$re = '/\[!file(?:\s*title="([^"]*?)"\s*icon="([^"]*?)")?]\(([^)]+)\)/m';
$str = '// from this: [!file title="This is my title" icon="rocket"](file.txt)
attributes = [
"title" : "This is my title",
"icon" : "rocket",
"item" : "file.txt"
]
or from this: [!file](../files/docs/terms.pdf)
attributes = [
"title" : "",
"icon" : "",
"item" : "../files/docs/terms.pdf"
]';
preg_match_all($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