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

Comparing CBOR-XS/XS.pm (file contents):
Revision 1.3 by root, Sat Oct 26 11:08:34 2013 UTC vs.
Revision 1.28 by root, Thu Nov 28 16:09:04 2013 UTC

…		…
12	$perl_value = decode_cbor $binary_cbor_data;	12	$perl_value = decode_cbor $binary_cbor_data;
13		13
14	# OO-interface	14	# OO-interface
15		15
16	$coder = CBOR::XS->new;	16	$coder = CBOR::XS->new;
17	#TODO	17	$binary_cbor_data = $coder->encode ($perl_value);
		18	$perl_value = $coder->decode ($binary_cbor_data);
		19
		20	# prefix decoding
		21
		22	my $many_cbor_strings = ...;
		23	while (length $many_cbor_strings) {
		24	my ($data, $length) = $cbor->decode_prefix ($many_cbor_strings);
		25	# data was decoded
		26	substr $many_cbor_strings, 0, $length, ""; # remove decoded cbor string
		27	}
18		28
19	=head1 DESCRIPTION	29	=head1 DESCRIPTION
20		30
21	WARNING! THIS IS A PRE-ALPHA RELEASE! IT WILL CRASH, CORRUPT YOUR DATA AND	31	This module converts Perl data structures to the Concise Binary Object
22	EAT YOUR CHILDREN!	32	Representation (CBOR) and vice versa. CBOR is a fast binary serialisation
		33	format that aims to use an (almost) superset of the JSON data model, i.e.
		34	when you can represent something useful in JSON, you should be able to
		35	represent it in CBOR.
23		36
24	This module converts Perl data structures to CBOR and vice versa. Its	37	In short, CBOR is a faster and quite compact binary alternative to JSON,
		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).
		56
25	primary goal is to be I<correct> and its secondary goal is to be	57	The primary goal of this module is to be I<correct> and the secondary goal
26	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.
27		59
28	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
29	vice versa.	61	vice versa.
30		62
31	=cut	63	=cut
32		64
33	package CBOR::XS;	65	package CBOR::XS;
34		66
35	use common::sense;	67	use common::sense;
36		68
37	our $VERSION = 0.02;	69	our $VERSION = '1.0';
38	our @ISA = qw(Exporter);	70	our @ISA = qw(Exporter);
39		71
40	our @EXPORT = qw(encode_cbor decode_cbor);	72	our @EXPORT = qw(encode_cbor decode_cbor);
41		73
42	use Exporter;	74	use Exporter;
43	use XSLoader;	75	use XSLoader;
44		76
		77	use Types::Serialiser;
		78
45	our $MAGIC = "\xd9\xd9\xf7";	79	our $MAGIC = "\xd9\xd9\xf7";
46		80
47	=head1 FUNCTIONAL INTERFACE	81	=head1 FUNCTIONAL INTERFACE
48		82
49	The following convenience methods are provided by this module. They are	83	The following convenience methods are provided by this module. They are
…		…
77	strings. All boolean flags described below are by default I<disabled>.	111	strings. All boolean flags described below are by default I<disabled>.
78		112
79	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
80	be chained:	114	be chained:
81		115
82	#TODO
83	my $cbor = CBOR::XS->new->encode ({a => [1,2]});	116	my $cbor = CBOR::XS->new->encode ({a => [1,2]});
84		117
85	=item $cbor = $cbor->max_depth ([$maximum_nesting_depth])	118	=item $cbor = $cbor->max_depth ([$maximum_nesting_depth])
86		119
87	=item $max_depth = $cbor->get_max_depth	120	=item $max_depth = $cbor->get_max_depth
…		…
121	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
122	C<0> is specified).	155	C<0> is specified).
123		156
124	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.
125		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
126	=item $cbor_data = $cbor->encode ($perl_scalar)	272	=item $cbor_data = $cbor->encode ($perl_scalar)
127		273
128	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
129	representation.	275	representation.
130		276
…		…
163		309
164	=head2 CBOR -> PERL	310	=head2 CBOR -> PERL
165		311
166	=over 4	312	=over 4
167		313
168	=item True, False	314	=item integers
169		315
170	These CBOR values become C<CBOR::XS::true> and C<CBOR::XS::false>,	316	CBOR integers become (numeric) perl scalars. On perls without 64 bit
		317	support, 64 bit integers will be truncated or otherwise corrupted.
