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96c33d98 |
1 | package Hash::Util; |
2 | |
3 | require 5.007003; |
4 | use strict; |
5 | use Carp; |
6 | use warnings; |
7 | use warnings::register; |
8 | use Scalar::Util qw(reftype); |
9 | |
10 | require Exporter; |
11 | our @ISA = qw(Exporter); |
12 | our @EXPORT_OK = qw( |
1e73acc8 |
13 | fieldhash fieldhashes |
14 | |
96c33d98 |
15 | all_keys |
16 | lock_keys unlock_keys |
17 | lock_value unlock_value |
18 | lock_hash unlock_hash |
19 | lock_keys_plus hash_locked |
20 | hidden_keys legal_keys |
21 | |
22 | lock_ref_keys unlock_ref_keys |
23 | lock_ref_value unlock_ref_value |
24 | lock_hashref unlock_hashref |
25 | lock_ref_keys_plus hashref_locked |
26 | hidden_ref_keys legal_ref_keys |
27 | |
28 | hash_seed hv_store |
29 | |
30 | ); |
1e73acc8 |
31 | our $VERSION = 0.07; |
96c33d98 |
32 | require DynaLoader; |
33 | local @ISA = qw(DynaLoader); |
34 | bootstrap Hash::Util $VERSION; |
35 | |
1e73acc8 |
36 | sub import { |
37 | my $class = shift; |
38 | if ( grep /fieldhash/, @_ ) { |
39 | require Hash::Util::FieldHash; |
40 | Hash::Util::FieldHash->import(':all'); # for re-export |
41 | } |
42 | unshift @_, $class; |
43 | goto &Exporter::import; |
44 | } |
45 | |
96c33d98 |
46 | |
47 | =head1 NAME |
48 | |
49 | Hash::Util - A selection of general-utility hash subroutines |
50 | |
51 | =head1 SYNOPSIS |
52 | |
1e73acc8 |
53 | # Field hashes |
54 | |
55 | use Hash::Util qw(fieldhash fieldhashes); |
56 | |
57 | # Create a single field hash |
58 | fieldhash my %foo; |
59 | |
60 | # Create three at once... |
61 | fieldhashes \ my(%foo, %bar, %baz); |
62 | # ...or any number |
63 | fieldhashes @hashrefs; |
64 | |
65 | # Restricted hashes |
66 | |
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67 | use Hash::Util qw( |
68 | hash_seed all_keys |
69 | lock_keys unlock_keys |
70 | lock_value unlock_value |
71 | lock_hash unlock_hash |
72 | lock_keys_plus hash_locked |
73 | hidden_keys legal_keys |
74 | ); |
75 | |
76 | %hash = (foo => 42, bar => 23); |
77 | # Ways to restrict a hash |
78 | lock_keys(%hash); |
79 | lock_keys(%hash, @keyset); |
80 | lock_keys_plus(%hash, @additional_keys); |
81 | |
82 | #Ways to inspect the properties of a restricted hash |
83 | my @legal=legal_keys(%hash); |
84 | my @hidden=hidden_keys(%hash); |
85 | my $ref=all_keys(%hash,@keys,@hidden); |
86 | my $is_locked=hash_locked(%hash); |
87 | |
88 | #Remove restrictions on the hash |
89 | unlock_keys(%hash); |
90 | |
91 | #Lock individual values in a hash |
92 | lock_value (%hash, 'foo'); |
93 | unlock_value(%hash, 'foo'); |
94 | |
95 | #Ways to change the restrictions on both keys and values |
96 | lock_hash (%hash); |
97 | unlock_hash(%hash); |
98 | |
99 | my $hashes_are_randomised = hash_seed() != 0; |
100 | |
101 | =head1 DESCRIPTION |
102 | |
103 | C<Hash::Util> contains special functions for manipulating hashes that |
104 | don't really warrant a keyword. |
105 | |
106 | By default C<Hash::Util> does not export anything. |
107 | |
1e73acc8 |
108 | =head2 Field hashes |
109 | |
110 | Field hashes are designed to maintain an association of a reference |
111 | with a value. The association is independent of the bless status of |
112 | the key, it is thread safe and garbage-collected. These properties |
