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Revision 1.27 by root, Thu Nov 28 15:43:24 2013 UTC vs.
Revision 1.52 by root, Mon Apr 25 18:17:17 2016 UTC

26 substr $many_cbor_strings, 0, $length, ""; # remove decoded cbor string 26 substr $many_cbor_strings, 0, $length, ""; # remove decoded cbor string
27 } 27 }
28 28
29=head1 DESCRIPTION 29=head1 DESCRIPTION
30 30
31WARNING! This module is very new, and not very well tested (that's up
32to you to do). Furthermore, details of the implementation might change
33freely before version 1.0. And lastly, most extensions depend on an IANA
34assignment, and until that assignment is official, this implementation is
35not interoperable with other implementations (even future versions of this
36module) until the assignment is done.
37
38You are still invited to try out CBOR, and this module.
39
40This module converts Perl data structures to the Concise Binary Object 31This module converts Perl data structures to the Concise Binary Object
41Representation (CBOR) and vice versa. CBOR is a fast binary serialisation 32Representation (CBOR) and vice versa. CBOR is a fast binary serialisation
42format that aims to use a superset of the JSON data model, i.e. when you 33format that aims to use an (almost) superset of the JSON data model, i.e.
43can represent something in JSON, you should be able to represent it in 34when you can represent something useful in JSON, you should be able to
44CBOR. 35represent it in CBOR.
45 36
46In short, CBOR is a faster and very compact binary alternative to JSON, 37In short, CBOR is a faster and quite compact binary alternative to JSON,
47with the added ability of supporting serialisation of Perl objects. (JSON 38with the added ability of supporting serialisation of Perl objects. (JSON
48often compresses better than CBOR though, so if you plan to compress the 39often compresses better than CBOR though, so if you plan to compress the
49data later you might want to compare both formats first). 40data later and speed is less important you might want to compare both
41formats first).
50 42
51To give you a general idea about speed, with texts in the megabyte range, 43To give you a general idea about speed, with texts in the megabyte range,
52C<CBOR::XS> usually encodes roughly twice as fast as L<Storable> or 44C<CBOR::XS> usually encodes roughly twice as fast as L<Storable> or
53L<JSON::XS> and decodes about 15%-30% faster than those. The shorter the 45L<JSON::XS> and decodes about 15%-30% faster than those. The shorter the
54data, the worse L<Storable> performs in comparison. 46data, the worse L<Storable> performs in comparison.
55 47
56As for compactness, C<CBOR::XS> encoded data structures are usually about 48Regarding compactness, C<CBOR::XS>-encoded data structures are usually
5720% smaller than the same data encoded as (compact) JSON or L<Storable>. 49about 20% smaller than the same data encoded as (compact) JSON or
50L<Storable>.
58 51
59In addition to the core CBOR data format, this module implements a number 52In addition to the core CBOR data format, this module implements a
60of extensions, to support cyclic and self-referencing data structures 53number of extensions, to support cyclic and shared data structures
61(see C<allow_sharing>), string deduplication (see C<pack_strings>) and 54(see C<allow_sharing> and C<allow_cycles>), string deduplication (see
62scalar references (always enabled). 55C<pack_strings>) and scalar references (always enabled).
63 56
64The primary goal of this module is to be I<correct> and the secondary goal 57The primary goal of this module is to be I<correct> and the secondary goal
65is to be I<fast>. To reach the latter goal it was written in C. 58is to be I<fast>. To reach the latter goal it was written in C.
66 59
67See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and 60See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and
71 64
72package CBOR::XS; 65package CBOR::XS;
73 66
74use common::sense; 67use common::sense;
75 68
76our $VERSION = 0.09; 69our $VERSION = 1.41;
77our @ISA = qw(Exporter); 70our @ISA = qw(Exporter);
78 71
79our @EXPORT = qw(encode_cbor decode_cbor); 72our @EXPORT = qw(encode_cbor decode_cbor);
80 73
81use Exporter; 74use Exporter;
187reference to the earlier value. 180reference to the earlier value.
188 181
189This means that such values will only be encoded once, and will not result 182This means that such values will only be encoded once, and will not result
190in a deep cloning of the value on decode, in decoders supporting the value 183in a deep cloning of the value on decode, in decoders supporting the value
191sharing extension. This also makes it possible to encode cyclic data 184sharing extension. This also makes it possible to encode cyclic data
192structures. 185structures (which need C<allow_cycles> to ne enabled to be decoded by this
186module).
