[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 1.14 by root, Tue Oct 29 20:59:16 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, with texts in the megabyte range, C<CBOR::XS>
		52	usually encodes roughly twice as fast as L<Storable> or L<JSON::XS> and
		53	decodes about 15%-30% faster than those. The shorter the data, the worse
		54	L<Storable> performs in comparison.
43		55
44	The primary goal of this module is to be I<correct> and the secondary goal	56	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.	57	is to be I<fast>. To reach the latter goal it was written in C.
46		58
47	See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and	59	See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and
…		…
51		63
52	package CBOR::XS;	64	package CBOR::XS;
53		65
54	use common::sense;	66	use common::sense;
55		67
56	our $VERSION = 0.03;	68	our $VERSION = 0.06;
57	our @ISA = qw(Exporter);	69	our @ISA = qw(Exporter);
58		70
59	our @EXPORT = qw(encode_cbor decode_cbor);	71	our @EXPORT = qw(encode_cbor decode_cbor);
60		72
61	use Exporter;	73	use Exporter;
…		…
221	C<1> and C<0> (for true and false) or to throw an exception on access (for	233	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.	234	error). See the L<Types::Serialiser> manpage for details.
223		235
224	=item CBOR tag 256 (perl object)	236	=item CBOR tag 256 (perl object)
225		237
226	The tag value C<256> (TODO: pending iana registration) will be used to	238	The tag value C<256> (TODO: pending iana registration) will be used
227	deserialise a Perl object.	239	to deserialise a Perl object serialised with C<FREEZE>. See L<OBJECT
228		240	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		241
237	=item CBOR tag 55799 (magic header)	242	=item CBOR tag 55799 (magic header)
238		243
239	The tag 55799 is ignored (this tag implements the magic header).	244	The tag 55799 is ignored (this tag implements the magic header).
240		245
…		…
283	C<1>, which get turned into false and true in CBOR.	288	C<1>, which get turned into false and true in CBOR.
284		289
285	=item CBOR::XS::Tagged objects	290	=item CBOR::XS::Tagged objects
286		291
287	Objects of this type must be arrays consisting of a single C<[tag, value]>	292	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	293	pair. The (numerical) tag will be encoded as a CBOR tag, the value will
289	encoded as appropriate for the value.	294	be encoded as appropriate for the value. You cna use C<CBOR::XS::tag> to
		295	create such objects.
290		296
291	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error	297	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error
292		298
293	These special values become CBOR true, CBOR false and CBOR undefined	299	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	300	values, respectively. You can also use C<\1>, C<\0> and C<\undef> directly
295	if you want.	301	if you want.
296		302
297	=item blessed objects	303	=item other blessed objects
298		304
299	Other blessed objects currently need to have a C<TO_CBOR> method. It	305	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	306	L<OBJECT SERIALISATION>, below, for details.
301	something that can be encoded in CBOR.
302		307
303	=item simple scalars	308	=item simple scalars
304		309
305	TODO	310	TODO
306	Simple Perl scalars (any scalar that is not a reference) are the most	311	Simple Perl scalars (any scalar that is not a reference) are the most
…		…
344	represent numerical values are supported, but might suffer loss of	349	represent numerical values are supported, but might suffer loss of
345	precision.	350	precision.
346		351
347	=back	352	=back
348		353
		354	=head2 OBJECT SERIALISATION
349		355
		356	This module knows two way to serialise a Perl object: The CBOR-specific
		357	way, and the generic way.
		358
		359	Whenever the encoder encounters a Perl object that it cnanot serialise
		360	directly (most of them), it will first look up the C<TO_CBOR> method on
		361	it.
		362
		363	If it has a C<TO_CBOR> method, it will call it with the object as only
		364	argument, and expects exactly one return value, which it will then
		365	substitute and encode it in the place of the object.
		366
		367	Otherwise, it will look up the C<FREEZE> method. If it exists, it will
		368	call it with the object as first argument, and the constant string C<CBOR>
		369	as the second argument, to distinguish it from other serialisers.
		370
		371	The C<FREEZE> method can return any number of values (i.e. zero or
		372	more). These will be encoded as CBOR perl object, together with the
		373	classname.
		374
		375	If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail
		376	with an error.
		377
		378	Objects encoded via C<TO_CBOR> cannot be automatically decoded, but
		379	objects encoded via C<FREEZE> can be decoded using the following protocol:
		380
		381	When an encoded CBOR perl object is encountered by the decoder, it will
		382	look up the C<THAW> method, by using the stored classname, and will fail
		383	if the method cannot be found.
		384
		385	After the lookup it will call the C<THAW> method with the stored classname
		386	as first argument, the constant string C<CBOR> as second argument, and all
		387	values returned by C<FREEZE> as remaining arguments.
		388
		389	=head4 EXAMPLES
		390
		391	Here is an example C<TO_CBOR> method:
		392
		393	sub My::Object::TO_CBOR {
		394	my ($obj) = @_;
		395
		396	["this is a serialised My::Object object", $obj->{id}]
		397	}
		398
		399	When a C<My::Object> is encoded to CBOR, it will instead encode a simple
		400	array with two members: a string, and the "object id". Decoding this CBOR
		401	string will yield a normal perl array reference in place of the object.
		402
		403	A more useful and practical example would be a serialisation method for
		404	the URI module. CBOR has a custom tag value for URIs, namely 32:
		405
		406	sub URI::TO_CBOR {
		407	my ($self) = @_;
		408	my $uri = "$self"; # stringify uri
		409	utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string
		410	CBOR::XS::tagged 32, "$_[0]"
		411	}
		412
		413	This will encode URIs as a UTF-8 string with tag 32, which indicates an
		414	URI.
		415
		416	Decoding such an URI will not (currently) give you an URI object, but
		417	instead a CBOR::XS::Tagged object with tag number 32 and the string -
		418	exactly what was returned by C<TO_CBOR>.
