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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.35 by root, Wed May 9 16:41:12 2007 UTC vs.
Revision 1.56 by root, Thu Jul 26 11:33:35 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 = '1.21';	86	our $VERSION = '1.43';
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->($hashref)])
		354
		355	When C<$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, any existing callback will
		365	be removed and C<decode> will not change the deserialised hash in any
		366	way.
		367
		368	Example, convert all JSON objects into the integer 5:
		369
		370	my $js = JSON::XS->new->filter_json_object (sub { 5 });
		371	# returns [5]
		372	$js->decode ('[{}]')
		373	# throw an exception because allow_nonref is not enabled
		374	# so a lone 5 is not allowed.
		375	$js->decode ('{"a":1, "b":2}');
		376
		377	=item $json = $json->filter_json_single_key_object ($key [=> $coderef->($value)])
		378
		379	Works remotely similar to C<filter_json_object>, but is only called for
		380	JSON objects having a single key named C<$key>.
		381
		382	This C<$coderef> is called before the one specified via
		383	C<filter_json_object>, if any. It gets passed the single value in the JSON
		384	object. If it returns a single value, it will be inserted into the data
		385	structure. If it returns nothing (not even C<undef> but the empty list),
		386	the callback from C<filter_json_object> will be called next, as if no
		387	single-key callback were specified.
		388
		389	If C<$coderef> is omitted or undefined, the corresponding callback will be
		390	disabled. There can only ever be one callback for a given key.
		391
		392	As this callback gets called less often then the C<filter_json_object>
		393	one, decoding speed will not usually suffer as much. Therefore, single-key
		394	objects make excellent targets to serialise Perl objects into, especially
		395	as single-key JSON objects are as close to the type-tagged value concept
		396	as JSON gets (its basically an ID/VALUE tuple). Of course, JSON does not
		397	support this in any way, so you need to make sure your data never looks
		398	like a serialised Perl hash.
		399
		400	Typical names for the single object key are C<__class_whatever__>, or
		401	C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even
		402	things like C<__class_md5sum(classname)__>, to reduce the risk of clashing
		403	with real hashes.
		404
		405	Example, decode JSON objects of the form C<< { "__widget__" => <id> } >>
		406	into the corresponding C<< $WIDGET{<id>} >> object:
		407
		408	# return whatever is in $WIDGET{5}:
		409	JSON::XS
		410	->new
		411	->filter_json_single_key_object (__widget__ => sub {
		412	$WIDGET{ $_[0] }
		413	})
		414	->decode ('{"__widget__": 5')
		415
		416	# this can be used with a TO_JSON method in some "widget" class
		417	# for serialisation to json:
		418	sub WidgetBase::TO_JSON {
		419	my ($self) = @_;
		420
		421	unless ($self->{id}) {
		422	$self->{id} = ..get..some..id..;
		423	$WIDGET{$self->{id}} = $self;
		424	}
		425
		426	{ __widget__ => $self->{id} }
		427	}
314		428
315	=item $json = $json->shrink ([$enable])	429	=item $json = $json->shrink ([$enable])
316		430
317	Perl usually over-allocates memory a bit when allocating space for	431	Perl usually over-allocates memory a bit when allocating space for
318	strings. This flag optionally resizes strings generated by either	432	strings. This flag optionally resizes strings generated by either
…		…
351	given character in a string.	465	given character in a string.
352		466
353	Setting the maximum depth to one disallows any nesting, so that ensures	467	Setting the maximum depth to one disallows any nesting, so that ensures
354	that the object is only a single hash/object or array.	468	that the object is only a single hash/object or array.
355		469
356	The argument to C<max_depth> will be rounded up to the next nearest power	470	The argument to C<max_depth> will be rounded up to the next highest power
357	of two.	471	of two. If no argument is given, the highest possible setting will be
		472	used, which is rarely useful.
		473
		474	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
		475
		476	=item $json = $json->max_size ([$maximum_string_size])
		477
		478	Set the maximum length a JSON text may have (in bytes) where decoding is
		479	being attempted. The default is C<0>, meaning no limit. When C<decode>
		480	is called on a string longer then this number of characters it will not
		481	attempt to decode the string but throw an exception. This setting has no
		482	effect on C<encode> (yet).
		483
		484	The argument to C<max_size> will be rounded up to the next B<highest>
		485	power of two (so may be more than requested). If no argument is given, the
		486	limit check will be deactivated (same as when C<0> is specified).
