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Revision 1.25 by root, Thu Nov 28 12:08:07 2013 UTC vs.
Revision 1.53 by root, Mon Apr 25 18:20:22 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(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<$enable> is true (or missing), then C<encode> will try not to encode
224also results in a very large runtime overhead (expect encoding times to be 238also results in a very large runtime overhead (expect encoding times to be
2252-4 times as high as without). 2392-4 times as high as without).
226 240
227It is recommended to leave it off unless you know your 241It is recommended to leave it off unless you know your
228communications partner supports the stringref extension to CBOR 242communications partner supports the stringref extension to CBOR
229(http://cbor.schmorp.de/stringref), as without decoder support, the 243(L<http://cbor.schmorp.de/stringref>), as without decoder support, the
230resulting data structure might not be usable. 244resulting data structure might not be usable.
231 245
232If C<$enable> is false (the default), then C<encode> will encode strings 246If C<$enable> is false (the default), then C<encode> will encode strings
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.
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.
237 320
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 = $cbor->get_filter
241 324
259function, C<CBOR::XS::default_filter>, is used. This function simply looks 342function, C<CBOR::XS::default_filter>, is used. This function simply looks
260up the tag in the C<%CBOR::XS::FILTER> hash. If an entry exists it must be 343up the tag in the C<%CBOR::XS::FILTER> hash. If an entry exists it must be
261a code reference that is called with tag and value, and is responsible for 344a code reference that is called with tag and value, and is responsible for
262decoding the value. If no entry exists, it returns no values. 345decoding the value. If no entry exists, it returns no values.
263 346
264Example: decode all tags not handled internally into CBOR::XS::Tagged 347Example: decode all tags not handled internally into C<CBOR::XS::Tagged>
265objects, with no other special handling (useful when working with 348objects, with no other special handling (useful when working with
266potentially "unsafe" CBOR data). 349potentially "unsafe" CBOR data).
267 350
268 CBOR::XS->new->filter (sub { })->decode ($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
323CBOR integers become (numeric) perl scalars. On perls without 64 bit 470CBOR integers become (numeric) perl scalars. On perls without 64 bit
324support, 64 bit integers will be truncated or otherwise corrupted. 471support, 64 bit integers will be truncated or otherwise corrupted.
325 472
326=item byte strings 473=item byte strings
327 474
328Byte strings will become octet strings in Perl (the byte values 0..255 475Byte strings will become octet strings in Perl (the Byte values 0..255
329will simply become characters of the same value in Perl). 476will simply become characters of the same value in Perl).
330 477
331=item UTF-8 strings 478=item UTF-8 strings
332 479
333UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be 480UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be
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
424 # dump as number 574 # dump as number
425 encode_cbor [2] # yields [2] 575 encode_cbor [2] # yields [2]
426 encode_cbor [-3.0e17] # yields [-3e+17] 576 encode_cbor [-3.0e17] # yields [-3e+17]
427 my $value = 5; encode_cbor [$value] # yields [5] 577 my $value = 5; encode_cbor [$value] # yields [5]
428 578
429 # used as string, so dump as string 579 # used as string, so dump as string (either byte or text)
430 print $value; 580 print $value;
431 encode_cbor [$value] # yields ["5"] 581 encode_cbor [$value] # yields ["5"]
432 582
433 # undef becomes null 583 # undef becomes null
434 encode_cbor [undef] # yields [null] 584 encode_cbor [undef] # yields [null]
437 587
438 my $x = 3.1; # some variable containing a number 588 my $x = 3.1; # some variable containing a number
439 "$x"; # stringified 589 "$x"; # stringified
440 $x .= ""; # another, more awkward way to stringify 590 $x .= ""; # another, more awkward way to stringify
441 print $x; # perl does it for you, too, quite often 591 print $x; # perl does it for you, too, quite often
592
593You can force whether a string is encoded as byte or text string by using
594C<utf8::upgrade> and C<utf8::downgrade> (if C<text_strings> is disabled):
595
596 utf8::upgrade $x; # encode $x as text string
597 utf8::downgrade $x; # encode $x as byte string
598
599Perl doesn't define what operations up- and downgrade strings, so if the
600difference between byte and text is important, you should up- or downgrade
601your string as late as possible before encoding. You can also force the
602use of CBOR text strings by using C<text_keys> or C<text_strings>.
