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1 | package Tie::RefHash; |
2 | ||
3 | our $VERSION = 1.32; | |
4 | ||
5 | =head1 NAME | |
6 | ||
7 | Tie::RefHash - use references as hash keys | |
8 | ||
9 | =head1 SYNOPSIS | |
10 | ||
11 | require 5.004; | |
12 | use Tie::RefHash; | |
13 | tie HASHVARIABLE, 'Tie::RefHash', LIST; | |
14 | tie HASHVARIABLE, 'Tie::RefHash::Nestable', LIST; | |
15 | ||
16 | untie HASHVARIABLE; | |
17 | ||
18 | =head1 DESCRIPTION | |
19 | ||
20 | This module provides the ability to use references as hash keys if you | |
21 | first C<tie> the hash variable to this module. Normally, only the | |
22 | keys of the tied hash itself are preserved as references; to use | |
23 | references as keys in hashes-of-hashes, use Tie::RefHash::Nestable, | |
24 | included as part of Tie::RefHash. | |
25 | ||
26 | It is implemented using the standard perl TIEHASH interface. Please | |
27 | see the C<tie> entry in perlfunc(1) and perltie(1) for more information. | |
28 | ||
29 | The Nestable version works by looking for hash references being stored | |
30 | and converting them to tied hashes so that they too can have | |
31 | references as keys. This will happen without warning whenever you | |
32 | store a reference to one of your own hashes in the tied hash. | |
33 | ||
34 | =head1 EXAMPLE | |
35 | ||
36 | use Tie::RefHash; | |
37 | tie %h, 'Tie::RefHash'; | |
38 | $a = []; | |
39 | $b = {}; | |
40 | $c = \*main; | |
41 | $d = \"gunk"; | |
42 | $e = sub { 'foo' }; | |
43 | %h = ($a => 1, $b => 2, $c => 3, $d => 4, $e => 5); | |
44 | $a->[0] = 'foo'; | |
45 | $b->{foo} = 'bar'; | |
46 | for (keys %h) { | |
47 | print ref($_), "\n"; | |
48 | } | |
49 | ||
50 | tie %h, 'Tie::RefHash::Nestable'; | |
51 | $h{$a}->{$b} = 1; | |
52 | for (keys %h, keys %{$h{$a}}) { | |
53 | print ref($_), "\n"; | |
54 | } | |
55 | ||
56 | =head1 AUTHOR | |
57 | ||
58 | Gurusamy Sarathy gsar@activestate.com | |
59 | ||
60 | 'Nestable' by Ed Avis ed@membled.com | |
61 | ||
62 | =head1 VERSION | |
63 | ||
64 | Version 1.32 | |
65 | ||
66 | =head1 SEE ALSO | |
67 | ||
68 | perl(1), perlfunc(1), perltie(1) | |
69 | ||
70 | =cut | |
71 | ||
72 | use Tie::Hash; | |
73 | use vars '@ISA'; | |
74 | @ISA = qw(Tie::Hash); | |
75 | use strict; | |
76 | ||
77 | require overload; # to support objects with overloaded "" | |
78 | ||
79 | sub TIEHASH { | |
80 | my $c = shift; | |
81 | my $s = []; | |
82 | bless $s, $c; | |
83 | while (@_) { | |
84 | $s->STORE(shift, shift); | |
85 | } | |
86 | return $s; | |
87 | } | |
88 | ||
89 | sub FETCH { | |
90 | my($s, $k) = @_; | |
91 | if (ref $k) { | |
92 | my $kstr = overload::StrVal($k); | |
93 | if (defined $s->[0]{$kstr}) { | |
94 | $s->[0]{$kstr}[1]; | |
95 | } | |
96 | else { | |
97 | undef; | |
98 | } | |
99 | } | |
100 | else { | |
101 | $s->[1]{$k}; | |
102 | } | |
103 | } | |
104 | ||
105 | sub STORE { | |
106 | my($s, $k, $v) = @_; | |
107 | if (ref $k) { | |
108 | $s->[0]{overload::StrVal($k)} = [$k, $v]; | |
109 | } | |
110 | else { | |
111 | $s->[1]{$k} = $v; | |
112 | } | |
113 | $v; | |
114 | } | |
115 | ||
116 | sub DELETE { | |
117 | my($s, $k) = @_; | |
118 | (ref $k) | |
119 | ? (delete($s->[0]{overload::StrVal($k)}) || [])->[1] | |
120 | : delete($s->[1]{$k}); | |
121 | } | |
122 | ||
123 | sub EXISTS { | |
124 | my($s, $k) = @_; | |
125 | (ref $k) ? exists($s->[0]{overload::StrVal($k)}) : exists($s->[1]{$k}); | |
126 | } | |
127 | ||
128 | sub FIRSTKEY { | |
129 | my $s = shift; | |
130 | keys %{$s->[0]}; # reset iterator | |
131 | keys %{$s->[1]}; # reset iterator | |
132 | $s->[2] = 0; # flag for iteration, see NEXTKEY | |
133 | $s->NEXTKEY; | |
134 | } | |
135 | ||
136 | sub NEXTKEY { | |
137 | my $s = shift; | |
138 | my ($k, $v); | |
139 | if (!$s->[2]) { | |
140 | if (($k, $v) = each %{$s->[0]}) { | |
141 | return $v->[0]; | |
142 | } | |
143 | else { | |
144 | $s->[2] = 1; | |
145 | } | |
146 | } | |
147 | return each %{$s->[1]}; | |
148 | } | |
149 | ||
150 | sub CLEAR { | |
151 | my $s = shift; | |
152 | $s->[2] = 0; | |
153 | %{$s->[0]} = (); | |
154 | %{$s->[1]} = (); | |
155 | } | |
156 | ||
157 | package Tie::RefHash::Nestable; | |
158 | use vars '@ISA'; | |
159 | @ISA = 'Tie::RefHash'; | |
160 | ||
161 | sub STORE { | |
162 | my($s, $k, $v) = @_; | |
163 | if (ref($v) eq 'HASH' and not tied %$v) { | |
164 | my @elems = %$v; | |
165 | tie %$v, ref($s), @elems; | |
166 | } | |
167 | $s->SUPER::STORE($k, $v); | |
168 | } | |
169 | ||
170 | 1; |