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

Comparing CBOR-XS/XS.pm (file contents):
Revision 1.6 by root, Sun Oct 27 20:40:25 2013 UTC vs.
Revision 1.29 by root, Sat Nov 30 15:23:59 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 IS A PRE-ALPHA RELEASE! IT WILL CRASH, CORRUPT YOUR DATA
32	AND EAT YOUR CHILDREN! (Actually, apart from being untested and a bit
33	feature-limited, it might already be useful).
34
35	This module converts Perl data structures to the Concise Binary Object	31	This module converts Perl data structures to the Concise Binary Object
36	Representation (CBOR) and vice versa. CBOR is a fast binary serialisation	32	Representation (CBOR) and vice versa. CBOR is a fast binary serialisation
37	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.
38	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
39	CBOR.	35	represent it in CBOR.
40		36
41	This makes it a faster and more compact binary alternative to JSON, with	37	In short, CBOR is a faster and quite compact binary alternative to JSON,
42	the added ability of supporting serialising of perl objects.	38	with the added ability of supporting serialisation of Perl objects. (JSON
		39	often compresses better than CBOR though, so if you plan to compress the
		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 (see
		54	C<allow_sharing>), string deduplication (see C<pack_strings>) and scalar
		55	references (always enabled).
43		56
44	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
45	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.
46		59
47	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
…		…
51		64
52	package CBOR::XS;	65	package CBOR::XS;
53		66
54	use common::sense;	67	use common::sense;
55		68
56	our $VERSION = 0.03;	69	our $VERSION = '1.0';
57	our @ISA = qw(Exporter);	70	our @ISA = qw(Exporter);
58		71
59	our @EXPORT = qw(encode_cbor decode_cbor);	72	our @EXPORT = qw(encode_cbor decode_cbor);
60		73
61	use Exporter;	74	use Exporter;
…		…
98	strings. All boolean flags described below are by default I<disabled>.	111	strings. All boolean flags described below are by default I<disabled>.
99		112
100	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
101	be chained:	114	be chained:
102		115
103	#TODO
104	my $cbor = CBOR::XS->new->encode ({a => [1,2]});	116	my $cbor = CBOR::XS->new->encode ({a => [1,2]});
105		117
106	=item $cbor = $cbor->max_depth ([$maximum_nesting_depth])	118	=item $cbor = $cbor->max_depth ([$maximum_nesting_depth])
107		119
108	=item $max_depth = $cbor->get_max_depth	120	=item $max_depth = $cbor->get_max_depth
…		…
142	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
143	C<0> is specified).	155	C<0> is specified).
144		156
145	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.
146		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.
		186
		187	It is recommended to leave it off unless you know your
		188	communication partner supports the value sharing extensions to CBOR
		189	(L<http://cbor.schmorp.de/value-sharing>), as without decoder support, the
		190	resulting data structure might be unusable.
		191
		192	Detecting shared values incurs a runtime overhead when values are encoded
		193	that have a reference counter large than one, and might unnecessarily
		194	increase the encoded size, as potentially shared values are encode as
		195	sharable whether or not they are actually shared.
		196
		197	At the moment, only targets of references can be shared (e.g. scalars,
		198	arrays or hashes pointed to by a reference). Weirder constructs, such as
		199	an array with multiple "copies" of the I<same> string, which are hard but
		200	not impossible to create in Perl, are not supported (this is the same as
		201	with L<Storable>).
		202
		203	If C<$enable> is false (the default), then C<encode> will encode shared
		204	data structures repeatedly, unsharing them in the process. Cyclic data
		205	structures cannot be encoded in this mode.
		206
		207	This option does not affect C<decode> in any way - shared values and
		208	references will always be decoded properly if present.
		209
		210	=item $cbor = $cbor->pack_strings ([$enable])
		211
		212	=item $enabled = $cbor->get_pack_strings
		213
		214	If C<$enable> is true (or missing), then C<encode> will try not to encode
		215	the same string twice, but will instead encode a reference to the string
		216	instead. Depending on your data format, this can save a lot of space, but
		217	also results in a very large runtime overhead (expect encoding times to be
		218	2-4 times as high as without).
