[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 1.9 by root, Mon Oct 28 21:28:14 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	WARNING! This module is very new, and not very well tested (that's up to
22	EAT YOUR CHILDREN!	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.
23		37
24	This module converts Perl data structures to CBOR and vice versa. Its	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
		41	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
		43	can represent something in JSON, you should be able to represent it in
		44	CBOR.
		45
		46	In short, CBOR is a faster and very compact binary alternative to JSON,
		47	with the added ability of supporting serialisation of Perl objects.
		48
25	primary goal is to be I<correct> and its secondary goal is to be	49	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.	50	is to be I<fast>. To reach the latter goal it was written in C.
27		51
28	See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and	52	See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and
29	vice versa.	53	vice versa.
30		54
31	=cut	55	=cut
32		56
33	package CBOR::XS;	57	package CBOR::XS;
34		58
35	use common::sense;	59	use common::sense;
36		60
37	our $VERSION = 0.02;	61	our $VERSION = 0.05;
38	our @ISA = qw(Exporter);	62	our @ISA = qw(Exporter);
39		63
40	our @EXPORT = qw(encode_cbor decode_cbor);	64	our @EXPORT = qw(encode_cbor decode_cbor);
41		65
42	use Exporter;	66	use Exporter;
43	use XSLoader;	67	use XSLoader;
		68
		69	use Types::Serialiser;
44		70
45	our $MAGIC = "\xd9\xd9\xf7";	71	our $MAGIC = "\xd9\xd9\xf7";
46		72
47	=head1 FUNCTIONAL INTERFACE	73	=head1 FUNCTIONAL INTERFACE
48		74
…		…
163		189
164	=head2 CBOR -> PERL	190	=head2 CBOR -> PERL
165		191
166	=over 4	192	=over 4
167		193
168	=item True, False	194	=item integers
169		195
170	These CBOR values become C<CBOR::XS::true> and C<CBOR::XS::false>,	196	CBOR integers become (numeric) perl scalars. On perls without 64 bit
		197	support, 64 bit integers will be truncated or otherwise corrupted.
		198
		199	=item byte strings
		200
		201	Byte strings will become octet strings in Perl (the byte values 0..255
		202	will simply become characters of the same value in Perl).
		203
		204	=item UTF-8 strings
		205
		206	UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be
		207	decoded into proper Unicode code points. At the moment, the validity of
		208	the UTF-8 octets will not be validated - corrupt input will result in
		209	corrupted Perl strings.
		210
		211	=item arrays, maps
		212
		213	CBOR arrays and CBOR maps will be converted into references to a Perl
		214	array or hash, respectively. The keys of the map will be stringified
		215	during this process.
		216
		217	=item null
		218
		219	CBOR null becomes C<undef> in Perl.
		220
		221	=item true, false, undefined
		222
		223	These CBOR values become C<Types:Serialiser::true>,
		224	C<Types:Serialiser::false> and C<Types::Serialiser::error>,
171	respectively. They are overloaded to act almost exactly like the numbers	225	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	226	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.	227	error). See the L<Types::Serialiser> manpage for details.
174		228
175	=item Null, Undefined	229	=item CBOR tag 256 (perl object)
176		230
177	CBOR Null and Undefined values becomes C<undef> in Perl (in the future,	231	The tag value C<256> (TODO: pending iana registration) will be used
178	Undefined may raise an exception).	232	to deserialise a Perl object serialised with C<FREEZE>. See "OBJECT
		233	SERIALISATION", below, for details.
		234
		235	=item CBOR tag 55799 (magic header)
		236
		237	The tag 55799 is ignored (this tag implements the magic header).
		238
		239	=item other CBOR tags
		240
		241	Tagged items consists of a numeric tag and another CBOR value. Tags not
		242	handled internally are currently converted into a L<CBOR::XS::Tagged>
		243	object, which is simply a blessed array reference consisting of the
		244	numeric tag value followed by the (decoded) CBOR value.
		245
		246	In the future, support for user-supplied conversions might get added.
		247
		248	=item anything else
		249
		250	Anything else (e.g. unsupported simple values) will raise a decoding
		251	error.
179		252
180	=back	253	=back
181		254
182		255
183	=head2 PERL -> CBOR	256	=head2 PERL -> CBOR
…		…
188		261
189	=over 4	262	=over 4
190		263
191	=item hash references	264	=item hash references
192		265
193	Perl hash references become CBOR maps. As there is no inherent ordering	266	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	267	hash keys (or CBOR maps), they will usually be encoded in a pseudo-random
195	pseudo-random order.	268	order.
		269
		270	Currently, tied hashes will use the indefinite-length format, while normal
		271	hashes will use the fixed-length format.
