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

Comparing CBOR-XS/XS.pm (file contents):
Revision 1.13 by root, Tue Oct 29 15:56:31 2013 UTC vs.
Revision 1.38 by root, Tue Dec 3 10:23:55 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).
		42
		43	To give you a general idea about speed, with texts in the megabyte range,
		44	C<CBOR::XS> usually encodes roughly twice as fast as L<Storable> or
		45	L<JSON::XS> and decodes about 15%-30% faster than those. The shorter the
		46	data, the worse L<Storable> performs in comparison.
		47
		48	Regarding compactness, C<CBOR::XS>-encoded data structures are usually
		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).
50		56
51	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
52	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.
53		59
54	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
…		…
58		64
59	package CBOR::XS;	65	package CBOR::XS;
60		66
61	use common::sense;	67	use common::sense;
62		68
63	our $VERSION = 0.06;	69	our $VERSION = 1.12;
64	our @ISA = qw(Exporter);	70	our @ISA = qw(Exporter);
65		71
66	our @EXPORT = qw(encode_cbor decode_cbor);	72	our @EXPORT = qw(encode_cbor decode_cbor);
67		73
68	use Exporter;	74	use Exporter;
…		…
105	strings. All boolean flags described below are by default I<disabled>.	111	strings. All boolean flags described below are by default I<disabled>.
106		112
107	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
108	be chained:	114	be chained:
109		115
110	#TODO
111	my $cbor = CBOR::XS->new->encode ({a => [1,2]});	116	my $cbor = CBOR::XS->new->encode ({a => [1,2]});
112		117
113	=item $cbor = $cbor->max_depth ([$maximum_nesting_depth])	118	=item $cbor = $cbor->max_depth ([$maximum_nesting_depth])
114		119
115	=item $max_depth = $cbor->get_max_depth	120	=item $max_depth = $cbor->get_max_depth
…		…
149	If no argument is given, the limit check will be deactivated (same as when	154	If no argument is given, the limit check will be deactivated (same as when
150	C<0> is specified).	155	C<0> is specified).
151		156
152	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	157	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
153		158
		159	=item $cbor = $cbor->allow_unknown ([$enable])
		160
		161	=item $enabled = $cbor->get_allow_unknown
		162
		163	If C<$enable> is true (or missing), then C<encode> will I<not> throw an
		164	exception when it encounters values it cannot represent in CBOR (for
		165	example, filehandles) but instead will encode a CBOR C<error> value.
		166
		167	If C<$enable> is false (the default), then C<encode> will throw an
		168	exception when it encounters anything it cannot encode as CBOR.
		169
		170	This option does not affect C<decode> in any way, and it is recommended to
		171	leave it off unless you know your communications partner.
		172
		173	=item $cbor = $cbor->allow_sharing ([$enable])
		174
		175	=item $enabled = $cbor->get_allow_sharing
		176
		177	If C<$enable> is true (or missing), then C<encode> will not double-encode
		178	values that have been referenced before (e.g. when the same object, such
		179	as an array, is referenced multiple times), but instead will emit a
		180	reference to the earlier value.
		181
		182	This means that such values will only be encoded once, and will not result
		183	in a deep cloning of the value on decode, in decoders supporting the value
		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.
		192
		193	Detecting shared values incurs a runtime overhead when values are encoded
		194	that have a reference counter large than one, and might unnecessarily
		195	increase the encoded size, as potentially shared values are encode as
		196	shareable whether or not they are actually shared.
		197
		198	At the moment, only targets of references can be shared (e.g. scalars,
		199	arrays or hashes pointed to by a reference). Weirder constructs, such as
		200	an array with multiple "copies" of the I<same> string, which are hard but
		201	not impossible to create in Perl, are not supported (this is the same as
		202	with L<Storable>).
		203
		204	If C<$enable> is false (the default), then C<encode> will encode shared
		205	data structures repeatedly, unsharing them in the process. Cyclic data
		206	structures cannot be encoded in this mode.
		207
		208	This option does not affect C<decode> in any way - shared values and
		209	references will always be decoded properly if present.