		219
		220	It is recommended to leave it off unless you know your
		221	communications partner supports the stringref extension to CBOR
		222	(L<http://cbor.schmorp.de/stringref>), as without decoder support, the
		223	resulting data structure might not be usable.
		224
		225	If C<$enable> is false (the default), then C<encode> will encode strings
		226	the standard CBOR way.
		227
		228	This option does not affect C<decode> in any way - string references will
		229	always be decoded properly if present.
		230
		231	=item $cbor = $cbor->filter ([$cb->($tag, $value)])
		232
		233	=item $cb_or_undef = $cbor->get_filter
		234
		235	Sets or replaces the tagged value decoding filter (when C<$cb> is
		236	specified) or clears the filter (if no argument or C<undef> is provided).
		237
		238	The filter callback is called only during decoding, when a non-enforced
		239	tagged value has been decoded (see L<TAG HANDLING AND EXTENSIONS> for a
		240	list of enforced tags). For specific tags, it's often better to provide a
		241	default converter using the C<%CBOR::XS::FILTER> hash (see below).
		242
		243	The first argument is the numerical tag, the second is the (decoded) value
		244	that has been tagged.
		245
		246	The filter function should return either exactly one value, which will
		247	replace the tagged value in the decoded data structure, or no values,
		248	which will result in default handling, which currently means the decoder
		249	creates a C<CBOR::XS::Tagged> object to hold the tag and the value.
		250
		251	When the filter is cleared (the default state), the default filter
		252	function, C<CBOR::XS::default_filter>, is used. This function simply looks
		253	up the tag in the C<%CBOR::XS::FILTER> hash. If an entry exists it must be
		254	a code reference that is called with tag and value, and is responsible for
		255	decoding the value. If no entry exists, it returns no values.
		256
		257	Example: decode all tags not handled internally into C<CBOR::XS::Tagged>
		258	objects, with no other special handling (useful when working with
		259	potentially "unsafe" CBOR data).
		260
		261	CBOR::XS->new->filter (sub { })->decode ($cbor_data);
		262
		263	Example: provide a global filter for tag 1347375694, converting the value
		264	into some string form.
		265
		266	$CBOR::XS::FILTER{1347375694} = sub {
		267	my ($tag, $value);
		268
		269	"tag 1347375694 value $value"
		270	};
		271
147	=item $cbor_data = $cbor->encode ($perl_scalar)	272	=item $cbor_data = $cbor->encode ($perl_scalar)
148		273
149	Converts the given Perl data structure (a scalar value) to its CBOR	274	Converts the given Perl data structure (a scalar value) to its CBOR
150	representation.	275	representation.
151		276
…		…
191	CBOR integers become (numeric) perl scalars. On perls without 64 bit	316	CBOR integers become (numeric) perl scalars. On perls without 64 bit
192	support, 64 bit integers will be truncated or otherwise corrupted.	317	support, 64 bit integers will be truncated or otherwise corrupted.
193		318
194	=item byte strings	319	=item byte strings
195		320
196	Byte strings will become octet strings in Perl (the byte values 0..255	321	Byte strings will become octet strings in Perl (the Byte values 0..255
197	will simply become characters of the same value in Perl).	322	will simply become characters of the same value in Perl).
198		323
199	=item UTF-8 strings	324	=item UTF-8 strings
200		325
201	UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be	326	UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be
…		…
219	C<Types:Serialiser::false> and C<Types::Serialiser::error>,	344	C<Types:Serialiser::false> and C<Types::Serialiser::error>,
220	respectively. They are overloaded to act almost exactly like the numbers	345	respectively. They are overloaded to act almost exactly like the numbers
221	C<1> and C<0> (for true and false) or to throw an exception on access (for	346	C<1> and C<0> (for true and false) or to throw an exception on access (for
222	error). See the L<Types::Serialiser> manpage for details.	347	error). See the L<Types::Serialiser> manpage for details.
