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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.33 by root, Wed May 9 16:10:37 2007 UTC vs.
Revision 1.51 by root, Mon Jul 2 01:12:27 2007 UTC

…		…
9	# exported functions, they croak on error	9	# exported functions, they croak on error
10	# and expect/generate UTF-8	10	# and expect/generate UTF-8
11		11
12	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;	12	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;
13	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;	13	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;
14
15	# objToJson and jsonToObj aliases to to_json and from_json
16	# are exported for compatibility to the JSON module,
17	# but should not be used in new code.
18		14
19	# OO-interface	15	# OO-interface
20		16
21	$coder = JSON::XS->new->ascii->pretty->allow_nonref;	17	$coder = JSON::XS->new->ascii->pretty->allow_nonref;
22	$pretty_printed_unencoded = $coder->encode ($perl_scalar);	18	$pretty_printed_unencoded = $coder->encode ($perl_scalar);
…		…
85		81
86	package JSON::XS;	82	package JSON::XS;
87		83
88	use strict;	84	use strict;
89		85
90	BEGIN {
91	our $VERSION = '1.12';	86	our $VERSION = '1.4';
92	our @ISA = qw(Exporter);	87	our @ISA = qw(Exporter);
93		88
94	our @EXPORT = qw(to_json from_json objToJson jsonToObj);	89	our @EXPORT = qw(to_json from_json);
95	require Exporter;
96		90
97	require XSLoader;	91	use Exporter;
98	XSLoader::load JSON::XS::, $VERSION;	92	use XSLoader;
99	}
100		93
101	=head1 FUNCTIONAL INTERFACE	94	=head1 FUNCTIONAL INTERFACE
102		95
103	The following convinience methods are provided by this module. They are	96	The following convinience methods are provided by this module. They are
104	exported by default:	97	exported by default:
…		…
126	This function call is functionally identical to:	119	This function call is functionally identical to:
127		120
128	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)	121	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
129		122
130	except being faster.	123	except being faster.
		124
		125	=item $is_boolean = JSON::XS::is_bool $scalar
		126
		127	Returns true if the passed scalar represents either JSON::XS::true or
		128	JSON::XS::false, two constants that act like C<1> and C<0>, respectively
		129	and are used to represent JSON C<true> and C<false> values in Perl.
		130
		131	See MAPPING, below, for more information on how JSON values are mapped to
		132	Perl.
131		133
132	=back	134	=back
133		135
134		136
135	=head1 OBJECT-ORIENTED INTERFACE	137	=head1 OBJECT-ORIENTED INTERFACE
…		…
309	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,	311	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,
310	resulting in an invalid JSON text:	312	resulting in an invalid JSON text:
311		313
312	JSON::XS->new->allow_nonref->encode ("Hello, World!")	314	JSON::XS->new->allow_nonref->encode ("Hello, World!")
313	=> "Hello, World!"	315	=> "Hello, World!"
		316
		317	=item $json = $json->allow_blessed ([$enable])
		318
		319	If C<$enable> is true (or missing), then the C<encode> method will not
		320	barf when it encounters a blessed reference. Instead, the value of the
		321	B<convert_blessed> option will decide wether C<null> (C<convert_blessed>
		322	disabled or no C<to_json> method found) or a representation of the
		323	object (C<convert_blessed> enabled and C<to_json> method found) is being
		324	encoded. Has no effect on C<decode>.
		325
		326	If C<$enable> is false (the default), then C<encode> will throw an
		327	exception when it encounters a blessed object.
		328
		329	=item $json = $json->convert_blessed ([$enable])
		330
		331	If C<$enable> is true (or missing), then C<encode>, upon encountering a
		332	blessed object, will check for the availability of the C<TO_JSON> method
		333	on the object's class. If found, it will be called in scalar context
		334	and the resulting scalar will be encoded instead of the object. If no
		335	C<TO_JSON> method is found, the value of C<allow_blessed> will decide what
		336	to do.
		337
		338	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
		339	returns other blessed objects, those will be handled in the same
		340	way. C<TO_JSON> must take care of not causing an endless recursion cycle
		341	(== crash) in this case. The name of C<TO_JSON> was chosen because other
		342	methods called by the Perl core (== not by the user of the object) are
		343	usually in upper case letters and to avoid collisions with the C<to_json>
		344	function.
		345
		346	This setting does not yet influence C<decode> in any way, but in the
		347	future, global hooks might get installed that influence C<decode> and are
		348	enabled by this setting.
		349
		350	If C<$enable> is false, then the C<allow_blessed> setting will decide what
		351	to do when a blessed object is found.
