[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 1.60 by root, Tue Apr 26 16:26:24 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
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 = 1.5;
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	FUTURE DIRECTION: the motivation behind this option is to avoid I<real>
		224	cycles - future versions of this module might chose to decode cyclic data
		225	structures using weak references when this option is off, instead of
		226	throwing an error.
		227
		228	This option does not affect C<encode> in any way - shared values and
		229	references will always be encoded properly if present.
		230
		231	=item $cbor = $cbor->pack_strings ([$enable])
		232
		233	=item $enabled = $cbor->get_pack_strings
		234
		235	If C<$enable> is true (or missing), then C<encode> will try not to encode
		236	the same string twice, but will instead encode a reference to the string
		237	instead. Depending on your data format, this can save a lot of space, but
		238	also results in a very large runtime overhead (expect encoding times to be
		239	2-4 times as high as without).
		240
		241	It is recommended to leave it off unless you know your
		242	communications partner supports the stringref extension to CBOR
		243	(L<http://cbor.schmorp.de/stringref>), as without decoder support, the
		244	resulting data structure might not be usable.
		245
		246	If C<$enable> is false (the default), then C<encode> will encode strings
		247	the standard CBOR way.
		248
		249	This option does not affect C<decode> in any way - string references will
		250	always be decoded properly if present.
		251
		252	=item $cbor = $cbor->text_keys ([$enable])
		253
		254	=item $enabled = $cbor->get_text_keys
		255
		256	If C<$enabled> is true (or missing), then C<encode> will encode all
		257	perl hash keys as CBOR text strings/UTF-8 string, upgrading them as needed.
		258
		259	If C<$enable> is false (the default), then C<encode> will encode hash keys
		260	normally - upgraded perl strings (strings internally encoded as UTF-8) as
		261	CBOR text strings, and downgraded perl strings as CBOR byte strings.
		262
		263	This option does not affect C<decode> in any way.
		264
		265	This option is useful for interoperability with CBOR decoders that don't
		266	treat byte strings as a form of text. It is especially useful as Perl
		267	gives very little control over hash keys.
		268
		269	Enabling this option can be slow, as all downgraded hash keys that are
		270	encoded need to be scanned and converted to UTF-8.
		271
		272	=item $cbor = $cbor->text_strings ([$enable])
		273
		274	=item $enabled = $cbor->get_text_strings
		275
		276	This option works similar to C<text_keys>, above, but works on all strings
		277	(including hash keys), so C<text_keys> has no further effect after
		278	enabling C<text_strings>.
		279
		280	If C<$enabled> is true (or missing), then C<encode> will encode all perl
		281	strings as CBOR text strings/UTF-8 strings, upgrading them as needed.
		282
		283	If C<$enable> is false (the default), then C<encode> will encode strings
		284	normally (but see C<text_keys>) - upgraded perl strings (strings
		285	internally encoded as UTF-8) as CBOR text strings, and downgraded perl
		286	strings as CBOR byte strings.
		287
		288	This option does not affect C<decode> in any way.
		289
		290	This option has similar advantages and disadvantages as C<text_keys>. In
		291	addition, this option effectively removes the ability to encode byte
		292	strings, which might break some C<FREEZE> and C<TO_CBOR> methods that rely
		293	on this, such as bignum encoding, so this option is mainly useful for very
		294	simple data.
		295
		296	=item $cbor = $cbor->validate_utf8 ([$enable])
		297
		298	=item $enabled = $cbor->get_validate_utf8
		299
		300	If C<$enable> is true (or missing), then C<decode> will validate that
		301	elements (text strings) containing UTF-8 data in fact contain valid UTF-8
		302	data (instead of blindly accepting it). This validation obviously takes
		303	extra time during decoding.
		304
		305	The concept of "valid UTF-8" used is perl's concept, which is a superset
		306	of the official UTF-8.
		307
		308	If C<$enable> is false (the default), then C<decode> will blindly accept
		309	UTF-8 data, marking them as valid UTF-8 in the resulting data structure
		310	regardless of whether that's true or not.
		311
		312	Perl isn't too happy about corrupted UTF-8 in strings, but should
		313	generally not crash or do similarly evil things. Extensions might be not
		314	so forgiving, so it's recommended to turn on this setting if you receive
		315	untrusted CBOR.
		316
		317	This option does not affect C<encode> in any way - strings that are
		318	supposedly valid UTF-8 will simply be dumped into the resulting CBOR
		319	string without checking whether that is, in fact, true or not.
