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

Comparing CBOR-XS/XS.pm (file contents):
Revision 1.1 by root, Fri Oct 25 23:09:45 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 = 0.01;	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;
		70
		71	our $MAGIC = "\xd9\xd9\xf7";
44		72
45	=head1 FUNCTIONAL INTERFACE	73	=head1 FUNCTIONAL INTERFACE
46		74
47	The following convenience methods are provided by this module. They are	75	The following convenience methods are provided by this module. They are
48	exported by default:	76	exported by default:
…		…
161		189
162	=head2 CBOR -> PERL	190	=head2 CBOR -> PERL
163		191
164	=over 4	192	=over 4
165		193
166	=item True, False	194	=item integers
167		195
168	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>,
169	respectively. They are overloaded to act almost exactly like the numbers	225	respectively. They are overloaded to act almost exactly like the numbers
170	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
171	the C<CBOR::XS::is_bool> function.	227	error). See the L<Types::Serialiser> manpage for details.
172		228
173	=item null	229	=item CBOR tag 256 (perl object)
174		230
175	A CBOR Null value becomes C<undef> in Perl.	231	The tag value C<256> (TODO: pending iana registration) will be used
		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.
176		252
177	=back	253	=back
178		254
179		255
180	=head2 PERL -> CBOR	256	=head2 PERL -> CBOR
…		…
185		261
186	=over 4	262	=over 4
187		263
188	=item hash references	264	=item hash references
189		265
190	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
191	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
192	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.
193		272
194	=item array references	273	=item array references
195		274
196	Perl array references become CBOR arrays.	275	Perl array references become fixed-length CBOR arrays.
197		276
198	=item other references	277	=item other references
199		278
200	Other unblessed references are generally not allowed and will cause an	279	Other unblessed references are generally not allowed and will cause an
201	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
202	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.
203		282
204	=item CBOR::XS::true, CBOR::XS::false	283	=item CBOR::XS::Tagged objects
205		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
206	These special values become CBOR True and CBOR False values,	291	These special values become CBOR true, CBOR false and CBOR undefined
207	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.
208		294
209	=item blessed objects	295	=item other blessed objects
210		296
211	Blessed objects are not directly representable in CBOR. TODO	297	Other blessed objects are serialised via C<TO_CBOR> or C<FREEZE>. See
212	See the	298	"OBJECT SERIALISATION", below, for details.
213	C<allow_blessed> and C<convert_blessed> methods on various options on
214	how to deal with this: basically, you can choose between throwing an
215	exception, encoding the reference as if it weren't blessed, or provide
216	your own serialiser method.
217		299
218	=item simple scalars	300	=item simple scalars
219		301
220	TODO	302	TODO
221	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
222	difficult objects to encode: CBOR::XS will encode undefined scalars as	304	difficult objects to encode: CBOR::XS will encode undefined scalars as
223	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
224	before encoding as CBOR strings, and anything else as number value:	306	before encoding as CBOR strings, and anything else as number value:
225		307
226	# dump as number	308	# dump as number
227	encode_cbor [2] # yields [2]	309	encode_cbor [2] # yields [2]
228	encode_cbor [-3.0e17] # yields [-3e+17]	310	encode_cbor [-3.0e17] # yields [-3e+17]
…		…
250		332
251	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
252	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
253	:).	335	:).
254		336
255	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
256	binary to decimal conversion follows the same rules as in Perl, which	338	representation. Floating-point values will use either the IEEE single
257	can differ to other languages). Also, your perl interpreter might expose	339	format if possible without loss of precision, otherwise the IEEE double
258	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
259	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
260	error to pass those in.	342	precision.
261		343
262	=back	344	=back
263		345
		346	=head2 OBJECT SERIALISATION
264		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 => $variant)
		441	}
		442
		443
		444	=head1 MAGIC HEADER
		445
		446	There is no way to distinguish CBOR from other formats
		447	programmatically. To make it easier to distinguish CBOR from other
		448	formats, the CBOR specification has a special "magic string" that can be
		449	prepended to any CBOR string without changing it's meaning.
		450
		451	This string is available as C<$CBOR::XS::MAGIC>. This module does not
		452	prepend this string tot he CBOR data it generates, but it will ignroe it
		453	if present, so users can prepend this string as a "file type" indicator as
		454	required.
		455
		456
265	=head2 CBOR and JSON	457	=head1 CBOR and JSON
266		458
267	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.
268		470
269		471
270	=head1 SECURITY CONSIDERATIONS	472	=head1 SECURITY CONSIDERATIONS
271		473
272	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
…		…
340	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
341	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.
342		544
343	=cut	545	=cut
344		546
345	our $true = do { bless \(my $dummy = 1), "CBOR::XS::Boolean" };
346	our $false = do { bless \(my $dummy = 0), "CBOR::XS::Boolean" };
347
348	sub true() { $true }
349	sub false() { $false }
350
351	sub is_bool($) {
352	UNIVERSAL::isa $_[0], "CBOR::XS::Boolean"
353	# or UNIVERSAL::isa $_[0], "CBOR::Literal"
354	}
355
356	XSLoader::load "CBOR::XS", $VERSION;	547	XSLoader::load "CBOR::XS", $VERSION;
357
358	package CBOR::XS::Boolean;
359
360	use overload
361	"0+" => sub { ${$_[0]} },
362	"++" => sub { $_[0] = ${$_[0]} + 1 },
363	"--" => sub { $_[0] = ${$_[0]} - 1 },
364	fallback => 1;
365
366	1;
367		548
368	=head1 SEE ALSO	549	=head1 SEE ALSO
369		550
370	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,
371	serialisation.	552	serialisation.
372		553
		554	The L<Types::Serialiser> module provides the data model for true, false
		555	and error values.
		556
373	=head1 AUTHOR	557	=head1 AUTHOR
374		558
375	Marc Lehmann <schmorp@schmorp.de>	559	Marc Lehmann <schmorp@schmorp.de>
376	http://home.schmorp.de/	560	http://home.schmorp.de/
377		561
378	=cut	562	=cut
379		563
		564	1
		565

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Comparing CBOR-XS/XS.pm (file contents): Revision 1.1 by root, Fri Oct 25 23:09:45 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 1.1 by root, Fri Oct 25 23:09:45 2013 UTC vs.
Revision 1.9 by root, Mon Oct 28 21:28:14 2013 UTC