Question

$pattern = "/\[url\=(.*)\](.*)\[\/url\]/i";

My pattern above rewrites bbcode to html but I want to exclude links from my own domain. Is it possible to modify the regex so it will work for all external links but not for links with my own domain?

Answer 1

Whenever you want to do something like that you normally use the preg_replace_callback function.

It allows you to specify a callback function that can check further conditions prior offering the replacement string which allows to “replace” with the same so no replacement is done.

$pattern = "/\[url\=(.*)\](.*)\[\/url\]/i";
$callback = function($matches)
{
    $url = $matches[1];
    if (is_own_domain_url($url)) {
        return $matches[0]; # no changes
    } else {
        $title = $matches[2];
        return sprintf('<a href="%s">%s</a>'
                , htmlspecialchars($url)
                , htmlspecialchars($title)
        );
    }
}

$html = preg_replace_callback($pattern $callback, $bbcode);