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

Comparing CBOR-XS/XS.pm (file contents):
Revision 1.2 by root, Sat Oct 26 10:41:12 2013 UTC vs.
Revision 1.7 by root, Sun Oct 27 22:35:15 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 IS A PRE-ALPHA RELEASE! IT WILL CRASH, CORRUPT YOUR DATA
22	EAT YOUR CHILDREN!	32	AND EAT YOUR CHILDREN! (Actually, apart from being untested and a bit
		33	feature-limited, it might already be useful).
23		34
24	This module converts Perl data structures to CBOR and vice versa. Its	35	This module converts Perl data structures to the Concise Binary Object
		36	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
		38	can represent something in JSON, you should be able to represent it in
		39	CBOR.
		40
		41	This makes it a faster and more compact binary alternative to JSON, with
		42	the added ability of supporting serialising of perl objects.
		43
25	primary goal is to be I<correct> and its secondary goal is to be	44	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.	45	is to be I<fast>. To reach the latter goal it was written in C.
27		46
28	See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and	47	See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and
29	vice versa.	48	vice versa.
30		49
31	=cut	50	=cut
32		51
33	package CBOR::XS;	52	package CBOR::XS;
34		53
35	use common::sense;	54	use common::sense;
36		55
37	our $VERSION = 0.01;	56	our $VERSION = 0.03;
38	our @ISA = qw(Exporter);	57	our @ISA = qw(Exporter);
39		58
40	our @EXPORT = qw(encode_cbor decode_cbor);	59	our @EXPORT = qw(encode_cbor decode_cbor);
41		60
42	use Exporter;	61	use Exporter;
43	use XSLoader;	62	use XSLoader;
		63
		64	use Types::Serialiser;
		65
		66	our $MAGIC = "\xd9\xd9\xf7";
44		67
45	=head1 FUNCTIONAL INTERFACE	68	=head1 FUNCTIONAL INTERFACE
46		69
47	The following convenience methods are provided by this module. They are	70	The following convenience methods are provided by this module. They are
48	exported by default:	71	exported by default:
…		…
161		184
162	=head2 CBOR -> PERL	185	=head2 CBOR -> PERL
163		186
164	=over 4	187	=over 4
165		188
166	=item True, False	189	=item integers
167		190
168	These CBOR values become C<CBOR::XS::true> and C<CBOR::XS::false>,	191	CBOR integers become (numeric) perl scalars. On perls without 64 bit
		192	support, 64 bit integers will be truncated or otherwise corrupted.
		193
		194	=item byte strings
		195
		196	Byte strings will become octet strings in Perl (the byte values 0..255
		197	will simply become characters of the same value in Perl).
		198
		199	=item UTF-8 strings
		200
		201	UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be
		202	decoded into proper Unicode code points. At the moment, the validity of
		203	the UTF-8 octets will not be validated - corrupt input will result in
		204	corrupted Perl strings.
		205
		206	=item arrays, maps
		207
		208	CBOR arrays and CBOR maps will be converted into references to a Perl
		209	array or hash, respectively. The keys of the map will be stringified
		210	during this process.
		211
		212	=item null
		213
		214	CBOR null becomes C<undef> in Perl.
		215
		216	=item true, false, undefined
		217
		218	These CBOR values become C<Types:Serialiser::true>,
		219	C<Types:Serialiser::false> and C<Types::Serialiser::error>,
169	respectively. They are overloaded to act almost exactly like the numbers	220	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	221	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.	222	error). See the L<Types::Serialiser> manpage for details.
172		223
173	=item Null, Undefined	224	=item CBOR tag 256 (perl object)
174		225
175	CBOR Null and Undefined values becomes C<undef> in Perl (in the future,	226	The tag value C<256> (TODO: pending iana registration) will be used
176	Undefined may raise an exception).	227	to deserialise a Perl object serialised with C<FREEZE>. See "OBJECT
		228	SERIALISATION", below, for details.
		229
		230	=item CBOR tag 55799 (magic header)
		231
		232	The tag 55799 is ignored (this tag implements the magic header).
		233
		234	=item other CBOR tags
		235
		236	Tagged items consists of a numeric tag and another CBOR value. Tags not
		237	handled internally are currently converted into a L<CBOR::XS::Tagged>
		238	object, which is simply a blessed array reference consisting of the
		239	numeric tag value followed by the (decoded) CBOR value.
