$re = '/^Content\/([A-Z][a-zA-z0-9\_]*\/)*(BP|T|M|MI)\_[A-Z].[a-zA-Z]+\.(uasset|umap)/m';
$str = 'Content/Ass/Ass/Bdd_01/BP_Asset.uasset';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php