超链接转换成绝对地址,能否完全使用正则解决?该如何处理

超链接转换成绝对地址,能否完全使用正则解决?
从网页抓取到的超链接格式多变,怎样全部转换成绝对地址呢?

PHP code

<!--Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/--><?php $paths=array("http://we.us","x.y.z","a.b.cn/en/","http://a.b.cn/en/js","a.b.cn/js/","a.b.cn/en/js/ext","a.b.cn/en/css/ext/");$files=array("http://so.do.i","http://a.b.cn/","./","../","../../","../js/","/js","/css/blue.css","../../en/js/ad.js");foreach($paths as $path){  foreach($files as $file){    echo realfile($path,$file);  }}function realfile($path,$file){//返回文件file的绝对地址,//如果文件地址是相对地址,则以路径path为参照/*    $real=$path.$file;//要完善的内容*/    return '<li>'.$real.'';}?>

------解决方案--------------------
舉例說明，沒看太懂你要的效果.