223		348
224	=item CBOR tag 256 (perl object)	349	=item tagged values
225		350
226	The tag value C<256> (TODO: pending iana registration) will be used to
227	deserialise a Perl object.
228
229	TODO For this to work, the class must be loaded and must have a
230	C<FROM_CBOR> method. The decoder will then call the C<FROM_CBOR> method
231	with the constructor arguments provided by the C<TO_CBOR> method (see
232	below).
233
234	The C<FROM_CBOR> method must return a single value that will then be used
235	as the deserialised value.
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	351	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		352
248	In the future, support for user-supplied conversions might get added.	353	See L<TAG HANDLING AND EXTENSIONS> and the description of C<< ->filter >>
		354	for details on which tags are handled how.
249		355
250	=item anything else	356	=item anything else
251		357
252	Anything else (e.g. unsupported simple values) will raise a decoding	358	Anything else (e.g. unsupported simple values) will raise a decoding
253	error.	359	error.
…		…
256		362
257		363
258	=head2 PERL -> CBOR	364	=head2 PERL -> CBOR
259		365
260	The mapping from Perl to CBOR is slightly more difficult, as Perl is a	366	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	367	typeless language. That means this module can only guess which CBOR type
262	a Perl value.	368	is meant by a perl value.
263		369
264	=over 4	370	=over 4
265		371
266	=item hash references	372	=item hash references
267		373
268	Perl hash references become CBOR maps. As there is no inherent ordering in	374	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	375	hash keys (or CBOR maps), they will usually be encoded in a pseudo-random
270	order.	376	order. This order can be different each time a hahs is encoded.
271		377
272	Currently, tied hashes will use the indefinite-length format, while normal	378	Currently, tied hashes will use the indefinite-length format, while normal
273	hashes will use the fixed-length format.	379	hashes will use the fixed-length format.
274		380
275	=item array references	381	=item array references
276		382
277	Perl array references become fixed-length CBOR arrays.	383	Perl array references become fixed-length CBOR arrays.
278		384
279	=item other references	385	=item other references
280		386
281	Other unblessed references are generally not allowed and will cause an	387	Other unblessed references will be represented using
282	exception to be thrown, except for references to the integers C<0> and	388	the indirection tag extension (tag value C<22098>,
283	C<1>, which get turned into false and true in CBOR.	389	L<http://cbor.schmorp.de/indirection>). CBOR decoders are guaranteed
		390	to be able to decode these values somehow, by either "doing the right
		391	thing", decoding into a generic tagged object, simply ignoring the tag, or
		392	something else.
284		393
285	=item CBOR::XS::Tagged objects	394	=item CBOR::XS::Tagged objects
286		395
287	Objects of this type must be arrays consisting of a single C<[tag, value]>	396	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 be	397	pair. The (numerical) tag will be encoded as a CBOR tag, the value will
289	encoded as appropriate for the value.	398	be encoded as appropriate for the value. You must use C<CBOR::XS::tag> to
		399	create such objects.
290		400
291	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error	401	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error
292		402
293	These special values become CBOR true, CBOR false and CBOR undefined	403	These special values become CBOR true, CBOR false and CBOR undefined
294	values, respectively. You can also use C<\1>, C<\0> and C<\undef> directly	404	values, respectively. You can also use C<\1>, C<\0> and C<\undef> directly
295	if you want.	405	if you want.
296		406
297	=item blessed objects	407	=item other blessed objects
298		408
299	Other blessed objects currently need to have a C<TO_CBOR> method. It	409	Other blessed objects are serialised via C<TO_CBOR> or C<FREEZE>. See
300	will be called on every object that is being serialised, and must return	410	L<TAG HANDLING AND EXTENSIONS> for specific classes handled by this
301	something that can be encoded in CBOR.	411	module, and L<OBJECT SERIALISATION> for generic object serialisation.
