PHP自定义UBB

function ubb($Text) {
  $Text=trim($Text);
  //$Text=htmlspecialchars($Text);
//http://blog.ddian.cn
  $Text=preg_replace("/\t/is","  ",$Text);
  $Text=preg_replace("/[h1](.+?)[/h1]/is","<h1>\1</h1>",$Text);
  $Text=preg_replace("/[h2](.+?)[/h2]/is","<h2>\1</h2>",$Text);
  $Text=preg_replace("/[h3](.+?)[/h3]/is","<h3>\1</h3>",$Text);
  $Text=preg_replace("/[h4](.+?)[/h4]/is","<h4>\1</h4>",$Text);
  $Text=preg_replace("/[h5](.+?)[/h5]/is","<h5>\1</h5>",$Text);
  $Text=preg_replace("/[h6](.+?)[/h6]/is","<h6>\1</h6>",$Text);
  $Text=preg_replace("/[separator]/is","",$Text);
  $Text=preg_replace("/[center](.+?)[/center]/is","<center>\1</center>",$Text);
  $Text=preg_replace("/[url=http://([^[]*)](.+?)[/url]/is","<a href="http://\1" target=_blank>\2</a>",$Text);
  $Text=preg_replace("/[url=([^[]*)](.+?)[/url]/is","<a href="http://\1" target=_blank>\2</a>",$Text);
  $Text=preg_replace("/[url]http://([^[]*)[/url]/is","<a href="http://\1" target=_blank>\1</a>",$Text);
  $Text=preg_replace("/[url]([^[]*)[/url]/is","<a href="\1" target=_blank>\1</a>",$Text);
  $Text=preg_replace("/[img](.+?)[/img]/is","<img  src=\1 alt="PHP自定义UBB" >",$Text);
  $Text=preg_replace("/[color=(.+?)](.+?)[/color]/is","<font color=\1>\2</font>",$Text);
  $Text=preg_replace("/[size=(.+?)](.+?)[/size]/is","<font size=\1>\2</font>",$Text);
  $Text=preg_replace("/[sup](.+?)[/sup]/is","<sup>\1</sup>",$Text);
  $Text=preg_replace("/[sub](.+?)[/sub]/is","<sub>\1</sub>",$Text);
  $Text=preg_replace("/[pre](.+?)[/pre]/is","<pre class="brush:php;toolbar:false;">\1