I have requirement to get Currency code from the given string using RUTA.

I am using this script to get Currency codes.

W{REGEXP("(?i)(USD|EUR|AUD)")  -> MARK(EntityType)}; 

But If we get $,€,US Dollar, it is not detecting. Whenever we get US dollar or $ assign it to USD variable.

So my requirement is, 

Input: US dollar

Output:USD

Input: €

Output:EUR

I am trying to use this script but this is not working.

DECLARE USD; W{REGEXP("(?i)(USD|EUR|AUD)")  -> MARK(EntityType)}}; | SPECIAL{REGEXP("\\$") -> USD};

Thanks in advance