302		412
303	=item simple scalars	413	=item simple scalars
304		414
305	TODO
306	Simple Perl scalars (any scalar that is not a reference) are the most	415	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	416	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	417	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:	418	before encoding as CBOR strings, and anything else as number value:
310		419
311	# dump as number	420	# dump as number
312	encode_cbor [2] # yields [2]	421	encode_cbor [2] # yields [2]
313	encode_cbor [-3.0e17] # yields [-3e+17]	422	encode_cbor [-3.0e17] # yields [-3e+17]
314	my $value = 5; encode_cbor [$value] # yields [5]	423	my $value = 5; encode_cbor [$value] # yields [5]
315		424
316	# used as string, so dump as string	425	# used as string, so dump as string (either byte or text)
317	print $value;	426	print $value;
318	encode_cbor [$value] # yields ["5"]	427	encode_cbor [$value] # yields ["5"]
319		428
320	# undef becomes null	429	# undef becomes null
321	encode_cbor [undef] # yields [null]	430	encode_cbor [undef] # yields [null]
…		…
324		433
325	my $x = 3.1; # some variable containing a number	434	my $x = 3.1; # some variable containing a number
326	"$x"; # stringified	435	"$x"; # stringified
327	$x .= ""; # another, more awkward way to stringify	436	$x .= ""; # another, more awkward way to stringify
328	print $x; # perl does it for you, too, quite often	437	print $x; # perl does it for you, too, quite often
		438
		439	You can force whether a string ie encoded as byte or text string by using
		440	C<utf8::upgrade> and C<utf8::downgrade>):
		441
		442	utf8::upgrade $x; # encode $x as text string
		443	utf8::downgrade $x; # encode $x as byte string
		444
		445	Perl doesn't define what operations up- and downgrade strings, so if the
		446	difference between byte and text is important, you should up- or downgrade
		447	your string as late as possible before encoding.
329		448
330	You can force the type to be a CBOR number by numifying it:	449	You can force the type to be a CBOR number by numifying it:
331		450
332	my $x = "3"; # some variable containing a string	451	my $x = "3"; # some variable containing a string
333	$x += 0; # numify it, ensuring it will be dumped as a number	452	$x += 0; # numify it, ensuring it will be dumped as a number
…		…
344	represent numerical values are supported, but might suffer loss of	463	represent numerical values are supported, but might suffer loss of
345	precision.	464	precision.
346		465
347	=back	466	=back
348		467
		468	=head2 OBJECT SERIALISATION
349		469
		470	This module implements both a CBOR-specific and the generic
		471	L<Types::Serialier> object serialisation protocol. The following
		472	subsections explain both methods.
		473
		474	=head3 ENCODING
		475
		476	This module knows two way to serialise a Perl object: The CBOR-specific
		477	way, and the generic way.
		478
		479	Whenever the encoder encounters a Perl object that it cannot serialise
		480	directly (most of them), it will first look up the C<TO_CBOR> method on
		481	it.
		482
		483	If it has a C<TO_CBOR> method, it will call it with the object as only
		484	argument, and expects exactly one return value, which it will then
		485	substitute and encode it in the place of the object.
		486
		487	Otherwise, it will look up the C<FREEZE> method. If it exists, it will
		488	call it with the object as first argument, and the constant string C<CBOR>
		489	as the second argument, to distinguish it from other serialisers.
		490
		491	The C<FREEZE> method can return any number of values (i.e. zero or
		492	more). These will be encoded as CBOR perl object, together with the
		493	classname.
		494
		495	These methods I<MUST NOT> change the data structure that is being
		496	serialised. Failure to comply to this can result in memory corruption -
		497	and worse.
		498
		499	If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail
		500	with an error.
		501
		502	=head3 DECODING
		503
		504	Objects encoded via C<TO_CBOR> cannot (normally) be automatically decoded,
		505	but objects encoded via C<FREEZE> can be decoded using the following
		506	protocol:
		507
		508	When an encoded CBOR perl object is encountered by the decoder, it will
		509	look up the C<THAW> method, by using the stored classname, and will fail
		510	if the method cannot be found.
