[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 1.13 by root, Tue Oct 29 15:56:31 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	31	WARNING! This module is very new, and not very well tested (that's up to
32	AND EAT YOUR CHILDREN! (Actually, apart from being untested and a bit	32	you to do). Furthermore, details of the implementation might change freely
33	feature-limited, it might already be useful).	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.
		37
		38	You are still invited to try out CBOR, and this module.
34		39
35	This module converts Perl data structures to the Concise Binary Object	40	This module converts Perl data structures to the Concise Binary Object
36	Representation (CBOR) and vice versa. CBOR is a fast binary serialisation	41	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	42	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	43	can represent something in JSON, you should be able to represent it in
39	CBOR.	44	CBOR.
40		45
41	This makes it a faster and more compact binary alternative to JSON, with	46	In short, CBOR is a faster and very compact binary alternative to JSON,
42	the added ability of supporting serialising of perl objects.	47	with the added ability of supporting serialisation of Perl objects. (JSON
		48	often compresses better than CBOR though, so if you plan to compress the
		49	data later you might want to compare both formats first).
43		50
44	The primary goal of this module is to be I<correct> and the secondary goal	51	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.	52	is to be I<fast>. To reach the latter goal it was written in C.
46		53
47	See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and	54	See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and
…		…
51		58
52	package CBOR::XS;	59	package CBOR::XS;
53		60
54	use common::sense;	61	use common::sense;
55		62
56	our $VERSION = 0.03;	63	our $VERSION = 0.06;
57	our @ISA = qw(Exporter);	64	our @ISA = qw(Exporter);
58		65
59	our @EXPORT = qw(encode_cbor decode_cbor);	66	our @EXPORT = qw(encode_cbor decode_cbor);
60		67
61	use Exporter;	68	use Exporter;
…		…
221	C<1> and C<0> (for true and false) or to throw an exception on access (for	228	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.	229	error). See the L<Types::Serialiser> manpage for details.
223		230
224	=item CBOR tag 256 (perl object)	231	=item CBOR tag 256 (perl object)
225		232
226	The tag value C<256> (TODO: pending iana registration) will be used to	233	The tag value C<256> (TODO: pending iana registration) will be used
227	deserialise a Perl object.	234	to deserialise a Perl object serialised with C<FREEZE>. See L<OBJECT
228		235	SERIALISATION>, below, for details.
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		236
237	=item CBOR tag 55799 (magic header)	237	=item CBOR tag 55799 (magic header)
238		238
239	The tag 55799 is ignored (this tag implements the magic header).	239	The tag 55799 is ignored (this tag implements the magic header).
240		240
…		…
283	C<1>, which get turned into false and true in CBOR.	283	C<1>, which get turned into false and true in CBOR.
284		284
285	=item CBOR::XS::Tagged objects	285	=item CBOR::XS::Tagged objects
286		286
287	Objects of this type must be arrays consisting of a single C<[tag, value]>	287	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	288	pair. The (numerical) tag will be encoded as a CBOR tag, the value will
289	encoded as appropriate for the value.	289	be encoded as appropriate for the value. You cna use C<CBOR::XS::tag> to
		290	create such objects.
290		291
291	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error	292	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error
292		293
293	These special values become CBOR true, CBOR false and CBOR undefined	294	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	295	values, respectively. You can also use C<\1>, C<\0> and C<\undef> directly
295	if you want.	296	if you want.
296		297
297	=item blessed objects	298	=item other blessed objects
298		299
299	Other blessed objects currently need to have a C<TO_CBOR> method. It	300	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	301	L<OBJECT SERIALISATION>, below, for details.
301	something that can be encoded in CBOR.
302		302
303	=item simple scalars	303	=item simple scalars
304		304
305	TODO	305	TODO
306	Simple Perl scalars (any scalar that is not a reference) are the most	306	Simple Perl scalars (any scalar that is not a reference) are the most
…		…
344	represent numerical values are supported, but might suffer loss of	344	represent numerical values are supported, but might suffer loss of
345	precision.	345	precision.
346		346
347	=back	347	=back
348		348
		349	=head2 OBJECT SERIALISATION
349		350
		351	This module knows two way to serialise a Perl object: The CBOR-specific
		352	way, and the generic way.