		240
		241	In the future, support for user-supplied conversions might get added.
		242
		243	=item anything else
		244
		245	Anything else (e.g. unsupported simple values) will raise a decoding
		246	error.
177		247
178	=back	248	=back
179		249
180		250
181	=head2 PERL -> CBOR	251	=head2 PERL -> CBOR
…		…
186		256
187	=over 4	257	=over 4
188		258
189	=item hash references	259	=item hash references
190		260
191	Perl hash references become CBOR maps. As there is no inherent ordering	261	Perl hash references become CBOR maps. As there is no inherent ordering in
192	in hash keys (or CBOR maps), they will usually be encoded in a	262	hash keys (or CBOR maps), they will usually be encoded in a pseudo-random
193	pseudo-random order.	263	order.
		264
		265	Currently, tied hashes will use the indefinite-length format, while normal
		266	hashes will use the fixed-length format.
194		267
195	=item array references	268	=item array references
196		269
197	Perl array references become CBOR arrays.	270	Perl array references become fixed-length CBOR arrays.
198		271
199	=item other references	272	=item other references
200		273
201	Other unblessed references are generally not allowed and will cause an	274	Other unblessed references are generally not allowed and will cause an
202	exception to be thrown, except for references to the integers C<0> and	275	exception to be thrown, except for references to the integers C<0> and
203	C<1>, which get turned into C<False> and C<True> in CBOR.	276	C<1>, which get turned into false and true in CBOR.
204		277
205	=item CBOR::XS::true, CBOR::XS::false	278	=item CBOR::XS::Tagged objects
206		279
		280	Objects of this type must be arrays consisting of a single C<[tag, value]>
		281	pair. The (numerical) tag will be encoded as a CBOR tag, the value will be
		282	encoded as appropriate for the value.
		283
		284	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error
		285
207	These special values become CBOR True and CBOR False values,	286	These special values become CBOR true, CBOR false and CBOR undefined
208	respectively. You can also use C<\1> and C<\0> directly if you want.	287	values, respectively. You can also use C<\1>, C<\0> and C<\undef> directly
		288	if you want.
209		289
210	=item blessed objects	290	=item other blessed objects
211		291
212	Blessed objects are not directly representable in CBOR. TODO	292	Other blessed objects are serialised via C<TO_CBOR> or C<FREEZE>. See
213	See the	293	"OBJECT SERIALISATION", below, for details.
214	C<allow_blessed> and C<convert_blessed> methods on various options on
215	how to deal with this: basically, you can choose between throwing an
216	exception, encoding the reference as if it weren't blessed, or provide
217	your own serialiser method.
218		294
219	=item simple scalars	295	=item simple scalars
220		296
221	TODO	297	TODO
222	Simple Perl scalars (any scalar that is not a reference) are the most	298	Simple Perl scalars (any scalar that is not a reference) are the most
223	difficult objects to encode: CBOR::XS will encode undefined scalars as	299	difficult objects to encode: CBOR::XS will encode undefined scalars as
224	CBOR C<Null> values, scalars that have last been used in a string context	300	CBOR null values, scalars that have last been used in a string context
225	before encoding as CBOR strings, and anything else as number value:	301	before encoding as CBOR strings, and anything else as number value:
226		302
227	# dump as number	303	# dump as number
228	encode_cbor [2] # yields [2]	304	encode_cbor [2] # yields [2]
229	encode_cbor [-3.0e17] # yields [-3e+17]	305	encode_cbor [-3.0e17] # yields [-3e+17]
…		…
251		327
252	You can not currently force the type in other, less obscure, ways. Tell me	328	You can not currently force the type in other, less obscure, ways. Tell me
253	if you need this capability (but don't forget to explain why it's needed	329	if you need this capability (but don't forget to explain why it's needed
254	:).	330	:).
