Commit | Line | Data |
49293501 |
1 | package Hash::Util; |
2 | |
3 | require 5.007003; |
4 | use strict; |
49293501 |
5 | use Carp; |
6 | |
7 | require Exporter; |
8 | our @ISA = qw(Exporter); |
9 | our @EXPORT_OK = qw(lock_keys unlock_keys lock_value unlock_value |
10 | lock_hash unlock_hash |
11 | ); |
12 | our $VERSION = 0.04; |
13 | |
49293501 |
14 | =head1 NAME |
15 | |
16 | Hash::Util - A selection of general-utility hash subroutines |
17 | |
18 | =head1 SYNOPSIS |
19 | |
20 | use Hash::Util qw(lock_keys unlock_keys |
21 | lock_value unlock_value |
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22 | lock_hash unlock_hash); |
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23 | |
24 | %hash = (foo => 42, bar => 23); |
25 | lock_keys(%hash); |
26 | lock_keys(%hash, @keyset); |
27 | unlock_keys(%hash); |
28 | |
29 | lock_value (%hash, 'foo'); |
30 | unlock_value(%hash, 'foo'); |
31 | |
32 | lock_hash (%hash); |
33 | unlock_hash(%hash); |
34 | |
49293501 |
35 | =head1 DESCRIPTION |
36 | |
37 | C<Hash::Util> contains special functions for manipulating hashes that |
38 | don't really warrant a keyword. |
39 | |
40 | By default C<Hash::Util> does not export anything. |
41 | |
42 | =head2 Restricted hashes |
43 | |
44 | 5.8.0 introduces the ability to restrict a hash to a certain set of |
45 | keys. No keys outside of this set can be added. It also introduces |
46 | the ability to lock an individual key so it cannot be deleted and the |
47 | value cannot be changed. |
48 | |
49 | This is intended to largely replace the deprecated pseudo-hashes. |
50 | |
51 | =over 4 |
52 | |
53 | =item lock_keys |
54 | |
55 | =item unlock_keys |
56 | |
57 | lock_keys(%hash); |
58 | lock_keys(%hash, @keys); |
59 | |
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60 | Restricts the given %hash's set of keys to @keys. If @keys is not |
61 | given it restricts it to its current keyset. No more keys can be |
62 | added. delete() and exists() will still work, but it does not effect |
63 | the set of allowed keys. |
64 | |
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65 | unlock_keys(%hash;) |
66 | |
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67 | Removes the restriction on the %hash's keyset. |
68 | |
69 | =cut |
70 | |
71 | sub lock_keys (\%;@) { |
72 | my($hash, @keys) = @_; |
73 | |
74 | if( @keys ) { |
75 | my %keys = map { ($_ => 1) } @keys; |
76 | my %original_keys = map { ($_ => 1) } keys %$hash; |
77 | foreach my $k (keys %original_keys) { |
78 | die sprintf "Hash has key '$k' which is not in the new key ". |
79 | "set at %s line %d\n", (caller)[1,2] |
80 | unless $keys{$k}; |
81 | } |
82 | |
83 | foreach my $k (@keys) { |
84 | $hash->{$k} = undef unless exists $hash->{$k}; |
85 | } |
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86 | Internals::SvREADONLY %$hash, 1; |
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87 | |
88 | foreach my $k (@keys) { |
89 | delete $hash->{$k} unless $original_keys{$k}; |
90 | } |
91 | } |
92 | else { |
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93 | Internals::SvREADONLY %$hash, 1; |
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94 | } |
95 | |
96 | return undef; |
97 | } |
98 | |
99 | sub unlock_keys (\%) { |
100 | my($hash) = shift; |
101 | |
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102 | Internals::SvREADONLY %$hash, 0; |
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103 | return undef; |
104 | } |
105 | |
106 | =item lock_value |
107 | |
108 | =item unlock_value |
109 | |
110 | lock_key (%hash, $key); |
111 | unlock_key(%hash, $key); |
112 | |
113 | Locks and unlocks an individual key of a hash. The value of a locked |
114 | key cannot be changed. |
115 | |
116 | %hash must have already been locked for this to have useful effect. |
117 | |
118 | =cut |
119 | |
120 | sub lock_value (\%$) { |
121 | my($hash, $key) = @_; |
122 | carp "Cannot usefully lock values in an unlocked hash" |
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123 | unless Internals::SvREADONLY %$hash; |
124 | Internals::SvREADONLY $hash->{$key}, 1; |
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125 | } |
126 | |
127 | sub unlock_value (\%$) { |
128 | my($hash, $key) = @_; |
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129 | Internals::SvREADONLY $hash->{$key}, 0; |
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130 | } |
131 | |
132 | |
133 | =item B<lock_hash> |
134 | |
135 | =item B<unlock_hash> |
136 | |
137 | lock_hash(%hash); |
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138 | |
139 | lock_hash() locks an entire hash, making all keys and values readonly. |
140 | No value can be changed, no keys can be added or deleted. |
141 | |
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142 | unlock_hash(%hash); |
143 | |
144 | unlock_hash() does the opposite of lock_hash(). All keys and values |
145 | are made read/write. All values can be changed and keys can be added |
146 | and deleted. |
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147 | |
148 | =cut |
149 | |
150 | sub lock_hash (\%) { |
151 | my($hash) = shift; |
152 | |
153 | lock_keys(%$hash); |
154 | |
155 | foreach my $key (keys %$hash) { |
156 | lock_value(%$hash, $key); |
157 | } |
158 | |
159 | return 1; |
160 | } |
161 | |
162 | sub unlock_hash (\%) { |
163 | my($hash) = shift; |
164 | |
165 | foreach my $key (keys %$hash) { |
166 | unlock_value(%$hash, $key); |
167 | } |
168 | |
169 | unlock_keys(%$hash); |
170 | |
171 | return 1; |
172 | } |
173 | |
174 | |
175 | =back |
176 | |
177 | =head1 AUTHOR |
178 | |
179 | Michael G Schwern <schwern@pobox.com> on top of code by Nick |
180 | Ing-Simmons and Jeffrey Friedl. |
181 | |
182 | =head1 SEE ALSO |
183 | |
184 | L<Scalar::Util>, L<List::Util>, L<Hash::Util> |
185 | |
186 | =cut |
187 | |
188 | 1; |