		320
		321	=item $cbor = $cbor->filter ([$cb->($tag, $value)])
		322
		323	=item $cb_or_undef = $cbor->get_filter
		324
		325	Sets or replaces the tagged value decoding filter (when C<$cb> is
		326	specified) or clears the filter (if no argument or C<undef> is provided).
		327
		328	The filter callback is called only during decoding, when a non-enforced
		329	tagged value has been decoded (see L<TAG HANDLING AND EXTENSIONS> for a
		330	list of enforced tags). For specific tags, it's often better to provide a
		331	default converter using the C<%CBOR::XS::FILTER> hash (see below).
		332
		333	The first argument is the numerical tag, the second is the (decoded) value
		334	that has been tagged.
		335
		336	The filter function should return either exactly one value, which will
		337	replace the tagged value in the decoded data structure, or no values,
		338	which will result in default handling, which currently means the decoder
		339	creates a C<CBOR::XS::Tagged> object to hold the tag and the value.
		340
		341	When the filter is cleared (the default state), the default filter
		342	function, C<CBOR::XS::default_filter>, is used. This function simply looks
		343	up the tag in the C<%CBOR::XS::FILTER> hash. If an entry exists it must be
		344	a code reference that is called with tag and value, and is responsible for
		345	decoding the value. If no entry exists, it returns no values.
		346
		347	Example: decode all tags not handled internally into C<CBOR::XS::Tagged>
		348	objects, with no other special handling (useful when working with
		349	potentially "unsafe" CBOR data).
		350
		351	CBOR::XS->new->filter (sub { })->decode ($cbor_data);
		352
		353	Example: provide a global filter for tag 1347375694, converting the value
		354	into some string form.
		355
		356	$CBOR::XS::FILTER{1347375694} = sub {
		357	my ($tag, $value);
		358
		359	"tag 1347375694 value $value"
		360	};
208		361
209	=item $cbor_data = $cbor->encode ($perl_scalar)	362	=item $cbor_data = $cbor->encode ($perl_scalar)
210		363
211	Converts the given Perl data structure (a scalar value) to its CBOR	364	Converts the given Perl data structure (a scalar value) to its CBOR
212	representation.	365	representation.
…		…
226	and you need to know where the first CBOR string ends amd the next one	379	and you need to know where the first CBOR string ends amd the next one
227	starts.	380	starts.
228		381
229	CBOR::XS->new->decode_prefix ("......")	382	CBOR::XS->new->decode_prefix ("......")
230	=> ("...", 3)	383	=> ("...", 3)
		384
		385	=back
		386
		387	=head2 INCREMENTAL PARSING
		388
		389	In some cases, there is the need for incremental parsing of JSON
		390	texts. While this module always has to keep both CBOR text and resulting
		391	Perl data structure in memory at one time, it does allow you to parse a
		392	CBOR stream incrementally, using a similar to using "decode_prefix" to see
		393	if a full CBOR object is available, but is much more efficient.
		394
		395	It basically works by parsing as much of a CBOR string as possible - if
		396	the CBOR data is not complete yet, the pasrer will remember where it was,
		397	to be able to restart when more data has been accumulated. Once enough
		398	data is available to either decode a complete CBOR value or raise an
		399	error, a real decode will be attempted.
		400
		401	A typical use case would be a network protocol that consists of sending
		402	and receiving CBOR-encoded messages. The solution that works with CBOR and
		403	about anything else is by prepending a length to every CBOR value, so the
		404	receiver knows how many octets to read. More compact (and slightly slower)
		405	would be to just send CBOR values back-to-back, as C<CBOR::XS> knows where
		406	a CBOR value ends, and doesn't need an explicit length.
		407
		408	The following methods help with this:
		409
		410	=over 4
		411
		412	=item @decoded = $cbor->incr_parse ($buffer)
		413
		414	This method attempts to decode exactly one CBOR value from the beginning
		415	of the given C<$buffer>. The value is removed from the C<$buffer> on
		416	success. When C<$buffer> doesn't contain a complete value yet, it returns
		417	nothing. Finally, when the C<$buffer> doesn't start with something
		418	that could ever be a valid CBOR value, it raises an exception, just as
		419	C<decode> would. In the latter case the decoder state is undefined and
		420	must be reset before being able to parse further.
		421
		422	This method modifies the C<$buffer> in place. When no CBOR value can be
		423	decoded, the decoder stores the current string offset. On the next call,
		424	continues decoding at the place where it stopped before. For this to make
		425	sense, the C<$buffer> must begin with the same octets as on previous
		426	unsuccessful calls.
