0: #!/usr/bin/perl -w
1: #
2: # treemap BLOCK HASHREF
3: # treemap BLOCK ARRAYREF
4: #
5: #   Works like map, for arbitrary nested data structures. Data are
6: #   are modified in-place (unlike map). Returns the original reference.
7: #   Hash keys are not modified.
8: #
9: #   UPDATE: now handles scalar references, and trimmed an unnecessary line
10: #   as suggested by dkubb (thanks!)
11: #
12: #   Handles cyclical references just fine, thank you.
13: #
14: sub treemap (&$) { &_treemap }
15: sub _treemap {
16:   my ($code, $node, $refs) = @_;
17:   if (not my $type = ref $node) {
18:     local $_ = $node;
19:     $node = &$code();
20:   }
21:   elsif (not exists $refs->{$node}) {
22:     undef $refs->{$node};   # sneaky, eh?
23:     if ($type eq 'HASH') {
24:       $node->{$_} = _treemap($code, $node->{$_}, $refs) for keys %$node;
25:     }
26:     elsif ($type eq 'ARRAY') {
27:       $_ = _treemap($code, $_, $refs) for @$node;
28:     }
29:     elsif ($type eq 'SCALAR') {
30:       $node = \_treemap($code, $$node, $refs);
31:     }
32:   }
33:   $node;
34: }
35: 
36: ####################### EXAMPLE #############################
37: 
38: $data = {
39:           'nums' => [
40:                       'one',
41:                       'two',
42:                       'three',
43:                       'four',
44:                       [
45:                         'five',
46:                         'six',
47:                         [
48:                           'seven',
49:                           'eight',
50:                         ]]],
51:           'two' => '2',
52:           'doh'  => \'blah blah',
53:           'more' => {
54:                       'a' => 'vala',
55:                       'b' => 'valb',
56:                       'c' => 'valc',
57:                       'd' => 'vald'
58:                     }
59:         };
60: 
61: use Data::Dumper;
62: print Dumper treemap { "-=\U$_=-" } $data;
63: print Dumper treemap { s/\W/./g; $_ } $data;
64: print Dumper treemap { reverse lc } $data;