442 603
443You can force the type to be a CBOR number by numifying it: 604You can force the type to be a CBOR number by numifying it:
444 605
445 my $x = "3"; # some variable containing a string 606 my $x = "3"; # some variable containing a string
446 $x += 0; # numify it, ensuring it will be dumped as a number 607 $x += 0; # numify it, ensuring it will be dumped as a number
459 620
460=back 621=back
461 622
462=head2 OBJECT SERIALISATION 623=head2 OBJECT SERIALISATION
463 624
625This module implements both a CBOR-specific and the generic
626L<Types::Serialier> object serialisation protocol. The following
627subsections explain both methods.
628
629=head3 ENCODING
630
464This module knows two way to serialise a Perl object: The CBOR-specific 631This module knows two way to serialise a Perl object: The CBOR-specific
465way, and the generic way. 632way, and the generic way.
466 633
467Whenever the encoder encounters a Perl object that it cnanot serialise 634Whenever the encoder encounters a Perl object that it cannot serialise
468directly (most of them), it will first look up the C<TO_CBOR> method on 635directly (most of them), it will first look up the C<TO_CBOR> method on
469it. 636it.
470 637
471If it has a C<TO_CBOR> method, it will call it with the object as only 638If it has a C<TO_CBOR> method, it will call it with the object as only
472argument, and expects exactly one return value, which it will then 639argument, and expects exactly one return value, which it will then
478 645
479The C<FREEZE> method can return any number of values (i.e. zero or 646The C<FREEZE> method can return any number of values (i.e. zero or
480more). These will be encoded as CBOR perl object, together with the 647more). These will be encoded as CBOR perl object, together with the
481classname. 648classname.
482 649
650These methods I<MUST NOT> change the data structure that is being
651serialised. Failure to comply to this can result in memory corruption -
652and worse.
653
483If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail 654If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail
484with an error. 655with an error.
485 656
657=head3 DECODING
658
486Objects encoded via C<TO_CBOR> cannot be automatically decoded, but 659Objects encoded via C<TO_CBOR> cannot (normally) be automatically decoded,
487objects encoded via C<FREEZE> can be decoded using the following protocol: 660but objects encoded via C<FREEZE> can be decoded using the following
661protocol:
488 662
489When an encoded CBOR perl object is encountered by the decoder, it will 663When an encoded CBOR perl object is encountered by the decoder, it will
490look up the C<THAW> method, by using the stored classname, and will fail 664look up the C<THAW> method, by using the stored classname, and will fail
491if the method cannot be found. 665if the method cannot be found.
492 666
493After the lookup it will call the C<THAW> method with the stored classname 667After the lookup it will call the C<THAW> method with the stored classname
494as first argument, the constant string C<CBOR> as second argument, and all 668as first argument, the constant string C<CBOR> as second argument, and all
495values returned by C<FREEZE> as remaining arguments. 669values returned by C<FREEZE> as remaining arguments.
496 670
497=head4 EXAMPLES 671=head3 EXAMPLES
498 672
499Here is an example C<TO_CBOR> method: 673Here is an example C<TO_CBOR> method:
500 674
501 sub My::Object::TO_CBOR { 675 sub My::Object::TO_CBOR {
502 my ($obj) = @_; 676 my ($obj) = @_;
513 687
514 sub URI::TO_CBOR { 688 sub URI::TO_CBOR {
515 my ($self) = @_; 689 my ($self) = @_;
516 my $uri = "$self"; # stringify uri 690 my $uri = "$self"; # stringify uri
517 utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string 691 utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string
518 CBOR::XS::tagged 32, "$_[0]" 692 CBOR::XS::tag 32, "$_[0]"
519 } 693 }
520 694
521This will encode URIs as a UTF-8 string with tag 32, which indicates an 695This will encode URIs as a UTF-8 string with tag 32, which indicates an
522URI. 696URI.
523 697
534 "$self" # encode url string 708 "$self" # encode url string
535 } 709 }
536 710
537 sub URI::THAW { 711 sub URI::THAW {
538 my ($class, $serialiser, $uri) = @_; 712 my ($class, $serialiser, $uri) = @_;
539
540 $class->new ($uri) 713 $class->new ($uri)
541 } 714 }
542 715
543Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For 716Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For
544example, a C<FREEZE> method that returns "type", "id" and "variant" values 717example, a C<FREEZE> method that returns "type", "id" and "variant" values
675additional tags (such as base64url). 848additional tags (such as base64url).