196		272
197	=item array references	273	=item array references
198		274
199	Perl array references become CBOR arrays.	275	Perl array references become fixed-length CBOR arrays.
200		276
201	=item other references	277	=item other references
202		278
203	Other unblessed references are generally not allowed and will cause an	279	Other unblessed references are generally not allowed and will cause an
204	exception to be thrown, except for references to the integers C<0> and	280	exception to be thrown, except for references to the integers C<0> and
205	C<1>, which get turned into C<False> and C<True> in CBOR.	281	C<1>, which get turned into false and true in CBOR.
206		282
207	=item CBOR::XS::true, CBOR::XS::false	283	=item CBOR::XS::Tagged objects
208		284
		285	Objects of this type must be arrays consisting of a single C<[tag, value]>
		286	pair. The (numerical) tag will be encoded as a CBOR tag, the value will be
		287	encoded as appropriate for the value.
		288
		289	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error
		290
209	These special values become CBOR True and CBOR False values,	291	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.	292	values, respectively. You can also use C<\1>, C<\0> and C<\undef> directly
		293	if you want.
211		294
212	=item blessed objects	295	=item other blessed objects
213		296
214	Blessed objects are not directly representable in CBOR. TODO	297	Other blessed objects are serialised via C<TO_CBOR> or C<FREEZE>. See
215	See the	298	"OBJECT SERIALISATION", below, for details.
216	C<allow_blessed> and C<convert_blessed> methods on various options on
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		299
221	=item simple scalars	300	=item simple scalars
222		301
223	TODO	302	TODO
224	Simple Perl scalars (any scalar that is not a reference) are the most	303	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	304	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	305	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:	306	before encoding as CBOR strings, and anything else as number value:
228		307
229	# dump as number	308	# dump as number
230	encode_cbor [2] # yields [2]	309	encode_cbor [2] # yields [2]
231	encode_cbor [-3.0e17] # yields [-3e+17]	310	encode_cbor [-3.0e17] # yields [-3e+17]
…		…
253		332
254	You can not currently force the type in other, less obscure, ways. Tell me	333	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	334	if you need this capability (but don't forget to explain why it's needed
256	:).	335	:).
257		336
258	Note that numerical precision has the same meaning as under Perl (so	337	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	338	representation. Floating-point values will use either the IEEE single
260	can differ to other languages). Also, your perl interpreter might expose	339	format if possible without loss of precision, otherwise the IEEE double
261	extensions to the floating point numbers of your platform, such as	340	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	341	represent numerical values are supported, but might suffer loss of
263	error to pass those in.	342	precision.
264		343
265	=back	344	=back
266		345
		346	=head2 OBJECT SERIALISATION
267		347
		348	This module knows two way to serialise a Perl object: The CBOR-specific
		349	way, and the generic way.
		350
		351	Whenever the encoder encounters a Perl object that it cnanot serialise
		352	directly (most of them), it will first look up the C<TO_CBOR> method on
		353	it.
		354
		355	If it has a C<TO_CBOR> method, it will call it with the object as only
		356	argument, and expects exactly one return value, which it will then
		357	substitute and encode it in the place of the object.
		358
		359	Otherwise, it will look up the C<FREEZE> method. If it exists, it will
		360	call it with the object as first argument, and the constant string C<CBOR>
		361	as the second argument, to distinguish it from other serialisers.
		362
		363	The C<FREEZE> method can return any number of values (i.e. zero or
		364	more). These will be encoded as CBOR perl object, together with the
		365	classname.
		366
		367	If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail
		368	with an error.
		369
		370	Objects encoded via C<TO_CBOR> cannot be automatically decoded, but
		371	objects encoded via C<FREEZE> can be decoded using the following protocol:
		372
		373	When an encoded CBOR perl object is encountered by the decoder, it will
		374	look up the C<THAW> method, by using the stored classname, and will fail
		375	if the method cannot be found.
		376
		377	After the lookup it will call the C<THAW> method with the stored classname
		378	as first argument, the constant string C<CBOR> as second argument, and all
		379	values returned by C<FREEZE> as remaining arguments.
		380
		381	=head4 EXAMPLES
		382
		383	Here is an example C<TO_CBOR> method:
		384
		385	sub My::Object::TO_CBOR {
		386	my ($obj) = @_;
		387
		388	["this is a serialised My::Object object", $obj->{id}]
		389	}
		390
		391	When a C<My::Object> is encoded to CBOR, it will instead encode a simple
		392	array with two members: a string, and the "object id". Decoding this CBOR
		393	string will yield a normal perl array reference in place of the object.
		394
		395	A more useful and practical example would be a serialisation method for
		396	the URI module. CBOR has a custom tag value for URIs, namely 32:
		397
		398	sub URI::TO_CBOR {
		399	my ($self) = @_;
		400	my $uri = "$self"; # stringify uri
		401	utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string
		402	CBOR::XS::tagged 32, "$_[0]"
		403	}
		404
		405	This will encode URIs as a UTF-8 string with tag 32, which indicates an
		406	URI.
		407
		408	Decoding such an URI will not (currently) give you an URI object, but
		409	instead a CBOR::XS::Tagged object with tag number 32 and the string -
		410	exactly what was returned by C<TO_CBOR>.