		419
		420	To serialise an object so it can automatically be deserialised, you need
		421	to use C<FREEZE> and C<THAW>. To take the URI module as example, this
		422	would be a possible implementation:
		423
		424	sub URI::FREEZE {
		425	my ($self, $serialiser) = @_;
		426	"$self" # encode url string
		427	}
		428
		429	sub URI::THAW {
		430	my ($class, $serialiser, $uri) = @_;
		431
		432	$class->new ($uri)
		433	}
		434
		435	Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For
		436	example, a C<FREEZE> method that returns "type", "id" and "variant" values
		437	would cause an invocation of C<THAW> with 5 arguments:
		438
		439	sub My::Object::FREEZE {
		440	my ($self, $serialiser) = @_;
		441
		442	($self->{type}, $self->{id}, $self->{variant})
		443	}
		444
		445	sub My::Object::THAW {
		446	my ($class, $serialiser, $type, $id, $variant) = @_;
		447
		448	$class-<new (type => $type, id => $id, variant => $variant)
		449	}
		450
		451
350	=head2 MAGIC HEADER	452	=head1 MAGIC HEADER
351		453
352	There is no way to distinguish CBOR from other formats	454	There is no way to distinguish CBOR from other formats
353	programmatically. To make it easier to distinguish CBOR from other	455	programmatically. To make it easier to distinguish CBOR from other
354	formats, the CBOR specification has a special "magic string" that can be	456	formats, the CBOR specification has a special "magic string" that can be
355	prepended to any CBOR string without changing it's meaning.	457	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	460	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	461	if present, so users can prepend this string as a "file type" indicator as
360	required.	462	required.
361		463
362		464
		465	=head1 THE CBOR::XS::Tagged CLASS
		466
		467	CBOR has the concept of tagged values - any CBOR value can be tagged with
		468	a numeric 64 bit number, which are centrally administered.
		469
		470	C<CBOR::XS> handles a few tags internally when en- or decoding. You can
		471	also create tags yourself by encoding C<CBOR::XS::Tagged> objects, and the
		472	decoder will create C<CBOR::XS::Tagged> objects itself when it hits an
		473	unknown tag.
		474
		475	These objects are simply blessed array references - the first member of
		476	the array being the numerical tag, the second being the value.
		477
		478	You can interact with C<CBOR::XS::Tagged> objects in the following ways:
		479
		480	=over 4
		481
		482	=item $tagged = CBOR::XS::tag $tag, $value
		483
		484	This function(!) creates a new C<CBOR::XS::Tagged> object using the given
		485	C<$tag> (0..2**64-1) to tag the given C<$value> (which can be any Perl
		486	value that can be encoded in CBOR, including serialisable Perl objects and
		487	C<CBOR::XS::Tagged> objects).
		488
		489	=item $tagged->[0]
		490
		491	=item $tagged->[0] = $new_tag
		492
		493	=item $tag = $tagged->tag
		494
		495	=item $new_tag = $tagged->tag ($new_tag)
		496
		497	Access/mutate the tag.
		498
		499	=item $tagged->[1]
		500
		501	=item $tagged->[1] = $new_value
		502
		503	=item $value = $tagged->value
		504
		505	=item $new_value = $tagged->value ($new_value)
		506
		507	Access/mutate the tagged value.
		508
		509	=back
		510
		511	=cut
		512
		513	sub tag($$) {
		514	bless [@_], CBOR::XS::Tagged::;
		515	}
		516
		517	sub CBOR::XS::Tagged::tag {
		518	$_[0][0] = $_[1] if $#_;
		519	$_[0][0]
		520	}
		521
		522	sub CBOR::XS::Tagged::value {
		523	$_[0][1] = $_[1] if $#_;
		524	$_[0][1]
		525	}
		526
		527	=head2 EXAMPLES
		528
		529	Here are some examples of C<CBOR::XS::Tagged> uses to tag objects.
		530
		531	You can look up CBOR tag value and emanings in the IANA registry at
		532	L<http://www.iana.org/assignments/cbor-tags/cbor-tags.xhtml>.
		533
		534	Prepend a magic header (C<$CBOR::XS::MAGIC>):
		535
		536	my $cbor = encode_cbor CBOR::XS::tag 55799, $value;
		537	# same as:
		538	my $cbor = $CBOR::XS::MAGIC . encode_cbor $value;
		539
		540	Serialise some URIs and a regex in an array:
		541
		542	my $cbor = encode_cbor [
		543	(CBOR::XS::tag 32, "http://www.nethype.de/"),
		544	(CBOR::XS::tag 32, "http://software.schmorp.de/"),
		545	(CBOR::XS::tag 35, "^[Pp][Ee][Rr][lL]\$"),
		546	];
		547
		548	Wrap CBOR data in CBOR:
		549
		550	my $cbor_cbor = encode_cbor
		551	CBOR::XS::tag 24,
		552	encode_cbor [1, 2, 3];
		553
363	=head2 CBOR and JSON	554	=head1 CBOR and JSON
364		555
365	CBOR is supposed to implement a superset of the JSON data model, and is,	556	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	557	with some coercion, able to represent all JSON texts (something that other
367	"binary JSON" formats such as BSON generally do not support).	558	"binary JSON" formats such as BSON generally do not support).
368		559

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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 1.14 by root, Tue Oct 29 20:59:16 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 1.14 by root, Tue Oct 29 20:59:16 2013 UTC