf][x80-xbf]/", $text, $ar); 
$length = count($ar[0]); 
} 
return $length; 
} 
$str = "

x1s

测试

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