		511
		512	After the lookup it will call the C<THAW> method with the stored classname
		513	as first argument, the constant string C<CBOR> as second argument, and all
		514	values returned by C<FREEZE> as remaining arguments.
		515
		516	=head3 EXAMPLES
		517
		518	Here is an example C<TO_CBOR> method:
		519
		520	sub My::Object::TO_CBOR {
		521	my ($obj) = @_;
		522
		523	["this is a serialised My::Object object", $obj->{id}]
		524	}
		525
		526	When a C<My::Object> is encoded to CBOR, it will instead encode a simple
		527	array with two members: a string, and the "object id". Decoding this CBOR
		528	string will yield a normal perl array reference in place of the object.
		529
		530	A more useful and practical example would be a serialisation method for
		531	the URI module. CBOR has a custom tag value for URIs, namely 32:
		532
		533	sub URI::TO_CBOR {
		534	my ($self) = @_;
		535	my $uri = "$self"; # stringify uri
		536	utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string
		537	CBOR::XS::tag 32, "$_[0]"
		538	}
		539
		540	This will encode URIs as a UTF-8 string with tag 32, which indicates an
		541	URI.
		542
		543	Decoding such an URI will not (currently) give you an URI object, but
		544	instead a CBOR::XS::Tagged object with tag number 32 and the string -
		545	exactly what was returned by C<TO_CBOR>.
		546
		547	To serialise an object so it can automatically be deserialised, you need
		548	to use C<FREEZE> and C<THAW>. To take the URI module as example, this
		549	would be a possible implementation:
		550
		551	sub URI::FREEZE {
		552	my ($self, $serialiser) = @_;
		553	"$self" # encode url string
		554	}
		555
		556	sub URI::THAW {
		557	my ($class, $serialiser, $uri) = @_;
		558
		559	$class->new ($uri)
		560	}
		561
		562	Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For
		563	example, a C<FREEZE> method that returns "type", "id" and "variant" values
		564	would cause an invocation of C<THAW> with 5 arguments:
		565
		566	sub My::Object::FREEZE {
		567	my ($self, $serialiser) = @_;
		568
		569	($self->{type}, $self->{id}, $self->{variant})
		570	}
		571
		572	sub My::Object::THAW {
		573	my ($class, $serialiser, $type, $id, $variant) = @_;
		574
		575	$class-<new (type => $type, id => $id, variant => $variant)
		576	}
		577
		578
350	=head2 MAGIC HEADER	579	=head1 MAGIC HEADER
351		580
352	There is no way to distinguish CBOR from other formats	581	There is no way to distinguish CBOR from other formats
353	programmatically. To make it easier to distinguish CBOR from other	582	programmatically. To make it easier to distinguish CBOR from other
354	formats, the CBOR specification has a special "magic string" that can be	583	formats, the CBOR specification has a special "magic string" that can be
355	prepended to any CBOR string without changing it's meaning.	584	prepended to any CBOR string without changing its meaning.
356		585
357	This string is available as C<$CBOR::XS::MAGIC>. This module does not	586	This string is available as C<$CBOR::XS::MAGIC>. This module does not
358	prepend this string tot he CBOR data it generates, but it will ignroe it	587	prepend this string to the CBOR data it generates, but it will ignore it
359	if present, so users can prepend this string as a "file type" indicator as	588	if present, so users can prepend this string as a "file type" indicator as
360	required.	589	required.
361		590
362		591
		592	=head1 THE CBOR::XS::Tagged CLASS
		593
		594	CBOR has the concept of tagged values - any CBOR value can be tagged with
		595	a numeric 64 bit number, which are centrally administered.
		596
		597	C<CBOR::XS> handles a few tags internally when en- or decoding. You can
		598	also create tags yourself by encoding C<CBOR::XS::Tagged> objects, and the
		599	decoder will create C<CBOR::XS::Tagged> objects itself when it hits an
		600	unknown tag.