		210
		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 = $cbor->validate_utf8 ([$enable])
		248
		249	=item $enabled = $cbor->get_validate_utf8
		250
		251	If C<$enable> is true (or missing), then C<decode> will validate that
		252	elements (text strings) containing UTF-8 data in fact contain valid UTF-8
		253	data (instead of blindly accepting it). This validation obviously takes
		254	extra time during decoding.
		255
		256	The concept of "valid UTF-8" used is perl's concept, which is a superset
		257	of the official UTF-8.
		258
		259	If C<$enable> is false (the default), then C<decode> will blindly accept
		260	UTF-8 data, marking them as valid UTF-8 in the resulting data structure
		261	regardless of whether thats true or not.
		262
		263	Perl isn't too happy about corrupted UTF-8 in strings, but should
		264	generally not crash or do similarly evil things. Extensions might be not
		265	so forgiving, so it's recommended to turn on this setting if you receive
		266	untrusted CBOR.
		267
		268	This option does not affect C<encode> in any way - strings that are
		269	supposedly valid UTF-8 will simply be dumped into the resulting CBOR
		270	string without checking whether that is, in fact, true or not.
		271
		272	=item $cbor = $cbor->filter ([$cb->($tag, $value)])
		273
		274	=item $cb_or_undef = $cbor->get_filter
		275
		276	Sets or replaces the tagged value decoding filter (when C<$cb> is
		277	specified) or clears the filter (if no argument or C<undef> is provided).
		278
		279	The filter callback is called only during decoding, when a non-enforced
		280	tagged value has been decoded (see L<TAG HANDLING AND EXTENSIONS> for a
		281	list of enforced tags). For specific tags, it's often better to provide a
		282	default converter using the C<%CBOR::XS::FILTER> hash (see below).
		283
		284	The first argument is the numerical tag, the second is the (decoded) value
		285	that has been tagged.
		286
		287	The filter function should return either exactly one value, which will
		288	replace the tagged value in the decoded data structure, or no values,
		289	which will result in default handling, which currently means the decoder
		290	creates a C<CBOR::XS::Tagged> object to hold the tag and the value.
		291
		292	When the filter is cleared (the default state), the default filter
		293	function, C<CBOR::XS::default_filter>, is used. This function simply looks
		294	up the tag in the C<%CBOR::XS::FILTER> hash. If an entry exists it must be
		295	a code reference that is called with tag and value, and is responsible for
		296	decoding the value. If no entry exists, it returns no values.
		297
		298	Example: decode all tags not handled internally into C<CBOR::XS::Tagged>
		299	objects, with no other special handling (useful when working with
		300	potentially "unsafe" CBOR data).
		301
		302	CBOR::XS->new->filter (sub { })->decode ($cbor_data);
		303
		304	Example: provide a global filter for tag 1347375694, converting the value
		305	into some string form.
		306
		307	$CBOR::XS::FILTER{1347375694} = sub {
		308	my ($tag, $value);
		309
		310	"tag 1347375694 value $value"
		311	};
		312
154	=item $cbor_data = $cbor->encode ($perl_scalar)	313	=item $cbor_data = $cbor->encode ($perl_scalar)
155		314
156	Converts the given Perl data structure (a scalar value) to its CBOR	315	Converts the given Perl data structure (a scalar value) to its CBOR
157	representation.	316	representation.
158		317
…		…
198	CBOR integers become (numeric) perl scalars. On perls without 64 bit	357	CBOR integers become (numeric) perl scalars. On perls without 64 bit
199	support, 64 bit integers will be truncated or otherwise corrupted.	358	support, 64 bit integers will be truncated or otherwise corrupted.
200		359
201	=item byte strings	360	=item byte strings
202		361
203	Byte strings will become octet strings in Perl (the byte values 0..255	362	Byte strings will become octet strings in Perl (the Byte values 0..255
204	will simply become characters of the same value in Perl).	363	will simply become characters of the same value in Perl).
205		364
206	=item UTF-8 strings	365	=item UTF-8 strings
207		366
208	UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be	367	UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be
…		…
226	C<Types:Serialiser::false> and C<Types::Serialiser::error>,	385	C<Types:Serialiser::false> and C<Types::Serialiser::error>,
227	respectively. They are overloaded to act almost exactly like the numbers	386	respectively. They are overloaded to act almost exactly like the numbers
228	C<1> and C<0> (for true and false) or to throw an exception on access (for	387	C<1> and C<0> (for true and false) or to throw an exception on access (for
229	error). See the L<Types::Serialiser> manpage for details.	388	error). See the L<Types::Serialiser> manpage for details.
