$re = '~((?:\[\s*(?<name>[a-zA-Z0-9-_]+)\s*(?:\=\s*(?<bbCode>\"(?:[^\"\\\\\\\\]*(?:\\\\\\\\.[^\"\\\\\\\\]*)*)\"|((?:(?!=\s*|\]|\/\])[^\s])+)))?\s*(?<parameters>(?:\s*(?:\w+(?:\s*\=\s*\"(?:[^\"\\\\\\\\]*(?:\\\\\\\\.[^\"\\\\\\\\]*)*)\"|\s*\=\s*((?:(?!=\s*|\]|\/\])[^\s])+)|(?=\s|\]|\/\s*\]|$))))*)\s*(?:\](?<content>.*?)\[\s*(?<markerContent>\/)\s*(\k<name>)\s*\]|\]|(?<marker>\/)\s*\])))~umi';
$str = '[style-background=red]
[style-color=blue]';
preg_match_all($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