[ViewVC] Diff of: cvs/CBOR-XS/XS.pm

Comparing CBOR-XS/XS.pm (file contents):
Revision 1.19 by root, Wed Nov 20 01:09:46 2013 UTC vs.
Revision 1.32 by root, Sat Nov 30 18:42:27 2013 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
31	WARNING! This module is very new, and not very well tested (that's up to
32	you to do). Furthermore, details of the implementation might change freely
33	before version 1.0. And lastly, the object serialisation protocol depends
34	on a pending IANA assignment, and until that assignment is official, this
35	implementation is not interoperable with other implementations (even
36	future versions of this module) until the assignment is done.
37
38	You are still invited to try out CBOR, and this module.
39
40	This module converts Perl data structures to the Concise Binary Object	31	This module converts Perl data structures to the Concise Binary Object
41	Representation (CBOR) and vice versa. CBOR is a fast binary serialisation	32	Representation (CBOR) and vice versa. CBOR is a fast binary serialisation
42	format that aims to use a superset of the JSON data model, i.e. when you	33	format that aims to use an (almost) superset of the JSON data model, i.e.
43	can represent something in JSON, you should be able to represent it in	34	when you can represent something useful in JSON, you should be able to
44	CBOR.	35	represent it in CBOR.
45		36
46	In short, CBOR is a faster and very compact binary alternative to JSON,	37	In short, CBOR is a faster and quite compact binary alternative to JSON,
47	with the added ability of supporting serialisation of Perl objects. (JSON	38	with the added ability of supporting serialisation of Perl objects. (JSON
48	often compresses better than CBOR though, so if you plan to compress the	39	often compresses better than CBOR though, so if you plan to compress the
49	data later you might want to compare both formats first).	40	data later and speed is less important you might want to compare both
		41	formats first).
50		42
51	To give you a general idea about speed, with texts in the megabyte range,	43	To give you a general idea about speed, with texts in the megabyte range,
52	C<CBOR::XS> usually encodes roughly twice as fast as L<Storable> or	44	C<CBOR::XS> usually encodes roughly twice as fast as L<Storable> or
53	L<JSON::XS> and decodes about 15%-30% faster than those. The shorter the	45	L<JSON::XS> and decodes about 15%-30% faster than those. The shorter the
54	data, the worse L<Storable> performs in comparison.	46	data, the worse L<Storable> performs in comparison.
55		47
56	As for compactness, C<CBOR::XS> encoded data structures are usually about	48	Regarding compactness, C<CBOR::XS>-encoded data structures are usually
57	20% smaller than the same data encoded as (compact) JSON or L<Storable>.	49	about 20% smaller than the same data encoded as (compact) JSON or
		50	L<Storable>.
		51
		52	In addition to the core CBOR data format, this module implements a
		53	number of extensions, to support cyclic and shared data structures
		54	(see C<allow_sharing> and C<allow_cycles>), string deduplication (see
		55	C<pack_strings>) and scalar references (always enabled).
58		56
59	The primary goal of this module is to be I<correct> and the secondary goal	57	The primary goal of this module is to be I<correct> and the secondary goal
60	is to be I<fast>. To reach the latter goal it was written in C.	58	is to be I<fast>. To reach the latter goal it was written in C.
61		59
62	See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and	60	See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and
…		…
66		64
67	package CBOR::XS;	65	package CBOR::XS;
68		66
69	use common::sense;	67	use common::sense;
70		68
71	our $VERSION = 0.08;	69	our $VERSION = 1.1;
72	our @ISA = qw(Exporter);	70	our @ISA = qw(Exporter);
73		71
74	our @EXPORT = qw(encode_cbor decode_cbor);	72	our @EXPORT = qw(encode_cbor decode_cbor);
75		73
76	use Exporter;	74	use Exporter;
…		…
113	strings. All boolean flags described below are by default I<disabled>.	111	strings. All boolean flags described below are by default I<disabled>.
114		112
115	The mutators for flags all return the CBOR object again and thus calls can	113	The mutators for flags all return the CBOR object again and thus calls can
116	be chained:	114	be chained:
117		115
118	#TODO
119	my $cbor = CBOR::XS->new->encode ({a => [1,2]});	116	my $cbor = CBOR::XS->new->encode ({a => [1,2]});
120		117
121	=item $cbor = $cbor->max_depth ([$maximum_nesting_depth])	118	=item $cbor = $cbor->max_depth ([$maximum_nesting_depth])
122		119
123	=item $max_depth = $cbor->get_max_depth	120	=item $max_depth = $cbor->get_max_depth
…		…
171	exception when it encounters anything it cannot encode as CBOR.	168	exception when it encounters anything it cannot encode as CBOR.