230		389
231	=item CBOR tag 256 (perl object)	390	=item tagged values
232		391
233	The tag value C<256> (TODO: pending iana registration) will be used
234	to deserialise a Perl object serialised with C<FREEZE>. See L<OBJECT
235	SERIALISATION>, below, for details.
236
237	=item CBOR tag 55799 (magic header)
238
239	The tag 55799 is ignored (this tag implements the magic header).
240
241	=item other CBOR tags
242
243	Tagged items consists of a numeric tag and another CBOR value. Tags not	392	Tagged items consists of a numeric tag and another CBOR value.
244	handled internally are currently converted into a L<CBOR::XS::Tagged>
245	object, which is simply a blessed array reference consisting of the
246	numeric tag value followed by the (decoded) CBOR value.
247		393
248	In the future, support for user-supplied conversions might get added.	394	See L<TAG HANDLING AND EXTENSIONS> and the description of C<< ->filter >>
		395	for details on which tags are handled how.
249		396
250	=item anything else	397	=item anything else
251		398
252	Anything else (e.g. unsupported simple values) will raise a decoding	399	Anything else (e.g. unsupported simple values) will raise a decoding
253	error.	400	error.
…		…
256		403
257		404
258	=head2 PERL -> CBOR	405	=head2 PERL -> CBOR
259		406
260	The mapping from Perl to CBOR is slightly more difficult, as Perl is a	407	The mapping from Perl to CBOR is slightly more difficult, as Perl is a
261	truly typeless language, so we can only guess which CBOR type is meant by	408	typeless language. That means this module can only guess which CBOR type
262	a Perl value.	409	is meant by a perl value.
263		410
264	=over 4	411	=over 4
265		412
266	=item hash references	413	=item hash references
267		414
268	Perl hash references become CBOR maps. As there is no inherent ordering in	415	Perl hash references become CBOR maps. As there is no inherent ordering in
269	hash keys (or CBOR maps), they will usually be encoded in a pseudo-random	416	hash keys (or CBOR maps), they will usually be encoded in a pseudo-random
270	order.	417	order. This order can be different each time a hahs is encoded.
271		418
272	Currently, tied hashes will use the indefinite-length format, while normal	419	Currently, tied hashes will use the indefinite-length format, while normal
273	hashes will use the fixed-length format.	420	hashes will use the fixed-length format.
274		421
275	=item array references	422	=item array references
276		423
277	Perl array references become fixed-length CBOR arrays.	424	Perl array references become fixed-length CBOR arrays.
278		425
279	=item other references	426	=item other references
280		427
281	Other unblessed references are generally not allowed and will cause an	428	Other unblessed references will be represented using
282	exception to be thrown, except for references to the integers C<0> and	429	the indirection tag extension (tag value C<22098>,
283	C<1>, which get turned into false and true in CBOR.	430	L<http://cbor.schmorp.de/indirection>). CBOR decoders are guaranteed
		431	to be able to decode these values somehow, by either "doing the right
		432	thing", decoding into a generic tagged object, simply ignoring the tag, or
		433	something else.
284		434
285	=item CBOR::XS::Tagged objects	435	=item CBOR::XS::Tagged objects
286		436
287	Objects of this type must be arrays consisting of a single C<[tag, value]>	437	Objects of this type must be arrays consisting of a single C<[tag, value]>
288	pair. The (numerical) tag will be encoded as a CBOR tag, the value will	438	pair. The (numerical) tag will be encoded as a CBOR tag, the value will
289	be encoded as appropriate for the value. You cna use C<CBOR::XS::tag> to	439	be encoded as appropriate for the value. You must use C<CBOR::XS::tag> to
290	create such objects.	440	create such objects.
291		441
292	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error	442	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error
293		443
294	These special values become CBOR true, CBOR false and CBOR undefined	444	These special values become CBOR true, CBOR false and CBOR undefined
…		…
296	if you want.	446	if you want.