		427
		428	You can call this method in scalar context, in which case it either
		429	returns a decoded value or C<undef>. This makes it impossible to
		430	distinguish between CBOR null values (which decode to C<undef>) and an
		431	unsuccessful decode, which is often acceptable.
		432
		433	=item @decoded = $cbor->incr_parse_multiple ($buffer)
		434
		435	Same as C<incr_parse>, but attempts to decode as many CBOR values as
		436	possible in one go, instead of at most one. Calls to C<incr_parse> and
		437	C<incr_parse_multiple> can be interleaved.
		438
		439	=item $cbor->incr_reset
		440
		441	Resets the incremental decoder. This throws away any saved state, so that
		442	subsequent calls to C<incr_parse> or C<incr_parse_multiple> start to parse
		443	a new CBOR value from the beginning of the C<$buffer> again.
		444
		445	This method can be caled at any time, but it I<must> be called if you want
		446	to change your C<$buffer> or there was a decoding error and you want to
		447	reuse the C<$cbor> object for future incremental parsings.
231		448
232	=back	449	=back
233		450
234		451
235	=head1 MAPPING	452	=head1 MAPPING
…		…
253	CBOR integers become (numeric) perl scalars. On perls without 64 bit	470	CBOR integers become (numeric) perl scalars. On perls without 64 bit
254	support, 64 bit integers will be truncated or otherwise corrupted.	471	support, 64 bit integers will be truncated or otherwise corrupted.
255		472
256	=item byte strings	473	=item byte strings
257		474
258	Byte strings will become octet strings in Perl (the byte values 0..255	475	Byte strings will become octet strings in Perl (the Byte values 0..255
259	will simply become characters of the same value in Perl).	476	will simply become characters of the same value in Perl).
260		477
261	=item UTF-8 strings	478	=item UTF-8 strings
262		479
263	UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be	480	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>,	498	C<Types:Serialiser::false> and C<Types::Serialiser::error>,
282	respectively. They are overloaded to act almost exactly like the numbers	499	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	500	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.	501	error). See the L<Types::Serialiser> manpage for details.
285		502
286	=item CBOR tag 256 (perl object)	503	=item tagged values
287		504
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	505	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		506
303	In the future, support for user-supplied conversions might get added.	507	See L<TAG HANDLING AND EXTENSIONS> and the description of C<< ->filter >>
		508	for details on which tags are handled how.
304		509
305	=item anything else	510	=item anything else
306		511
307	Anything else (e.g. unsupported simple values) will raise a decoding	512	Anything else (e.g. unsupported simple values) will raise a decoding
308	error.	513	error.
…		…
311		516
312		517
313	=head2 PERL -> CBOR	518	=head2 PERL -> CBOR
314		519
315	The mapping from Perl to CBOR is slightly more difficult, as Perl is a	520	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	521	typeless language. That means this module can only guess which CBOR type
317	a Perl value.	522	is meant by a perl value.
318		523
319	=over 4	524	=over 4
320		525
321	=item hash references	526	=item hash references
322		527
323	Perl hash references become CBOR maps. As there is no inherent ordering in	528	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	529	hash keys (or CBOR maps), they will usually be encoded in a pseudo-random
325	order.	530	order. This order can be different each time a hash is encoded.
326		531
327	Currently, tied hashes will use the indefinite-length format, while normal	532	Currently, tied hashes will use the indefinite-length format, while normal
328	hashes will use the fixed-length format.	533	hashes will use the fixed-length format.
329		534
330	=item array references	535	=item array references
331		536
332	Perl array references become fixed-length CBOR arrays.	537	Perl array references become fixed-length CBOR arrays.
333		538
334	=item other references	539	=item other references
335		540
336	Other unblessed references are generally not allowed and will cause an	541	Other unblessed references will be represented using
337	exception to be thrown, except for references to the integers C<0> and	542	the indirection tag extension (tag value C<22098>,
338	C<1>, which get turned into false and true in CBOR.	543	L<http://cbor.schmorp.de/indirection>). CBOR decoders are guaranteed
		544	to be able to decode these values somehow, by either "doing the right
		545	thing", decoding into a generic tagged object, simply ignoring the tag, or
		546	something else.
339		547
340	=item CBOR::XS::Tagged objects	548	=item CBOR::XS::Tagged objects
341		549
342	Objects of this type must be arrays consisting of a single C<[tag, value]>	550	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	551	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	552	be encoded as appropriate for the value. You must use C<CBOR::XS::tag> to
345	create such objects.	553	create such objects.
346		554
347	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error	555	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error
348		556
349	These special values become CBOR true, CBOR false and CBOR undefined	557	These special values become CBOR true, CBOR false and CBOR undefined
…		…
351	if you want.	559	if you want.
