| 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; |