[Cmake] Problem with Regular expressions

[Amit C Kr Saluja]

Hi,

I am using SOURCE_GROUP( )  command with a regular expression to group
all
*.s *.S files with ".*\.[sS]$" . Cmake gives error that it does not
support this expression.
For grouping all the *.txt & *.cmake files with ".*(.txt | .cmake )$",
then too it does not group these files.

Can anybody help? Is I am wrong with the regular expressions or Cmake
has another interpretation of regular expression?

Regards
Amit Saluja