352		560
353	=item other blessed objects	561	=item other blessed objects
354		562
355	Other blessed objects are serialised via C<TO_CBOR> or C<FREEZE>. See	563	Other blessed objects are serialised via C<TO_CBOR> or C<FREEZE>. See
356	L<OBJECT SERIALISATION>, below, for details.	564	L<TAG HANDLING AND EXTENSIONS> for specific classes handled by this
		565	module, and L<OBJECT SERIALISATION> for generic object serialisation.
357		566
358	=item simple scalars	567	=item simple scalars
359		568
360	TODO
361	Simple Perl scalars (any scalar that is not a reference) are the most	569	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	570	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	571	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:	572	before encoding as CBOR strings, and anything else as number value:
365		573
366	# dump as number	574	# dump as number
367	encode_cbor [2] # yields [2]	575	encode_cbor [2] # yields [2]
368	encode_cbor [-3.0e17] # yields [-3e+17]	576	encode_cbor [-3.0e17] # yields [-3e+17]
369	my $value = 5; encode_cbor [$value] # yields [5]	577	my $value = 5; encode_cbor [$value] # yields [5]
370		578
371	# used as string, so dump as string	579	# used as string, so dump as string (either byte or text)
372	print $value;	580	print $value;
373	encode_cbor [$value] # yields ["5"]	581	encode_cbor [$value] # yields ["5"]
374		582
375	# undef becomes null	583	# undef becomes null
376	encode_cbor [undef] # yields [null]	584	encode_cbor [undef] # yields [null]
…		…
379		587
380	my $x = 3.1; # some variable containing a number	588	my $x = 3.1; # some variable containing a number
381	"$x"; # stringified	589	"$x"; # stringified
382	$x .= ""; # another, more awkward way to stringify	590	$x .= ""; # another, more awkward way to stringify
383	print $x; # perl does it for you, too, quite often	591	print $x; # perl does it for you, too, quite often
		592
		593	You can force whether a string is encoded as byte or text string by using
		594	C<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
		599	Perl doesn't define what operations up- and downgrade strings, so if the
		600	difference between byte and text is important, you should up- or downgrade
		601	your string as late as possible before encoding. You can also force the
		602	use of CBOR text strings by using C<text_keys> or C<text_strings>.
384		603
385	You can force the type to be a CBOR number by numifying it:	604	You can force the type to be a CBOR number by numifying it:
386		605
387	my $x = "3"; # some variable containing a string	606	my $x = "3"; # some variable containing a string
388	$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
…		…
401		620
402	=back	621	=back
403		622
404	=head2 OBJECT SERIALISATION	623	=head2 OBJECT SERIALISATION
405		624
		625	This module implements both a CBOR-specific and the generic
		626	L<Types::Serialier> object serialisation protocol. The following
		627	subsections explain both methods.
		628
		629	=head3 ENCODING
		630
406	This module knows two way to serialise a Perl object: The CBOR-specific	631	This module knows two way to serialise a Perl object: The CBOR-specific
407	way, and the generic way.	632	way, and the generic way.
408		633
409	Whenever the encoder encounters a Perl object that it cnanot serialise	634	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	635	directly (most of them), it will first look up the C<TO_CBOR> method on
411	it.	636	it.
412		637
413	If it has a C<TO_CBOR> method, it will call it with the object as only	638	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	639	argument, and expects exactly one return value, which it will then
…		…
420		645
421	The C<FREEZE> method can return any number of values (i.e. zero or	646	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	647	more). These will be encoded as CBOR perl object, together with the
423	classname.	648	classname.
424		649
		650	These methods I<MUST NOT> change the data structure that is being
		651	serialised. Failure to comply to this can result in memory corruption -
		652	and worse.
		653
425	If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail	654	If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail
426	with an error.	655	with an error.
427		656
		657	=head3 DECODING
		658
428	Objects encoded via C<TO_CBOR> cannot be automatically decoded, but	659	Objects encoded via C<TO_CBOR> cannot (normally) be automatically decoded,
429	objects encoded via C<FREEZE> can be decoded using the following protocol:	660	but objects encoded via C<FREEZE> can be decoded using the following
		661	protocol:
430		662
431	When an encoded CBOR perl object is encountered by the decoder, it will	663	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	664	look up the C<THAW> method, by using the stored classname, and will fail
433	if the method cannot be found.	665	if the method cannot be found.
434		666
435	After the lookup it will call the C<THAW> method with the stored classname	667	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	668	as first argument, the constant string C<CBOR> as second argument, and all
437	values returned by C<FREEZE> as remaining arguments.	669	values returned by C<FREEZE> as remaining arguments.