		318
		319	=item byte strings
		320
		321	Byte strings will become octet strings in Perl (the Byte values 0..255
		322	will simply become characters of the same value in Perl).
		323
		324	=item UTF-8 strings
		325
		326	UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be
		327	decoded into proper Unicode code points. At the moment, the validity of
		328	the UTF-8 octets will not be validated - corrupt input will result in
		329	corrupted Perl strings.
		330
		331	=item arrays, maps
		332
		333	CBOR arrays and CBOR maps will be converted into references to a Perl
		334	array or hash, respectively. The keys of the map will be stringified
		335	during this process.
		336
		337	=item null
		338
		339	CBOR null becomes C<undef> in Perl.
		340
		341	=item true, false, undefined
		342
		343	These CBOR values become C<Types:Serialiser::true>,
		344	C<Types:Serialiser::false> and C<Types::Serialiser::error>,
171	respectively. They are overloaded to act almost exactly like the numbers	345	respectively. They are overloaded to act almost exactly like the numbers
172	C<1> and C<0>. You can check whether a scalar is a CBOR boolean by using	346	C<1> and C<0> (for true and false) or to throw an exception on access (for
173	the C<CBOR::XS::is_bool> function.	347	error). See the L<Types::Serialiser> manpage for details.
174		348
175	=item Null, Undefined	349	=item tagged values
176		350
177	CBOR Null and Undefined values becomes C<undef> in Perl (in the future,	351	Tagged items consists of a numeric tag and another CBOR value.
178	Undefined may raise an exception).	352
		353	See L<TAG HANDLING AND EXTENSIONS> and the description of C<< ->filter >>
		354	for details on which tags are handled how.
		355
		356	=item anything else
		357
		358	Anything else (e.g. unsupported simple values) will raise a decoding
		359	error.
179		360
180	=back	361	=back
181		362
182		363
183	=head2 PERL -> CBOR	364	=head2 PERL -> CBOR
184		365
185	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
186	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
187	a Perl value.	368	is meant by a perl value.
188		369
189	=over 4	370	=over 4
190		371
191	=item hash references	372	=item hash references
192		373
193	Perl hash references become CBOR maps. As there is no inherent ordering	374	Perl hash references become CBOR maps. As there is no inherent ordering in
194	in hash keys (or CBOR maps), they will usually be encoded in a	375	hash keys (or CBOR maps), they will usually be encoded in a pseudo-random
195	pseudo-random order.	376	order. This order can be different each time a hahs is encoded.
		377
		378	Currently, tied hashes will use the indefinite-length format, while normal
		379	hashes will use the fixed-length format.
196		380
197	=item array references	381	=item array references
198		382
199	Perl array references become CBOR arrays.	383	Perl array references become fixed-length CBOR arrays.
200		384
201	=item other references	385	=item other references
202		386
203	Other unblessed references are generally not allowed and will cause an	387	Other unblessed references will be represented using
204	exception to be thrown, except for references to the integers C<0> and	388	the indirection tag extension (tag value C<22098>,
205	C<1>, which get turned into C<False> and C<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.
206		393
207	=item CBOR::XS::true, CBOR::XS::false	394	=item CBOR::XS::Tagged objects
208		395
		396	Objects of this type must be arrays consisting of a single C<[tag, value]>
		397	pair. The (numerical) tag will be encoded as a CBOR tag, the value will
		398	be encoded as appropriate for the value. You must use C<CBOR::XS::tag> to
		399	create such objects.
		400
		401	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error
		402
209	These special values become CBOR True and CBOR False values,	403	These special values become CBOR true, CBOR false and CBOR undefined
210	respectively. You can also use C<\1> and C<\0> directly if you want.	404	values, respectively. You can also use C<\1>, C<\0> and C<\undef> directly
		405	if you want.
211		406
212	=item blessed objects	407	=item other blessed objects
213		408
214	Blessed objects are not directly representable in CBOR. TODO	409	Other blessed objects are serialised via C<TO_CBOR> or C<FREEZE>. See
215	See the	410	L<TAG HANDLING AND EXTENSIONS> for specific classes handled by this
216	C<allow_blessed> and C<convert_blessed> methods on various options on	411	module, and L<OBJECT SERIALISATION> for generic object serialisation.