297		447
298	=item other blessed objects	448	=item other blessed objects
299		449
300	Other blessed objects are serialised via C<TO_CBOR> or C<FREEZE>. See	450	Other blessed objects are serialised via C<TO_CBOR> or C<FREEZE>. See
301	L<OBJECT SERIALISATION>, below, for details.	451	L<TAG HANDLING AND EXTENSIONS> for specific classes handled by this
		452	module, and L<OBJECT SERIALISATION> for generic object serialisation.
302		453
303	=item simple scalars	454	=item simple scalars
304		455
305	TODO
306	Simple Perl scalars (any scalar that is not a reference) are the most	456	Simple Perl scalars (any scalar that is not a reference) are the most
307	difficult objects to encode: CBOR::XS will encode undefined scalars as	457	difficult objects to encode: CBOR::XS will encode undefined scalars as
308	CBOR null values, scalars that have last been used in a string context	458	CBOR null values, scalars that have last been used in a string context
309	before encoding as CBOR strings, and anything else as number value:	459	before encoding as CBOR strings, and anything else as number value:
310		460
311	# dump as number	461	# dump as number
312	encode_cbor [2] # yields [2]	462	encode_cbor [2] # yields [2]
313	encode_cbor [-3.0e17] # yields [-3e+17]	463	encode_cbor [-3.0e17] # yields [-3e+17]
314	my $value = 5; encode_cbor [$value] # yields [5]	464	my $value = 5; encode_cbor [$value] # yields [5]
315		465
316	# used as string, so dump as string	466	# used as string, so dump as string (either byte or text)
317	print $value;	467	print $value;
318	encode_cbor [$value] # yields ["5"]	468	encode_cbor [$value] # yields ["5"]
319		469
320	# undef becomes null	470	# undef becomes null
321	encode_cbor [undef] # yields [null]	471	encode_cbor [undef] # yields [null]
…		…
324		474
325	my $x = 3.1; # some variable containing a number	475	my $x = 3.1; # some variable containing a number
326	"$x"; # stringified	476	"$x"; # stringified
327	$x .= ""; # another, more awkward way to stringify	477	$x .= ""; # another, more awkward way to stringify
328	print $x; # perl does it for you, too, quite often	478	print $x; # perl does it for you, too, quite often
		479
		480	You can force whether a string ie encoded as byte or text string by using
		481	C<utf8::upgrade> and C<utf8::downgrade>):
		482
		483	utf8::upgrade $x; # encode $x as text string
		484	utf8::downgrade $x; # encode $x as byte string
		485
		486	Perl doesn't define what operations up- and downgrade strings, so if the
		487	difference between byte and text is important, you should up- or downgrade
		488	your string as late as possible before encoding.
329		489
330	You can force the type to be a CBOR number by numifying it:	490	You can force the type to be a CBOR number by numifying it:
331		491
332	my $x = "3"; # some variable containing a string	492	my $x = "3"; # some variable containing a string
333	$x += 0; # numify it, ensuring it will be dumped as a number	493	$x += 0; # numify it, ensuring it will be dumped as a number
…		…
346		506
347	=back	507	=back
348		508
349	=head2 OBJECT SERIALISATION	509	=head2 OBJECT SERIALISATION
350		510
		511	This module implements both a CBOR-specific and the generic
		512	L<Types::Serialier> object serialisation protocol. The following
		513	subsections explain both methods.
		514
		515	=head3 ENCODING
		516
351	This module knows two way to serialise a Perl object: The CBOR-specific	517	This module knows two way to serialise a Perl object: The CBOR-specific
352	way, and the generic way.	518	way, and the generic way.
353		519
354	Whenever the encoder encounters a Perl object that it cnanot serialise	520	Whenever the encoder encounters a Perl object that it cannot serialise
355	directly (most of them), it will first look up the C<TO_CBOR> method on	521	directly (most of them), it will first look up the C<TO_CBOR> method on
356	it.	522	it.
357		523
358	If it has a C<TO_CBOR> method, it will call it with the object as only	524	If it has a C<TO_CBOR> method, it will call it with the object as only
359	argument, and expects exactly one return value, which it will then	525	argument, and expects exactly one return value, which it will then
…		…
365		531
366	The C<FREEZE> method can return any number of values (i.e. zero or	532	The C<FREEZE> method can return any number of values (i.e. zero or
367	more). These will be encoded as CBOR perl object, together with the	533	more). These will be encoded as CBOR perl object, together with the
368	classname.	534	classname.