438		670
439	=head4 EXAMPLES	671	=head3 EXAMPLES
440		672
441	Here is an example C<TO_CBOR> method:	673	Here is an example C<TO_CBOR> method:
442		674
443	sub My::Object::TO_CBOR {	675	sub My::Object::TO_CBOR {
444	my ($obj) = @_;	676	my ($obj) = @_;
…		…
455		687
456	sub URI::TO_CBOR {	688	sub URI::TO_CBOR {
457	my ($self) = @_;	689	my ($self) = @_;
458	my $uri = "$self"; # stringify uri	690	my $uri = "$self"; # stringify uri
459	utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string	691	utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string
460	CBOR::XS::tagged 32, "$_[0]"	692	CBOR::XS::tag 32, "$_[0]"
461	}	693	}
462		694
463	This will encode URIs as a UTF-8 string with tag 32, which indicates an	695	This will encode URIs as a UTF-8 string with tag 32, which indicates an
464	URI.	696	URI.
465		697
…		…
476	"$self" # encode url string	708	"$self" # encode url string
477	}	709	}
478		710
479	sub URI::THAW {	711	sub URI::THAW {
480	my ($class, $serialiser, $uri) = @_;	712	my ($class, $serialiser, $uri) = @_;
481
482	$class->new ($uri)	713	$class->new ($uri)
483	}	714	}
484		715
485	Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For	716	Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For
486	example, a C<FREEZE> method that returns "type", "id" and "variant" values	717	example, a C<FREEZE> method that returns "type", "id" and "variant" values
…		…
601	CBOR::XS::tag 24,	832	CBOR::XS::tag 24,
602	encode_cbor [1, 2, 3];	833	encode_cbor [1, 2, 3];
603		834
604	=head1 TAG HANDLING AND EXTENSIONS	835	=head1 TAG HANDLING AND EXTENSIONS
605		836
606	This section describes how this module handles specific tagged values and	837	This section describes how this module handles specific tagged values
607	extensions. If a tag is not mentioned here, then the default handling	838	and extensions. If a tag is not mentioned here and no additional filters
		839	are provided for it, then the default handling applies (creating a
608	applies (creating a CBOR::XS::Tagged object on decoding, and only encoding	840	CBOR::XS::Tagged object on decoding, and only encoding the tag when
609	the tag when explicitly requested).	841	explicitly requested).
		842
		843	Tags not handled specifically are currently converted into a
		844	L<CBOR::XS::Tagged> object, which is simply a blessed array reference
		845	consisting of the numeric tag value followed by the (decoded) CBOR value.
610		846
611	Future versions of this module reserve the right to special case	847	Future versions of this module reserve the right to special case
612	additional tags (such as bigfloat or base64url).	848	additional tags (such as base64url).
		849
		850	=head2 ENFORCED TAGS
		851
		852	These tags are always handled when decoding, and their handling cannot be
		853	overridden by the user.
613		854
614	=over 4	855	=over 4
615		856
616	=item <unassigned> (perl-object, L<http://cbor.schmorp.de/perl-object>)	857	=item 26 (perl-object, L<http://cbor.schmorp.de/perl-object>)
617		858
618	These tags are automatically created for serialisable objects using the	859	These tags are automatically created (and decoded) for serialisable
619	C<FREEZE/THAW> methods (the L<Types::Serialier> object serialisation	860	objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object
620	protocol).	861	serialisation protocol). See L<OBJECT SERIALISATION> for details.
621		862
622	=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>)
623		864
624	These tags are automatically decoded when encountered, resulting in	865	These tags are automatically decoded when encountered (and they do not
		866	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	867	shared values in the decoded object. They are only encoded, however, when
626	C<allow_sharable> is enabled.	868	C<allow_sharing> is enabled.
		869
		870	Not all shared values can be successfully decoded: values that reference
		871	themselves will I<currently> decode as C<undef> (this is not the same
		872	as a reference pointing to itself, which will be represented as a value
		873	that contains an indirect reference to itself - these will be decoded
		874	properly).
		875
		876	Note that considerably more shared value data structures can be decoded
		877	than will be encoded - currently, only values pointed to by references
		878	will be shared, others will not. While non-reference shared values can be
		879	generated in Perl with some effort, they were considered too unimportant
		880	to be supported in the encoder. The decoder, however, will decode these
		881	values as shared values.