217	how to deal with this: basically, you can choose between throwing an
218	exception, encoding the reference as if it weren't blessed, or provide
219	your own serialiser method.
220		412
221	=item simple scalars	413	=item simple scalars
222		414
223	TODO
224	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
225	difficult objects to encode: CBOR::XS will encode undefined scalars as	416	difficult objects to encode: CBOR::XS will encode undefined scalars as
226	CBOR C<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
227	before encoding as CBOR strings, and anything else as number value:	418	before encoding as CBOR strings, and anything else as number value:
228		419
229	# dump as number	420	# dump as number
230	encode_cbor [2] # yields [2]	421	encode_cbor [2] # yields [2]
231	encode_cbor [-3.0e17] # yields [-3e+17]	422	encode_cbor [-3.0e17] # yields [-3e+17]
232	my $value = 5; encode_cbor [$value] # yields [5]	423	my $value = 5; encode_cbor [$value] # yields [5]
233		424
234	# used as string, so dump as string	425	# used as string, so dump as string (either byte or text)
235	print $value;	426	print $value;
236	encode_cbor [$value] # yields ["5"]	427	encode_cbor [$value] # yields ["5"]
237		428
238	# undef becomes null	429	# undef becomes null
239	encode_cbor [undef] # yields [null]	430	encode_cbor [undef] # yields [null]
…		…
243	my $x = 3.1; # some variable containing a number	434	my $x = 3.1; # some variable containing a number
244	"$x"; # stringified	435	"$x"; # stringified
245	$x .= ""; # another, more awkward way to stringify	436	$x .= ""; # another, more awkward way to stringify
246	print $x; # perl does it for you, too, quite often	437	print $x; # perl does it for you, too, quite often
247		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.
		448
248	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:
249		450
250	my $x = "3"; # some variable containing a string	451	my $x = "3"; # some variable containing a string
251	$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
252	$x *= 1; # same thing, the choice is yours.	453	$x *= 1; # same thing, the choice is yours.
253		454
254	You can not currently force the type in other, less obscure, ways. Tell me	455	You can not currently force the type in other, less obscure, ways. Tell me
255	if you need this capability (but don't forget to explain why it's needed	456	if you need this capability (but don't forget to explain why it's needed
256	:).	457	:).
257		458
258	Note that numerical precision has the same meaning as under Perl (so	459	Perl values that seem to be integers generally use the shortest possible
259	binary to decimal conversion follows the same rules as in Perl, which	460	representation. Floating-point values will use either the IEEE single
260	can differ to other languages). Also, your perl interpreter might expose	461	format if possible without loss of precision, otherwise the IEEE double
261	extensions to the floating point numbers of your platform, such as	462	format will be used. Perls that use formats other than IEEE double to
262	infinities or NaN's - these cannot be represented in CBOR, and it is an	463	represent numerical values are supported, but might suffer loss of
263	error to pass those in.	464	precision.
264		465
265	=back	466	=back
266		467
		468	=head2 OBJECT SERIALISATION
267		469
		470	This module knows two way to serialise a Perl object: The CBOR-specific
		471	way, and the generic way.
		472
		473	Whenever the encoder encounters a Perl object that it cnanot serialise
		474	directly (most of them), it will first look up the C<TO_CBOR> method on
		475	it.
		476
		477	If it has a C<TO_CBOR> method, it will call it with the object as only
		478	argument, and expects exactly one return value, which it will then
		479	substitute and encode it in the place of the object.
		480
		481	Otherwise, it will look up the C<FREEZE> method. If it exists, it will
		482	call it with the object as first argument, and the constant string C<CBOR>
		483	as the second argument, to distinguish it from other serialisers.
		484
		485	The C<FREEZE> method can return any number of values (i.e. zero or
		486	more). These will be encoded as CBOR perl object, together with the
		487	classname.
		488
		489	If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail
		490	with an error.
		491
		492	Objects encoded via C<TO_CBOR> cannot be automatically decoded, but
		493	objects encoded via C<FREEZE> can be decoded using the following protocol:
		494
		495	When an encoded CBOR perl object is encountered by the decoder, it will
		496	look up the C<THAW> method, by using the stored classname, and will fail
		497	if the method cannot be found.
		498
		499	After the lookup it will call the C<THAW> method with the stored classname
		500	as first argument, the constant string C<CBOR> as second argument, and all
		501	values returned by C<FREEZE> as remaining arguments.