172		169
173	This option does not affect C<decode> in any way, and it is recommended to	170	This option does not affect C<decode> in any way, and it is recommended to
174	leave it off unless you know your communications partner.	171	leave it off unless you know your communications partner.
175		172
176	=item $cbor = $cbor->allow_sharable ([$enable])	173	=item $cbor = $cbor->allow_sharing ([$enable])
177		174
178	=item $enabled = $cbor->get_allow_sharable	175	=item $enabled = $cbor->get_allow_sharing
179		176
180	If C<$enable> is true (or missing), then C<encode> will not double-encode	177	If C<$enable> is true (or missing), then C<encode> will not double-encode
181	values that have been seen before (e.g. when the same object, such as an	178	values that have been referenced before (e.g. when the same object, such
182	array, is referenced multiple times), but instead will emit a reference to	179	as an array, is referenced multiple times), but instead will emit a
183	the earlier value.	180	reference to the earlier value.
184		181
185	This means that such values will only be encoded once, and will not result	182	This means that such values will only be encoded once, and will not result
186	in a deep cloning of the value on decode, in decoders supporting the value	183	in a deep cloning of the value on decode, in decoders supporting the value
187	sharing extension.	184	sharing extension. This also makes it possible to encode cyclic data
		185	structures (which need C<allow_cycles> to ne enabled to be decoded by this
		186	module).
		187
		188	It is recommended to leave it off unless you know your
		189	communication partner supports the value sharing extensions to CBOR
		190	(L<http://cbor.schmorp.de/value-sharing>), as without decoder support, the
		191	resulting data structure might be unusable.
188		192
189	Detecting shared values incurs a runtime overhead when values are encoded	193	Detecting shared values incurs a runtime overhead when values are encoded
190	that have a reference counter large than one, and might unnecessarily	194	that have a reference counter large than one, and might unnecessarily
191	increase the encoded size, as potentially shared values are encode as	195	increase the encoded size, as potentially shared values are encode as
192	sharable whether or not they are actually shared.	196	shareable whether or not they are actually shared.
193		197
194	At the moment, all shared values will be detected, even weird and unusual	198	At the moment, only targets of references can be shared (e.g. scalars,
195	cases, such as an array with multiple "copies" of the I<same> scalar,	199	arrays or hashes pointed to by a reference). Weirder constructs, such as
196	which are hard but not impossible to create in Perl (L<Storable> for	200	an array with multiple "copies" of the I<same> string, which are hard but
197	example doesn't handle these cases). If this turns out ot be a performance	201	not impossible to create in Perl, are not supported (this is the same as
198	issue then future versions might limit the shared value detection to	202	with L<Storable>).
199	references only.
200		203
201	If C<$enable> is false (the default), then C<encode> will encode	204	If C<$enable> is false (the default), then C<encode> will encode shared
202	exception when it encounters anything it cannot encode as CBOR.	205	data structures repeatedly, unsharing them in the process. Cyclic data
		206	structures cannot be encoded in this mode.
203		207
204	This option does not affect C<decode> in any way - shared values and	208	This option does not affect C<decode> in any way - shared values and
205	references will always be decoded properly if present. It is recommended	209	references will always be decoded properly if present.
206	to leave it off unless you know your communications partner supports the	210
207	value sharing extensions to CBOR (http://cbor.schmorp.de/value-sharing).	211	=item $cbor = $cbor->allow_cycles ([$enable])
		212
		213	=item $enabled = $cbor->get_allow_cycles
		214
		215	If C<$enable> is true (or missing), then C<decode> will happily decode
		216	self-referential (cyclic) data structures. By default these will not be
		217	decoded, as they need manual cleanup to avoid memory leaks, so code that
		218	isn't prepared for this will not leak memory.
		219
		220	If C<$enable> is false (the default), then C<decode> will throw an error
		221	when it encounters a self-referential/cyclic data structure.
		222
		223	This option does not affect C<encode> in any way - shared values and
		224	references will always be decoded properly if present.
		225
		226	=item $cbor = $cbor->pack_strings ([$enable])
		227
		228	=item $enabled = $cbor->get_pack_strings
		229
		230	If C<$enable> is true (or missing), then C<encode> will try not to encode
		231	the same string twice, but will instead encode a reference to the string
		232	instead. Depending on your data format, this can save a lot of space, but
		233	also results in a very large runtime overhead (expect encoding times to be
		234	2-4 times as high as without).
