Something like this: 

use strict;
use warnings;

my $input = "1*(2+3)*(3+4)+5*(6+7)";
my $level  = 0;
my $tab    = "| ";
my %action = (
          '('       => sub { print "\n", $tab x ++$level, shift },
          ')'       => sub { print "\n", $tab x $level--, shift },
          '+'       => sub { print "This one>>>" unless $level; print 
+shift },
          'default' => sub { print shift },
         );

( $action{$_} // $action{'default'} )->($_) for $input =~ /./g;

[download]

The additional effort is only worthwhile if you have ambitions beyond your initial question.

In reply to Re^3: Regex: first match that is not enclosed in parenthesis by hdb
in thread Regex: first match that is not enclosed in parenthesis by monkprentice

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