255		331
256	Note that numerical precision has the same meaning as under Perl (so	332	Perl values that seem to be integers generally use the shortest possible
257	binary to decimal conversion follows the same rules as in Perl, which	333	representation. Floating-point values will use either the IEEE single
258	can differ to other languages). Also, your perl interpreter might expose	334	format if possible without loss of precision, otherwise the IEEE double
259	extensions to the floating point numbers of your platform, such as	335	format will be used. Perls that use formats other than IEEE double to
260	infinities or NaN's - these cannot be represented in CBOR, and it is an	336	represent numerical values are supported, but might suffer loss of
261	error to pass those in.	337	precision.
262		338
263	=back	339	=back
264		340
		341	=head2 OBJECT SERIALISATION
265		342
		343	This module knows two way to serialise a Perl object: The CBOR-specific
		344	way, and the generic way.
		345
		346	Whenever the encoder encounters a Perl object that it cnanot serialise
		347	directly (most of them), it will first look up the C<TO_CBOR> method on
		348	it.
		349
		350	If it has a C<TO_CBOR> method, it will call it with the object as only
		351	argument, and expects exactly one return value, which it will then
		352	substitute and encode it in the place of the object.
		353
		354	Otherwise, it will look up the C<FREEZE> method. If it exists, it will
		355	call it with the object as first argument, and the constant string C<CBOR>
		356	as the second argument, to distinguish it from other serialisers.
		357
		358	The C<FREEZE> method can return any number of values (i.e. zero or
		359	more). These will be encoded as CBOR perl object, together with the
		360	classname.
		361
		362	If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail
		363	with an error.
		364
		365	Objects encoded via C<TO_CBOR> cannot be automatically decoded, but
		366	objects encoded via C<FREEZE> can be decoded using the following protocol:
		367
		368	When an encoded CBOR perl object is encountered by the decoder, it will
		369	look up the C<THAW> method, by using the stored classname, and will fail
		370	if the method cannot be found.
		371
		372	After the lookup it will call the C<THAW> method with the stored classname
		373	as first argument, the constant string C<CBOR> as second argument, and all
		374	values returned by C<FREEZE> as remaining arguments.
		375
		376	=head4 EXAMPLES
		377
		378	Here is an example C<TO_CBOR> method:
		379
		380	sub My::Object::TO_CBOR {
		381	my ($obj) = @_;
		382
		383	["this is a serialised My::Object object", $obj->{id}]
		384	}
		385
		386	When a C<My::Object> is encoded to CBOR, it will instead encode a simple
		387	array with two members: a string, and the "object id". Decoding this CBOR
		388	string will yield a normal perl array reference in place of the object.
		389
		390	A more useful and practical example would be a serialisation method for
		391	the URI module. CBOR has a custom tag value for URIs, namely 32:
		392
		393	sub URI::TO_CBOR {
		394	my ($self) = @_;
		395	my $uri = "$self"; # stringify uri
		396	utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string
		397	CBOR::XS::tagged 32, "$_[0]"
		398	}
		399
		400	This will encode URIs as a UTF-8 string with tag 32, which indicates an
		401	URI.
		402
		403	Decoding such an URI will not (currently) give you an URI object, but
		404	instead a CBOR::XS::Tagged object with tag number 32 and the string -
		405	exactly what was returned by C<TO_CBOR>.
		406
		407	To serialise an object so it can automatically be deserialised, you need
		408	to use C<FREEZE> and C<THAW>. To take the URI module as example, this
		409	would be a possible implementation:
		410
		411	sub URI::FREEZE {
		412	my ($self, $serialiser) = @_;
		413	"$self" # encode url string
		414	}
		415
		416	sub URI::THAW {
		417	my ($class, $serialiser, $uri) = @_;
		418
		419	$class->new ($uri)
		420	}
		421
		422	Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For
		423	example, a C<FREEZE> method that returns "type", "id" and "variant" values
		424	would cause an invocation of C<THAW> with 5 arguments:
		425
		426	sub My::Object::FREEZE {
		427	my ($self, $serialiser) = @_;
		428
		429	($self->{type}, $self->{id}, $self->{variant})
		430	}
		431
		432	sub My::Object::THAW {
		433	my ($class, $serialiser, $type, $id, $variant) = @_;
		434
		435	$class-<new (type => $type, id => $id, variant => $variant)
		436	}
		437
		438
		439	=head1 MAGIC HEADER
		440
		441	There is no way to distinguish CBOR from other formats
		442	programmatically. To make it easier to distinguish CBOR from other
		443	formats, the CBOR specification has a special "magic string" that can be
		444	prepended to any CBOR string without changing it's meaning.