		235
		236	It is recommended to leave it off unless you know your
		237	communications partner supports the stringref extension to CBOR
		238	(L<http://cbor.schmorp.de/stringref>), as without decoder support, the
		239	resulting data structure might not be usable.
		240
		241	If C<$enable> is false (the default), then C<encode> will encode strings
		242	the standard CBOR way.
		243
		244	This option does not affect C<decode> in any way - string references will
		245	always be decoded properly if present.
		246
		247	=item $cbor = $cbor->filter ([$cb->($tag, $value)])
		248
		249	=item $cb_or_undef = $cbor->get_filter
		250
		251	Sets or replaces the tagged value decoding filter (when C<$cb> is
		252	specified) or clears the filter (if no argument or C<undef> is provided).
		253
		254	The filter callback is called only during decoding, when a non-enforced
		255	tagged value has been decoded (see L<TAG HANDLING AND EXTENSIONS> for a
		256	list of enforced tags). For specific tags, it's often better to provide a
		257	default converter using the C<%CBOR::XS::FILTER> hash (see below).
		258
		259	The first argument is the numerical tag, the second is the (decoded) value
		260	that has been tagged.
		261
		262	The filter function should return either exactly one value, which will
		263	replace the tagged value in the decoded data structure, or no values,
		264	which will result in default handling, which currently means the decoder
		265	creates a C<CBOR::XS::Tagged> object to hold the tag and the value.
		266
		267	When the filter is cleared (the default state), the default filter
		268	function, C<CBOR::XS::default_filter>, is used. This function simply looks
		269	up the tag in the C<%CBOR::XS::FILTER> hash. If an entry exists it must be
		270	a code reference that is called with tag and value, and is responsible for
		271	decoding the value. If no entry exists, it returns no values.
		272
		273	Example: decode all tags not handled internally into C<CBOR::XS::Tagged>
		274	objects, with no other special handling (useful when working with
		275	potentially "unsafe" CBOR data).
		276
		277	CBOR::XS->new->filter (sub { })->decode ($cbor_data);
		278
		279	Example: provide a global filter for tag 1347375694, converting the value
		280	into some string form.
		281
		282	$CBOR::XS::FILTER{1347375694} = sub {
		283	my ($tag, $value);
		284
		285	"tag 1347375694 value $value"
		286	};
208		287
209	=item $cbor_data = $cbor->encode ($perl_scalar)	288	=item $cbor_data = $cbor->encode ($perl_scalar)
210		289
211	Converts the given Perl data structure (a scalar value) to its CBOR	290	Converts the given Perl data structure (a scalar value) to its CBOR
212	representation.	291	representation.
…		…
253	CBOR integers become (numeric) perl scalars. On perls without 64 bit	332	CBOR integers become (numeric) perl scalars. On perls without 64 bit
254	support, 64 bit integers will be truncated or otherwise corrupted.	333	support, 64 bit integers will be truncated or otherwise corrupted.
255		334
256	=item byte strings	335	=item byte strings
257		336
258	Byte strings will become octet strings in Perl (the byte values 0..255	337	Byte strings will become octet strings in Perl (the Byte values 0..255
259	will simply become characters of the same value in Perl).	338	will simply become characters of the same value in Perl).
260		339
261	=item UTF-8 strings	340	=item UTF-8 strings
262		341
263	UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be	342	UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be
…		…
281	C<Types:Serialiser::false> and C<Types::Serialiser::error>,	360	C<Types:Serialiser::false> and C<Types::Serialiser::error>,
282	respectively. They are overloaded to act almost exactly like the numbers	361	respectively. They are overloaded to act almost exactly like the numbers
283	C<1> and C<0> (for true and false) or to throw an exception on access (for	362	C<1> and C<0> (for true and false) or to throw an exception on access (for
284	error). See the L<Types::Serialiser> manpage for details.	363	error). See the L<Types::Serialiser> manpage for details.
285		364
286	=item CBOR tag 256 (perl object)	365	=item tagged values
287		366
288	The tag value C<256> (TODO: pending iana registration) will be used
289	to deserialise a Perl object serialised with C<FREEZE>. See L<OBJECT
290	SERIALISATION>, below, for details.
291
292	=item CBOR tag 55799 (magic header)
293
294	The tag 55799 is ignored (this tag implements the magic header).
295
296	=item other CBOR tags
297
298	Tagged items consists of a numeric tag and another CBOR value. Tags not	367	Tagged items consists of a numeric tag and another CBOR value.
