链接未链接的URL（BBCode）正则表达式

Question

I need a regex that looks for any URL that isn't already inside [url(=...)]...[/url] tags. In other words, I want to link any URL that isn't linked and replace the link with [url]link[/url] so that the parser I'm using can take care of it as it usually would.

I've been trying to get an understanding of negative lookaheads (which is apparently what I should make use of), but I just can't get it down.

This is what I've got so far:

preg_replace('/(?!\[url(=.*?)?\])(https?|ftps?|irc):\/\/(www\.)?(\w+(:\w+)?@)?[a-z0-9-]+(\.[a-z0-9-])*.*(?!\[\/url\])/i',"[url]$0[/url]",$Str);

Thanks

Answer 1

My solution:

<?php
$URLRegex = '/(?:(?<!(\[\/url\]|\[\/url=))(\s|^))';     // No [url]-tag in front and is start of string, or has whitespace in front
$URLRegex.= '(';                                        // Start capturing URL
$URLRegex.= '(https?|ftps?|ircs?):\/\/';                // Protocol
$URLRegex.= '\S+';                                      // Any non-space character
$URLRegex.= ')';                                        // Stop capturing URL
$URLRegex.= '(?:(?<![[:punct:]])|(?<=\/))(\s|\.?$)/i';  // Doesn't end with punctuation (excluding /) and is end of string (with a possible dot at the end), or has whitespace after

$Str = preg_replace($URLRegex,"$2[url]$3[/url]$5",$Str);
?>