676 849
677=head2 ENFORCED TAGS 850=head2 ENFORCED TAGS
678 851
679These tags are always handled when decoding, and their handling cannot be 852These tags are always handled when decoding, and their handling cannot be
680overriden by the user. 853overridden by the user.
681 854
682=over 4 855=over 4
683 856
684=item <unassigned> (perl-object, L<http://cbor.schmorp.de/perl-object>) 857=item 26 (perl-object, L<http://cbor.schmorp.de/perl-object>)
685 858
686These tags are automatically created (and decoded) for serialisable 859These tags are automatically created (and decoded) for serialisable
687objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object 860objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object
688serialisation protocol). See L<OBJECT SERIALISATION> for details. 861serialisation protocol). See L<OBJECT SERIALISATION> for details.
689 862
690=item <unassigned>, <unassigned> (sharable, sharedref, L <http://cbor.schmorp.de/value-sharing>) 863=item 28, 29 (shareable, sharedref, L<http://cbor.schmorp.de/value-sharing>)
691 864
692These tags are automatically decoded when encountered, resulting in 865These tags are automatically decoded when encountered (and they do not
866result in a cyclic data structure, see C<allow_cycles>), resulting in
693shared values in the decoded object. They are only encoded, however, when 867shared values in the decoded object. They are only encoded, however, when
694C<allow_sharable> is enabled. 868C<allow_sharing> is enabled.
695 869
870Not all shared values can be successfully decoded: values that reference
871themselves will I<currently> decode as C<undef> (this is not the same
872as a reference pointing to itself, which will be represented as a value
873that contains an indirect reference to itself - these will be decoded
874properly).
875
876Note that considerably more shared value data structures can be decoded
877than will be encoded - currently, only values pointed to by references
878will be shared, others will not. While non-reference shared values can be
879generated in Perl with some effort, they were considered too unimportant
880to be supported in the encoder. The decoder, however, will decode these
881values as shared values.
882
696=item <unassigned>, <unassigned> (stringref-namespace, stringref, L <http://cbor.schmorp.de/stringref>) 883=item 256, 25 (stringref-namespace, stringref, L<http://cbor.schmorp.de/stringref>)
697 884
698These tags are automatically decoded when encountered. They are only 885These tags are automatically decoded when encountered. They are only
699encoded, however, when C<pack_strings> is enabled. 886encoded, however, when C<pack_strings> is enabled.
700 887
701=item 22098 (indirection, L<http://cbor.schmorp.de/indirection>) 888=item 22098 (indirection, L<http://cbor.schmorp.de/indirection>)
702 889
703This tag is automatically generated when a reference are encountered (with 890This tag is automatically generated when a reference are encountered (with
704the exception of hash and array refernces). It is converted to a reference 891the exception of hash and array references). It is converted to a reference
705when decoding. 892when decoding.
706 893
707=item 55799 (self-describe CBOR, RFC 7049) 894=item 55799 (self-describe CBOR, RFC 7049)
708 895
709This value is not generated on encoding (unless explicitly requested by 896This value is not generated on encoding (unless explicitly requested by
712=back 899=back
713 900
714=head2 NON-ENFORCED TAGS 901=head2 NON-ENFORCED TAGS
715 902
716These tags have default filters provided when decoding. Their handling can 903These tags have default filters provided when decoding. Their handling can
717be overriden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by 904be overridden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by
718providing a custom C<filter> callback when decoding. 905providing a custom C<filter> callback when decoding.
719 906
720When they result in decoding into a specific Perl class, the module 907When they result in decoding into a specific Perl class, the module
721usually provides a corresponding C<TO_CBOR> method as well. 908usually provides a corresponding C<TO_CBOR> method as well.
722 909
725provide these modules. The decoding usually fails with an exception if the 912provide these modules. The decoding usually fails with an exception if the
726required module cannot be loaded. 913required module cannot be loaded.
727 914
728=over 4 915=over 4
729 916
917=item 0, 1 (date/time string, seconds since the epoch)
918
919These tags are decoded into L<Time::Piece> objects. The corresponding
920C<Time::Piece::TO_CBOR> method always encodes into tag 1 values currently.