299	handled internally are currently converted into a L<CBOR::XS::Tagged>
300	object, which is simply a blessed array reference consisting of the
301	numeric tag value followed by the (decoded) CBOR value.
302		368
303	In the future, support for user-supplied conversions might get added.	369	See L<TAG HANDLING AND EXTENSIONS> and the description of C<< ->filter >>
		370	for details on which tags are handled how.
304		371
305	=item anything else	372	=item anything else
306		373
307	Anything else (e.g. unsupported simple values) will raise a decoding	374	Anything else (e.g. unsupported simple values) will raise a decoding
308	error.	375	error.
…		…
311		378
312		379
313	=head2 PERL -> CBOR	380	=head2 PERL -> CBOR
314		381
315	The mapping from Perl to CBOR is slightly more difficult, as Perl is a	382	The mapping from Perl to CBOR is slightly more difficult, as Perl is a
316	truly typeless language, so we can only guess which CBOR type is meant by	383	typeless language. That means this module can only guess which CBOR type
317	a Perl value.	384	is meant by a perl value.
318		385
319	=over 4	386	=over 4
320		387
321	=item hash references	388	=item hash references
322		389
323	Perl hash references become CBOR maps. As there is no inherent ordering in	390	Perl hash references become CBOR maps. As there is no inherent ordering in
324	hash keys (or CBOR maps), they will usually be encoded in a pseudo-random	391	hash keys (or CBOR maps), they will usually be encoded in a pseudo-random
325	order.	392	order. This order can be different each time a hahs is encoded.
326		393
327	Currently, tied hashes will use the indefinite-length format, while normal	394	Currently, tied hashes will use the indefinite-length format, while normal
328	hashes will use the fixed-length format.	395	hashes will use the fixed-length format.
329		396
330	=item array references	397	=item array references
331		398
332	Perl array references become fixed-length CBOR arrays.	399	Perl array references become fixed-length CBOR arrays.
333		400
334	=item other references	401	=item other references
335		402
336	Other unblessed references are generally not allowed and will cause an	403	Other unblessed references will be represented using
337	exception to be thrown, except for references to the integers C<0> and	404	the indirection tag extension (tag value C<22098>,
338	C<1>, which get turned into false and true in CBOR.	405	L<http://cbor.schmorp.de/indirection>). CBOR decoders are guaranteed
		406	to be able to decode these values somehow, by either "doing the right
		407	thing", decoding into a generic tagged object, simply ignoring the tag, or
		408	something else.
339		409
340	=item CBOR::XS::Tagged objects	410	=item CBOR::XS::Tagged objects
341		411
342	Objects of this type must be arrays consisting of a single C<[tag, value]>	412	Objects of this type must be arrays consisting of a single C<[tag, value]>
343	pair. The (numerical) tag will be encoded as a CBOR tag, the value will	413	pair. The (numerical) tag will be encoded as a CBOR tag, the value will
344	be encoded as appropriate for the value. You cna use C<CBOR::XS::tag> to	414	be encoded as appropriate for the value. You must use C<CBOR::XS::tag> to
345	create such objects.	415	create such objects.
346		416
347	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error	417	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error
348		418
349	These special values become CBOR true, CBOR false and CBOR undefined	419	These special values become CBOR true, CBOR false and CBOR undefined
…		…
351	if you want.	421	if you want.
352		422
353	=item other blessed objects	423	=item other blessed objects
354		424
355	Other blessed objects are serialised via C<TO_CBOR> or C<FREEZE>. See	425	Other blessed objects are serialised via C<TO_CBOR> or C<FREEZE>. See
356	L<OBJECT SERIALISATION>, below, for details.	426	L<TAG HANDLING AND EXTENSIONS> for specific classes handled by this
		427	module, and L<OBJECT SERIALISATION> for generic object serialisation.
