[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 1.17 by root, Wed Oct 30 10:11:04 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).
		50
		51	To give you a general idea about speed, with texts in the megabyte range,
		52	C<CBOR::XS> usually encodes roughly twice as fast as L<Storable> or
		53	L<JSON::XS> and decodes about 15%-30% faster than those. The shorter the
		54	data, the worse L<Storable> performs in comparison.
		55
		56	As for compactness, C<CBOR::XS> encoded data structures are usually about
		57	20% smaller than the same data encoded as (compact) JSON or L<Storable>.
43		58
44	The primary goal of this module is to be I<correct> and the secondary goal	59	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.	60	is to be I<fast>. To reach the latter goal it was written in C.
46		61
47	See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and	62	See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and
…		…
51		66
52	package CBOR::XS;	67	package CBOR::XS;
53		68
54	use common::sense;	69	use common::sense;
55		70
56	our $VERSION = 0.03;	71	our $VERSION = 0.08;
57	our @ISA = qw(Exporter);	72	our @ISA = qw(Exporter);
58		73
59	our @EXPORT = qw(encode_cbor decode_cbor);	74	our @EXPORT = qw(encode_cbor decode_cbor);
60		75
61	use Exporter;	76	use Exporter;
…		…
221	C<1> and C<0> (for true and false) or to throw an exception on access (for	236	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.	237	error). See the L<Types::Serialiser> manpage for details.
223		238
224	=item CBOR tag 256 (perl object)	239	=item CBOR tag 256 (perl object)
225		240
226	The tag value C<256> (TODO: pending iana registration) will be used to	241	The tag value C<256> (TODO: pending iana registration) will be used
227	deserialise a Perl object.	242	to deserialise a Perl object serialised with C<FREEZE>. See L<OBJECT
228		243	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		244
237	=item CBOR tag 55799 (magic header)	245	=item CBOR tag 55799 (magic header)
238		246
239	The tag 55799 is ignored (this tag implements the magic header).	247	The tag 55799 is ignored (this tag implements the magic header).
240		248
…		…
283	C<1>, which get turned into false and true in CBOR.	291	C<1>, which get turned into false and true in CBOR.
284		292
285	=item CBOR::XS::Tagged objects	293	=item CBOR::XS::Tagged objects
286		294
287	Objects of this type must be arrays consisting of a single C<[tag, value]>	295	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	296	pair. The (numerical) tag will be encoded as a CBOR tag, the value will
289	encoded as appropriate for the value.	297	be encoded as appropriate for the value. You cna use C<CBOR::XS::tag> to
		298	create such objects.
290		299
291	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error	300	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error
292		301
293	These special values become CBOR true, CBOR false and CBOR undefined	302	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	303	values, respectively. You can also use C<\1>, C<\0> and C<\undef> directly
295	if you want.	304	if you want.
296		305
297	=item blessed objects	306	=item other blessed objects
298		307
299	Other blessed objects currently need to have a C<TO_CBOR> method. It	308	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	309	L<OBJECT SERIALISATION>, below, for details.
301	something that can be encoded in CBOR.
302		310
303	=item simple scalars	311	=item simple scalars
304		312
305	TODO	313	TODO
306	Simple Perl scalars (any scalar that is not a reference) are the most	314	Simple Perl scalars (any scalar that is not a reference) are the most
…		…
344	represent numerical values are supported, but might suffer loss of	352	represent numerical values are supported, but might suffer loss of
345	precision.	353	precision.
346		354
347	=back	355	=back
348		356
		357	=head2 OBJECT SERIALISATION
349		358
		359	This module knows two way to serialise a Perl object: The CBOR-specific
		360	way, and the generic way.
		361
		362	Whenever the encoder encounters a Perl object that it cnanot serialise
		363	directly (most of them), it will first look up the C<TO_CBOR> method on
		364	it.
		365
		366	If it has a C<TO_CBOR> method, it will call it with the object as only
		367	argument, and expects exactly one return value, which it will then
		368	substitute and encode it in the place of the object.
		369
		370	Otherwise, it will look up the C<FREEZE> method. If it exists, it will
		371	call it with the object as first argument, and the constant string C<CBOR>
		372	as the second argument, to distinguish it from other serialisers.
		373
		374	The C<FREEZE> method can return any number of values (i.e. zero or
		375	more). These will be encoded as CBOR perl object, together with the
		376	classname.
		377
		378	If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail
		379	with an error.
		380
		381	Objects encoded via C<TO_CBOR> cannot be automatically decoded, but
		382	objects encoded via C<FREEZE> can be decoded using the following protocol:
		383
		384	When an encoded CBOR perl object is encountered by the decoder, it will
		385	look up the C<THAW> method, by using the stored classname, and will fail
		386	if the method cannot be found.
		387
		388	After the lookup it will call the C<THAW> method with the stored classname
		389	as first argument, the constant string C<CBOR> as second argument, and all
		390	values returned by C<FREEZE> as remaining arguments.
		391
		392	=head4 EXAMPLES
		393
		394	Here is an example C<TO_CBOR> method:
		395
		396	sub My::Object::TO_CBOR {
		397	my ($obj) = @_;
		398
		399	["this is a serialised My::Object object", $obj->{id}]
		400	}
		401
		402	When a C<My::Object> is encoded to CBOR, it will instead encode a simple
		403	array with two members: a string, and the "object id". Decoding this CBOR
		404	string will yield a normal perl array reference in place of the object.