369		535
		536	These methods I<MUST NOT> change the data structure that is being
		537	serialised. Failure to comply to this can result in memory corruption -
		538	and worse.
		539
370	If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail	540	If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail
371	with an error.	541	with an error.
372		542
		543	=head3 DECODING
		544
373	Objects encoded via C<TO_CBOR> cannot be automatically decoded, but	545	Objects encoded via C<TO_CBOR> cannot (normally) be automatically decoded,
374	objects encoded via C<FREEZE> can be decoded using the following protocol:	546	but objects encoded via C<FREEZE> can be decoded using the following
		547	protocol:
375		548
376	When an encoded CBOR perl object is encountered by the decoder, it will	549	When an encoded CBOR perl object is encountered by the decoder, it will
377	look up the C<THAW> method, by using the stored classname, and will fail	550	look up the C<THAW> method, by using the stored classname, and will fail
378	if the method cannot be found.	551	if the method cannot be found.
379		552
380	After the lookup it will call the C<THAW> method with the stored classname	553	After the lookup it will call the C<THAW> method with the stored classname
381	as first argument, the constant string C<CBOR> as second argument, and all	554	as first argument, the constant string C<CBOR> as second argument, and all
382	values returned by C<FREEZE> as remaining arguments.	555	values returned by C<FREEZE> as remaining arguments.
383		556
384	=head4 EXAMPLES	557	=head3 EXAMPLES
385		558
386	Here is an example C<TO_CBOR> method:	559	Here is an example C<TO_CBOR> method:
387		560
388	sub My::Object::TO_CBOR {	561	sub My::Object::TO_CBOR {
389	my ($obj) = @_;	562	my ($obj) = @_;
…		…
400		573
401	sub URI::TO_CBOR {	574	sub URI::TO_CBOR {
402	my ($self) = @_;	575	my ($self) = @_;
403	my $uri = "$self"; # stringify uri	576	my $uri = "$self"; # stringify uri
404	utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string	577	utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string
405	CBOR::XS::tagged 32, "$_[0]"	578	CBOR::XS::tag 32, "$_[0]"
406	}	579	}
407		580
408	This will encode URIs as a UTF-8 string with tag 32, which indicates an	581	This will encode URIs as a UTF-8 string with tag 32, which indicates an
409	URI.	582	URI.
410		583
…		…
447	=head1 MAGIC HEADER	620	=head1 MAGIC HEADER
448		621
449	There is no way to distinguish CBOR from other formats	622	There is no way to distinguish CBOR from other formats
450	programmatically. To make it easier to distinguish CBOR from other	623	programmatically. To make it easier to distinguish CBOR from other
451	formats, the CBOR specification has a special "magic string" that can be	624	formats, the CBOR specification has a special "magic string" that can be
452	prepended to any CBOR string without changing it's meaning.	625	prepended to any CBOR string without changing its meaning.
453		626
454	This string is available as C<$CBOR::XS::MAGIC>. This module does not	627	This string is available as C<$CBOR::XS::MAGIC>. This module does not
455	prepend this string tot he CBOR data it generates, but it will ignroe it	628	prepend this string to the CBOR data it generates, but it will ignore it
456	if present, so users can prepend this string as a "file type" indicator as	629	if present, so users can prepend this string as a "file type" indicator as
457	required.	630	required.
458		631
459		632
460	=head1 THE CBOR::XS::Tagged CLASS	633	=head1 THE CBOR::XS::Tagged CLASS
…		…
543	Wrap CBOR data in CBOR:	716	Wrap CBOR data in CBOR:
544		717
545	my $cbor_cbor = encode_cbor	718	my $cbor_cbor = encode_cbor
546	CBOR::XS::tag 24,	719	CBOR::XS::tag 24,
547	encode_cbor [1, 2, 3];	720	encode_cbor [1, 2, 3];
		721
		722	=head1 TAG HANDLING AND EXTENSIONS
		723
		724	This section describes how this module handles specific tagged values
		725	and extensions. If a tag is not mentioned here and no additional filters
		726	are provided for it, then the default handling applies (creating a
		727	CBOR::XS::Tagged object on decoding, and only encoding the tag when
		728	explicitly requested).