921
922The L<Time::Piece> API is generally surprisingly bad, and fractional
923seconds are only accidentally kept intact, so watch out. On the plus side,
924the module comes with perl since 5.10, which has to count for something.
925
730=item 2, 3 (positive/negative bignum) 926=item 2, 3 (positive/negative bignum)
731 927
732These tags are decoded into L<Math::BigInt> objects. The corresponding 928These tags are decoded into L<Math::BigInt> objects. The corresponding
733C<Math::BigInt::TO_CBOR> method encodes "small" bigints into normal CBOR 929C<Math::BigInt::TO_CBOR> method encodes "small" bigints into normal CBOR
734integers, and others into positive/negative CBOR bignums. 930integers, and others into positive/negative CBOR bignums.
755C<URI::TO_CBOR> method again results in a CBOR URI value. 951C<URI::TO_CBOR> method again results in a CBOR URI value.
756 952
757=back 953=back
758 954
759=cut 955=cut
760
761our %FILTER = (
762 # 0 # rfc4287 datetime, utf-8
763 # 1 # unix timestamp, any
764
765 2 => sub { # pos bigint
766 require Math::BigInt;
767 Math::BigInt->new ("0x" . unpack "H*", pop)
768 },
769
770 3 => sub { # neg bigint
771 require Math::BigInt;
772 -Math::BigInt->new ("0x" . unpack "H*", pop)
773 },
774
775 4 => sub { # decimal fraction, array
776 require Math::BigFloat;
777 Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
778 },
779
780 5 => sub { # bigfloat, array
781 require Math::BigFloat;
782 scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2)
783 },
784
785 21 => sub { pop }, # expected conversion to base64url encoding
786 22 => sub { pop }, # expected conversion to base64 encoding
787 23 => sub { pop }, # expected conversion to base16 encoding
788
789 # 24 # embedded cbor, byte string
790
791 32 => sub {
792 require URI;
793 URI->new (pop)
794 },
795
796 # 33 # base64url rfc4648, utf-8
797 # 34 # base64 rfc46484, utf-8
798 # 35 # regex pcre/ecma262, utf-8
799 # 36 # mime message rfc2045, utf-8
800);
801
802 956
803=head1 CBOR and JSON 957=head1 CBOR and JSON
804 958
805CBOR is supposed to implement a superset of the JSON data model, and is, 959CBOR is supposed to implement a superset of the JSON data model, and is,
806with some coercion, able to represent all JSON texts (something that other 960with some coercion, able to represent all JSON texts (something that other
867properly. Half precision types are accepted, but not encoded. 1021properly. Half precision types are accepted, but not encoded.
868 1022
869Strict mode and canonical mode are not implemented. 1023Strict mode and canonical mode are not implemented.
870 1024
871 1025
1026=head1 LIMITATIONS ON PERLS WITHOUT 64-BIT INTEGER SUPPORT
1027
1028On perls that were built without 64 bit integer support (these are rare
1029nowadays, even on 32 bit architectures, as all major Perl distributions
1030are built with 64 bit integer support), support for any kind of 64 bit
1031integer in CBOR is very limited - most likely, these 64 bit values will
1032be truncated, corrupted, or otherwise not decoded correctly. This also
1033includes string, array and map sizes that are stored as 64 bit integers.
1034
1035
872=head1 THREADS 1036=head1 THREADS
873 1037
874This module is I<not> guaranteed to be thread safe and there are no 1038This module is I<not> guaranteed to be thread safe and there are no
875plans to change this until Perl gets thread support (as opposed to the 1039plans to change this until Perl gets thread support (as opposed to the
876horribly slow so-called "threads" which are simply slow and bloated 1040horribly slow so-called "threads" which are simply slow and bloated
889service. I put the contact address into my modules for a reason. 1053service. I put the contact address into my modules for a reason.
890 1054
891=cut 1055=cut
892 1056
893our %FILTER = ( 1057our %FILTER = (
894 # 0 # rfc4287 datetime, utf-8 1058 0 => sub { # rfc4287 datetime, utf-8
895 # 1 # unix timestamp, any 1059 require Time::Piece;
1060 # Time::Piece::Strptime uses the "incredibly flexible date parsing routine"
1061 # from FreeBSD, which can't parse ISO 8601, RFC3339, RFC4287 or much of anything
1062 # else either. Whats incredibe over standard strptime totally escapes me.