		882
		883	=item 256, 25 (stringref-namespace, stringref, L<http://cbor.schmorp.de/stringref>)
		884
		885	These tags are automatically decoded when encountered. They are only
		886	encoded, however, when C<pack_strings> is enabled.
627		887
628	=item 22098 (indirection, L<http://cbor.schmorp.de/indirection>)	888	=item 22098 (indirection, L<http://cbor.schmorp.de/indirection>)
629		889
630	This tag is automatically generated when a reference are encountered (with	890	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	891	the exception of hash and array references). It is converted to a reference
632	when decoding.	892	when decoding.
633		893
634	=item 55799 (self-describe CBOR, RFC 7049)	894	=item 55799 (self-describe CBOR, RFC 7049)
635		895
636	This value is not generated on encoding (unless explicitly requested by	896	This value is not generated on encoding (unless explicitly requested by
637	the user), and is simply ignored when decoding.	897	the user), and is simply ignored when decoding.
638		898
639	=back	899	=back
640		900
		901	=head2 NON-ENFORCED TAGS
		902
		903	These tags have default filters provided when decoding. Their handling can
		904	be overridden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by
		905	providing a custom C<filter> callback when decoding.
		906
		907	When they result in decoding into a specific Perl class, the module
		908	usually provides a corresponding C<TO_CBOR> method as well.
		909
		910	When any of these need to load additional modules that are not part of the
		911	perl core distribution (e.g. L<URI>), it is (currently) up to the user to
		912	provide these modules. The decoding usually fails with an exception if the
		913	required module cannot be loaded.
		914
		915	=over 4
		916
		917	=item 0, 1 (date/time string, seconds since the epoch)
		918
		919	These tags are decoded into L<Time::Piece> objects. The corresponding
		920	C<Time::Piece::TO_CBOR> method always encodes into tag 1 values currently.
		921
		922	The L<Time::Piece> API is generally surprisingly bad, and fractional
		923	seconds are only accidentally kept intact, so watch out. On the plus side,
		924	the module comes with perl since 5.10, which has to count for something.
		925
		926	=item 2, 3 (positive/negative bignum)
		927
		928	These tags are decoded into L<Math::BigInt> objects. The corresponding
		929	C<Math::BigInt::TO_CBOR> method encodes "small" bigints into normal CBOR
		930	integers, and others into positive/negative CBOR bignums.
		931
		932	=item 4, 5, 264, 265 (decimal fraction/bigfloat)
		933
		934	Both decimal fractions and bigfloats are decoded into L<Math::BigFloat>
		935	objects. The corresponding C<Math::BigFloat::TO_CBOR> method I<always>
		936	encodes into a decimal fraction (either tag 4 or 264).
		937
		938	NaN and infinities are not encoded properly, as they cannot be represented
		939	in CBOR.
		940
		941	See L<BIGNUM SECURITY CONSIDERATIONS> for more info.
		942
		943	=item 30 (rational numbers)
		944
		945	These tags are decoded into L<Math::BigRat> objects. The corresponding
		946	C<Math::BigRat::TO_CBOR> method encodes rational numbers with denominator
		947	C<1> via their numerator only, i.e., they become normal integers or
		948	C<bignums>.
		949
		950	See L<BIGNUM SECURITY CONSIDERATIONS> for more info.
		951
		952	=item 21, 22, 23 (expected later JSON conversion)
		953
		954	CBOR::XS is not a CBOR-to-JSON converter, and will simply ignore these
		955	tags.
		956
		957	=item 32 (URI)
		958
		959	These objects decode into L<URI> objects. The corresponding
		960	C<URI::TO_CBOR> method again results in a CBOR URI value.
		961
		962	=back
		963
		964	=cut
641		965
642	=head1 CBOR and JSON	966	=head1 CBOR and JSON
643		967
644	CBOR is supposed to implement a superset of the JSON data model, and is,	968	CBOR is supposed to implement a superset of the JSON data model, and is,
645	with some coercion, able to represent all JSON texts (something that other	969	with some coercion, able to represent all JSON texts (something that other
…		…
687	Also keep in mind that CBOR::XS might leak contents of your Perl data	1011	Also keep in mind that CBOR::XS might leak contents of your Perl data
688	structures in its error messages, so when you serialise sensitive	1012	structures in its error messages, so when you serialise sensitive
689	information you might want to make sure that exceptions thrown by CBOR::XS	1013	information you might want to make sure that exceptions thrown by CBOR::XS
690	will not end up in front of untrusted eyes.	1014	will not end up in front of untrusted eyes.