357		428
358	=item simple scalars	429	=item simple scalars
359		430
360	TODO
361	Simple Perl scalars (any scalar that is not a reference) are the most	431	Simple Perl scalars (any scalar that is not a reference) are the most
362	difficult objects to encode: CBOR::XS will encode undefined scalars as	432	difficult objects to encode: CBOR::XS will encode undefined scalars as
363	CBOR null values, scalars that have last been used in a string context	433	CBOR null values, scalars that have last been used in a string context
364	before encoding as CBOR strings, and anything else as number value:	434	before encoding as CBOR strings, and anything else as number value:
365		435
366	# dump as number	436	# dump as number
367	encode_cbor [2] # yields [2]	437	encode_cbor [2] # yields [2]
368	encode_cbor [-3.0e17] # yields [-3e+17]	438	encode_cbor [-3.0e17] # yields [-3e+17]
369	my $value = 5; encode_cbor [$value] # yields [5]	439	my $value = 5; encode_cbor [$value] # yields [5]
370		440
371	# used as string, so dump as string	441	# used as string, so dump as string (either byte or text)
372	print $value;	442	print $value;
373	encode_cbor [$value] # yields ["5"]	443	encode_cbor [$value] # yields ["5"]
374		444
375	# undef becomes null	445	# undef becomes null
376	encode_cbor [undef] # yields [null]	446	encode_cbor [undef] # yields [null]
…		…
379		449
380	my $x = 3.1; # some variable containing a number	450	my $x = 3.1; # some variable containing a number
381	"$x"; # stringified	451	"$x"; # stringified
382	$x .= ""; # another, more awkward way to stringify	452	$x .= ""; # another, more awkward way to stringify
383	print $x; # perl does it for you, too, quite often	453	print $x; # perl does it for you, too, quite often
		454
		455	You can force whether a string ie encoded as byte or text string by using
		456	C<utf8::upgrade> and C<utf8::downgrade>):
		457
		458	utf8::upgrade $x; # encode $x as text string
		459	utf8::downgrade $x; # encode $x as byte string
		460
		461	Perl doesn't define what operations up- and downgrade strings, so if the
		462	difference between byte and text is important, you should up- or downgrade
		463	your string as late as possible before encoding.
384		464
385	You can force the type to be a CBOR number by numifying it:	465	You can force the type to be a CBOR number by numifying it:
386		466
387	my $x = "3"; # some variable containing a string	467	my $x = "3"; # some variable containing a string
388	$x += 0; # numify it, ensuring it will be dumped as a number	468	$x += 0; # numify it, ensuring it will be dumped as a number
…		…
401		481
402	=back	482	=back
403		483
404	=head2 OBJECT SERIALISATION	484	=head2 OBJECT SERIALISATION
405		485
		486	This module implements both a CBOR-specific and the generic
		487	L<Types::Serialier> object serialisation protocol. The following
		488	subsections explain both methods.
		489
		490	=head3 ENCODING
		491
406	This module knows two way to serialise a Perl object: The CBOR-specific	492	This module knows two way to serialise a Perl object: The CBOR-specific
407	way, and the generic way.	493	way, and the generic way.
408		494
409	Whenever the encoder encounters a Perl object that it cnanot serialise	495	Whenever the encoder encounters a Perl object that it cannot serialise
410	directly (most of them), it will first look up the C<TO_CBOR> method on	496	directly (most of them), it will first look up the C<TO_CBOR> method on
411	it.	497	it.
412		498
413	If it has a C<TO_CBOR> method, it will call it with the object as only	499	If it has a C<TO_CBOR> method, it will call it with the object as only
414	argument, and expects exactly one return value, which it will then	500	argument, and expects exactly one return value, which it will then
…		…
420		506
421	The C<FREEZE> method can return any number of values (i.e. zero or	507	The C<FREEZE> method can return any number of values (i.e. zero or
422	more). These will be encoded as CBOR perl object, together with the	508	more). These will be encoded as CBOR perl object, together with the
423	classname.	509	classname.
424		510
		511	These methods I<MUST NOT> change the data structure that is being
		512	serialised. Failure to comply to this can result in memory corruption -
		513	and worse.
		514
425	If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail	515	If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail
426	with an error.	516	with an error.
427		517
		518	=head3 DECODING
		519
428	Objects encoded via C<TO_CBOR> cannot be automatically decoded, but	520	Objects encoded via C<TO_CBOR> cannot (normally) be automatically decoded,
429	objects encoded via C<FREEZE> can be decoded using the following protocol:	521	but objects encoded via C<FREEZE> can be decoded using the following
		522	protocol:
430		523
431	When an encoded CBOR perl object is encountered by the decoder, it will	524	When an encoded CBOR perl object is encountered by the decoder, it will
432	look up the C<THAW> method, by using the stored classname, and will fail	525	look up the C<THAW> method, by using the stored classname, and will fail
433	if the method cannot be found.	526	if the method cannot be found.