113 | are desirable in the construction of inside-out classes. |
114 | |
115 | When used with keys that are plain scalars (not references), field |
116 | hashes behave like normal hashes. |
117 | |
118 | Field hashes are defined in a separate module for which C<Hash::Util> |
119 | is a front end. For a detailed description see L<Hash::Util::FieldHash>. |
120 | |
96c33d98 |
121 | =head2 Restricted hashes |
122 | |
123 | 5.8.0 introduces the ability to restrict a hash to a certain set of |
124 | keys. No keys outside of this set can be added. It also introduces |
125 | the ability to lock an individual key so it cannot be deleted and the |
126 | ability to ensure that an individual value cannot be changed. |
127 | |
128 | This is intended to largely replace the deprecated pseudo-hashes. |
129 | |
130 | =over 4 |
131 | |
132 | =item B<lock_keys> |
133 | |
134 | =item B<unlock_keys> |
135 | |
136 | lock_keys(%hash); |
137 | lock_keys(%hash, @keys); |
138 | |
139 | Restricts the given %hash's set of keys to @keys. If @keys is not |
140 | given it restricts it to its current keyset. No more keys can be |
141 | added. delete() and exists() will still work, but will not alter |
142 | the set of allowed keys. B<Note>: the current implementation prevents |
143 | the hash from being bless()ed while it is in a locked state. Any attempt |
144 | to do so will raise an exception. Of course you can still bless() |
145 | the hash before you call lock_keys() so this shouldn't be a problem. |
146 | |
147 | unlock_keys(%hash); |
148 | |
149 | Removes the restriction on the %hash's keyset. |
150 | |
151 | B<Note> that if any of the values of the hash have been locked they will not be unlocked |
152 | after this sub executes. |
153 | |
154 | Both routines return a reference to the hash operated on. |
155 | |
156 | =cut |
157 | |
158 | sub lock_ref_keys { |
159 | my($hash, @keys) = @_; |
160 | |
161 | Internals::hv_clear_placeholders %$hash; |
162 | if( @keys ) { |
163 | my %keys = map { ($_ => 1) } @keys; |
164 | my %original_keys = map { ($_ => 1) } keys %$hash; |
165 | foreach my $k (keys %original_keys) { |
166 | croak "Hash has key '$k' which is not in the new key set" |
167 | unless $keys{$k}; |
168 | } |
169 | |
170 | foreach my $k (@keys) { |
171 | $hash->{$k} = undef unless exists $hash->{$k}; |
172 | } |
173 | Internals::SvREADONLY %$hash, 1; |
174 | |
175 | foreach my $k (@keys) { |
176 | delete $hash->{$k} unless $original_keys{$k}; |
177 | } |
178 | } |
179 | else { |
180 | Internals::SvREADONLY %$hash, 1; |
181 | } |
182 | |
183 | return $hash; |
184 | } |
185 | |
186 | sub unlock_ref_keys { |
187 | my $hash = shift; |
188 | |
189 | Internals::SvREADONLY %$hash, 0; |
190 | return $hash; |
191 | } |
192 | |
193 | sub lock_keys (\%;@) { lock_ref_keys(@_) } |
194 | sub unlock_keys (\%) { unlock_ref_keys(@_) } |
195 | |
196 | =item B<lock_keys_plus> |
197 | |
198 | lock_keys_plus(%hash,@additional_keys) |
199 | |
200 | Similar to C<lock_keys()>, with the difference being that the optional key list |
201 | specifies keys that may or may not be already in the hash. Essentially this is |
202 | an easier way to say |
203 | |
204 | lock_keys(%hash,@additional_keys,keys %hash); |
205 | |
206 | Returns a reference to %hash |
207 | |
208 | =cut |
209 | |
210 | |