358		487
359	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	488	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
360		489
361	=item $json_text = $json->encode ($perl_scalar)	490	=item $json_text = $json->encode ($perl_scalar)
362		491
…		…
402		531
403	For the more enlightened: note that in the following descriptions,	532	For the more enlightened: note that in the following descriptions,
404	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>	533	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
405	refers to the abstract Perl language itself.	534	refers to the abstract Perl language itself.
406		535
		536
407	=head2 JSON -> PERL	537	=head2 JSON -> PERL
408		538
409	=over 4	539	=over 4
410		540
411	=item object	541	=item object
…		…
423	are represented by the same codepoints in the Perl string, so no manual	553	are represented by the same codepoints in the Perl string, so no manual
424	decoding is necessary.	554	decoding is necessary.
425		555
426	=item number	556	=item number
427		557
428	A JSON number becomes either an integer or numeric (floating point)	558	A JSON number becomes either an integer, numeric (floating point) or
429	scalar in perl, depending on its range and any fractional parts. On the	559	string scalar in perl, depending on its range and any fractional parts. On
430	Perl level, there is no difference between those as Perl handles all the	560	the Perl level, there is no difference between those as Perl handles all
431	conversion details, but an integer may take slightly less memory and might	561	the conversion details, but an integer may take slightly less memory and
432	represent more values exactly than (floating point) numbers.	562	might represent more values exactly than (floating point) numbers.
		563
		564	If the number consists of digits only, JSON::XS will try to represent
		565	it as an integer value. If that fails, it will try to represent it as
		566	a numeric (floating point) value if that is possible without loss of
		567	precision. Otherwise it will preserve the number as a string value.
		568
		569	Numbers containing a fractional or exponential part will always be
		570	represented as numeric (floating point) values, possibly at a loss of
		571	precision.
		572
		573	This might create round-tripping problems as numbers might become strings,
		574	but as Perl is typeless there is no other way to do it.
433		575
434	=item true, false	576	=item true, false
435		577
436	These JSON atoms become C<0>, C<1>, respectively. Information is lost in	578	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
437	this process. Future versions might represent those values differently,	579	respectively. They are overloaded to act almost exactly like the numbers
438	but they will be guarenteed to act like these integers would normally in	580	C<1> and C<0>. You can check wether a scalar is a JSON boolean by using
439	Perl.	581	the C<JSON::XS::is_bool> function.
440		582
441	=item null	583	=item null
442		584
443	A JSON null atom becomes C<undef> in Perl.	585	A JSON null atom becomes C<undef> in Perl.
444		586
445	=back	587	=back
		588
446		589
447	=head2 PERL -> JSON	590	=head2 PERL -> JSON
448		591
449	The mapping from Perl to JSON is slightly more difficult, as Perl is a	592	The mapping from Perl to JSON is slightly more difficult, as Perl is a
450	truly typeless language, so we can only guess which JSON type is meant by	593	truly typeless language, so we can only guess which JSON type is meant by
…		…
475	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can	618	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
476	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.	619	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
477		620
478	to_json [\0,JSON::XS::true] # yields [false,true]	621	to_json [\0,JSON::XS::true] # yields [false,true]
479		622
		623	=item JSON::XS::true, JSON::XS::false
		624
		625	These special values become JSON true and JSON false values,
		626	respectively. You cna alos use C<\1> and C<\0> directly if you want.
		627
480	=item blessed objects	628	=item blessed objects
481		629
482	Blessed objects are not allowed. JSON::XS currently tries to encode their	630	Blessed objects are not allowed. JSON::XS currently tries to encode their
483	underlying representation (hash- or arrayref), but this behaviour might	631	underlying representation (hash- or arrayref), but this behaviour might
484	change in future versions.	632	change in future versions.
…		…
605		753
606	Does not check input for validity.	754	Does not check input for validity.
607		755
608	=back	756	=back
609		757
		758
		759	=head2 JSON and YAML
		760
		761	You often hear that JSON is a subset (or a close subset) of YAML. This is,
		762	however, a mass hysteria and very far from the truth. In general, there is
		763	no way to configure JSON::XS to output a data structure as valid YAML.
		764
		765	If you really must use JSON::XS to generate YAML, you should use this
		766	algorithm (subject to change in future versions):
		767
		768	my $to_yaml = JSON::XS->new->utf8->space_after (1);
		769	my $yaml = $to_yaml->encode ($ref) . "\n";
		770
		771	This will usually generate JSON texts that also parse as valid
		772	YAML. Please note that YAML has hardcoded limits on (simple) object key
		773	lengths that JSON doesn't have, so you should make sure that your hash
		774	keys are noticably shorter than the 1024 characters YAML allows.