		729
		730	Tags not handled specifically are currently converted into a
		731	L<CBOR::XS::Tagged> object, which is simply a blessed array reference
		732	consisting of the numeric tag value followed by the (decoded) CBOR value.
		733
		734	Future versions of this module reserve the right to special case
		735	additional tags (such as base64url).
		736
		737	=head2 ENFORCED TAGS
		738
		739	These tags are always handled when decoding, and their handling cannot be
		740	overriden by the user.
		741
		742	=over 4
		743
		744	=item 26 (perl-object, L<http://cbor.schmorp.de/perl-object>)
		745
		746	These tags are automatically created (and decoded) for serialisable
		747	objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object
		748	serialisation protocol). See L<OBJECT SERIALISATION> for details.
		749
		750	=item 28, 29 (shareable, sharedref, L <http://cbor.schmorp.de/value-sharing>)
		751
		752	These tags are automatically decoded when encountered (and they do not
		753	result in a cyclic data structure, see C<allow_cycles>), resulting in
		754	shared values in the decoded object. They are only encoded, however, when
		755	C<allow_sharing> is enabled.
		756
		757	Not all shared values can be successfully decoded: values that reference
		758	themselves will I<currently> decode as C<undef> (this is not the same
		759	as a reference pointing to itself, which will be represented as a value
		760	that contains an indirect reference to itself - these will be decoded
		761	properly).
		762
		763	Note that considerably more shared value data structures can be decoded
		764	than will be encoded - currently, only values pointed to by references
		765	will be shared, others will not. While non-reference shared values can be
		766	generated in Perl with some effort, they were considered too unimportant
		767	to be supported in the encoder. The decoder, however, will decode these
		768	values as shared values.
		769
		770	=item 256, 25 (stringref-namespace, stringref, L <http://cbor.schmorp.de/stringref>)
		771
		772	These tags are automatically decoded when encountered. They are only
		773	encoded, however, when C<pack_strings> is enabled.
		774
		775	=item 22098 (indirection, L<http://cbor.schmorp.de/indirection>)
		776
		777	This tag is automatically generated when a reference are encountered (with
		778	the exception of hash and array refernces). It is converted to a reference
		779	when decoding.
		780
		781	=item 55799 (self-describe CBOR, RFC 7049)
		782
		783	This value is not generated on encoding (unless explicitly requested by
		784	the user), and is simply ignored when decoding.
		785
		786	=back
		787
		788	=head2 NON-ENFORCED TAGS
		789
		790	These tags have default filters provided when decoding. Their handling can
		791	be overriden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by
		792	providing a custom C<filter> callback when decoding.
		793
		794	When they result in decoding into a specific Perl class, the module
		795	usually provides a corresponding C<TO_CBOR> method as well.
		796
		797	When any of these need to load additional modules that are not part of the
		798	perl core distribution (e.g. L<URI>), it is (currently) up to the user to
		799	provide these modules. The decoding usually fails with an exception if the
		800	required module cannot be loaded.
		801
		802	=over 4
		803
		804	=item 0, 1 (date/time string, seconds since the epoch)
		805
		806	These tags are decoded into L<Time::Piece> objects. The corresponding
		807	C<Time::Piece::TO_CBOR> method always encodes into tag 1 values currently.
		808
		809	The L<Time::Piece> API is generally surprisingly bad, and fractional
		810	seconds are only accidentally kept intact, so watch out. On the plus side,
		811	the module comes with perl since 5.10, which has to count for something.
		812
		813	=item 2, 3 (positive/negative bignum)
		814
		815	These tags are decoded into L<Math::BigInt> objects. The corresponding
		816	C<Math::BigInt::TO_CBOR> method encodes "small" bigints into normal CBOR
		817	integers, and others into positive/negative CBOR bignums.
		818
		819	=item 4, 5 (decimal fraction/bigfloat)
		820
		821	Both decimal fractions and bigfloats are decoded into L<Math::BigFloat>
		822	objects. The corresponding C<Math::BigFloat::TO_CBOR> method I<always>
		823	encodes into a decimal fraction.