434		527
435	After the lookup it will call the C<THAW> method with the stored classname	528	After the lookup it will call the C<THAW> method with the stored classname
436	as first argument, the constant string C<CBOR> as second argument, and all	529	as first argument, the constant string C<CBOR> as second argument, and all
437	values returned by C<FREEZE> as remaining arguments.	530	values returned by C<FREEZE> as remaining arguments.
438		531
439	=head4 EXAMPLES	532	=head3 EXAMPLES
440		533
441	Here is an example C<TO_CBOR> method:	534	Here is an example C<TO_CBOR> method:
442		535
443	sub My::Object::TO_CBOR {	536	sub My::Object::TO_CBOR {
444	my ($obj) = @_;	537	my ($obj) = @_;
…		…
455		548
456	sub URI::TO_CBOR {	549	sub URI::TO_CBOR {
457	my ($self) = @_;	550	my ($self) = @_;
458	my $uri = "$self"; # stringify uri	551	my $uri = "$self"; # stringify uri
459	utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string	552	utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string
460	CBOR::XS::tagged 32, "$_[0]"	553	CBOR::XS::tag 32, "$_[0]"
461	}	554	}
462		555
463	This will encode URIs as a UTF-8 string with tag 32, which indicates an	556	This will encode URIs as a UTF-8 string with tag 32, which indicates an
464	URI.	557	URI.
465		558
…		…
601	CBOR::XS::tag 24,	694	CBOR::XS::tag 24,
602	encode_cbor [1, 2, 3];	695	encode_cbor [1, 2, 3];
603		696
604	=head1 TAG HANDLING AND EXTENSIONS	697	=head1 TAG HANDLING AND EXTENSIONS
605		698
606	This section describes how this module handles specific tagged values and	699	This section describes how this module handles specific tagged values
607	extensions. If a tag is not mentioned here, then the default handling	700	and extensions. If a tag is not mentioned here and no additional filters
		701	are provided for it, then the default handling applies (creating a
608	applies (creating a CBOR::XS::Tagged object on decoding, and only encoding	702	CBOR::XS::Tagged object on decoding, and only encoding the tag when
609	the tag when explicitly requested).	703	explicitly requested).
		704
		705	Tags not handled specifically are currently converted into a
		706	L<CBOR::XS::Tagged> object, which is simply a blessed array reference
		707	consisting of the numeric tag value followed by the (decoded) CBOR value.
610		708
611	Future versions of this module reserve the right to special case	709	Future versions of this module reserve the right to special case
612	additional tags (such as bigfloat or base64url).	710	additional tags (such as base64url).
		711
		712	=head2 ENFORCED TAGS
		713
		714	These tags are always handled when decoding, and their handling cannot be
		715	overriden by the user.
613		716
614	=over 4	717	=over 4
615		718
616	=item <unassigned> (perl-object, L<http://cbor.schmorp.de/perl-object>)	719	=item 26 (perl-object, L<http://cbor.schmorp.de/perl-object>)
617		720
618	These tags are automatically created for serialisable objects using the	721	These tags are automatically created (and decoded) for serialisable
619	C<FREEZE/THAW> methods (the L<Types::Serialier> object serialisation	722	objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object
620	protocol).	723	serialisation protocol). See L<OBJECT SERIALISATION> for details.
621		724
622	=item <unassigned>, <unassigned> (sharable, sharedref, L <http://cbor.schmorp.de/value-sharing>)	725	=item 28, 29 (shareable, sharedref, L <http://cbor.schmorp.de/value-sharing>)
623		726
624	These tags are automatically decoded when encountered, resulting in	727	These tags are automatically decoded when encountered (and they do not
		728	result in a cyclic data structure, see C<allow_cycles>), resulting in
625	shared values in the decoded object. They are only encoded, however, when	729	shared values in the decoded object. They are only encoded, however, when
626	C<allow_sharable> is enabled.	730	C<allow_sharing> is enabled.
		731
		732	Not all shared values can be successfully decoded: values that reference
		733	themselves will I<currently> decode as C<undef> (this is not the same
		734	as a reference pointing to itself, which will be represented as a value
		735	that contains an indirect reference to itself - these will be decoded
		736	properly).
		737
		738	Note that considerably more shared value data structures can be decoded
		739	than will be encoded - currently, only values pointed to by references
		740	will be shared, others will not. While non-reference shared values can be
		741	generated in Perl with some effort, they were considered too unimportant
		742	to be supported in the encoder. The decoder, however, will decode these
		743	values as shared values.