		352
		353	=item $json = $json->filter_json_object ([$coderef])
		354
		355	When C<$coderef> is specified, it will be called from C<decode> each
		356	time it decodes a JSON object. The only argument is a reference to the
		357	newly-created hash. If the code references returns a single scalar (which
		358	need not be a reference), this value (i.e. a copy of that scalar to avoid
		359	aliasing) is inserted into the deserialised data structure. If it returns
		360	an empty list (NOTE: I<not> C<undef>, which is a valid scalar), the
		361	original deserialised hash will be inserted. This setting can slow down
		362	decoding considerably.
		363
		364	When C<$coderef> is omitted or undefined, C<decode> will not change the
		365	deserialised hash in any way. This is maximally fast.
		366
		367	Example, convert all JSON objects into the integer 5:
		368
		369	my $js = JSON::XS->new->filter_json_object (sub { 5 });
		370	# returns [5]
		371	$js->decode ('[{}]')
		372	# throw an exception because allow_nonref is not enabled:
		373	$js->decode ('{"a":1, "b":2}');
		374
		375	=item $json = $json->filter_json_single_key_object ([$coderef])
		376
		377	Works like C<filter_json_object>, but is only called for JSON objects
		378	having only a single key.
		379
		380	This C<$coderef> is called before the one specified via
		381	C<filter_json_object>, if any. If it returns something, that will be
		382	inserted into the data structure. If it returns nothing, the callback
		383	from C<filter_json_object> will be called next. If you want to force
		384	insertion of single-key objects even in the presence of a mutating
		385	C<filter_json_object> callback, simply return the passed hash.
		386
		387	As this callback gets called less often then the C<filter_json_object>
		388	one, decoding speed will not usually suffer as much. Therefore, single-key
		389	objects make excellent targets to serialise Perl objects into, especially
		390	as single-key JSON objects are as close to the type-tagged value concept
		391	as JSON gets (its basically an ID/VALUE tuple). Of course, JSON does not
		392	support this in any way, so you need to make sure your data never looks
		393	like a serialised Perl hash.
		394
		395	Typical names for the single object key are C<__class_whatever__>, or
		396	C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even
		397	things like C<__class_md5sum(classname)__>, to reduce the risk of clashing
		398	with real hashes.
		399
		400	Example, decode JSON objects of the form C<< { "__widget__" => <id> } >>
		401	into the corresponding C<< $WIDGET{<id>} >> object:
		402
		403	# return whatever is in $WIDGET{5}:
		404	JSON::XS
		405	->new
		406	->filter_json_single_key_object (sub {
		407	exists $_[0]{__widget__}
		408	? $WIDGET{ $_[0]{__widget__} }
		409	: ()
		410	})
		411	->decode ('{"__widget__": 5')
		412
		413	# this can be used with a TO_JSON method in some "widget" class
		414	# for serialisation to json:
		415	sub WidgetBase::TO_JSON {
		416	my ($self) = @_;
		417
		418	unless ($self->{id}) {
		419	$self->{id} = ..get..some..id..;
		420	$WIDGET{$self->{id}} = $self;
		421	}
		422
		423	{ __widget__ => $self->{id} }
		424	}
314		425
315	=item $json = $json->shrink ([$enable])	426	=item $json = $json->shrink ([$enable])
316		427
317	Perl usually over-allocates memory a bit when allocating space for	428	Perl usually over-allocates memory a bit when allocating space for
318	strings. This flag optionally resizes strings generated by either	429	strings. This flag optionally resizes strings generated by either
…		…
351	given character in a string.	462	given character in a string.
352		463
353	Setting the maximum depth to one disallows any nesting, so that ensures	464	Setting the maximum depth to one disallows any nesting, so that ensures
354	that the object is only a single hash/object or array.	465	that the object is only a single hash/object or array.
355		466
356	The argument to C<max_depth> will be rounded up to the next nearest power	467	The argument to C<max_depth> will be rounded up to the next highest power
357	of two.	468	of two. If no argument is given, the highest possible setting will be
		469	used, which is rarely useful.
		470
		471	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
		472
		473	=item $json = $json->max_size ([$maximum_string_size])
		474
		475	Set the maximum length a JSON text may have (in bytes) where decoding is
		476	being attempted. The default is C<0>, meaning no limit. When C<decode>
		477	is called on a string longer then this number of characters it will not
		478	attempt to decode the string but throw an exception. This setting has no
		479	effect on C<encode> (yet).
		480
		481	The argument to C<max_size> will be rounded up to the next B<highest>
		482	power of two (so may be more than requested). If no argument is given, the
		483	limit check will be deactivated (same as when C<0> is specified).