		353
		354	Whenever the encoder encounters a Perl object that it cnanot serialise
		355	directly (most of them), it will first look up the C<TO_CBOR> method on
		356	it.
		357
		358	If it has a C<TO_CBOR> method, it will call it with the object as only
		359	argument, and expects exactly one return value, which it will then
		360	substitute and encode it in the place of the object.
		361
		362	Otherwise, it will look up the C<FREEZE> method. If it exists, it will
		363	call it with the object as first argument, and the constant string C<CBOR>
		364	as the second argument, to distinguish it from other serialisers.
		365
		366	The C<FREEZE> method can return any number of values (i.e. zero or
		367	more). These will be encoded as CBOR perl object, together with the
		368	classname.
		369
		370	If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail
		371	with an error.
		372
		373	Objects encoded via C<TO_CBOR> cannot be automatically decoded, but
		374	objects encoded via C<FREEZE> can be decoded using the following protocol:
		375
		376	When an encoded CBOR perl object is encountered by the decoder, it will
		377	look up the C<THAW> method, by using the stored classname, and will fail
		378	if the method cannot be found.
		379
		380	After the lookup it will call the C<THAW> method with the stored classname
		381	as first argument, the constant string C<CBOR> as second argument, and all
		382	values returned by C<FREEZE> as remaining arguments.
		383
		384	=head4 EXAMPLES
		385
		386	Here is an example C<TO_CBOR> method:
		387
		388	sub My::Object::TO_CBOR {
		389	my ($obj) = @_;
		390
		391	["this is a serialised My::Object object", $obj->{id}]
		392	}
		393
		394	When a C<My::Object> is encoded to CBOR, it will instead encode a simple
		395	array with two members: a string, and the "object id". Decoding this CBOR
		396	string will yield a normal perl array reference in place of the object.
		397
		398	A more useful and practical example would be a serialisation method for
		399	the URI module. CBOR has a custom tag value for URIs, namely 32:
		400
		401	sub URI::TO_CBOR {
		402	my ($self) = @_;
		403	my $uri = "$self"; # stringify uri
		404	utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string
		405	CBOR::XS::tagged 32, "$_[0]"
		406	}
		407
		408	This will encode URIs as a UTF-8 string with tag 32, which indicates an
		409	URI.
		410
		411	Decoding such an URI will not (currently) give you an URI object, but
		412	instead a CBOR::XS::Tagged object with tag number 32 and the string -
		413	exactly what was returned by C<TO_CBOR>.
		414
		415	To serialise an object so it can automatically be deserialised, you need
		416	to use C<FREEZE> and C<THAW>. To take the URI module as example, this
		417	would be a possible implementation:
		418
		419	sub URI::FREEZE {
		420	my ($self, $serialiser) = @_;
		421	"$self" # encode url string
		422	}
		423
		424	sub URI::THAW {
		425	my ($class, $serialiser, $uri) = @_;
		426
		427	$class->new ($uri)
		428	}
		429
		430	Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For
		431	example, a C<FREEZE> method that returns "type", "id" and "variant" values
		432	would cause an invocation of C<THAW> with 5 arguments:
		433
		434	sub My::Object::FREEZE {
		435	my ($self, $serialiser) = @_;
		436
		437	($self->{type}, $self->{id}, $self->{variant})
		438	}
		439
		440	sub My::Object::THAW {
		441	my ($class, $serialiser, $type, $id, $variant) = @_;
		442
		443	$class-<new (type => $type, id => $id, variant => $variant)
		444	}
		445
		446
350	=head2 MAGIC HEADER	447	=head1 MAGIC HEADER
351		448
352	There is no way to distinguish CBOR from other formats	449	There is no way to distinguish CBOR from other formats
353	programmatically. To make it easier to distinguish CBOR from other	450	programmatically. To make it easier to distinguish CBOR from other
354	formats, the CBOR specification has a special "magic string" that can be	451	formats, the CBOR specification has a special "magic string" that can be
355	prepended to any CBOR string without changing it's meaning.	452	prepended to any CBOR string without changing it's meaning.