		502
		503	=head4 EXAMPLES
		504
		505	Here is an example C<TO_CBOR> method:
		506
		507	sub My::Object::TO_CBOR {
		508	my ($obj) = @_;
		509
		510	["this is a serialised My::Object object", $obj->{id}]
		511	}
		512
		513	When a C<My::Object> is encoded to CBOR, it will instead encode a simple
		514	array with two members: a string, and the "object id". Decoding this CBOR
		515	string will yield a normal perl array reference in place of the object.
		516
		517	A more useful and practical example would be a serialisation method for
		518	the URI module. CBOR has a custom tag value for URIs, namely 32:
		519
		520	sub URI::TO_CBOR {
		521	my ($self) = @_;
		522	my $uri = "$self"; # stringify uri
		523	utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string
		524	CBOR::XS::tag 32, "$_[0]"
		525	}
		526
		527	This will encode URIs as a UTF-8 string with tag 32, which indicates an
		528	URI.
		529
		530	Decoding such an URI will not (currently) give you an URI object, but
		531	instead a CBOR::XS::Tagged object with tag number 32 and the string -
		532	exactly what was returned by C<TO_CBOR>.
		533
		534	To serialise an object so it can automatically be deserialised, you need
		535	to use C<FREEZE> and C<THAW>. To take the URI module as example, this
		536	would be a possible implementation:
		537
		538	sub URI::FREEZE {
		539	my ($self, $serialiser) = @_;
		540	"$self" # encode url string
		541	}
		542
		543	sub URI::THAW {
		544	my ($class, $serialiser, $uri) = @_;
		545
		546	$class->new ($uri)
		547	}
		548
		549	Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For
		550	example, a C<FREEZE> method that returns "type", "id" and "variant" values
		551	would cause an invocation of C<THAW> with 5 arguments:
		552
		553	sub My::Object::FREEZE {
		554	my ($self, $serialiser) = @_;
		555
		556	($self->{type}, $self->{id}, $self->{variant})
		557	}
		558
		559	sub My::Object::THAW {
		560	my ($class, $serialiser, $type, $id, $variant) = @_;
		561
		562	$class-<new (type => $type, id => $id, variant => $variant)
		563	}
		564
		565
268	=head2 MAGIC HEADER	566	=head1 MAGIC HEADER
269		567
270	There is no way to distinguish CBOR from other formats	568	There is no way to distinguish CBOR from other formats
271	programmatically. To make it easier to distinguish CBOR from other	569	programmatically. To make it easier to distinguish CBOR from other
272	formats, the CBOR specification has a special "magic string" that can be	570	formats, the CBOR specification has a special "magic string" that can be
273	prepended to any CBOR string without changing it's meaning.	571	prepended to any CBOR string without changing its meaning.
274		572
275	This string is available as C<$CBOR::XS::MAGIC>. This module does not	573	This string is available as C<$CBOR::XS::MAGIC>. This module does not
276	prepend this string tot he CBOR data it generates, but it will ignroe it	574	prepend this string to the CBOR data it generates, but it will ignore it
277	if present, so users can prepend this string as a "file type" indicator as	575	if present, so users can prepend this string as a "file type" indicator as
278	required.	576	required.
279		577
280		578
		579	=head1 THE CBOR::XS::Tagged CLASS
		580
		581	CBOR has the concept of tagged values - any CBOR value can be tagged with
		582	a numeric 64 bit number, which are centrally administered.
		583
		584	C<CBOR::XS> handles a few tags internally when en- or decoding. You can
		585	also create tags yourself by encoding C<CBOR::XS::Tagged> objects, and the
		586	decoder will create C<CBOR::XS::Tagged> objects itself when it hits an
		587	unknown tag.
		588
		589	These objects are simply blessed array references - the first member of
		590	the array being the numerical tag, the second being the value.
