REGEXP_REPLACE to extract just the diskgroup name from a file name (regular expression help)

Hi,

I'm wondering if anyone out there is really good with regular expression syntax and can fill in the regular express to extract just the ASM diskgroup name from an ASM datafile name.

For example on Oracle 10g DBMS_METADATA.GET_DDL returns the full file name when extracting tablespace DDL (note 11g does not):

SQL> select dbms_metadata.get_ddl('TABLESPACE','USERS') from dual;

DBMS_METADATA.GET_DDL('TABLESPACE','USERS')

--------------------------------------------------------------------------

  CREATE TABLESPACE "USERS" DATAFILE

  '+DATA/orcl/datafile/users.271.882125073' SIZE 5242880

  AUTOEXTEND ON NEXT 1310720 MAXSIZE 32767M

  LOGGING ONLINE PERMANENT BLOCKSIZE 8192

What I'd like to do is wrap a REGEXP_REPLACE around that to make the file name just '+DATA'.  Basically just the diskgroup name, still in the single quotes.  The "/" slash to the end of the file name (everything with the grey background) removed.