		824
		825	CBOR cannot represent bigfloats with I<very> large exponents - conversion
		826	of such big float objects is undefined.
		827
		828	Also, NaN and infinities are not encoded properly.
		829
		830	=item 21, 22, 23 (expected later JSON conversion)
		831
		832	CBOR::XS is not a CBOR-to-JSON converter, and will simply ignore these
		833	tags.
		834
		835	=item 32 (URI)
		836
		837	These objects decode into L<URI> objects. The corresponding
		838	C<URI::TO_CBOR> method again results in a CBOR URI value.
		839
		840	=back
		841
		842	=cut
		843
		844	our %FILTER = (
		845	# 0 # rfc4287 datetime, utf-8
		846	# 1 # unix timestamp, any
		847
		848	2 => sub { # pos bigint
		849	require Math::BigInt;
		850	Math::BigInt->new ("0x" . unpack "H*", pop)
		851	},
		852
		853	3 => sub { # neg bigint
		854	require Math::BigInt;
		855	-Math::BigInt->new ("0x" . unpack "H*", pop)
		856	},
		857
		858	4 => sub { # decimal fraction, array
		859	require Math::BigFloat;
		860	Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
		861	},
		862
		863	5 => sub { # bigfloat, array
		864	require Math::BigFloat;
		865	scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2)
		866	},
		867
		868	21 => sub { pop }, # expected conversion to base64url encoding
		869	22 => sub { pop }, # expected conversion to base64 encoding
		870	23 => sub { pop }, # expected conversion to base16 encoding
		871
		872	# 24 # embedded cbor, byte string
		873
		874	32 => sub {
		875	require URI;
		876	URI->new (pop)
		877	},
		878
		879	# 33 # base64url rfc4648, utf-8
		880	# 34 # base64 rfc46484, utf-8
		881	# 35 # regex pcre/ecma262, utf-8
		882	# 36 # mime message rfc2045, utf-8
		883	);
		884
548		885
549	=head1 CBOR and JSON	886	=head1 CBOR and JSON
550		887
551	CBOR is supposed to implement a superset of the JSON data model, and is,	888	CBOR is supposed to implement a superset of the JSON data model, and is,
552	with some coercion, able to represent all JSON texts (something that other	889	with some coercion, able to represent all JSON texts (something that other
…		…
613	properly. Half precision types are accepted, but not encoded.	950	properly. Half precision types are accepted, but not encoded.
614		951
615	Strict mode and canonical mode are not implemented.	952	Strict mode and canonical mode are not implemented.
616		953
617		954
		955	=head1 LIMITATIONS ON PERLS WITHOUT 64-BIT INTEGER SUPPORT
		956
		957	On perls that were built without 64 bit integer support (these are rare
		958	nowadays, even on 32 bit architectures), support for any kind of 64 bit
		959	integer in CBOR is very limited - most likely, these 64 bit values will
		960	be truncated, corrupted, or otherwise not decoded correctly. This also
		961	includes string, array and map sizes that are stored as 64 bit integers.
		962
		963
618	=head1 THREADS	964	=head1 THREADS
619		965
620	This module is I<not> guaranteed to be thread safe and there are no	966	This module is I<not> guaranteed to be thread safe and there are no
621	plans to change this until Perl gets thread support (as opposed to the	967	plans to change this until Perl gets thread support (as opposed to the
622	horribly slow so-called "threads" which are simply slow and bloated	968	horribly slow so-called "threads" which are simply slow and bloated
…		…
634	Please refrain from using rt.cpan.org or any other bug reporting	980	Please refrain from using rt.cpan.org or any other bug reporting
635	service. I put the contact address into my modules for a reason.	981	service. I put the contact address into my modules for a reason.
636		982
637	=cut	983	=cut
638		984
		985	our %FILTER = (
		986	0 => sub { # rfc4287 datetime, utf-8
		987	require Time::Piece;
		988	# Time::Piece::Strptime uses the "incredibly flexible date parsing routine"
		989	# from FreeBSD, which can't parse ISO 8601, RFC3339, RFC4287 or much of anything
		990	# else either. Whats incredibe over standard strptime totally escapes me.