691		1015
		1016
		1017	=head1 BIGNUM SECURITY CONSIDERATIONS
		1018
		1019	CBOR::XS provides a C<TO_CBOR> method for both L<Math::BigInt> and
		1020	L<Math::BigFloat> that tries to encode the number in the simplest possible
		1021	way, that is, either a CBOR integer, a CBOR bigint/decimal fraction (tag
		1022	4) or an arbitrary-exponent decimal fraction (tag 264). Rational numbers
		1023	(L<Math::BigRat>, tag 30) can also contain bignums as members.
		1024
		1025	CBOR::XS will also understand base-2 bigfloat or arbitrary-exponent
		1026	bigfloats (tags 5 and 265), but it will never generate these on its own.
		1027
		1028	Using the built-in L<Math::BigInt::Calc> support, encoding and decoding
		1029	decimal fractions is generally fast. Decoding bigints can be slow for very
		1030	big numbers (tens of thousands of digits, something that could potentially
		1031	be caught by limiting the size of CBOR texts), and decoding bigfloats or
		1032	arbitrary-exponent bigfloats can be I<extremely> slow (minutes, decades)
		1033	for large exponents (roughly 40 bit and longer).
		1034
		1035	Additionally, L<Math::BigInt> can take advantage of other bignum
		1036	libraries, such as L<Math::GMP>, which cannot handle big floats with large
		1037	exponents, and might simply abort or crash your program, due to their code
		1038	quality.
		1039
		1040	This can be a concern if you want to parse untrusted CBOR. If it is, you
		1041	might want to disable decoding of tag 2 (bigint) and 3 (negative bigint)
		1042	types. You should also disable types 5 and 265, as these can be slow even
		1043	without bigints.
		1044
		1045	Disabling bigints will also partially or fully disable types that rely on
		1046	them, e.g. rational numbers that use bignums.
		1047
		1048
692	=head1 CBOR IMPLEMENTATION NOTES	1049	=head1 CBOR IMPLEMENTATION NOTES
693		1050
694	This section contains some random implementation notes. They do not	1051	This section contains some random implementation notes. They do not
695	describe guaranteed behaviour, but merely behaviour as-is implemented	1052	describe guaranteed behaviour, but merely behaviour as-is implemented
696	right now.	1053	right now.
…		…
704	Only the double data type is supported for NV data types - when Perl uses	1061	Only the double data type is supported for NV data types - when Perl uses
705	long double to represent floating point values, they might not be encoded	1062	long double to represent floating point values, they might not be encoded
706	properly. Half precision types are accepted, but not encoded.	1063	properly. Half precision types are accepted, but not encoded.
707		1064
708	Strict mode and canonical mode are not implemented.	1065	Strict mode and canonical mode are not implemented.
		1066
		1067
		1068	=head1 LIMITATIONS ON PERLS WITHOUT 64-BIT INTEGER SUPPORT
		1069
		1070	On perls that were built without 64 bit integer support (these are rare
		1071	nowadays, even on 32 bit architectures, as all major Perl distributions
		1072	are built with 64 bit integer support), support for any kind of 64 bit
		1073	integer in CBOR is very limited - most likely, these 64 bit values will
		1074	be truncated, corrupted, or otherwise not decoded correctly. This also
		1075	includes string, array and map sizes that are stored as 64 bit integers.
709		1076
710		1077
711	=head1 THREADS	1078	=head1 THREADS
712		1079
713	This module is I<not> guaranteed to be thread safe and there are no	1080	This module is I<not> guaranteed to be thread safe and there are no
…		…
727	Please refrain from using rt.cpan.org or any other bug reporting	1094	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.	1095	service. I put the contact address into my modules for a reason.
729		1096
730	=cut	1097	=cut
731		1098
		1099	our %FILTER = (
		1100	0 => sub { # rfc4287 datetime, utf-8
		1101	require Time::Piece;
		1102	# Time::Piece::Strptime uses the "incredibly flexible date parsing routine"
		1103	# from FreeBSD, which can't parse ISO 8601, RFC3339, RFC4287 or much of anything
		1104	# else either. Whats incredibe over standard strptime totally escapes me.
		1105	# doesn't do fractional times, either. sigh.
		1106	# In fact, it's all a lie, it uses whatever strptime it wants, and of course,
		1107	# they are all incompatible. The openbsd one simply ignores %z (but according to the
		1108	# docs, it would be much more incredibly flexible indeed. If it worked, that is.).