358		484
359	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	485	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
360		486
361	=item $json_text = $json->encode ($perl_scalar)	487	=item $json_text = $json->encode ($perl_scalar)
362		488
…		…
374		500
375	JSON numbers and strings become simple Perl scalars. JSON arrays become	501	JSON numbers and strings become simple Perl scalars. JSON arrays become
376	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes	502	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
377	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.	503	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
378		504
		505	=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
		506
		507	This works like the C<decode> method, but instead of raising an exception
		508	when there is trailing garbage after the first JSON object, it will
		509	silently stop parsing there and return the number of characters consumed
		510	so far.
		511
		512	This is useful if your JSON texts are not delimited by an outer protocol
		513	(which is not the brightest thing to do in the first place) and you need
		514	to know where the JSON text ends.
		515
		516	JSON::XS->new->decode_prefix ("[1] the tail")
		517	=> ([], 3)
		518
379	=back	519	=back
380		520
381		521
382	=head1 MAPPING	522	=head1 MAPPING
383		523
…		…
387	(what you put in comes out as something equivalent).	527	(what you put in comes out as something equivalent).
388		528
389	For the more enlightened: note that in the following descriptions,	529	For the more enlightened: note that in the following descriptions,
390	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>	530	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
391	refers to the abstract Perl language itself.	531	refers to the abstract Perl language itself.
		532
392		533
393	=head2 JSON -> PERL	534	=head2 JSON -> PERL
394		535
395	=over 4	536	=over 4
396		537
…		…
417	conversion details, but an integer may take slightly less memory and might	558	conversion details, but an integer may take slightly less memory and might
418	represent more values exactly than (floating point) numbers.	559	represent more values exactly than (floating point) numbers.
419		560
420	=item true, false	561	=item true, false
421		562
422	These JSON atoms become C<0>, C<1>, respectively. Information is lost in	563	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
423	this process. Future versions might represent those values differently,	564	respectively. They are overloaded to act almost exactly like the numbers
424	but they will be guarenteed to act like these integers would normally in	565	C<1> and C<0>. You can check wether a scalar is a JSON boolean by using
425	Perl.	566	the C<JSON::XS::is_bool> function.
426		567
427	=item null	568	=item null
428		569
429	A JSON null atom becomes C<undef> in Perl.	570	A JSON null atom becomes C<undef> in Perl.
430		571
431	=back	572	=back
		573
432		574
433	=head2 PERL -> JSON	575	=head2 PERL -> JSON
434		576
435	The mapping from Perl to JSON is slightly more difficult, as Perl is a	577	The mapping from Perl to JSON is slightly more difficult, as Perl is a
436	truly typeless language, so we can only guess which JSON type is meant by	578	truly typeless language, so we can only guess which JSON type is meant by
…		…
461	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can	603	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
462	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.	604	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
463		605
464	to_json [\0,JSON::XS::true] # yields [false,true]	606	to_json [\0,JSON::XS::true] # yields [false,true]
465		607
		608	=item JSON::XS::true, JSON::XS::false
		609
		610	These special values become JSON true and JSON false values,
		611	respectively. You cna alos use C<\1> and C<\0> directly if you want.
		612
466	=item blessed objects	613	=item blessed objects
467		614
468	Blessed objects are not allowed. JSON::XS currently tries to encode their	615	Blessed objects are not allowed. JSON::XS currently tries to encode their
469	underlying representation (hash- or arrayref), but this behaviour might	616	underlying representation (hash- or arrayref), but this behaviour might
470	change in future versions.	617	change in future versions.
…		…
591		738
592	Does not check input for validity.	739	Does not check input for validity.
593		740
594	=back	741	=back
595		742
		743
		744	=head2 JSON and YAML
		745
		746	You often hear that JSON is a subset (or a close subset) of YAML. This is,
		747	however, a mass hysteria and very far from the truth. In general, there is
		748	no way to configure JSON::XS to output a data structure as valid YAML.
		749
		750	If you really must use JSON::XS to generate YAML, you should use this
		751	algorithm (subject to change in future versions):
		752
		753	my $to_yaml = JSON::XS->new->utf8->space_after (1);
		754	my $yaml = $to_yaml->encode ($ref) . "\n";
		755
		756	This will usually generate JSON texts that also parse as valid
		757	YAML. Please note that YAML has hardcoded limits on (simple) object key
		758	lengths that JSON doesn't have, so you should make sure that your hash
		759	keys are noticably shorter than the 1024 characters YAML allows.
