#!/usr/bin/perl

use strict;

sub traverse($);

#my $hash = {
#    key0 => 'value0',
#    key1 => { key2 => 'value2' },
#    key3 => { key4 => 'value4', key5 => { key6 => 'value6' } }
#};
my  %hash;
$hash{key0} = 'value0';
$hash{key1}{key2} = 'value2';
$hash{key3}{key4} = 'value4';
$hash{key3}{key5}{key6} = 'value6';

traverse(\%hash);

sub traverse($) {
    my $r = shift;
    if (ref($r) eq 'HASH') {
        for my $v (values %$r) {
            traverse($v);
        }
    }
    elsif (ref($r) eq 'SCALAR') {
        print "SCALAR:\t'$r'\n";
    }
    elsif (ref($r) eq 'ARRAY') {
        print "ARRAY:\t'$r'\n";
    }
    elsif (ref($r) eq 'REF') {
        print "REF:\t'$r'\n";
    }
    elsif (ref($r) eq 'LVALUE') {
        print "LVALUE:\t'$r'\n";
    }
    elsif (ref($r) eq 'CODE') {
        print "CODE:\t'$r'\n";
    }
    elsif (ref($r) eq 'GLOB') {
        print "GLOB:\t'$r'\n";
    }
    else {
        print "unexpected value:\t'$r'\n"
    }
}