print doFunc( "MAIN", "B(1)+C(2)" );
sub doFunc{
   my $theFunc = shift;
   local $_ = shift;
   my $re;
   $re = ${{
"B(1)+C(2)" => '1|2',
}}{$_}||quotemeta;

   print "$theFunc: '$_'=~/$re/\n";
   print join"\n",/(\w+)\(($re)\)/g,"\n";

   if( $_ ne $re ) {
      $_ =~ s/(\w+)\(($re)\)/&doFunc($1,$2)/eg; # /ego works /eg fails
   }
    return "func $theFunc returns <$_>";
}