		760
		761	There might be other incompatibilities that I am not aware of. In general
		762	you should not try to generate YAML with a JSON generator or vice versa,
		763	or try to parse JSON with a YAML parser or vice versa: chances are high
		764	that you will run into severe interoperability problems.
		765
		766
596	=head2 SPEED	767	=head2 SPEED
597		768
598	It seems that JSON::XS is surprisingly fast, as shown in the following	769	It seems that JSON::XS is surprisingly fast, as shown in the following
599	tables. They have been generated with the help of the C<eg/bench> program	770	tables. They have been generated with the help of the C<eg/bench> program
600	in the JSON::XS distribution, to make it easy to compare on your own	771	in the JSON::XS distribution, to make it easy to compare on your own
601	system.	772	system.
602		773
603	First comes a comparison between various modules using a very short JSON	774	First comes a comparison between various modules using a very short
604	string:	775	single-line JSON string:
605		776
606	{"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null}	777	{"method": "handleMessage", "params": ["user1", "we were just talking"], \
		778	"id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
607		779
608	It shows the number of encodes/decodes per second (JSON::XS uses the	780	It shows the number of encodes/decodes per second (JSON::XS uses
609	functional interface, while JSON::XS/2 uses the OO interface with	781	the functional interface, while JSON::XS/2 uses the OO interface
610	pretty-printing and hashkey sorting enabled). Higher is better:	782	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
		783	shrink). Higher is better:
611		784
		785	Storable \| 15779.925 \| 14169.946 \|
		786	-----------+------------+------------+
612	module \| encode \| decode \|	787	module \| encode \| decode \|
613	-----------\|------------\|------------\|	788	-----------\|------------\|------------\|
614	JSON \| 11488.516 \| 7823.035 \|	789	JSON \| 4990.842 \| 4088.813 \|
615	JSON::DWIW \| 94708.054 \| 129094.260 \|	790	JSON::DWIW \| 51653.990 \| 71575.154 \|
616	JSON::PC \| 63884.157 \| 128528.212 \|	791	JSON::PC \| 65948.176 \| 74631.744 \|
617	JSON::Syck \| 34898.677 \| 42096.911 \|	792	JSON::PP \| 8931.652 \| 3817.168 \|
618	JSON::XS \| 654027.064 \| 396423.669 \|	793	JSON::Syck \| 24877.248 \| 27776.848 \|
619	JSON::XS/2 \| 371564.190 \| 371725.613 \|	794	JSON::XS \| 388361.481 \| 227951.304 \|
		795	JSON::XS/2 \| 227951.304 \| 218453.333 \|
		796	JSON::XS/3 \| 338250.323 \| 218453.333 \|
		797	Storable \| 16500.016 \| 135300.129 \|
620	-----------+------------+------------+	798	-----------+------------+------------+
621		799
622	That is, JSON::XS is more than six times faster than JSON::DWIW on	800	That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
623	encoding, more than three times faster on decoding, and about thirty times	801	about three times faster on decoding, and over fourty times faster
624	faster than JSON, even with pretty-printing and key sorting.	802	than JSON, even with pretty-printing and key sorting. It also compares
		803	favourably to Storable for small amounts of data.
625		804
626	Using a longer test string (roughly 18KB, generated from Yahoo! Locals	805	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
627	search API (http://nanoref.com/yahooapis/mgPdGg):	806	search API (http://nanoref.com/yahooapis/mgPdGg):
628		807
629	module \| encode \| decode \|	808	module \| encode \| decode \|
630	-----------\|------------\|------------\|	809	-----------\|------------\|------------\|
631	JSON \| 273.023 \| 44.674 \|	810	JSON \| 55.260 \| 34.971 \|
632	JSON::DWIW \| 1089.383 \| 1145.704 \|	811	JSON::DWIW \| 825.228 \| 1082.513 \|
633	JSON::PC \| 3097.419 \| 2393.921 \|	812	JSON::PC \| 3571.444 \| 2394.829 \|
634	JSON::Syck \| 514.060 \| 843.053 \|	813	JSON::PP \| 210.987 \| 32.574 \|
635	JSON::XS \| 6479.668 \| 3636.364 \|	814	JSON::Syck \| 552.551 \| 787.544 \|
636	JSON::XS/2 \| 3774.221 \| 3599.124 \|	815	JSON::XS \| 5780.463 \| 4854.519 \|
		816	JSON::XS/2 \| 3869.998 \| 4798.975 \|
		817	JSON::XS/3 \| 5862.880 \| 4798.975 \|
		818	Storable \| 4445.002 \| 5235.027 \|
637	-----------+------------+------------+	819	-----------+------------+------------+
638		820
639	Again, JSON::XS leads by far.	821	Again, JSON::XS leads by far (except for Storable which non-surprisingly
		822	decodes faster).