193 187
194It is recommended to leave it off unless you know your 188It is recommended to leave it off unless you know your
195communication partner supports the value sharing extensions to CBOR 189communication partner supports the value sharing extensions to CBOR
196(L<http://cbor.schmorp.de/value-sharing>), as without decoder support, the 190(L<http://cbor.schmorp.de/value-sharing>), as without decoder support, the
197resulting data structure might be unusable. 191resulting data structure might be unusable.
198 192
199Detecting shared values incurs a runtime overhead when values are encoded 193Detecting shared values incurs a runtime overhead when values are encoded
200that have a reference counter large than one, and might unnecessarily 194that have a reference counter large than one, and might unnecessarily
201increase the encoded size, as potentially shared values are encode as 195increase the encoded size, as potentially shared values are encode as
202sharable whether or not they are actually shared. 196shareable whether or not they are actually shared.
203 197
204At the moment, only targets of references can be shared (e.g. scalars, 198At the moment, only targets of references can be shared (e.g. scalars,
205arrays or hashes pointed to by a reference). Weirder constructs, such as 199arrays or hashes pointed to by a reference). Weirder constructs, such as
206an array with multiple "copies" of the I<same> string, which are hard but 200an array with multiple "copies" of the I<same> string, which are hard but
207not impossible to create in Perl, are not supported (this is the same as 201not impossible to create in Perl, are not supported (this is the same as
212structures cannot be encoded in this mode. 206structures cannot be encoded in this mode.
213 207
214This option does not affect C<decode> in any way - shared values and 208This option does not affect C<decode> in any way - shared values and
215references will always be decoded properly if present. 209references will always be decoded properly if present.
216 210
211=item $cbor = $cbor->allow_cycles ([$enable])
212
213=item $enabled = $cbor->get_allow_cycles
214
215If C<$enable> is true (or missing), then C<decode> will happily decode
216self-referential (cyclic) data structures. By default these will not be
217decoded, as they need manual cleanup to avoid memory leaks, so code that
218isn't prepared for this will not leak memory.
219
220If C<$enable> is false (the default), then C<decode> will throw an error
221when it encounters a self-referential/cyclic data structure.
222
223FUTURE DIRECTION: the motivation behind this option is to avoid I<real>
224cycles - future versions of this module might chose to decode cyclic data
225structures using weak references when this option is off, instead of
226throwing an error.
227
228This option does not affect C<encode> in any way - shared values and
229references will always be encoded properly if present.
230
217=item $cbor = $cbor->pack_strings ([$enable]) 231=item $cbor = $cbor->pack_strings ([$enable])
218 232
219=item $enabled = $cbor->get_pack_strings 233=item $enabled = $cbor->get_pack_strings
220 234
221If C<$enable> is true (or missing), then C<encode> will try not to encode 235If C<$enable> is true (or missing), then C<encode> will try not to encode
233the standard CBOR way. 247the standard CBOR way.
234 248
235This option does not affect C<decode> in any way - string references will 249This option does not affect C<decode> in any way - string references will
236always be decoded properly if present. 250always be decoded properly if present.
237 251
252=item $cbor = $cbor->text_keys ([$enable])
253
254=item $enabled = $cbor->get_text_keys
255
256If C<$enabled> is true (or missing), then C<encode> will encode all
257perl hash keys as CBOR text strings/UTF-8 string, upgrading them as needed.
258
259If C<$enable> is false (the default), then C<encode> will encode hash keys
260normally - upgraded perl strings (strings internally encoded as UTF-8) as
261CBOR text strings, and downgraded perl strings as CBOR byte strings.
262
263This option does not affect C<decode> in any way.
264
265This option is useful for interoperability with CBOR decoders that don't
266treat byte strings as a form of text. It is especially useful as Perl
267gives very little control over hash keys.
268
269Enabling this option can be slow, as all downgraded hash keys that are
270encoded need to be scanned and converted to UTF-8.
271
272=item $cbor = $cbor->text_strings ([$enable])
273
274=item $enabled = $cbor->get_text_strings
275
276This option works similar to C<text_keys>, above, but works on all strings
277(including hash keys), so C<text_keys> has no further effect after
278enabling C<text_strings>.
279
280If C<$enabled> is true (or missing), then C<encode> will encode all perl
281strings as CBOR text strings/UTF-8 strings, upgrading them as needed.