		775
		776	There might be other incompatibilities that I am not aware of. In general
		777	you should not try to generate YAML with a JSON generator or vice versa,
		778	or try to parse JSON with a YAML parser or vice versa: chances are high
		779	that you will run into severe interoperability problems.
		780
		781
610	=head2 SPEED	782	=head2 SPEED
611		783
612	It seems that JSON::XS is surprisingly fast, as shown in the following	784	It seems that JSON::XS is surprisingly fast, as shown in the following
613	tables. They have been generated with the help of the C<eg/bench> program	785	tables. They have been generated with the help of the C<eg/bench> program
614	in the JSON::XS distribution, to make it easy to compare on your own	786	in the JSON::XS distribution, to make it easy to compare on your own
615	system.	787	system.
616		788
617	First comes a comparison between various modules using a very short JSON	789	First comes a comparison between various modules using a very short
618	string:	790	single-line JSON string:
619		791
620	{"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null}	792	{"method": "handleMessage", "params": ["user1", "we were just talking"], \
		793	"id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
621		794
622	It shows the number of encodes/decodes per second (JSON::XS uses the	795	It shows the number of encodes/decodes per second (JSON::XS uses
623	functional interface, while JSON::XS/2 uses the OO interface with	796	the functional interface, while JSON::XS/2 uses the OO interface
624	pretty-printing and hashkey sorting enabled). Higher is better:	797	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
		798	shrink). Higher is better:
625		799
		800	Storable \| 15779.925 \| 14169.946 \|
		801	-----------+------------+------------+
626	module \| encode \| decode \|	802	module \| encode \| decode \|
627	-----------\|------------\|------------\|	803	-----------\|------------\|------------\|
628	JSON \| 11488.516 \| 7823.035 \|	804	JSON \| 4990.842 \| 4088.813 \|
629	JSON::DWIW \| 94708.054 \| 129094.260 \|	805	JSON::DWIW \| 51653.990 \| 71575.154 \|
630	JSON::PC \| 63884.157 \| 128528.212 \|	806	JSON::PC \| 65948.176 \| 74631.744 \|
631	JSON::Syck \| 34898.677 \| 42096.911 \|	807	JSON::PP \| 8931.652 \| 3817.168 \|
632	JSON::XS \| 654027.064 \| 396423.669 \|	808	JSON::Syck \| 24877.248 \| 27776.848 \|
633	JSON::XS/2 \| 371564.190 \| 371725.613 \|	809	JSON::XS \| 388361.481 \| 227951.304 \|
		810	JSON::XS/2 \| 227951.304 \| 218453.333 \|
		811	JSON::XS/3 \| 338250.323 \| 218453.333 \|
		812	Storable \| 16500.016 \| 135300.129 \|
634	-----------+------------+------------+	813	-----------+------------+------------+
635		814
636	That is, JSON::XS is more than six times faster than JSON::DWIW on	815	That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
637	encoding, more than three times faster on decoding, and about thirty times	816	about three times faster on decoding, and over fourty times faster
638	faster than JSON, even with pretty-printing and key sorting.	817	than JSON, even with pretty-printing and key sorting. It also compares
		818	favourably to Storable for small amounts of data.
639		819
640	Using a longer test string (roughly 18KB, generated from Yahoo! Locals	820	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
641	search API (http://nanoref.com/yahooapis/mgPdGg):	821	search API (http://nanoref.com/yahooapis/mgPdGg):
642		822
643	module \| encode \| decode \|	823	module \| encode \| decode \|
644	-----------\|------------\|------------\|	824	-----------\|------------\|------------\|
645	JSON \| 273.023 \| 44.674 \|	825	JSON \| 55.260 \| 34.971 \|
646	JSON::DWIW \| 1089.383 \| 1145.704 \|	826	JSON::DWIW \| 825.228 \| 1082.513 \|
647	JSON::PC \| 3097.419 \| 2393.921 \|	827	JSON::PC \| 3571.444 \| 2394.829 \|
648	JSON::Syck \| 514.060 \| 843.053 \|	828	JSON::PP \| 210.987 \| 32.574 \|
649	JSON::XS \| 6479.668 \| 3636.364 \|	829	JSON::Syck \| 552.551 \| 787.544 \|
650	JSON::XS/2 \| 3774.221 \| 3599.124 \|	830	JSON::XS \| 5780.463 \| 4854.519 \|
		831	JSON::XS/2 \| 3869.998 \| 4798.975 \|
		832	JSON::XS/3 \| 5862.880 \| 4798.975 \|
		833	Storable \| 4445.002 \| 5235.027 \|
651	-----------+------------+------------+	834	-----------+------------+------------+
652		835
653	Again, JSON::XS leads by far.	836	Again, JSON::XS leads by far (except for Storable which non-surprisingly
		837	decodes faster).