211 | sub lock_ref_keys_plus { |
212 | my ($hash,@keys)=@_; |
213 | my @delete; |
214 | Internals::hv_clear_placeholders(%$hash); |
215 | foreach my $key (@keys) { |
216 | unless (exists($hash->{$key})) { |
217 | $hash->{$key}=undef; |
218 | push @delete,$key; |
219 | } |
220 | } |
221 | Internals::SvREADONLY(%$hash,1); |
222 | delete @{$hash}{@delete}; |
223 | return $hash |
224 | } |
225 | |
226 | sub lock_keys_plus(\%;@) { lock_ref_keys_plus(@_) } |
227 | |
228 | |
229 | =item B<lock_value> |
230 | |
231 | =item B<unlock_value> |
232 | |
233 | lock_value (%hash, $key); |
234 | unlock_value(%hash, $key); |
235 | |
236 | Locks and unlocks the value for an individual key of a hash. The value of a |
237 | locked key cannot be changed. |
238 | |
239 | Unless %hash has already been locked the key/value could be deleted |
240 | regardless of this setting. |
241 | |
242 | Returns a reference to the %hash. |
243 | |
244 | =cut |
245 | |
246 | sub lock_ref_value { |
247 | my($hash, $key) = @_; |
248 | # I'm doubtful about this warning, as it seems not to be true. |
249 | # Marking a value in the hash as RO is useful, regardless |
250 | # of the status of the hash itself. |
251 | carp "Cannot usefully lock values in an unlocked hash" |
252 | if !Internals::SvREADONLY(%$hash) && warnings::enabled; |
253 | Internals::SvREADONLY $hash->{$key}, 1; |
254 | return $hash |
255 | } |
256 | |
257 | sub unlock_ref_value { |
258 | my($hash, $key) = @_; |
259 | Internals::SvREADONLY $hash->{$key}, 0; |
260 | return $hash |
261 | } |
262 | |
263 | sub lock_value (\%$) { lock_ref_value(@_) } |
264 | sub unlock_value (\%$) { unlock_ref_value(@_) } |
265 | |
266 | |
267 | =item B<lock_hash> |
268 | |
269 | =item B<unlock_hash> |
270 | |
271 | lock_hash(%hash); |
272 | |
273 | lock_hash() locks an entire hash, making all keys and values readonly. |
274 | No value can be changed, no keys can be added or deleted. |
275 | |
276 | unlock_hash(%hash); |
277 | |
278 | unlock_hash() does the opposite of lock_hash(). All keys and values |
279 | are made writable. All values can be changed and keys can be added |
280 | and deleted. |
281 | |
282 | Returns a reference to the %hash. |
283 | |
284 | =cut |
285 | |
286 | sub lock_hashref { |
287 | my $hash = shift; |
288 | |
289 | lock_ref_keys($hash); |
290 | |
291 | foreach my $value (values %$hash) { |
292 | Internals::SvREADONLY($value,1); |
293 | } |
294 | |
295 | return $hash; |
296 | } |
297 | |
298 | sub unlock_hashref { |
299 | my $hash = shift; |
300 | |
301 | foreach my $value (values %$hash) { |
302 | Internals::SvREADONLY($value, 0); |
303 | } |
304 | |
305 | unlock_ref_keys($hash); |
306 | |
307 | return $hash; |
308 | } |
309 | |
310 | sub lock_hash (\%) { lock_hashref(@_) } |
311 | sub unlock_hash (\%) { unlock_hashref(@_) } |
312 | |
313 | =item B<lock_hash_recurse> |
314 | |
315 | =item B<unlock_hash_recurse> |
316 | |
317 | lock_hash_recurse(%hash); |
318 | |
319 | lock_hash() locks an entire hash and any hashes it references recursively, |
320 | making all keys and values readonly. No value can be changed, no keys can |
321 | be added or deleted. |
322 | |
323 | B<Only> recurses into hashes that are referenced by another hash. Thus a |
324 | Hash of Hashes (HoH) will all be restricted, but a Hash of Arrays of Hashes |