1063 # doesn't do fractional times, either. sigh.
1064 # In fact, it's all a lie, it uses whatever strptime it wants, and of course,
1065 # they are all incompatible. The openbsd one simply ignores %z (but according to the
1066 # docs, it would be much more incredibly flexible indeed. If it worked, that is.).
1067 scalar eval {
1068 my $s = $_[1];
1069
1070 $s =~ s/Z$/+00:00/;
1071 $s =~ s/(\.[0-9]+)?([+-][0-9][0-9]):([0-9][0-9])$//
1072 or die;
1073
1074 my $b = $1 - ($2 * 60 + $3) * 60; # fractional part + offset. hopefully
1075 my $d = Time::Piece->strptime ($s, "%Y-%m-%dT%H:%M:%S");
1076
1077 Time::Piece::gmtime ($d->epoch + $b)
1078 } || die "corrupted CBOR date/time string ($_[0])";
1079 },
1080
1081 1 => sub { # seconds since the epoch, possibly fractional
1082 require Time::Piece;
1083 scalar Time::Piece::gmtime (pop)
1084 },
896 1085
897 2 => sub { # pos bigint 1086 2 => sub { # pos bigint
898 require Math::BigInt; 1087 require Math::BigInt;
899 Math::BigInt->new ("0x" . unpack "H*", pop) 1088 Math::BigInt->new ("0x" . unpack "H*", pop)
900 }, 1089 },
909 Math::BigFloat->new ($_[1][1] . "E" . $_[1][0]) 1098 Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
910 }, 1099 },
911 1100
912 5 => sub { # bigfloat, array 1101 5 => sub { # bigfloat, array
913 require Math::BigFloat; 1102 require Math::BigFloat;
914 scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2) 1103 scalar Math::BigFloat->new ($_[1][1]) * Math::BigFloat->new (2)->bpow ($_[1][0])
915 }, 1104 },
916 1105
917 21 => sub { pop }, # expected conversion to base64url encoding 1106 21 => sub { pop }, # expected conversion to base64url encoding
918 22 => sub { pop }, # expected conversion to base64 encoding 1107 22 => sub { pop }, # expected conversion to base64 encoding
919 23 => sub { pop }, # expected conversion to base16 encoding 1108 23 => sub { pop }, # expected conversion to base16 encoding
936} 1125}
937 1126
938sub URI::TO_CBOR { 1127sub URI::TO_CBOR {
939 my $uri = $_[0]->as_string; 1128 my $uri = $_[0]->as_string;
940 utf8::upgrade $uri; 1129 utf8::upgrade $uri;
941 CBOR::XS::tag 32, $uri 1130 tag 32, $uri
942} 1131}
943 1132
944sub Math::BigInt::TO_CBOR { 1133sub Math::BigInt::TO_CBOR {
945 if ($_[0] >= -2147483648 && $_[0] <= 2147483647) { 1134 if ($_[0] >= -2147483648 && $_[0] <= 2147483647) {
946 $_[0]->numify 1135 $_[0]->numify
947 } else { 1136 } else {
948 my $hex = substr $_[0]->as_hex, 2; 1137 my $hex = substr $_[0]->as_hex, 2;
949 $hex = "0$hex" if 1 & length $hex; # sigh 1138 $hex = "0$hex" if 1 & length $hex; # sigh
950 CBOR::XS::tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex 1139 tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex
951 } 1140 }
952} 1141}
953 1142
954sub Math::BigFloat::TO_CBOR { 1143sub Math::BigFloat::TO_CBOR {
955 my ($m, $e) = $_[0]->parts; 1144 my ($m, $e) = $_[0]->parts;
956 CBOR::XS::tag 4, [$e->numify, $m] 1145 tag 4, [$e->numify, $m]
1146}
1147
1148sub Time::Piece::TO_CBOR {
1149 tag 1, 0 + $_[0]->epoch
957} 1150}
958 1151
959XSLoader::load "CBOR::XS", $VERSION; 1152XSLoader::load "CBOR::XS", $VERSION;
960 1153
961=head1 SEE ALSO 1154=head1 SEE ALSO

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