640		823
641	On large strings containing lots of high unicode characters, some modules	824	On large strings containing lots of high unicode characters, some modules
642	(such as JSON::PC) seem to decode faster than JSON::XS, but the result	825	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
643	will be broken due to missing (or wrong) unicode handling. Others refuse	826	will be broken due to missing (or wrong) unicode handling. Others refuse
644	to decode or encode properly, so it was impossible to prepare a fair	827	to decode or encode properly, so it was impossible to prepare a fair
…		…
657	Second, you need to avoid resource-starving attacks. That means you should	840	Second, you need to avoid resource-starving attacks. That means you should
658	limit the size of JSON texts you accept, or make sure then when your	841	limit the size of JSON texts you accept, or make sure then when your
659	resources run out, thats just fine (e.g. by using a separate process that	842	resources run out, thats just fine (e.g. by using a separate process that
660	can crash safely). The size of a JSON text in octets or characters is	843	can crash safely). The size of a JSON text in octets or characters is
661	usually a good indication of the size of the resources required to decode	844	usually a good indication of the size of the resources required to decode
662	it into a Perl structure.	845	it into a Perl structure. While JSON::XS can check the size of the JSON
		846	text, it might be too late when you already have it in memory, so you
		847	might want to check the size before you accept the string.
663		848
664	Third, JSON::XS recurses using the C stack when decoding objects and	849	Third, JSON::XS recurses using the C stack when decoding objects and
665	arrays. The C stack is a limited resource: for instance, on my amd64	850	arrays. The C stack is a limited resource: for instance, on my amd64
666	machine with 8MB of stack size I can decode around 180k nested arrays but	851	machine with 8MB of stack size I can decode around 180k nested arrays but
667	only 14k nested JSON objects (due to perl itself recursing deeply on croak	852	only 14k nested JSON objects (due to perl itself recursing deeply on croak
…		…
672		857
673	And last but least, something else could bomb you that I forgot to think	858	And last but least, something else could bomb you that I forgot to think
674	of. In that case, you get to keep the pieces. I am always open for hints,	859	of. In that case, you get to keep the pieces. I am always open for hints,
675	though...	860	though...
676		861
		862	If you are using JSON::XS to return packets to consumption
		863	by javascript scripts in a browser you should have a look at
		864	L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether
		865	you are vulnerable to some common attack vectors (which really are browser
		866	design bugs, but it is still you who will have to deal with it, as major
		867	browser developers care only for features, not about doing security
		868	right).
		869
677		870
678	=head1 BUGS	871	=head1 BUGS
679		872
680	While the goal of this module is to be correct, that unfortunately does	873	While the goal of this module is to be correct, that unfortunately does
681	not mean its bug-free, only that I think its design is bug-free. It is	874	not mean its bug-free, only that I think its design is bug-free. It is
682	still relatively early in its development. If you keep reporting bugs they	875	still relatively early in its development. If you keep reporting bugs they
683	will be fixed swiftly, though.	876	will be fixed swiftly, though.
684		877
685	=cut	878	=cut
686		879
		880	our $true = do { bless \(my $dummy = "1"), "JSON::XS::Boolean" };
		881	our $false = do { bless \(my $dummy = "0"), "JSON::XS::Boolean" };
		882
687	sub true() { \1 }	883	sub true() { $true }
688	sub false() { \0 }	884	sub false() { $false }
		885
		886	sub is_bool($) {
		887	UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
		888	# or UNIVERSAL::isa $_[0], "JSON::Literal"
		889	}
		890
		891	XSLoader::load "JSON::XS", $VERSION;
		892
		893	package JSON::XS::Boolean;
		894
		895	use overload
		896	"0+" => sub { ${$_[0]} },
		897	"++" => sub { $_[0] = ${$_[0]} + 1 },
		898	"--" => sub { $_[0] = ${$_[0]} - 1 },
		899	fallback => 1;
689		900
690	1;	901	1;
691		902
692	=head1 AUTHOR	903	=head1 AUTHOR
693		904

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Comparing JSON-XS/XS.pm (file contents): Revision 1.33 by root, Wed May 9 16:10:37 2007 UTC vs. Revision 1.51 by root, Mon Jul 2 01:12:27 2007 UTC

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Comparing JSON-XS/XS.pm (file contents):
Revision 1.33 by root, Wed May 9 16:10:37 2007 UTC vs.
Revision 1.51 by root, Mon Jul 2 01:12:27 2007 UTC