use strict;
 # example 2
my $text = doFunc( "MAIN", "A(B(2)+C(D()))" ); 
 print "Example 2: $text\n";

 sub doFunc
 {
   my( $theFunc, $theParam ,$re) = @_;

   {no warnings "uninitialized";
   ($re=$theParam)=~s/((\()|(\))|.)/${[')']}[!$3]\Q$1\E${['(']}[!$2]/gs;
}
   $re= join'|',map{quotemeta}eval{$theParam=~/$re/};
   die $@ if $@=~/unmatched/;
#$re = qr/$re/;
   print "$theFunc: '$theParam' =~ /$re/\n";
   print join"\n",$theParam=~/([A-Z]+)\(($re)\)/g,"\n";
   $theParam =~ s/([A-Z]+)\(($re)\)/&doFunc($1,$2)/ge;
    return "func $theFunc returns <$theParam>";
}
#returns
#Example 2: func MAIN returns <func A returns <func B returns <2>+C(D())>>
#should return
#Example 2: func MAIN returns <func A returns <func B returns <2>+func C ret\urns <func D returns <>>>>
#