php实现使用正则将文本中的网址转换成链接标签

function text2links($str='') {
??? if($str=='' or !preg_match('/(http|www.|@)/i',$str)) { return $str; }
??? $lines = explode("n",$str); $new_text = '';
??? while (list($k,$l) = each($lines)) {
??????? // replace links:
??????? $l = preg_replace("/([ t]|^)www./i","1http://www.",$l);
??????? $l = preg_replace("/([ t]|^)ftp./i","1ftp://ftp.",$l);
??????? $l = preg_replace("/(http://[^ )rn!]+)/i",
??????????? "<a href="1">1</a>",$l);
??????? $l = preg_replace("/(https://[^ )rn!]+)/i",$l);
??????? $l = preg_replace("/(ftp://[^ )rn!]+)/i",$l);
??????? $l = preg_replace(
??????????? "/([-a-z0-9_]+(.[_a-z0-9-]+)*@([a-z0-9-]+(.[a-z0-9-]+)+))/i",
??????????? "<a href="mailto:1">1</a>",$l);
??????? $new_text .= $l."n";
??? }
??? return $new_text;
}