282
283If C<$enable> is false (the default), then C<encode> will encode strings
284normally (but see C<text_keys>) - upgraded perl strings (strings
285internally encoded as UTF-8) as CBOR text strings, and downgraded perl
286strings as CBOR byte strings.
287
288This option does not affect C<decode> in any way.
289
290This option has similar advantages and disadvantages as C<text_keys>. In
291addition, this option effectively removes the ability to encode byte
292strings, which might break some C<FREEZE> and C<TO_CBOR> methods that rely
293on this, such as bignum encoding, so this option is mainly useful for very
294simple data.
295
296=item $cbor = $cbor->validate_utf8 ([$enable])
297
298=item $enabled = $cbor->get_validate_utf8
299
300If C<$enable> is true (or missing), then C<decode> will validate that
301elements (text strings) containing UTF-8 data in fact contain valid UTF-8
302data (instead of blindly accepting it). This validation obviously takes
303extra time during decoding.
304
305The concept of "valid UTF-8" used is perl's concept, which is a superset
306of the official UTF-8.
307
308If C<$enable> is false (the default), then C<decode> will blindly accept
309UTF-8 data, marking them as valid UTF-8 in the resulting data structure
310regardless of whether that's true or not.
311
312Perl isn't too happy about corrupted UTF-8 in strings, but should
313generally not crash or do similarly evil things. Extensions might be not
314so forgiving, so it's recommended to turn on this setting if you receive
315untrusted CBOR.
316
317This option does not affect C<encode> in any way - strings that are
318supposedly valid UTF-8 will simply be dumped into the resulting CBOR
319string without checking whether that is, in fact, true or not.
320
238=item $cbor = $cbor->filter ([$cb->($tag, $value)]) 321=item $cbor = $cbor->filter ([$cb->($tag, $value)])
239 322
240=item $cb_or_undef = $cbor->get_filter 323=item $cb_or_undef = $cbor->get_filter
241 324
242Sets or replaces the tagged value decoding filter (when C<$cb> is 325Sets or replaces the tagged value decoding filter (when C<$cb> is
259function, C<CBOR::XS::default_filter>, is used. This function simply looks 342function, C<CBOR::XS::default_filter>, is used. This function simply looks
260up the tag in the C<%CBOR::XS::FILTER> hash. If an entry exists it must be 343up the tag in the C<%CBOR::XS::FILTER> hash. If an entry exists it must be
261a code reference that is called with tag and value, and is responsible for 344a code reference that is called with tag and value, and is responsible for
262decoding the value. If no entry exists, it returns no values. 345decoding the value. If no entry exists, it returns no values.
263 346
264Example: decode all tags not handled internally into CBOR::XS::Tagged 347Example: decode all tags not handled internally into C<CBOR::XS::Tagged>
265objects, with no other special handling (useful when working with 348objects, with no other special handling (useful when working with
266potentially "unsafe" CBOR data). 349potentially "unsafe" CBOR data).
267 350
268 CBOR::XS->new->filter (sub { })->decode ($cbor_data); 351 CBOR::XS->new->filter (sub { })->decode ($cbor_data);
269 352
296and you need to know where the first CBOR string ends amd the next one 379and you need to know where the first CBOR string ends amd the next one
297starts. 380starts.
298 381
299 CBOR::XS->new->decode_prefix ("......") 382 CBOR::XS->new->decode_prefix ("......")
300 => ("...", 3) 383 => ("...", 3)
384
385=back
386
387=head2 INCREMENTAL PARSING
388
389In some cases, there is the need for incremental parsing of JSON
390texts. While this module always has to keep both CBOR text and resulting
391Perl data structure in memory at one time, it does allow you to parse a
392CBOR stream incrementally, using a similar to using "decode_prefix" to see
393if a full CBOR object is available, but is much more efficient.
394
395It basically works by parsing as much of a CBOR string as possible - if
396the CBOR data is not complete yet, the pasrer will remember where it was,
397to be able to restart when more data has been accumulated. Once enough
398data is available to either decode a complete CBOR value or raise an
399error, a real decode will be attempted.
400
401A typical use case would be a network protocol that consists of sending
402and receiving CBOR-encoded messages. The solution that works with CBOR and
403about anything else is by prepending a length to every CBOR value, so the
404receiver knows how many octets to read. More compact (and slightly slower)
405would be to just send CBOR values back-to-back, as C<CBOR::XS> knows where
406a CBOR value ends, and doesn't need an explicit length.