		445
		446	This string is available as C<$CBOR::XS::MAGIC>. This module does not
		447	prepend this string tot he CBOR data it generates, but it will ignroe it
		448	if present, so users can prepend this string as a "file type" indicator as
		449	required.
		450
		451
266	=head2 CBOR and JSON	452	=head1 CBOR and JSON
267		453
268	TODO	454	CBOR is supposed to implement a superset of the JSON data model, and is,
		455	with some coercion, able to represent all JSON texts (something that other
		456	"binary JSON" formats such as BSON generally do not support).
		457
		458	CBOR implements some extra hints and support for JSON interoperability,
		459	and the spec offers further guidance for conversion between CBOR and
		460	JSON. None of this is currently implemented in CBOR, and the guidelines
		461	in the spec do not result in correct round-tripping of data. If JSON
		462	interoperability is improved in the future, then the goal will be to
		463	ensure that decoded JSON data will round-trip encoding and decoding to
		464	CBOR intact.
269		465
270		466
271	=head1 SECURITY CONSIDERATIONS	467	=head1 SECURITY CONSIDERATIONS
272		468
273	When you are using CBOR in a protocol, talking to untrusted potentially	469	When you are using CBOR in a protocol, talking to untrusted potentially
…		…
341	Please refrain from using rt.cpan.org or any other bug reporting	537	Please refrain from using rt.cpan.org or any other bug reporting
342	service. I put the contact address into my modules for a reason.	538	service. I put the contact address into my modules for a reason.
343		539
344	=cut	540	=cut
345		541
346	our $true = do { bless \(my $dummy = 1), "CBOR::XS::Boolean" };
347	our $false = do { bless \(my $dummy = 0), "CBOR::XS::Boolean" };
348
349	sub true() { $true }
350	sub false() { $false }
351
352	sub is_bool($) {
353	UNIVERSAL::isa $_[0], "CBOR::XS::Boolean"
354	# or UNIVERSAL::isa $_[0], "CBOR::Literal"
355	}
356
357	XSLoader::load "CBOR::XS", $VERSION;	542	XSLoader::load "CBOR::XS", $VERSION;
358
359	package CBOR::XS::Boolean;
360
361	use overload
362	"0+" => sub { ${$_[0]} },
363	"++" => sub { $_[0] = ${$_[0]} + 1 },
364	"--" => sub { $_[0] = ${$_[0]} - 1 },
365	fallback => 1;
366
367	1;
368		543
369	=head1 SEE ALSO	544	=head1 SEE ALSO
370		545
371	The L<JSON> and L<JSON::XS> modules that do similar, but human-readable,	546	The L<JSON> and L<JSON::XS> modules that do similar, but human-readable,
372	serialisation.	547	serialisation.
373		548
		549	The L<Types::Serialiser> module provides the data model for true, false
		550	and error values.
		551
374	=head1 AUTHOR	552	=head1 AUTHOR
375		553
376	Marc Lehmann <schmorp@schmorp.de>	554	Marc Lehmann <schmorp@schmorp.de>
377	http://home.schmorp.de/	555	http://home.schmorp.de/
378		556
379	=cut	557	=cut
380		558
		559	1
		560

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Comparing CBOR-XS/XS.pm (file contents): Revision 1.2 by root, Sat Oct 26 10:41:12 2013 UTC vs. Revision 1.7 by root, Sun Oct 27 22:35:15 2013 UTC

Diff Legend

Comparing CBOR-XS/XS.pm (file contents):
Revision 1.2 by root, Sat Oct 26 10:41:12 2013 UTC vs.
Revision 1.7 by root, Sun Oct 27 22:35:15 2013 UTC