		1109	scalar eval {
		1110	my $s = $_[1];
		1111
		1112	$s =~ s/Z$/+00:00/;
		1113	$s =~ s/(\.[0-9]+)?([+-][0-9][0-9]):([0-9][0-9])$//
		1114	or die;
		1115
		1116	my $b = $1 - ($2 * 60 + $3) * 60; # fractional part + offset. hopefully
		1117	my $d = Time::Piece->strptime ($s, "%Y-%m-%dT%H:%M:%S");
		1118
		1119	Time::Piece::gmtime ($d->epoch + $b)
		1120	} \|\| die "corrupted CBOR date/time string ($_[0])";
		1121	},
		1122
		1123	1 => sub { # seconds since the epoch, possibly fractional
		1124	require Time::Piece;
		1125	scalar Time::Piece::gmtime (pop)
		1126	},
		1127
		1128	2 => sub { # pos bigint
		1129	require Math::BigInt;
		1130	Math::BigInt->new ("0x" . unpack "H*", pop)
		1131	},
		1132
		1133	3 => sub { # neg bigint
		1134	require Math::BigInt;
		1135	-Math::BigInt->new ("0x" . unpack "H*", pop)
		1136	},
		1137
		1138	4 => sub { # decimal fraction, array
		1139	require Math::BigFloat;
		1140	Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
		1141	},
		1142
		1143	264 => sub { # decimal fraction with arbitrary exponent
		1144	require Math::BigFloat;
		1145	Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
		1146	},
		1147
		1148	5 => sub { # bigfloat, array
		1149	require Math::BigFloat;
		1150	scalar Math::BigFloat->new ($_[1][1]) * Math::BigFloat->new (2)->bpow ($_[1][0])
		1151	},
		1152
		1153	265 => sub { # bigfloat with arbitrary exponent
		1154	require Math::BigFloat;
		1155	scalar Math::BigFloat->new ($_[1][1]) * Math::BigFloat->new (2)->bpow ($_[1][0])
		1156	},
		1157
		1158	30 => sub { # rational number
		1159	require Math::BigRat;
		1160	Math::BigRat->new ("$_[1][0]/$_[1][1]") # separate parameters only work in recent versons
		1161	},
		1162
		1163	21 => sub { pop }, # expected conversion to base64url encoding
		1164	22 => sub { pop }, # expected conversion to base64 encoding
		1165	23 => sub { pop }, # expected conversion to base16 encoding
		1166
		1167	# 24 # embedded cbor, byte string
		1168
		1169	32 => sub {
		1170	require URI;
		1171	URI->new (pop)
		1172	},
		1173
		1174	# 33 # base64url rfc4648, utf-8
		1175	# 34 # base64 rfc46484, utf-8
		1176	# 35 # regex pcre/ecma262, utf-8
		1177	# 36 # mime message rfc2045, utf-8
		1178	);
		1179
		1180	sub CBOR::XS::default_filter {
		1181	&{ $FILTER{$_[0]} or return }
		1182	}
		1183
		1184	sub URI::TO_CBOR {
		1185	my $uri = $_[0]->as_string;
		1186	utf8::upgrade $uri;
		1187	tag 32, $uri
		1188	}
		1189
		1190	sub Math::BigInt::TO_CBOR {
		1191	if (-2147483648 <= $_[0] && $_[0] <= 2147483647) {
		1192	$_[0]->numify
		1193	} else {
		1194	my $hex = substr $_[0]->as_hex, 2;
		1195	$hex = "0$hex" if 1 & length $hex; # sigh
		1196	tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex
		1197	}
		1198	}
		1199
		1200	sub Math::BigFloat::TO_CBOR {
		1201	my ($m, $e) = $_[0]->parts;
		1202
		1203	-9223372036854775808 <= $e && $e <= 18446744073709551615
		1204	? tag 4, [$e->numify, $m]
		1205	: tag 264, [$e, $m]
		1206	}
		1207
		1208	sub Math::BigRat::TO_CBOR {
		1209	my ($n, $d) = $_[0]->parts;
		1210
		1211	# older versions of BigRat need *1, as they not always return numbers
		1212
		1213	$d*1 == 1
		1214	? $n*1
		1215	: tag 30, [$n1, $d1]
		1216	}
		1217
		1218	sub Time::Piece::TO_CBOR {
		1219	tag 1, 0 + $_[0]->epoch
		1220	}
		1221
732	XSLoader::load "CBOR::XS", $VERSION;	1222	XSLoader::load "CBOR::XS", $VERSION;
733		1223
734	=head1 SEE ALSO	1224	=head1 SEE ALSO
735		1225
736	The L<JSON> and L<JSON::XS> modules that do similar, but human-readable,	1226	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 1.60 by root, Tue Apr 26 16:26:24 2016 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 1.60 by root, Tue Apr 26 16:26:24 2016 UTC