		744
		745	=item 256, 25 (stringref-namespace, stringref, L <http://cbor.schmorp.de/stringref>)
		746
		747	These tags are automatically decoded when encountered. They are only
		748	encoded, however, when C<pack_strings> is enabled.
627		749
628	=item 22098 (indirection, L<http://cbor.schmorp.de/indirection>)	750	=item 22098 (indirection, L<http://cbor.schmorp.de/indirection>)
629		751
630	This tag is automatically generated when a reference are encountered (with	752	This tag is automatically generated when a reference are encountered (with
631	the exception of hash and array refernces). It is converted to a reference	753	the exception of hash and array refernces). It is converted to a reference
…		…
635		757
636	This value is not generated on encoding (unless explicitly requested by	758	This value is not generated on encoding (unless explicitly requested by
637	the user), and is simply ignored when decoding.	759	the user), and is simply ignored when decoding.
638		760
639	=back	761	=back
		762
		763	=head2 NON-ENFORCED TAGS
		764
		765	These tags have default filters provided when decoding. Their handling can
		766	be overriden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by
		767	providing a custom C<filter> callback when decoding.
		768
		769	When they result in decoding into a specific Perl class, the module
		770	usually provides a corresponding C<TO_CBOR> method as well.
		771
		772	When any of these need to load additional modules that are not part of the
		773	perl core distribution (e.g. L<URI>), it is (currently) up to the user to
		774	provide these modules. The decoding usually fails with an exception if the
		775	required module cannot be loaded.
		776
		777	=over 4
		778
		779	=item 2, 3 (positive/negative bignum)
		780
		781	These tags are decoded into L<Math::BigInt> objects. The corresponding
		782	C<Math::BigInt::TO_CBOR> method encodes "small" bigints into normal CBOR
		783	integers, and others into positive/negative CBOR bignums.
		784
		785	=item 4, 5 (decimal fraction/bigfloat)
		786
		787	Both decimal fractions and bigfloats are decoded into L<Math::BigFloat>
		788	objects. The corresponding C<Math::BigFloat::TO_CBOR> method I<always>
		789	encodes into a decimal fraction.
		790
		791	CBOR cannot represent bigfloats with I<very> large exponents - conversion
		792	of such big float objects is undefined.
		793
		794	Also, NaN and infinities are not encoded properly.
		795
		796	=item 21, 22, 23 (expected later JSON conversion)
		797
		798	CBOR::XS is not a CBOR-to-JSON converter, and will simply ignore these
		799	tags.
		800
		801	=item 32 (URI)
		802
		803	These objects decode into L<URI> objects. The corresponding
		804	C<URI::TO_CBOR> method again results in a CBOR URI value.
		805
		806	=back
		807
		808	=cut
		809
		810	our %FILTER = (
		811	# 0 # rfc4287 datetime, utf-8
		812	# 1 # unix timestamp, any
		813
		814	2 => sub { # pos bigint
		815	require Math::BigInt;
		816	Math::BigInt->new ("0x" . unpack "H*", pop)
		817	},
		818
		819	3 => sub { # neg bigint
		820	require Math::BigInt;
		821	-Math::BigInt->new ("0x" . unpack "H*", pop)
		822	},
		823
		824	4 => sub { # decimal fraction, array
		825	require Math::BigFloat;
		826	Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
		827	},
		828
		829	5 => sub { # bigfloat, array
		830	require Math::BigFloat;
		831	scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2)
		832	},
		833
		834	21 => sub { pop }, # expected conversion to base64url encoding
		835	22 => sub { pop }, # expected conversion to base64 encoding
		836	23 => sub { pop }, # expected conversion to base16 encoding
		837
		838	# 24 # embedded cbor, byte string
		839
		840	32 => sub {
		841	require URI;
		842	URI->new (pop)
		843	},
		844
		845	# 33 # base64url rfc4648, utf-8
		846	# 34 # base64 rfc46484, utf-8
		847	# 35 # regex pcre/ecma262, utf-8
		848	# 36 # mime message rfc2045, utf-8
		849	);
640		850
641		851
642	=head1 CBOR and JSON	852	=head1 CBOR and JSON
643		853
644	CBOR is supposed to implement a superset of the JSON data model, and is,	854	CBOR is supposed to implement a superset of the JSON data model, and is,
…		…
706	properly. Half precision types are accepted, but not encoded.	916	properly. Half precision types are accepted, but not encoded.