325 | (HoAoH) will only have the top hash restricted. |
326 | |
327 | unlock_hash_recurse(%hash); |
328 | |
329 | unlock_hash_recurse() does the opposite of lock_hash_recurse(). All keys and |
330 | values are made writable. All values can be changed and keys can be added |
331 | and deleted. Identical recursion restrictions apply as to lock_hash_recurse(). |
332 | |
333 | Returns a reference to the %hash. |
334 | |
335 | =cut |
336 | |
337 | sub lock_hashref_recurse { |
338 | my $hash = shift; |
339 | |
340 | lock_ref_keys($hash); |
341 | foreach my $value (values %$hash) { |
342 | if (reftype($value) eq 'HASH') { |
343 | lock_hashref_recurse($value); |
344 | } |
345 | Internals::SvREADONLY($value,1); |
346 | } |
347 | return $hash |
348 | } |
349 | |
350 | sub unlock_hashref_recurse { |
351 | my $hash = shift; |
352 | |
353 | foreach my $value (values %$hash) { |
354 | if (reftype($value) eq 'HASH') { |
355 | unlock_hashref_recurse($value); |
356 | } |
357 | Internals::SvREADONLY($value,1); |
358 | } |
359 | unlock_ref_keys($hash); |
360 | return $hash; |
361 | } |
362 | |
363 | sub lock_hash_recurse (\%) { lock_hashref_recurse(@_) } |
364 | sub unlock_hash_recurse (\%) { unlock_hashref_recurse(@_) } |
365 | |
366 | |
367 | =item B<hash_unlocked> |
368 | |
369 | hash_unlocked(%hash) and print "Hash is unlocked!\n"; |
370 | |
371 | Returns true if the hash and its keys are unlocked. |
372 | |
373 | =cut |
374 | |
375 | sub hashref_unlocked { |
376 | my $hash=shift; |
377 | return Internals::SvREADONLY($hash) |
378 | } |
379 | |
380 | sub hash_unlocked(\%) { hashref_unlocked(@_) } |
381 | |
382 | =for demerphqs_editor |
383 | sub legal_ref_keys{} |
384 | sub hidden_ref_keys{} |
385 | sub all_keys{} |
386 | |
387 | =cut |
388 | |
389 | sub legal_keys(\%) { legal_ref_keys(@_) } |
390 | sub hidden_keys(\%){ hidden_ref_keys(@_) } |
391 | |
392 | =item b<legal_keys> |
393 | |
394 | my @keys=legal_keys(%hash); |
395 | |
396 | Returns a list of the keys that are legal in a restricted hash. |
397 | In the case of an unrestricted hash this is identical to calling |
398 | keys(%hash). |
399 | |
400 | =item B<hidden_keys> |
401 | |
402 | my @keys=hidden_keys(%hash); |
403 | |
404 | Returns a list of the keys that are legal in a restricted hash but |
405 | do not have a value associated to them. Thus if 'foo' is a |
406 | "hidden" key of the %hash it will return false for both C<defined> |
407 | and C<exists> tests. |
408 | |
409 | In the case of an unrestricted hash this will return an empty list. |
410 | |
411 | B<NOTE> this is an experimental feature that is heavily dependent |
412 | on the current implementation of restricted hashes. Should the |
413 | implementation change this routine may become meaningless in which |
414 | case it will return an empty list. |
415 | |
416 | =item B<all_keys> |
417 | |
418 | all_keys(%hash,@keys,@hidden); |
419 | |
420 | Populates the arrays @keys with the all the keys that would pass |
421 | an C<exists> tests, and populates @hidden with the remaining legal |
422 | keys that have not been utilized. |
423 | |
424 | Returns a reference to the hash. |
425 | |
426 | In the case of an unrestricted hash this will be equivelent to |
427 | |
428 | $ref=do{ |
429 | @keys =keys %hash; |
430 | @hidden=(); |
431 | \%hash |
432 | }; |