		591
		592	You can interact with C<CBOR::XS::Tagged> objects in the following ways:
		593
		594	=over 4
		595
		596	=item $tagged = CBOR::XS::tag $tag, $value
		597
		598	This function(!) creates a new C<CBOR::XS::Tagged> object using the given
		599	C<$tag> (0..2**64-1) to tag the given C<$value> (which can be any Perl
		600	value that can be encoded in CBOR, including serialisable Perl objects and
		601	C<CBOR::XS::Tagged> objects).
		602
		603	=item $tagged->[0]
		604
		605	=item $tagged->[0] = $new_tag
		606
		607	=item $tag = $tagged->tag
		608
		609	=item $new_tag = $tagged->tag ($new_tag)
		610
		611	Access/mutate the tag.
		612
		613	=item $tagged->[1]
		614
		615	=item $tagged->[1] = $new_value
		616
		617	=item $value = $tagged->value
		618
		619	=item $new_value = $tagged->value ($new_value)
		620
		621	Access/mutate the tagged value.
		622
		623	=back
		624
		625	=cut
		626
		627	sub tag($$) {
		628	bless [@_], CBOR::XS::Tagged::;
		629	}
		630
		631	sub CBOR::XS::Tagged::tag {
		632	$_[0][0] = $_[1] if $#_;
		633	$_[0][0]
		634	}
		635
		636	sub CBOR::XS::Tagged::value {
		637	$_[0][1] = $_[1] if $#_;
		638	$_[0][1]
		639	}
		640
		641	=head2 EXAMPLES
		642
		643	Here are some examples of C<CBOR::XS::Tagged> uses to tag objects.
		644
		645	You can look up CBOR tag value and emanings in the IANA registry at
		646	L<http://www.iana.org/assignments/cbor-tags/cbor-tags.xhtml>.
		647
		648	Prepend a magic header (C<$CBOR::XS::MAGIC>):
		649
		650	my $cbor = encode_cbor CBOR::XS::tag 55799, $value;
		651	# same as:
		652	my $cbor = $CBOR::XS::MAGIC . encode_cbor $value;
		653
		654	Serialise some URIs and a regex in an array:
		655
		656	my $cbor = encode_cbor [
		657	(CBOR::XS::tag 32, "http://www.nethype.de/"),
		658	(CBOR::XS::tag 32, "http://software.schmorp.de/"),
		659	(CBOR::XS::tag 35, "^[Pp][Ee][Rr][lL]\$"),
		660	];
		661
		662	Wrap CBOR data in CBOR:
		663
		664	my $cbor_cbor = encode_cbor
		665	CBOR::XS::tag 24,
		666	encode_cbor [1, 2, 3];
		667
		668	=head1 TAG HANDLING AND EXTENSIONS
		669
		670	This section describes how this module handles specific tagged values
		671	and extensions. If a tag is not mentioned here and no additional filters
		672	are provided for it, then the default handling applies (creating a
		673	CBOR::XS::Tagged object on decoding, and only encoding the tag when
		674	explicitly requested).
		675
		676	Tags not handled specifically are currently converted into a
		677	L<CBOR::XS::Tagged> object, which is simply a blessed array reference
		678	consisting of the numeric tag value followed by the (decoded) CBOR value.
		679
		680	Future versions of this module reserve the right to special case
		681	additional tags (such as base64url).
		682
		683	=head2 ENFORCED TAGS
		684
		685	These tags are always handled when decoding, and their handling cannot be
		686	overriden by the user.
		687
		688	=over 4
		689
		690	=item 26 (perl-object, L<http://cbor.schmorp.de/perl-object>)
		691
		692	These tags are automatically created (and decoded) for serialisable
		693	objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object
		694	serialisation protocol). See L<OBJECT SERIALISATION> for details.
		695
		696	=item 28, 29 (sharable, sharedref, L <http://cbor.schmorp.de/value-sharing>)
		697
		698	These tags are automatically decoded when encountered, resulting in
		699	shared values in the decoded object. They are only encoded, however, when
		700	C<allow_sharable> is enabled.
		701
		702	=item 256, 25 (stringref-namespace, stringref, L <http://cbor.schmorp.de/stringref>)
		703
		704	These tags are automatically decoded when encountered. They are only
		705	encoded, however, when C<pack_strings> is enabled.
		706
		707	=item 22098 (indirection, L<http://cbor.schmorp.de/indirection>)
		708
		709	This tag is automatically generated when a reference are encountered (with
		710	the exception of hash and array refernces). It is converted to a reference
		711	when decoding.
		712
		713	=item 55799 (self-describe CBOR, RFC 7049)
		714
		715	This value is not generated on encoding (unless explicitly requested by
		716	the user), and is simply ignored when decoding.