407
408The following methods help with this:
409
410=over 4
411
412=item @decoded = $cbor->incr_parse ($buffer)
413
414This method attempts to decode exactly one CBOR value from the beginning
415of the given C<$buffer>. The value is removed from the C<$buffer> on
416success. When C<$buffer> doesn't contain a complete value yet, it returns
417nothing. Finally, when the C<$buffer> doesn't start with something
418that could ever be a valid CBOR value, it raises an exception, just as
419C<decode> would. In the latter case the decoder state is undefined and
420must be reset before being able to parse further.
421
422This method modifies the C<$buffer> in place. When no CBOR value can be
423decoded, the decoder stores the current string offset. On the next call,
424continues decoding at the place where it stopped before. For this to make
425sense, the C<$buffer> must begin with the same octets as on previous
426unsuccessful calls.
427
428You can call this method in scalar context, in which case it either
429returns a decoded value or C<undef>. This makes it impossible to
430distinguish between CBOR null values (which decode to C<undef>) and an
431unsuccessful decode, which is often acceptable.
432
433=item @decoded = $cbor->incr_parse_multiple ($buffer)
434
435Same as C<incr_parse>, but attempts to decode as many CBOR values as
436possible in one go, instead of at most one. Calls to C<incr_parse> and
437C<incr_parse_multiple> can be interleaved.
438
439=item $cbor->incr_reset
440
441Resets the incremental decoder. This throws away any saved state, so that
442subsequent calls to C<incr_parse> or C<incr_parse_multiple> start to parse
443a new CBOR value from the beginning of the C<$buffer> again.
444
445This method can be caled at any time, but it I<must> be called if you want
446to change your C<$buffer> or there was a decoding error and you want to
447reuse the C<$cbor> object for future incremental parsings.
301 448
302=back 449=back
303 450
304 451
305=head1 MAPPING 452=head1 MAPPING
356=item tagged values 503=item tagged values
357 504
358Tagged items consists of a numeric tag and another CBOR value. 505Tagged items consists of a numeric tag and another CBOR value.
359 506
360See L<TAG HANDLING AND EXTENSIONS> and the description of C<< ->filter >> 507See L<TAG HANDLING AND EXTENSIONS> and the description of C<< ->filter >>
361for details. 508for details on which tags are handled how.
362 509
363=item anything else 510=item anything else
364 511
365Anything else (e.g. unsupported simple values) will raise a decoding 512Anything else (e.g. unsupported simple values) will raise a decoding
366error. 513error.
369 516
370 517
371=head2 PERL -> CBOR 518=head2 PERL -> CBOR
372 519
373The mapping from Perl to CBOR is slightly more difficult, as Perl is a 520The mapping from Perl to CBOR is slightly more difficult, as Perl is a
374truly typeless language, so we can only guess which CBOR type is meant by 521typeless language. That means this module can only guess which CBOR type
375a Perl value. 522is meant by a perl value.
376 523
377=over 4 524=over 4
378 525
379=item hash references 526=item hash references
380 527
381Perl hash references become CBOR maps. As there is no inherent ordering in 528Perl hash references become CBOR maps. As there is no inherent ordering in
382hash keys (or CBOR maps), they will usually be encoded in a pseudo-random 529hash keys (or CBOR maps), they will usually be encoded in a pseudo-random
383order. 530order. This order can be different each time a hash is encoded.
384 531
385Currently, tied hashes will use the indefinite-length format, while normal 532Currently, tied hashes will use the indefinite-length format, while normal
386hashes will use the fixed-length format. 533hashes will use the fixed-length format.
387 534
388=item array references 535=item array references
389 536
390Perl array references become fixed-length CBOR arrays. 537Perl array references become fixed-length CBOR arrays.
391 538
392=item other references 539=item other references
393 540
394Other unblessed references are generally not allowed and will cause an 541Other unblessed references will be represented using
395exception to be thrown, except for references to the integers C<0> and 542the indirection tag extension (tag value C<22098>,
396C<1>, which get turned into false and true in CBOR. 543L<http://cbor.schmorp.de/indirection>). CBOR decoders are guaranteed
544to be able to decode these values somehow, by either "doing the right
545thing", decoding into a generic tagged object, simply ignoring the tag, or
546something else.