		405
		406	A more useful and practical example would be a serialisation method for
		407	the URI module. CBOR has a custom tag value for URIs, namely 32:
		408
		409	sub URI::TO_CBOR {
		410	my ($self) = @_;
		411	my $uri = "$self"; # stringify uri
		412	utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string
		413	CBOR::XS::tagged 32, "$_[0]"
		414	}
		415
		416	This will encode URIs as a UTF-8 string with tag 32, which indicates an
		417	URI.
		418
		419	Decoding such an URI will not (currently) give you an URI object, but
		420	instead a CBOR::XS::Tagged object with tag number 32 and the string -
		421	exactly what was returned by C<TO_CBOR>.
		422
		423	To serialise an object so it can automatically be deserialised, you need
		424	to use C<FREEZE> and C<THAW>. To take the URI module as example, this
		425	would be a possible implementation:
		426
		427	sub URI::FREEZE {
		428	my ($self, $serialiser) = @_;
		429	"$self" # encode url string
		430	}
		431
		432	sub URI::THAW {
		433	my ($class, $serialiser, $uri) = @_;
		434
		435	$class->new ($uri)
		436	}
		437
		438	Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For
		439	example, a C<FREEZE> method that returns "type", "id" and "variant" values
		440	would cause an invocation of C<THAW> with 5 arguments:
		441
		442	sub My::Object::FREEZE {
		443	my ($self, $serialiser) = @_;
		444
		445	($self->{type}, $self->{id}, $self->{variant})
		446	}
		447
		448	sub My::Object::THAW {
		449	my ($class, $serialiser, $type, $id, $variant) = @_;
		450
		451	$class-<new (type => $type, id => $id, variant => $variant)
		452	}
		453
		454
350	=head2 MAGIC HEADER	455	=head1 MAGIC HEADER
351		456
352	There is no way to distinguish CBOR from other formats	457	There is no way to distinguish CBOR from other formats
353	programmatically. To make it easier to distinguish CBOR from other	458	programmatically. To make it easier to distinguish CBOR from other
354	formats, the CBOR specification has a special "magic string" that can be	459	formats, the CBOR specification has a special "magic string" that can be
355	prepended to any CBOR string without changing it's meaning.	460	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	463	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	464	if present, so users can prepend this string as a "file type" indicator as
360	required.	465	required.
361		466
362		467
		468	=head1 THE CBOR::XS::Tagged CLASS
		469
		470	CBOR has the concept of tagged values - any CBOR value can be tagged with
		471	a numeric 64 bit number, which are centrally administered.
		472
		473	C<CBOR::XS> handles a few tags internally when en- or decoding. You can
		474	also create tags yourself by encoding C<CBOR::XS::Tagged> objects, and the
		475	decoder will create C<CBOR::XS::Tagged> objects itself when it hits an
		476	unknown tag.
		477
		478	These objects are simply blessed array references - the first member of
		479	the array being the numerical tag, the second being the value.
		480
		481	You can interact with C<CBOR::XS::Tagged> objects in the following ways:
		482
		483	=over 4
		484
		485	=item $tagged = CBOR::XS::tag $tag, $value
		486
		487	This function(!) creates a new C<CBOR::XS::Tagged> object using the given
		488	C<$tag> (0..2**64-1) to tag the given C<$value> (which can be any Perl
		489	value that can be encoded in CBOR, including serialisable Perl objects and
		490	C<CBOR::XS::Tagged> objects).
		491
		492	=item $tagged->[0]
		493
		494	=item $tagged->[0] = $new_tag
		495
		496	=item $tag = $tagged->tag
		497
		498	=item $new_tag = $tagged->tag ($new_tag)
		499
		500	Access/mutate the tag.
		501
		502	=item $tagged->[1]
		503
		504	=item $tagged->[1] = $new_value
		505
		506	=item $value = $tagged->value
		507
		508	=item $new_value = $tagged->value ($new_value)
		509
		510	Access/mutate the tagged value.
		511
		512	=back
		513
		514	=cut
		515
		516	sub tag($$) {
		517	bless [@_], CBOR::XS::Tagged::;
		518	}
		519
		520	sub CBOR::XS::Tagged::tag {
		521	$_[0][0] = $_[1] if $#_;
		522	$_[0][0]
		523	}
		524
		525	sub CBOR::XS::Tagged::value {
		526	$_[0][1] = $_[1] if $#_;
		527	$_[0][1]
		528	}
		529
		530	=head2 EXAMPLES
		531
		532	Here are some examples of C<CBOR::XS::Tagged> uses to tag objects.
		533
		534	You can look up CBOR tag value and emanings in the IANA registry at
		535	L<http://www.iana.org/assignments/cbor-tags/cbor-tags.xhtml>.
		536
		537	Prepend a magic header (C<$CBOR::XS::MAGIC>):
		538
		539	my $cbor = encode_cbor CBOR::XS::tag 55799, $value;
		540	# same as:
		541	my $cbor = $CBOR::XS::MAGIC . encode_cbor $value;
		542
		543	Serialise some URIs and a regex in an array:
		544
		545	my $cbor = encode_cbor [
		546	(CBOR::XS::tag 32, "http://www.nethype.de/"),
		547	(CBOR::XS::tag 32, "http://software.schmorp.de/"),
		548	(CBOR::XS::tag 35, "^[Pp][Ee][Rr][lL]\$"),
		549	];
		550
		551	Wrap CBOR data in CBOR:
		552
		553	my $cbor_cbor = encode_cbor
		554	CBOR::XS::tag 24,
		555	encode_cbor [1, 2, 3];
		556
363	=head2 CBOR and JSON	557	=head1 CBOR and JSON
364		558
365	CBOR is supposed to implement a superset of the JSON data model, and is,	559	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	560	with some coercion, able to represent all JSON texts (something that other
367	"binary JSON" formats such as BSON generally do not support).	561	"binary JSON" formats such as BSON generally do not support).
368		562

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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 1.17 by root, Wed Oct 30 10:11:04 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 1.17 by root, Wed Oct 30 10:11:04 2013 UTC