		601
		602	These objects are simply blessed array references - the first member of
		603	the array being the numerical tag, the second being the value.
		604
		605	You can interact with C<CBOR::XS::Tagged> objects in the following ways:
		606
		607	=over 4
		608
		609	=item $tagged = CBOR::XS::tag $tag, $value
		610
		611	This function(!) creates a new C<CBOR::XS::Tagged> object using the given
		612	C<$tag> (0..2**64-1) to tag the given C<$value> (which can be any Perl
		613	value that can be encoded in CBOR, including serialisable Perl objects and
		614	C<CBOR::XS::Tagged> objects).
		615
		616	=item $tagged->[0]
		617
		618	=item $tagged->[0] = $new_tag
		619
		620	=item $tag = $tagged->tag
		621
		622	=item $new_tag = $tagged->tag ($new_tag)
		623
		624	Access/mutate the tag.
		625
		626	=item $tagged->[1]
		627
		628	=item $tagged->[1] = $new_value
		629
		630	=item $value = $tagged->value
		631
		632	=item $new_value = $tagged->value ($new_value)
		633
		634	Access/mutate the tagged value.
		635
		636	=back
		637
		638	=cut
		639
		640	sub tag($$) {
		641	bless [@_], CBOR::XS::Tagged::;
		642	}
		643
		644	sub CBOR::XS::Tagged::tag {
		645	$_[0][0] = $_[1] if $#_;
		646	$_[0][0]
		647	}
		648
		649	sub CBOR::XS::Tagged::value {
		650	$_[0][1] = $_[1] if $#_;
		651	$_[0][1]
		652	}
		653
		654	=head2 EXAMPLES
		655
		656	Here are some examples of C<CBOR::XS::Tagged> uses to tag objects.
		657
		658	You can look up CBOR tag value and emanings in the IANA registry at
		659	L<http://www.iana.org/assignments/cbor-tags/cbor-tags.xhtml>.
		660
		661	Prepend a magic header (C<$CBOR::XS::MAGIC>):
		662
		663	my $cbor = encode_cbor CBOR::XS::tag 55799, $value;
		664	# same as:
		665	my $cbor = $CBOR::XS::MAGIC . encode_cbor $value;
		666
		667	Serialise some URIs and a regex in an array:
		668
		669	my $cbor = encode_cbor [
		670	(CBOR::XS::tag 32, "http://www.nethype.de/"),
		671	(CBOR::XS::tag 32, "http://software.schmorp.de/"),
		672	(CBOR::XS::tag 35, "^[Pp][Ee][Rr][lL]\$"),
		673	];
		674
		675	Wrap CBOR data in CBOR:
		676
		677	my $cbor_cbor = encode_cbor
		678	CBOR::XS::tag 24,
		679	encode_cbor [1, 2, 3];
		680
		681	=head1 TAG HANDLING AND EXTENSIONS
		682
		683	This section describes how this module handles specific tagged values
		684	and extensions. If a tag is not mentioned here and no additional filters
		685	are provided for it, then the default handling applies (creating a
		686	CBOR::XS::Tagged object on decoding, and only encoding the tag when
		687	explicitly requested).
		688
		689	Tags not handled specifically are currently converted into a
		690	L<CBOR::XS::Tagged> object, which is simply a blessed array reference
		691	consisting of the numeric tag value followed by the (decoded) CBOR value.
		692
		693	Future versions of this module reserve the right to special case
		694	additional tags (such as base64url).
		695
		696	=head2 ENFORCED TAGS
		697
		698	These tags are always handled when decoding, and their handling cannot be
		699	overriden by the user.
		700
		701	=over 4
		702
		703	=item 26 (perl-object, L<http://cbor.schmorp.de/perl-object>)
		704
		705	These tags are automatically created (and decoded) for serialisable
		706	objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object
		707	serialisation protocol). See L<OBJECT SERIALISATION> for details.