397 547
398=item CBOR::XS::Tagged objects 548=item CBOR::XS::Tagged objects
399 549
400Objects of this type must be arrays consisting of a single C<[tag, value]> 550Objects of this type must be arrays consisting of a single C<[tag, value]>
401pair. The (numerical) tag will be encoded as a CBOR tag, the value will 551pair. The (numerical) tag will be encoded as a CBOR tag, the value will
402be encoded as appropriate for the value. You cna use C<CBOR::XS::tag> to 552be encoded as appropriate for the value. You must use C<CBOR::XS::tag> to
403create such objects. 553create such objects.
404 554
405=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error 555=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error
406 556
407These special values become CBOR true, CBOR false and CBOR undefined 557These special values become CBOR true, CBOR false and CBOR undefined
469 619
470=back 620=back
471 621
472=head2 OBJECT SERIALISATION 622=head2 OBJECT SERIALISATION
473 623
624This module implements both a CBOR-specific and the generic
625L<Types::Serialier> object serialisation protocol. The following
626subsections explain both methods.
627
628=head3 ENCODING
629
474This module knows two way to serialise a Perl object: The CBOR-specific 630This module knows two way to serialise a Perl object: The CBOR-specific
475way, and the generic way. 631way, and the generic way.
476 632
477Whenever the encoder encounters a Perl object that it cnanot serialise 633Whenever the encoder encounters a Perl object that it cannot serialise
478directly (most of them), it will first look up the C<TO_CBOR> method on 634directly (most of them), it will first look up the C<TO_CBOR> method on
479it. 635it.
480 636
481If it has a C<TO_CBOR> method, it will call it with the object as only 637If it has a C<TO_CBOR> method, it will call it with the object as only
482argument, and expects exactly one return value, which it will then 638argument, and expects exactly one return value, which it will then
488 644
489The C<FREEZE> method can return any number of values (i.e. zero or 645The C<FREEZE> method can return any number of values (i.e. zero or
490more). These will be encoded as CBOR perl object, together with the 646more). These will be encoded as CBOR perl object, together with the
491classname. 647classname.
492 648
649These methods I<MUST NOT> change the data structure that is being
650serialised. Failure to comply to this can result in memory corruption -
651and worse.
652
493If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail 653If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail
494with an error. 654with an error.
495 655
656=head3 DECODING
657
496Objects encoded via C<TO_CBOR> cannot be automatically decoded, but 658Objects encoded via C<TO_CBOR> cannot (normally) be automatically decoded,
497objects encoded via C<FREEZE> can be decoded using the following protocol: 659but objects encoded via C<FREEZE> can be decoded using the following
660protocol:
498 661
499When an encoded CBOR perl object is encountered by the decoder, it will 662When an encoded CBOR perl object is encountered by the decoder, it will
500look up the C<THAW> method, by using the stored classname, and will fail 663look up the C<THAW> method, by using the stored classname, and will fail
501if the method cannot be found. 664if the method cannot be found.
502 665
503After the lookup it will call the C<THAW> method with the stored classname 666After the lookup it will call the C<THAW> method with the stored classname
504as first argument, the constant string C<CBOR> as second argument, and all 667as first argument, the constant string C<CBOR> as second argument, and all
505values returned by C<FREEZE> as remaining arguments. 668values returned by C<FREEZE> as remaining arguments.
506 669
507=head4 EXAMPLES 670=head3 EXAMPLES
508 671
509Here is an example C<TO_CBOR> method: 672Here is an example C<TO_CBOR> method:
510 673
511 sub My::Object::TO_CBOR { 674 sub My::Object::TO_CBOR {
512 my ($obj) = @_; 675 my ($obj) = @_;
523 686
524 sub URI::TO_CBOR { 687 sub URI::TO_CBOR {
525 my ($self) = @_; 688 my ($self) = @_;
526 my $uri = "$self"; # stringify uri 689 my $uri = "$self"; # stringify uri
527 utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string 690 utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string
528 CBOR::XS::tagged 32, "$_[0]" 691 CBOR::XS::tag 32, "$_[0]"
529 } 692 }
530 693
531This will encode URIs as a UTF-8 string with tag 32, which indicates an 694This will encode URIs as a UTF-8 string with tag 32, which indicates an
532URI. 695URI.