433 | |
434 | B<NOTE> this is an experimental feature that is heavily dependent |
435 | on the current implementation of restricted hashes. Should the |
436 | implementation change this routine may become meaningless in which |
437 | case it will behave identically to how it would behave on an |
438 | unrestrcited hash. |
439 | |
440 | =item B<hash_seed> |
441 | |
442 | my $hash_seed = hash_seed(); |
443 | |
444 | hash_seed() returns the seed number used to randomise hash ordering. |
445 | Zero means the "traditional" random hash ordering, non-zero means the |
446 | new even more random hash ordering introduced in Perl 5.8.1. |
447 | |
448 | B<Note that the hash seed is sensitive information>: by knowing it one |
449 | can craft a denial-of-service attack against Perl code, even remotely, |
450 | see L<perlsec/"Algorithmic Complexity Attacks"> for more information. |
451 | B<Do not disclose the hash seed> to people who don't need to know it. |
452 | See also L<perlrun/PERL_HASH_SEED_DEBUG>. |
453 | |
454 | =cut |
455 | |
456 | sub hash_seed () { |
457 | Internals::rehash_seed(); |
458 | } |
459 | |
460 | =item B<hv_store> |
461 | |
462 | my $sv=0; |
463 | hv_store(%hash,$key,$sv) or die "Failed to alias!"; |
464 | $hash{$key}=1; |
465 | print $sv; # prints 1 |
466 | |
467 | Stores an alias to a variable in a hash instead of copying the value. |
468 | |
469 | =back |
470 | |
471 | =head2 Operating on references to hashes. |
472 | |
473 | Most subroutines documented in this module have equivelent versions |
474 | that operate on references to hashes instead of native hashes. |
475 | The following is a list of these subs. They are identical except |
476 | in name and in that instead of taking a %hash they take a $hashref, |
477 | and additionally are not prototyped. |
478 | |
479 | =over 4 |
480 | |
481 | =item lock_ref_keys |
482 | |
483 | =item unlock_ref_keys |
484 | |
485 | =item lock_ref_keys_plus |
486 | |
487 | =item lock_ref_value |
488 | |
489 | =item unlock_ref_value |
490 | |
491 | =item lock_hashref |
492 | |
493 | =item unlock_hashref |
494 | |
495 | =item lock_hashref_recurse |
496 | |
497 | =item unlock_hashref_recurse |
498 | |
499 | =item hash_ref_unlocked |
500 | |
501 | =item legal_ref_keys |
502 | |
503 | =item hidden_ref_keys |
504 | |
505 | =back |
506 | |
507 | =head1 CAVEATS |
508 | |
509 | Note that the trapping of the restricted operations is not atomic: |
510 | for example |
511 | |
512 | eval { %hash = (illegal_key => 1) } |
513 | |
514 | leaves the C<%hash> empty rather than with its original contents. |
515 | |
516 | =head1 BUGS |
517 | |
518 | The interface exposed by this module is very close to the current |
519 | imlementation of restricted hashes. Over time it is expected that |
520 | this behavior will be extended and the interface abstracted further. |
521 | |
522 | =head1 AUTHOR |
523 | |
524 | Michael G Schwern <schwern@pobox.com> on top of code by Nick |
525 | Ing-Simmons and Jeffrey Friedl. |
526 | |
527 | hv_store() is from Array::RefElem, Copyright 2000 Gisle Aas. |
528 | |
529 | Additional code by Yves Orton. |
530 | |
531 | =head1 SEE ALSO |
532 | |
533 | L<Scalar::Util>, L<List::Util>, L<Hash::Util>, |
534 | and L<perlsec/"Algorithmic Complexity Attacks">. |
535 | |
536 | =cut |
537 | |
538 | 1; |