Thanks for all the good advice, I really appreciate it! I am impressed with the quick replies. Here is another solution I came up with that does not depend on any Perl library. It is not the most elegant, but it works:

#!/usr/bin/perl -wT

$escToken = "\263";

parseText( "Example 1: A(B(2))" );
parseText( "Example 2: A(B(2)+C(D()))" );

sub parseText
{
  my( $theText ) = @_;

  my $level = 0;
  print "== $theText\n";
  # add nesting level to parenthesis,
  # e.g. "A(B())" gets "A-esc-1(B-esc-2(-esc-2)-esc-1)"
  $theText =~ s/([\(\)])/addNestingLevel($1, \$level)/geo;
  $theText = doFunc( "MAIN", $theText );
  # clean up unbalanced mess
  $theText =~ s/$escToken\-*[0-9]+([\(\)])/$1/go;
  print "-> $theText\n";

  return $theText;
}

sub addNestingLevel
{
  my( $theParen, $theLevelRef ) = @_;

  my $result = "";
  if( $theParen eq "(" ) {
    $$theLevelRef++;
    $result = "$escToken$$theLevelRef$theParen";
  } else {
    $result = "$escToken$$theLevelRef$theParen";
    $$theLevelRef--;
  }
  return $result;
}

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

  $theParam =~ s/([A-Z]+)$escToken([0-9]+)\((.*?)$escToken\2\)/&doFunc
+($1,$3)/geo;

  my $result = "";

  if( $theFunc eq "MAIN" ) {
    $result = $theParam;
  } else {
    # dummy switch here for demonstration
    # this would be an elsif for each function
    $result = "func $theFunc returns <$theParam>";
  }

  return $result;
}
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-- Peter at Thoeny.com - http://TWiki.org/