533 696
544 "$self" # encode url string 707 "$self" # encode url string
545 } 708 }
546 709
547 sub URI::THAW { 710 sub URI::THAW {
548 my ($class, $serialiser, $uri) = @_; 711 my ($class, $serialiser, $uri) = @_;
549
550 $class->new ($uri) 712 $class->new ($uri)
551 } 713 }
552 714
553Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For 715Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For
554example, a C<FREEZE> method that returns "type", "id" and "variant" values 716example, a C<FREEZE> method that returns "type", "id" and "variant" values
685additional tags (such as base64url). 847additional tags (such as base64url).
686 848
687=head2 ENFORCED TAGS 849=head2 ENFORCED TAGS
688 850
689These tags are always handled when decoding, and their handling cannot be 851These tags are always handled when decoding, and their handling cannot be
690overriden by the user. 852overridden by the user.
691 853
692=over 4 854=over 4
693 855
694=item 26 (perl-object, L<http://cbor.schmorp.de/perl-object>) 856=item 26 (perl-object, L<http://cbor.schmorp.de/perl-object>)
695 857
696These tags are automatically created (and decoded) for serialisable 858These tags are automatically created (and decoded) for serialisable
697objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object 859objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object
698serialisation protocol). See L<OBJECT SERIALISATION> for details. 860serialisation protocol). See L<OBJECT SERIALISATION> for details.
699 861
700=item 28, 29 (sharable, sharedref, L <http://cbor.schmorp.de/value-sharing>) 862=item 28, 29 (shareable, sharedref, L<http://cbor.schmorp.de/value-sharing>)
701 863
702These tags are automatically decoded when encountered, resulting in 864These tags are automatically decoded when encountered (and they do not
865result in a cyclic data structure, see C<allow_cycles>), resulting in
703shared values in the decoded object. They are only encoded, however, when 866shared values in the decoded object. They are only encoded, however, when
704C<allow_sharable> is enabled. 867C<allow_sharing> is enabled.
705 868
869Not all shared values can be successfully decoded: values that reference
870themselves will I<currently> decode as C<undef> (this is not the same
871as a reference pointing to itself, which will be represented as a value
872that contains an indirect reference to itself - these will be decoded
873properly).
874
875Note that considerably more shared value data structures can be decoded
876than will be encoded - currently, only values pointed to by references
877will be shared, others will not. While non-reference shared values can be
878generated in Perl with some effort, they were considered too unimportant
879to be supported in the encoder. The decoder, however, will decode these
880values as shared values.
881
706=item 256, 25 (stringref-namespace, stringref, L <http://cbor.schmorp.de/stringref>) 882=item 256, 25 (stringref-namespace, stringref, L<http://cbor.schmorp.de/stringref>)
707 883
708These tags are automatically decoded when encountered. They are only 884These tags are automatically decoded when encountered. They are only
709encoded, however, when C<pack_strings> is enabled. 885encoded, however, when C<pack_strings> is enabled.
710 886
711=item 22098 (indirection, L<http://cbor.schmorp.de/indirection>) 887=item 22098 (indirection, L<http://cbor.schmorp.de/indirection>)
712 888
713This tag is automatically generated when a reference are encountered (with 889This tag is automatically generated when a reference are encountered (with
714the exception of hash and array refernces). It is converted to a reference 890the exception of hash and array references). It is converted to a reference
715when decoding. 891when decoding.
716 892
717=item 55799 (self-describe CBOR, RFC 7049) 893=item 55799 (self-describe CBOR, RFC 7049)
718 894
719This value is not generated on encoding (unless explicitly requested by 895This value is not generated on encoding (unless explicitly requested by
722=back 898=back
723 899
724=head2 NON-ENFORCED TAGS 900=head2 NON-ENFORCED TAGS
725 901
726These tags have default filters provided when decoding. Their handling can 902These tags have default filters provided when decoding. Their handling can
727be overriden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by 903be overridden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by
728providing a custom C<filter> callback when decoding. 904providing a custom C<filter> callback when decoding.
729 905
730When they result in decoding into a specific Perl class, the module 906When they result in decoding into a specific Perl class, the module
731usually provides a corresponding C<TO_CBOR> method as well. 907usually provides a corresponding C<TO_CBOR> method as well.
732 908
735provide these modules. The decoding usually fails with an exception if the 911provide these modules. The decoding usually fails with an exception if the
736required module cannot be loaded. 912required module cannot be loaded.