		411
		412	To serialise an object so it can automatically be deserialised, you need
		413	to use C<FREEZE> and C<THAW>. To take the URI module as example, this
		414	would be a possible implementation:
		415
		416	sub URI::FREEZE {
		417	my ($self, $serialiser) = @_;
		418	"$self" # encode url string
		419	}
		420
		421	sub URI::THAW {
		422	my ($class, $serialiser, $uri) = @_;
		423
		424	$class->new ($uri)
		425	}
		426
		427	Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For
		428	example, a C<FREEZE> method that returns "type", "id" and "variant" values
		429	would cause an invocation of C<THAW> with 5 arguments:
		430
		431	sub My::Object::FREEZE {
		432	my ($self, $serialiser) = @_;
		433
		434	($self->{type}, $self->{id}, $self->{variant})
		435	}
		436
		437	sub My::Object::THAW {
		438	my ($class, $serialiser, $type, $id, $variant) = @_;
		439
		440	$class-<new (type => $type, id => $id, variant => $variant)
		441	}
		442
		443
268	=head2 MAGIC HEADER	444	=head1 MAGIC HEADER
269		445
270	There is no way to distinguish CBOR from other formats	446	There is no way to distinguish CBOR from other formats
271	programmatically. To make it easier to distinguish CBOR from other	447	programmatically. To make it easier to distinguish CBOR from other
272	formats, the CBOR specification has a special "magic string" that can be	448	formats, the CBOR specification has a special "magic string" that can be
273	prepended to any CBOR string without changing it's meaning.	449	prepended to any CBOR string without changing it's meaning.
…		…
276	prepend this string tot he CBOR data it generates, but it will ignroe it	452	prepend this string tot he CBOR data it generates, but it will ignroe it
277	if present, so users can prepend this string as a "file type" indicator as	453	if present, so users can prepend this string as a "file type" indicator as
278	required.	454	required.
279		455
280		456
281	=head2 CBOR and JSON	457	=head1 CBOR and JSON
282		458
283	TODO	459	CBOR is supposed to implement a superset of the JSON data model, and is,
		460	with some coercion, able to represent all JSON texts (something that other
		461	"binary JSON" formats such as BSON generally do not support).
		462
		463	CBOR implements some extra hints and support for JSON interoperability,
		464	and the spec offers further guidance for conversion between CBOR and
		465	JSON. None of this is currently implemented in CBOR, and the guidelines
		466	in the spec do not result in correct round-tripping of data. If JSON
		467	interoperability is improved in the future, then the goal will be to
		468	ensure that decoded JSON data will round-trip encoding and decoding to
		469	CBOR intact.
284		470
285		471
286	=head1 SECURITY CONSIDERATIONS	472	=head1 SECURITY CONSIDERATIONS
287		473
288	When you are using CBOR in a protocol, talking to untrusted potentially	474	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	542	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.	543	service. I put the contact address into my modules for a reason.
358		544
359	=cut	545	=cut
360		546
361	our $true = do { bless \(my $dummy = 1), "CBOR::XS::Boolean" };
362	our $false = do { bless \(my $dummy = 0), "CBOR::XS::Boolean" };
363
364	sub true() { $true }
365	sub false() { $false }
366
367	sub is_bool($) {
368	UNIVERSAL::isa $_[0], "CBOR::XS::Boolean"
369	# or UNIVERSAL::isa $_[0], "CBOR::Literal"
370	}
371
372	XSLoader::load "CBOR::XS", $VERSION;	547	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		548
384	=head1 SEE ALSO	549	=head1 SEE ALSO
385		550
386	The L<JSON> and L<JSON::XS> modules that do similar, but human-readable,	551	The L<JSON> and L<JSON::XS> modules that do similar, but human-readable,
387	serialisation.	552	serialisation.
388		553
		554	The L<Types::Serialiser> module provides the data model for true, false
		555	and error values.
		556
389	=head1 AUTHOR	557	=head1 AUTHOR
390		558
391	Marc Lehmann <schmorp@schmorp.de>	559	Marc Lehmann <schmorp@schmorp.de>
392	http://home.schmorp.de/	560	http://home.schmorp.de/
393		561
394	=cut	562	=cut
395		563
		564	1
		565

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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 1.9 by root, Mon Oct 28 21:28:14 2013 UTC

Diff Legend

Comparing CBOR-XS/XS.pm (file contents):
Revision 1.3 by root, Sat Oct 26 11:08:34 2013 UTC vs.
Revision 1.9 by root, Mon Oct 28 21:28:14 2013 UTC