…		…
358	prepend this string tot he CBOR data it generates, but it will ignroe it	455	prepend this string tot he CBOR data it generates, but it will ignroe it
359	if present, so users can prepend this string as a "file type" indicator as	456	if present, so users can prepend this string as a "file type" indicator as
360	required.	457	required.
361		458
362		459
		460	=head1 THE CBOR::XS::Tagged CLASS
		461
		462	CBOR has the concept of tagged values - any CBOR value can be tagged with
		463	a numeric 64 bit number, which are centrally administered.
		464
		465	C<CBOR::XS> handles a few tags internally when en- or decoding. You can
		466	also create tags yourself by encoding C<CBOR::XS::Tagged> objects, and the
		467	decoder will create C<CBOR::XS::Tagged> objects itself when it hits an
		468	unknown tag.
		469
		470	These objects are simply blessed array references - the first member of
		471	the array being the numerical tag, the second being the value.
		472
		473	You can interact with C<CBOR::XS::Tagged> objects in the following ways:
		474
		475	=over 4
		476
		477	=item $tagged = CBOR::XS::tag $tag, $value
		478
		479	This function(!) creates a new C<CBOR::XS::Tagged> object using the given
		480	C<$tag> (0..2**64-1) to tag the given C<$value> (which can be any Perl
		481	value that can be encoded in CBOR, including serialisable Perl objects and
		482	C<CBOR::XS::Tagged> objects).
		483
		484	=item $tagged->[0]
		485
		486	=item $tagged->[0] = $new_tag
		487
		488	=item $tag = $tagged->tag
		489
		490	=item $new_tag = $tagged->tag ($new_tag)
		491
		492	Access/mutate the tag.
		493
		494	=item $tagged->[1]
		495
		496	=item $tagged->[1] = $new_value
		497
		498	=item $value = $tagged->value
		499
		500	=item $new_value = $tagged->value ($new_value)
		501
		502	Access/mutate the tagged value.
		503
		504	=back
		505
		506	=cut
		507
		508	sub tag($$) {
		509	bless [@_], CBOR::XS::Tagged::;
		510	}
		511
		512	sub CBOR::XS::Tagged::tag {
		513	$_[0][0] = $_[1] if $#_;
		514	$_[0][0]
		515	}
		516
		517	sub CBOR::XS::Tagged::value {
		518	$_[0][1] = $_[1] if $#_;
		519	$_[0][1]
		520	}
		521
		522	=head2 EXAMPLES
		523
		524	Here are some examples of C<CBOR::XS::Tagged> uses to tag objects.
		525
		526	You can look up CBOR tag value and emanings in the IANA registry at
		527	L<http://www.iana.org/assignments/cbor-tags/cbor-tags.xhtml>.
		528
		529	Prepend a magic header (C<$CBOR::XS::MAGIC>):
		530
		531	my $cbor = encode_cbor CBOR::XS::tag 55799, $value;
		532	# same as:
		533	my $cbor = $CBOR::XS::MAGIC . encode_cbor $value;
		534
		535	Serialise some URIs and a regex in an array:
		536
		537	my $cbor = encode_cbor [
		538	(CBOR::XS::tag 32, "http://www.nethype.de/"),
		539	(CBOR::XS::tag 32, "http://software.schmorp.de/"),
		540	(CBOR::XS::tag 35, "^[Pp][Ee][Rr][lL]\$"),
		541	];
		542
		543	Wrap CBOR data in CBOR:
		544
		545	my $cbor_cbor = encode_cbor
		546	CBOR::XS::tag 24,
		547	encode_cbor [1, 2, 3];
		548
363	=head2 CBOR and JSON	549	=head1 CBOR and JSON
364		550
365	CBOR is supposed to implement a superset of the JSON data model, and is,	551	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	552	with some coercion, able to represent all JSON texts (something that other
367	"binary JSON" formats such as BSON generally do not support).	553	"binary JSON" formats such as BSON generally do not support).
368		554

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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 1.13 by root, Tue Oct 29 15:56:31 2013 UTC

Diff Legend

Comparing CBOR-XS/XS.pm (file contents):
Revision 1.6 by root, Sun Oct 27 20:40:25 2013 UTC vs.
Revision 1.13 by root, Tue Oct 29 15:56:31 2013 UTC