		708
		709	=item 28, 29 (sharable, sharedref, L <http://cbor.schmorp.de/value-sharing>)
		710
		711	These tags are automatically decoded when encountered, resulting in
		712	shared values in the decoded object. They are only encoded, however, when
		713	C<allow_sharable> is enabled.
		714
		715	=item 256, 25 (stringref-namespace, stringref, L <http://cbor.schmorp.de/stringref>)
		716
		717	These tags are automatically decoded when encountered. They are only
		718	encoded, however, when C<pack_strings> is enabled.
		719
		720	=item 22098 (indirection, L<http://cbor.schmorp.de/indirection>)
		721
		722	This tag is automatically generated when a reference are encountered (with
		723	the exception of hash and array refernces). It is converted to a reference
		724	when decoding.
		725
		726	=item 55799 (self-describe CBOR, RFC 7049)
		727
		728	This value is not generated on encoding (unless explicitly requested by
		729	the user), and is simply ignored when decoding.
		730
		731	=back
		732
		733	=head2 NON-ENFORCED TAGS
		734
		735	These tags have default filters provided when decoding. Their handling can
		736	be overriden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by
		737	providing a custom C<filter> callback when decoding.
		738
		739	When they result in decoding into a specific Perl class, the module
		740	usually provides a corresponding C<TO_CBOR> method as well.
		741
		742	When any of these need to load additional modules that are not part of the
		743	perl core distribution (e.g. L<URI>), it is (currently) up to the user to
		744	provide these modules. The decoding usually fails with an exception if the
		745	required module cannot be loaded.
		746
		747	=over 4
		748
		749	=item 2, 3 (positive/negative bignum)
		750
		751	These tags are decoded into L<Math::BigInt> objects. The corresponding
		752	C<Math::BigInt::TO_CBOR> method encodes "small" bigints into normal CBOR
		753	integers, and others into positive/negative CBOR bignums.
		754
		755	=item 4, 5 (decimal fraction/bigfloat)
		756
		757	Both decimal fractions and bigfloats are decoded into L<Math::BigFloat>
		758	objects. The corresponding C<Math::BigFloat::TO_CBOR> method I<always>
		759	encodes into a decimal fraction.
		760
		761	CBOR cannot represent bigfloats with I<very> large exponents - conversion
		762	of such big float objects is undefined.
		763
		764	Also, NaN and infinities are not encoded properly.
		765
		766	=item 21, 22, 23 (expected later JSON conversion)
		767
		768	CBOR::XS is not a CBOR-to-JSON converter, and will simply ignore these
		769	tags.
		770
		771	=item 32 (URI)
		772
		773	These objects decode into L<URI> objects. The corresponding
		774	C<URI::TO_CBOR> method again results in a CBOR URI value.
		775
		776	=back
		777
		778	=cut
		779
		780	our %FILTER = (
		781	# 0 # rfc4287 datetime, utf-8
		782	# 1 # unix timestamp, any
		783
		784	2 => sub { # pos bigint
		785	require Math::BigInt;
		786	Math::BigInt->new ("0x" . unpack "H*", pop)
		787	},
		788
		789	3 => sub { # neg bigint
		790	require Math::BigInt;
		791	-Math::BigInt->new ("0x" . unpack "H*", pop)
		792	},
		793
		794	4 => sub { # decimal fraction, array
		795	require Math::BigFloat;
		796	Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
		797	},
		798
		799	5 => sub { # bigfloat, array
		800	require Math::BigFloat;
		801	scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2)
		802	},
		803
		804	21 => sub { pop }, # expected conversion to base64url encoding
		805	22 => sub { pop }, # expected conversion to base64 encoding
		806	23 => sub { pop }, # expected conversion to base16 encoding
		807
		808	# 24 # embedded cbor, byte string
		809
		810	32 => sub {
		811	require URI;
		812	URI->new (pop)
		813	},
		814
		815	# 33 # base64url rfc4648, utf-8
		816	# 34 # base64 rfc46484, utf-8
		817	# 35 # regex pcre/ecma262, utf-8
		818	# 36 # mime message rfc2045, utf-8
		819	);
		820
		821
363	=head2 CBOR and JSON	822	=head1 CBOR and JSON
364		823
365	CBOR is supposed to implement a superset of the JSON data model, and is,	824	CBOR is supposed to implement a superset of the JSON data model, and is,
366	with some coercion, able to represent all JSON texts (something that other	825	with some coercion, able to represent all JSON texts (something that other
367	"binary JSON" formats such as BSON generally do not support).	826	"binary JSON" formats such as BSON generally do not support).