		717
		718	=back
		719
		720	=head2 NON-ENFORCED TAGS
		721
		722	These tags have default filters provided when decoding. Their handling can
		723	be overriden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by
		724	providing a custom C<filter> callback when decoding.
		725
		726	When they result in decoding into a specific Perl class, the module
		727	usually provides a corresponding C<TO_CBOR> method as well.
		728
		729	When any of these need to load additional modules that are not part of the
		730	perl core distribution (e.g. L<URI>), it is (currently) up to the user to
		731	provide these modules. The decoding usually fails with an exception if the
		732	required module cannot be loaded.
		733
		734	=over 4
		735
		736	=item 2, 3 (positive/negative bignum)
		737
		738	These tags are decoded into L<Math::BigInt> objects. The corresponding
		739	C<Math::BigInt::TO_CBOR> method encodes "small" bigints into normal CBOR
		740	integers, and others into positive/negative CBOR bignums.
		741
		742	=item 4, 5 (decimal fraction/bigfloat)
		743
		744	Both decimal fractions and bigfloats are decoded into L<Math::BigFloat>
		745	objects. The corresponding C<Math::BigFloat::TO_CBOR> method I<always>
		746	encodes into a decimal fraction.
		747
		748	CBOR cannot represent bigfloats with I<very> large exponents - conversion
		749	of such big float objects is undefined.
		750
		751	Also, NaN and infinities are not encoded properly.
		752
		753	=item 21, 22, 23 (expected later JSON conversion)
		754
		755	CBOR::XS is not a CBOR-to-JSON converter, and will simply ignore these
		756	tags.
		757
		758	=item 32 (URI)
		759
		760	These objects decode into L<URI> objects. The corresponding
		761	C<URI::TO_CBOR> method again results in a CBOR URI value.
		762
		763	=back
		764
		765	=cut
		766
		767	our %FILTER = (
		768	# 0 # rfc4287 datetime, utf-8
		769	# 1 # unix timestamp, any
		770
		771	2 => sub { # pos bigint
		772	require Math::BigInt;
		773	Math::BigInt->new ("0x" . unpack "H*", pop)
		774	},
		775
		776	3 => sub { # neg bigint
		777	require Math::BigInt;
		778	-Math::BigInt->new ("0x" . unpack "H*", pop)
		779	},
		780
		781	4 => sub { # decimal fraction, array
		782	require Math::BigFloat;
		783	Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
		784	},
		785
		786	5 => sub { # bigfloat, array
		787	require Math::BigFloat;
		788	scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2)
		789	},
		790
		791	21 => sub { pop }, # expected conversion to base64url encoding
		792	22 => sub { pop }, # expected conversion to base64 encoding
		793	23 => sub { pop }, # expected conversion to base16 encoding
		794
		795	# 24 # embedded cbor, byte string
		796
		797	32 => sub {
		798	require URI;
		799	URI->new (pop)
		800	},
		801
		802	# 33 # base64url rfc4648, utf-8
		803	# 34 # base64 rfc46484, utf-8
		804	# 35 # regex pcre/ecma262, utf-8
		805	# 36 # mime message rfc2045, utf-8
		806	);
		807
		808
281	=head2 CBOR and JSON	809	=head1 CBOR and JSON
282		810
283	TODO	811	CBOR is supposed to implement a superset of the JSON data model, and is,
		812	with some coercion, able to represent all JSON texts (something that other
		813	"binary JSON" formats such as BSON generally do not support).
		814
		815	CBOR implements some extra hints and support for JSON interoperability,
		816	and the spec offers further guidance for conversion between CBOR and
		817	JSON. None of this is currently implemented in CBOR, and the guidelines
		818	in the spec do not result in correct round-tripping of data. If JSON
		819	interoperability is improved in the future, then the goal will be to
		820	ensure that decoded JSON data will round-trip encoding and decoding to
		821	CBOR intact.
284		822
285		823
286	=head1 SECURITY CONSIDERATIONS	824	=head1 SECURITY CONSIDERATIONS
287		825
288	When you are using CBOR in a protocol, talking to untrusted potentially	826	When you are using CBOR in a protocol, talking to untrusted potentially
…		…
356	Please refrain from using rt.cpan.org or any other bug reporting	894	Please refrain from using rt.cpan.org or any other bug reporting
357	service. I put the contact address into my modules for a reason.	895	service. I put the contact address into my modules for a reason.