737 913
738=over 4 914=over 4
739 915
916=item 0, 1 (date/time string, seconds since the epoch)
917
918These tags are decoded into L<Time::Piece> objects. The corresponding
919C<Time::Piece::TO_CBOR> method always encodes into tag 1 values currently.
920
921The L<Time::Piece> API is generally surprisingly bad, and fractional
922seconds are only accidentally kept intact, so watch out. On the plus side,
923the module comes with perl since 5.10, which has to count for something.
924
740=item 2, 3 (positive/negative bignum) 925=item 2, 3 (positive/negative bignum)
741 926
742These tags are decoded into L<Math::BigInt> objects. The corresponding 927These tags are decoded into L<Math::BigInt> objects. The corresponding
743C<Math::BigInt::TO_CBOR> method encodes "small" bigints into normal CBOR 928C<Math::BigInt::TO_CBOR> method encodes "small" bigints into normal CBOR
744integers, and others into positive/negative CBOR bignums. 929integers, and others into positive/negative CBOR bignums.
765C<URI::TO_CBOR> method again results in a CBOR URI value. 950C<URI::TO_CBOR> method again results in a CBOR URI value.
766 951
767=back 952=back
768 953
769=cut 954=cut
770
771our %FILTER = (
772 # 0 # rfc4287 datetime, utf-8
773 # 1 # unix timestamp, any
774
775 2 => sub { # pos bigint
776 require Math::BigInt;
777 Math::BigInt->new ("0x" . unpack "H*", pop)
778 },
779
780 3 => sub { # neg bigint
781 require Math::BigInt;
782 -Math::BigInt->new ("0x" . unpack "H*", pop)
783 },
784
785 4 => sub { # decimal fraction, array
786 require Math::BigFloat;
787 Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
788 },
789
790 5 => sub { # bigfloat, array
791 require Math::BigFloat;
792 scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2)
793 },
794
795 21 => sub { pop }, # expected conversion to base64url encoding
796 22 => sub { pop }, # expected conversion to base64 encoding
797 23 => sub { pop }, # expected conversion to base16 encoding
798
799 # 24 # embedded cbor, byte string
800
801 32 => sub {
802 require URI;
803 URI->new (pop)
804 },
805
806 # 33 # base64url rfc4648, utf-8
807 # 34 # base64 rfc46484, utf-8
808 # 35 # regex pcre/ecma262, utf-8
809 # 36 # mime message rfc2045, utf-8
810);
811
812 955
813=head1 CBOR and JSON 956=head1 CBOR and JSON
814 957
815CBOR is supposed to implement a superset of the JSON data model, and is, 958CBOR is supposed to implement a superset of the JSON data model, and is,
816with some coercion, able to represent all JSON texts (something that other 959with some coercion, able to represent all JSON texts (something that other
877properly. Half precision types are accepted, but not encoded. 1020properly. Half precision types are accepted, but not encoded.
878 1021
879Strict mode and canonical mode are not implemented. 1022Strict mode and canonical mode are not implemented.
880 1023
881 1024
1025=head1 LIMITATIONS ON PERLS WITHOUT 64-BIT INTEGER SUPPORT
1026
1027On perls that were built without 64 bit integer support (these are rare
1028nowadays, even on 32 bit architectures, as all major Perl distributions
1029are built with 64 bit integer support), support for any kind of 64 bit
1030integer in CBOR is very limited - most likely, these 64 bit values will
1031be truncated, corrupted, or otherwise not decoded correctly. This also
1032includes string, array and map sizes that are stored as 64 bit integers.
1033
1034
882=head1 THREADS 1035=head1 THREADS
883 1036
884This module is I<not> guaranteed to be thread safe and there are no 1037This module is I<not> guaranteed to be thread safe and there are no
885plans to change this until Perl gets thread support (as opposed to the 1038plans to change this until Perl gets thread support (as opposed to the
886horribly slow so-called "threads" which are simply slow and bloated 1039horribly slow so-called "threads" which are simply slow and bloated
899service. I put the contact address into my modules for a reason. 1052service. I put the contact address into my modules for a reason.
900 1053
901=cut 1054=cut
902 1055
903our %FILTER = ( 1056our %FILTER = (
904 # 0 # rfc4287 datetime, utf-8 1057 0 => sub { # rfc4287 datetime, utf-8
905 # 1 # unix timestamp, any 1058 require Time::Piece;
1059 # Time::Piece::Strptime uses the "incredibly flexible date parsing routine"
1060 # from FreeBSD, which can't parse ISO 8601, RFC3339, RFC4287 or much of anything
1061 # else either. Whats incredibe over standard strptime totally escapes me.
