What's the best way to extract links to images from CSS files with PHP?

I want 开发者_运维技巧to find all links to images from a CSS file.

E.g.

background-image: url(images/abc123.jpg);

I've found a PHP class called CSS parser but it doesn't seem to have a very large API. Is there a better CSS parser about?

I need to be able to modify the links in the file after I have extracted them too.

Thanks.

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function getImageUrls($input_string) {
   $matches = array();
   preg_match_all('/url\((.+?)\);/i', $input_string, $matches);
   return preg_replace('/url\((.+?)\);/i', '$1', $matches);
}

something like that anyways. pull the matches out and then format them to keep only the url path.