654		838
655	On large strings containing lots of high unicode characters, some modules	839	On large strings containing lots of high unicode characters, some modules
656	(such as JSON::PC) seem to decode faster than JSON::XS, but the result	840	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
657	will be broken due to missing (or wrong) unicode handling. Others refuse	841	will be broken due to missing (or wrong) unicode handling. Others refuse
658	to decode or encode properly, so it was impossible to prepare a fair	842	to decode or encode properly, so it was impossible to prepare a fair
…		…
671	Second, you need to avoid resource-starving attacks. That means you should	855	Second, you need to avoid resource-starving attacks. That means you should
672	limit the size of JSON texts you accept, or make sure then when your	856	limit the size of JSON texts you accept, or make sure then when your
673	resources run out, thats just fine (e.g. by using a separate process that	857	resources run out, thats just fine (e.g. by using a separate process that
674	can crash safely). The size of a JSON text in octets or characters is	858	can crash safely). The size of a JSON text in octets or characters is
675	usually a good indication of the size of the resources required to decode	859	usually a good indication of the size of the resources required to decode
676	it into a Perl structure.	860	it into a Perl structure. While JSON::XS can check the size of the JSON
		861	text, it might be too late when you already have it in memory, so you
		862	might want to check the size before you accept the string.
677		863
678	Third, JSON::XS recurses using the C stack when decoding objects and	864	Third, JSON::XS recurses using the C stack when decoding objects and
679	arrays. The C stack is a limited resource: for instance, on my amd64	865	arrays. The C stack is a limited resource: for instance, on my amd64
680	machine with 8MB of stack size I can decode around 180k nested arrays but	866	machine with 8MB of stack size I can decode around 180k nested arrays but
681	only 14k nested JSON objects (due to perl itself recursing deeply on croak	867	only 14k nested JSON objects (due to perl itself recursing deeply on croak
…		…
686		872
687	And last but least, something else could bomb you that I forgot to think	873	And last but least, something else could bomb you that I forgot to think
688	of. In that case, you get to keep the pieces. I am always open for hints,	874	of. In that case, you get to keep the pieces. I am always open for hints,
689	though...	875	though...
690		876
		877	If you are using JSON::XS to return packets to consumption
		878	by javascript scripts in a browser you should have a look at
		879	L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether
		880	you are vulnerable to some common attack vectors (which really are browser
		881	design bugs, but it is still you who will have to deal with it, as major
		882	browser developers care only for features, not about doing security
		883	right).
		884
691		885
692	=head1 BUGS	886	=head1 BUGS
693		887
694	While the goal of this module is to be correct, that unfortunately does	888	While the goal of this module is to be correct, that unfortunately does
695	not mean its bug-free, only that I think its design is bug-free. It is	889	not mean its bug-free, only that I think its design is bug-free. It is
696	still relatively early in its development. If you keep reporting bugs they	890	still relatively early in its development. If you keep reporting bugs they
697	will be fixed swiftly, though.	891	will be fixed swiftly, though.
698		892
699	=cut	893	=cut
700		894
		895	our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
		896	our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };
		897
701	sub true() { \1 }	898	sub true() { $true }
702	sub false() { \0 }	899	sub false() { $false }
		900
		901	sub is_bool($) {
		902	UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
		903	# or UNIVERSAL::isa $_[0], "JSON::Literal"
		904	}
		905
		906	XSLoader::load "JSON::XS", $VERSION;
		907
		908	package JSON::XS::Boolean;
		909
		910	use overload
		911	"0+" => sub { ${$_[0]} },
		912	"++" => sub { $_[0] = ${$_[0]} + 1 },
		913	"--" => sub { $_[0] = ${$_[0]} - 1 },
		914	fallback => 1;
703		915
704	1;	916	1;
705		917
706	=head1 AUTHOR	918	=head1 AUTHOR
707		919

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Comparing JSON-XS/XS.pm (file contents): Revision 1.35 by root, Wed May 9 16:41:12 2007 UTC vs. Revision 1.56 by root, Thu Jul 26 11:33:35 2007 UTC

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Comparing JSON-XS/XS.pm (file contents):
Revision 1.35 by root, Wed May 9 16:41:12 2007 UTC vs.
Revision 1.56 by root, Thu Jul 26 11:33:35 2007 UTC