1062 # doesn't do fractional times, either. sigh.
1063 # In fact, it's all a lie, it uses whatever strptime it wants, and of course,
1064 # they are all incompatible. The openbsd one simply ignores %z (but according to the
1065 # docs, it would be much more incredibly flexible indeed. If it worked, that is.).
1066 scalar eval {
1067 my $s = $_[1];
1068
1069 $s =~ s/Z$/+00:00/;
1070 $s =~ s/(\.[0-9]+)?([+-][0-9][0-9]):([0-9][0-9])$//
1071 or die;
1072
1073 my $b = $1 - ($2 * 60 + $3) * 60; # fractional part + offset. hopefully
1074 my $d = Time::Piece->strptime ($s, "%Y-%m-%dT%H:%M:%S");
1075
1076 Time::Piece::gmtime ($d->epoch + $b)
1077 } || die "corrupted CBOR date/time string ($_[0])";
1078 },
1079
1080 1 => sub { # seconds since the epoch, possibly fractional
1081 require Time::Piece;
1082 scalar Time::Piece::gmtime (pop)
1083 },
906 1084
907 2 => sub { # pos bigint 1085 2 => sub { # pos bigint
908 require Math::BigInt; 1086 require Math::BigInt;
909 Math::BigInt->new ("0x" . unpack "H*", pop) 1087 Math::BigInt->new ("0x" . unpack "H*", pop)
910 }, 1088 },
919 Math::BigFloat->new ($_[1][1] . "E" . $_[1][0]) 1097 Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
920 }, 1098 },
921 1099
922 5 => sub { # bigfloat, array 1100 5 => sub { # bigfloat, array
923 require Math::BigFloat; 1101 require Math::BigFloat;
924 scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2) 1102 scalar Math::BigFloat->new ($_[1][1]) * Math::BigFloat->new (2)->bpow ($_[1][0])
925 }, 1103 },
926 1104
927 21 => sub { pop }, # expected conversion to base64url encoding 1105 21 => sub { pop }, # expected conversion to base64url encoding
928 22 => sub { pop }, # expected conversion to base64 encoding 1106 22 => sub { pop }, # expected conversion to base64 encoding
929 23 => sub { pop }, # expected conversion to base16 encoding 1107 23 => sub { pop }, # expected conversion to base16 encoding
946} 1124}
947 1125
948sub URI::TO_CBOR { 1126sub URI::TO_CBOR {
949 my $uri = $_[0]->as_string; 1127 my $uri = $_[0]->as_string;
950 utf8::upgrade $uri; 1128 utf8::upgrade $uri;
951 CBOR::XS::tag 32, $uri 1129 tag 32, $uri
952} 1130}
953 1131
954sub Math::BigInt::TO_CBOR { 1132sub Math::BigInt::TO_CBOR {
955 if ($_[0] >= -2147483648 && $_[0] <= 2147483647) { 1133 if ($_[0] >= -2147483648 && $_[0] <= 2147483647) {
956 $_[0]->numify 1134 $_[0]->numify
957 } else { 1135 } else {
958 my $hex = substr $_[0]->as_hex, 2; 1136 my $hex = substr $_[0]->as_hex, 2;
959 $hex = "0$hex" if 1 & length $hex; # sigh 1137 $hex = "0$hex" if 1 & length $hex; # sigh
960 CBOR::XS::tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex 1138 tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex
961 } 1139 }
962} 1140}
963 1141
964sub Math::BigFloat::TO_CBOR { 1142sub Math::BigFloat::TO_CBOR {
965 my ($m, $e) = $_[0]->parts; 1143 my ($m, $e) = $_[0]->parts;
966 CBOR::XS::tag 4, [$e->numify, $m] 1144 tag 4, [$e->numify, $m]
1145}
1146
1147sub Time::Piece::TO_CBOR {
1148 tag 1, 0 + $_[0]->epoch
967} 1149}
968 1150
969XSLoader::load "CBOR::XS", $VERSION; 1151XSLoader::load "CBOR::XS", $VERSION;
970 1152
971=head1 SEE ALSO 1153=head1 SEE ALSO

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