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1 | package Tie::RefHash; |
2 | |
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3 | our $VERSION = '1.3_00'; |
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4 | |
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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; |
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14 | tie HASHVARIABLE, 'Tie::RefHash::Nestable', LIST; |
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15 | |
16 | untie HASHVARIABLE; |
17 | |
18 | =head1 DESCRIPTION |
19 | |
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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, |
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24 | included as part of Tie::RefHash. |
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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 | |
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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 | |
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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 | |
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50 | tie %h, 'Tie::RefHash::Nestable'; |
51 | $h{$a}->{$b} = 1; |
52 | for (keys %h, keys %{$h{$a}}) { |
53 | print ref($_), "\n"; |
54 | } |
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55 | |
56 | =head1 AUTHOR |
57 | |
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58 | Gurusamy Sarathy gsar@activestate.com |
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59 | |
60 | =head1 VERSION |
61 | |
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62 | Version 1.3 |
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63 | |
64 | =head1 SEE ALSO |
65 | |
66 | perl(1), perlfunc(1), perltie(1) |
67 | |
68 | =cut |
69 | |
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70 | use Tie::Hash; |
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71 | use vars '@ISA'; |
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72 | @ISA = qw(Tie::Hash); |
73 | use strict; |
74 | |
75 | sub TIEHASH { |
76 | my $c = shift; |
77 | my $s = []; |
78 | bless $s, $c; |
79 | while (@_) { |
80 | $s->STORE(shift, shift); |
81 | } |
82 | return $s; |
83 | } |
84 | |
85 | sub FETCH { |
86 | my($s, $k) = @_; |
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87 | if (ref $k) { |
88 | if (defined $s->[0]{"$k"}) { |
89 | $s->[0]{"$k"}[1]; |
90 | } |
91 | else { |
92 | undef; |
93 | } |
94 | } |
95 | else { |
96 | $s->[1]{$k}; |
97 | } |
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98 | } |
99 | |
100 | sub STORE { |
101 | my($s, $k, $v) = @_; |
102 | if (ref $k) { |
103 | $s->[0]{"$k"} = [$k, $v]; |
104 | } |
105 | else { |
106 | $s->[1]{$k} = $v; |
107 | } |
108 | $v; |
109 | } |
110 | |
111 | sub DELETE { |
112 | my($s, $k) = @_; |
113 | (ref $k) ? delete($s->[0]{"$k"}) : delete($s->[1]{$k}); |
114 | } |
115 | |
116 | sub EXISTS { |
117 | my($s, $k) = @_; |
118 | (ref $k) ? exists($s->[0]{"$k"}) : exists($s->[1]{$k}); |
119 | } |
120 | |
121 | sub FIRSTKEY { |
122 | my $s = shift; |
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123 | keys %{$s->[0]}; # reset iterator |
124 | keys %{$s->[1]}; # reset iterator |
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125 | $s->[2] = 0; |
126 | $s->NEXTKEY; |
127 | } |
128 | |
129 | sub NEXTKEY { |
130 | my $s = shift; |
131 | my ($k, $v); |
132 | if (!$s->[2]) { |
133 | if (($k, $v) = each %{$s->[0]}) { |
134 | return $s->[0]{"$k"}[0]; |
135 | } |
136 | else { |
137 | $s->[2] = 1; |
138 | } |
139 | } |
140 | return each %{$s->[1]}; |
141 | } |
142 | |
143 | sub CLEAR { |
144 | my $s = shift; |
145 | $s->[2] = 0; |
146 | %{$s->[0]} = (); |
147 | %{$s->[1]} = (); |
148 | } |
149 | |
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150 | package Tie::RefHash::Nestable; |
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151 | use vars '@ISA'; |
152 | @ISA = 'Tie::RefHash'; |
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153 | |
154 | sub STORE { |
155 | my($s, $k, $v) = @_; |
156 | if (ref($v) eq 'HASH' and not tied %$v) { |
157 | my @elems = %$v; |
158 | tie %$v, ref($s), @elems; |
159 | } |
160 | $s->SUPER::STORE($k, $v); |
161 | } |
162 | |
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163 | 1; |