		991	# doesn't do fractional times, either. sigh.
		992	# In fact, it's all a lie, it uses whatever strptime it wants, and of course,
		993	# they are all incomptible. The openbsd one simply ignores %z (but according to the
		994	# docs, it would be much more incredibly flexible indeed. If it worked, that is.).
		995	scalar eval {
		996	my $s = $_[1];
		997
		998	$s =~ s/Z$/+00:00/;
		999	$s =~ s/(\.[0-9]+)?([+-][0-9][0-9]):([0-9][0-9])$//
		1000	or die;
		1001
		1002	my $b = $1 - ($2 * 60 + $3) * 60; # fractional part + offset. hopefully
		1003	my $d = Time::Piece->strptime ($s, "%Y-%m-%dT%H:%M:%S");
		1004
		1005	Time::Piece::gmtime ($d->epoch + $b)
		1006	} \|\| die "corrupted CBOR date/time string ($_[0])";
		1007	},
		1008
		1009	1 => sub { # seconds since the epoch, possibly fractional
		1010	require Time::Piece;
		1011	scalar Time::Piece::gmtime (pop)
		1012	},
		1013
		1014	2 => sub { # pos bigint
		1015	require Math::BigInt;
		1016	Math::BigInt->new ("0x" . unpack "H*", pop)
		1017	},
		1018
		1019	3 => sub { # neg bigint
		1020	require Math::BigInt;
		1021	-Math::BigInt->new ("0x" . unpack "H*", pop)
		1022	},
		1023
		1024	4 => sub { # decimal fraction, array
		1025	require Math::BigFloat;
		1026	Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
		1027	},
		1028
		1029	5 => sub { # bigfloat, array
		1030	require Math::BigFloat;
		1031	scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2)
		1032	},
		1033
		1034	21 => sub { pop }, # expected conversion to base64url encoding
		1035	22 => sub { pop }, # expected conversion to base64 encoding
		1036	23 => sub { pop }, # expected conversion to base16 encoding
		1037
		1038	# 24 # embedded cbor, byte string
		1039
		1040	32 => sub {
		1041	require URI;
		1042	URI->new (pop)
		1043	},
		1044
		1045	# 33 # base64url rfc4648, utf-8
		1046	# 34 # base64 rfc46484, utf-8
		1047	# 35 # regex pcre/ecma262, utf-8
		1048	# 36 # mime message rfc2045, utf-8
		1049	);
		1050
		1051	sub CBOR::XS::default_filter {
		1052	&{ $FILTER{$_[0]} or return }
		1053	}
		1054
		1055	sub URI::TO_CBOR {
		1056	my $uri = $_[0]->as_string;
		1057	utf8::upgrade $uri;
		1058	tag 32, $uri
		1059	}
		1060
		1061	sub Math::BigInt::TO_CBOR {
		1062	if ($_[0] >= -2147483648 && $_[0] <= 2147483647) {
		1063	$_[0]->numify
		1064	} else {
		1065	my $hex = substr $_[0]->as_hex, 2;
		1066	$hex = "0$hex" if 1 & length $hex; # sigh
		1067	tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex
		1068	}
		1069	}
		1070
		1071	sub Math::BigFloat::TO_CBOR {
		1072	my ($m, $e) = $_[0]->parts;
		1073	tag 4, [$e->numify, $m]
		1074	}
		1075
		1076	sub Time::Piece::TO_CBOR {
		1077	tag 1, $_[0]->epoch
		1078	}
		1079
639	XSLoader::load "CBOR::XS", $VERSION;	1080	XSLoader::load "CBOR::XS", $VERSION;
640		1081
641	=head1 SEE ALSO	1082	=head1 SEE ALSO
642		1083
643	The L<JSON> and L<JSON::XS> modules that do similar, but human-readable,	1084	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 1.13 by root, Tue Oct 29 15:56:31 2013 UTC vs. Revision 1.38 by root, Tue Dec 3 10:23:55 2013 UTC

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Comparing CBOR-XS/XS.pm (file contents):
Revision 1.13 by root, Tue Oct 29 15:56:31 2013 UTC vs.
Revision 1.38 by root, Tue Dec 3 10:23:55 2013 UTC