358		896
359	=cut	897	=cut
360		898
361	our $true = do { bless \(my $dummy = 1), "CBOR::XS::Boolean" };	899	our %FILTER = (
362	our $false = do { bless \(my $dummy = 0), "CBOR::XS::Boolean" };	900	# 0 # rfc4287 datetime, utf-8
		901	# 1 # unix timestamp, any
363		902
364	sub true() { $true }	903	2 => sub { # pos bigint
365	sub false() { $false }	904	require Math::BigInt;
		905	Math::BigInt->new ("0x" . unpack "H*", pop)
		906	},
366		907
367	sub is_bool($) {	908	3 => sub { # neg bigint
368	UNIVERSAL::isa $_[0], "CBOR::XS::Boolean"	909	require Math::BigInt;
369	# or UNIVERSAL::isa $_[0], "CBOR::Literal"	910	-Math::BigInt->new ("0x" . unpack "H*", pop)
		911	},
		912
		913	4 => sub { # decimal fraction, array
		914	require Math::BigFloat;
		915	Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
		916	},
		917
		918	5 => sub { # bigfloat, array
		919	require Math::BigFloat;
		920	scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2)
		921	},
		922
		923	21 => sub { pop }, # expected conversion to base64url encoding
		924	22 => sub { pop }, # expected conversion to base64 encoding
		925	23 => sub { pop }, # expected conversion to base16 encoding
		926
		927	# 24 # embedded cbor, byte string
		928
		929	32 => sub {
		930	require URI;
		931	URI->new (pop)
		932	},
		933
		934	# 33 # base64url rfc4648, utf-8
		935	# 34 # base64 rfc46484, utf-8
		936	# 35 # regex pcre/ecma262, utf-8
		937	# 36 # mime message rfc2045, utf-8
		938	);
		939
		940	sub CBOR::XS::default_filter {
		941	&{ $FILTER{$_[0]} or return }
370	}	942	}
371		943
		944	sub URI::TO_CBOR {
		945	my $uri = $_[0]->as_string;
		946	utf8::upgrade $uri;
		947	CBOR::XS::tag 32, $uri
		948	}
		949
		950	sub Math::BigInt::TO_CBOR {
		951	if ($_[0] >= -2147483648 && $_[0] <= 2147483647) {
		952	$_[0]->numify
		953	} else {
		954	my $hex = substr $_[0]->as_hex, 2;
		955	$hex = "0$hex" if 1 & length $hex; # sigh
		956	CBOR::XS::tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex
		957	}
		958	}
		959
		960	sub Math::BigFloat::TO_CBOR {
		961	my ($m, $e) = $_[0]->parts;
		962	CBOR::XS::tag 4, [$e->numify, $m]
		963	}
		964
372	XSLoader::load "CBOR::XS", $VERSION;	965	XSLoader::load "CBOR::XS", $VERSION;
373
374	package CBOR::XS::Boolean;
375
376	use overload
377	"0+" => sub { ${$_[0]} },
378	"++" => sub { $_[0] = ${$_[0]} + 1 },
379	"--" => sub { $_[0] = ${$_[0]} - 1 },
380	fallback => 1;
381
382	1;
383		966
384	=head1 SEE ALSO	967	=head1 SEE ALSO
385		968
386	The L<JSON> and L<JSON::XS> modules that do similar, but human-readable,	969	The L<JSON> and L<JSON::XS> modules that do similar, but human-readable,
387	serialisation.	970	serialisation.
388		971
		972	The L<Types::Serialiser> module provides the data model for true, false
		973	and error values.
		974
389	=head1 AUTHOR	975	=head1 AUTHOR
390		976
391	Marc Lehmann <schmorp@schmorp.de>	977	Marc Lehmann <schmorp@schmorp.de>
392	http://home.schmorp.de/	978	http://home.schmorp.de/
393		979
394	=cut	980	=cut
395		981
		982	1
		983

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Comparing CBOR-XS/XS.pm (file contents): Revision 1.3 by root, Sat Oct 26 11:08:34 2013 UTC vs. Revision 1.28 by root, Thu Nov 28 16:09:04 2013 UTC

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Comparing CBOR-XS/XS.pm (file contents):
Revision 1.3 by root, Sat Oct 26 11:08:34 2013 UTC vs.
Revision 1.28 by root, Thu Nov 28 16:09:04 2013 UTC