Using Symfony 3.0, trying to set a callback on a JsonResponse fails for the following callback: Utils.callbacks[1].

The pattern in setCallback ^[$_\p{L}] $_\p{L}\p{Mn}\p{Mc}\p{Nd}\p{Pc}\x{200C}\x{200D}]*+$/u fails on anything containing brackets while this could be a valid callback.

This works for me ^[$_\p{L}][$_\p{L}\p{Mn}\p{Mc}\p{Nd}\p{Pc}\.]*+(\x{5b}\S+\x{5d})*$. This allows callbacks like foo.bar[1] but not foo.bar[].