[a] 1 [/a]转换为网址的UBB的正则

上面这个东东如何才能变成下面那个？

复制代码代码如下:

[a] 1 [/a] 2 [a]3[/a] 4 [/a] 5  [/a] 6 [a] 7 [/a]  [a] 8 [/a]  
<a f="1"> 1 <a f="2"> 2 <a f="3">3</a> 4 </a> 5  </a> 6 <a f="7"> 7 </a>  <a f="8"> 8 </a>  

function ff(a,b,c,d,e){

if(b) 
   {

return "如需引入外部Js需刷新才能执行]</div><BR>

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