707		917
708	Strict mode and canonical mode are not implemented.	918	Strict mode and canonical mode are not implemented.
709		919
710		920
		921	=head1 LIMITATIONS ON PERLS WITHOUT 64-BIT INTEGER SUPPORT
		922
		923	On perls that were built without 64 bit integer support (these are rare
		924	nowadays, even on 32 bit architectures), support for any kind of 64 bit
		925	integer in CBOR is very limited - most likely, these 64 bit values will
		926	be truncated, corrupted, or otherwise not decoded correctly. This also
		927	includes string, array and map sizes that are stored as 64 bit integers.
		928
		929
711	=head1 THREADS	930	=head1 THREADS
712		931
713	This module is I<not> guaranteed to be thread safe and there are no	932	This module is I<not> guaranteed to be thread safe and there are no
714	plans to change this until Perl gets thread support (as opposed to the	933	plans to change this until Perl gets thread support (as opposed to the
715	horribly slow so-called "threads" which are simply slow and bloated	934	horribly slow so-called "threads" which are simply slow and bloated
…		…
727	Please refrain from using rt.cpan.org or any other bug reporting	946	Please refrain from using rt.cpan.org or any other bug reporting
728	service. I put the contact address into my modules for a reason.	947	service. I put the contact address into my modules for a reason.
729		948
730	=cut	949	=cut
731		950
		951	our %FILTER = (
		952	# 0 # rfc4287 datetime, utf-8
		953	# 1 # unix timestamp, any
		954
		955	2 => sub { # pos bigint
		956	require Math::BigInt;
		957	Math::BigInt->new ("0x" . unpack "H*", pop)
		958	},
		959
		960	3 => sub { # neg bigint
		961	require Math::BigInt;
		962	-Math::BigInt->new ("0x" . unpack "H*", pop)
		963	},
		964
		965	4 => sub { # decimal fraction, array
		966	require Math::BigFloat;
		967	Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
		968	},
		969
		970	5 => sub { # bigfloat, array
		971	require Math::BigFloat;
		972	scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2)
		973	},
		974
		975	21 => sub { pop }, # expected conversion to base64url encoding
		976	22 => sub { pop }, # expected conversion to base64 encoding
		977	23 => sub { pop }, # expected conversion to base16 encoding
		978
		979	# 24 # embedded cbor, byte string
		980
		981	32 => sub {
		982	require URI;
		983	URI->new (pop)
		984	},
		985
		986	# 33 # base64url rfc4648, utf-8
		987	# 34 # base64 rfc46484, utf-8
		988	# 35 # regex pcre/ecma262, utf-8
		989	# 36 # mime message rfc2045, utf-8
		990	);
		991
		992	sub CBOR::XS::default_filter {
		993	&{ $FILTER{$_[0]} or return }
		994	}
		995
		996	sub URI::TO_CBOR {
		997	my $uri = $_[0]->as_string;
		998	utf8::upgrade $uri;
		999	CBOR::XS::tag 32, $uri
		1000	}
		1001
		1002	sub Math::BigInt::TO_CBOR {
		1003	if ($_[0] >= -2147483648 && $_[0] <= 2147483647) {
		1004	$_[0]->numify
		1005	} else {
		1006	my $hex = substr $_[0]->as_hex, 2;
		1007	$hex = "0$hex" if 1 & length $hex; # sigh
		1008	CBOR::XS::tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex
		1009	}
		1010	}
		1011
		1012	sub Math::BigFloat::TO_CBOR {
		1013	my ($m, $e) = $_[0]->parts;
		1014	CBOR::XS::tag 4, [$e->numify, $m]
		1015	}
		1016
732	XSLoader::load "CBOR::XS", $VERSION;	1017	XSLoader::load "CBOR::XS", $VERSION;
733		1018
734	=head1 SEE ALSO	1019	=head1 SEE ALSO
735		1020
736	The L<JSON> and L<JSON::XS> modules that do similar, but human-readable,	1021	The L<JSON> and L<JSON::XS> modules that do similar, but human-readable,

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Comparing CBOR-XS/XS.pm (file contents): Revision 1.19 by root, Wed Nov 20 01:09:46 2013 UTC vs. Revision 1.32 by root, Sat Nov 30 18:42:27 2013 UTC

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Comparing CBOR-XS/XS.pm (file contents):
Revision 1.19 by root, Wed Nov 20 01:09:46 2013 UTC vs.
Revision 1.32 by root, Sat Nov 30 18:42:27 2013 UTC