How get string inside bracket "()" using cmake regex

I am trying to get the string inside ‘( )’ by using CMake regex.
here is the example which I tried:

set(STR "example(arg1,arg2)")
string(REGEX MATCH "^\(.*\)$" ARG_STR ${STR}) 

expected: arg1,arg2, but I got example(arg1,arg2)
Please guide me how to fix this.

>Solution :

You can use a capturing group with a pattern lie

string(REGEX MATCH "\\(([^()]*)\\)" _ ${STR}) 

Then, you can access the contents using ${CMAKE_MATCH_1}, e.g.

message("ARGS_STR: ${CMAKE_MATCH_1}")

See CMAKE reference details:

New in version 3.9: All regular expression-related commands, including e.g. if(MATCHES), save subgroup matches in the variables CMAKE_MATCH_ for <n> 0..9.

Also, see the regex demo.