Codeigniter and preg_replace - php

Question

I use Codeigniter to create a multilingual website and everything works fine, but when I try to use the "alternative languages helper" by Luis I've got a problem. This helper uses a regular expression to replace the current language with the new one:
$new_uri = preg_replace('/^'.$actual_lang.'/', $lang, $uri);
The problem is that I have a URL like this: http://www.example.com/en/language/english/ and I want to replace only the first "en" without changing the word "english". I tried to use the limit for preg_replace:
$new_uri = preg_replace('/^'.$actual_lang.'/', $lang, $uri, 1);
but this doesn't work for me. Any ideas?

Answer 1

You could do something like this:
$regex = '#^'.preg_quote($actual_lang, '#').'(?=/|$)#';
$new_uri = preg_replace($regex, $lang, $uri);
The last capture pattern basically means "only match if the next character is a forward slash or the end of the string"...
Edit:
If the code you always want to replace is at the beginning of the path, you could always do:
if (stripos($url, $actual_lang) !== false) {
if (strpos($url, '://') !== false) {
$path = parse_url($url, PHP_URL_PATH);
} else {
$path = $url;
}
list($language, $rest) = explode('/', $path, 2);
if ($language == $actual_lang) {
$url = str_replace($path, $lang . '/' . $rest, $url);
}
}
It's a bit more code, but it should be fairly robust. You could always build a class to do this for you (by parsing, replacing and then rebuilding the URL)...

Answer 2

If you know what the beginning of the URL will always, be, use it in the regex!
$domain = "http://www.example.com/"
$regex = '#(?<=^' . preg_quote($domain, '#') . ')' . preg_quote($actual_lang, '#') . '\b#';
$new_uri = preg_replace($regex, $lang, $uri);
In the case of your example, the regular expression would become #(?<=^http://www.example.com/)en\b which would match en only if it followed the specified beginning of a domain ((?<=...) in a regular expression specifies a positive lookbehind) and is followed by a word boundary (so english wouldn't match).