368		827
…		…
448	Please refrain from using rt.cpan.org or any other bug reporting	907	Please refrain from using rt.cpan.org or any other bug reporting
449	service. I put the contact address into my modules for a reason.	908	service. I put the contact address into my modules for a reason.
450		909
451	=cut	910	=cut
452		911
		912	our %FILTER = (
		913	# 0 # rfc4287 datetime, utf-8
		914	# 1 # unix timestamp, any
		915
		916	2 => sub { # pos bigint
		917	require Math::BigInt;
		918	Math::BigInt->new ("0x" . unpack "H*", pop)
		919	},
		920
		921	3 => sub { # neg bigint
		922	require Math::BigInt;
		923	-Math::BigInt->new ("0x" . unpack "H*", pop)
		924	},
		925
		926	4 => sub { # decimal fraction, array
		927	require Math::BigFloat;
		928	Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
		929	},
		930
		931	5 => sub { # bigfloat, array
		932	require Math::BigFloat;
		933	scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2)
		934	},
		935
		936	21 => sub { pop }, # expected conversion to base64url encoding
		937	22 => sub { pop }, # expected conversion to base64 encoding
		938	23 => sub { pop }, # expected conversion to base16 encoding
		939
		940	# 24 # embedded cbor, byte string
		941
		942	32 => sub {
		943	require URI;
		944	URI->new (pop)
		945	},
		946
		947	# 33 # base64url rfc4648, utf-8
		948	# 34 # base64 rfc46484, utf-8
		949	# 35 # regex pcre/ecma262, utf-8
		950	# 36 # mime message rfc2045, utf-8
		951	);
		952
		953	sub CBOR::XS::default_filter {
		954	&{ $FILTER{$_[0]} or return }
		955	}
		956
		957	sub URI::TO_CBOR {
		958	my $uri = $_[0]->as_string;
		959	utf8::upgrade $uri;
		960	CBOR::XS::tag 32, $uri
		961	}
		962
		963	sub Math::BigInt::TO_CBOR {
		964	if ($_[0] >= -2147483648 && $_[0] <= 2147483647) {
		965	$_[0]->numify
		966	} else {
		967	my $hex = substr $_[0]->as_hex, 2;
		968	$hex = "0$hex" if 1 & length $hex; # sigh
		969	CBOR::XS::tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex
		970	}
		971	}
		972
		973	sub Math::BigFloat::TO_CBOR {
		974	my ($m, $e) = $_[0]->parts;
		975	CBOR::XS::tag 4, [$e->numify, $m]
		976	}
		977
453	XSLoader::load "CBOR::XS", $VERSION;	978	XSLoader::load "CBOR::XS", $VERSION;
454		979
455	=head1 SEE ALSO	980	=head1 SEE ALSO
456		981
457	The L<JSON> and L<JSON::XS> modules that do similar, but human-readable,	982	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 1.6 by root, Sun Oct 27 20:40:25 2013 UTC vs. Revision 1.29 by root, Sat Nov 30 15:23:59 2013 UTC

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Comparing CBOR-XS/XS.pm (file contents):
Revision 1.6 by root, Sun Oct 27 20:40:25 2013 UTC vs.
Revision 1.29 by root, Sat Nov 30 15:23:59 2013 UTC