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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.22 by root, Sun Mar 25 02:37:00 2007 UTC vs.
Revision 1.50 by root, Mon Jul 2 00:29:38 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 = '0.8';	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:
…		…
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.
131		124
		125	=item $is_boolean = JSON::XS::is_bool $scalar
		126
		127	Returns true if the passed scalar represents either JSON::XS::true or
		128	JSON::XS::false, two constants that act like C<1> and C<0>, respectively
		129	and are used to represent JSON C<true> and C<false> values in Perl.
		130
		131	See MAPPING, below, for more information on how JSON values are mapped to
		132	Perl.
		133
132	=back	134	=back
		135
133		136
134	=head1 OBJECT-ORIENTED INTERFACE	137	=head1 OBJECT-ORIENTED INTERFACE
135		138
136	The object oriented interface lets you configure your own encoding or	139	The object oriented interface lets you configure your own encoding or
137	decoding style, within the limits of supported formats.	140	decoding style, within the limits of supported formats.
…		…
153		156
154	If C<$enable> is true (or missing), then the C<encode> method will not	157	If C<$enable> is true (or missing), then the C<encode> method will not
155	generate characters outside the code range C<0..127> (which is ASCII). Any	158	generate characters outside the code range C<0..127> (which is ASCII). Any
156	unicode characters outside that range will be escaped using either a	159	unicode characters outside that range will be escaped using either a
157	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,	160	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
158	as per RFC4627.	161	as per RFC4627. The resulting encoded JSON text can be treated as a native
		162	unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
		163	or any other superset of ASCII.
159		164
160	If C<$enable> is false, then the C<encode> method will not escape Unicode	165	If C<$enable> is false, then the C<encode> method will not escape Unicode
161	characters unless required by the JSON syntax. This results in a faster	166	characters unless required by the JSON syntax or other flags. This results
162	and more compact format.	167	in a faster and more compact format.
		168
		169	The main use for this flag is to produce JSON texts that can be
		170	transmitted over a 7-bit channel, as the encoded JSON texts will not
		171	contain any 8 bit characters.
163		172
164	JSON::XS->new->ascii (1)->encode ([chr 0x10401])	173	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
165	=> ["\ud801\udc01"]	174	=> ["\ud801\udc01"]
		175
		176	=item $json = $json->latin1 ([$enable])
		177
		178	If C<$enable> is true (or missing), then the C<encode> method will encode
		179	the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
		180	outside the code range C<0..255>. The resulting string can be treated as a
		181	latin1-encoded JSON text or a native unicode string. The C<decode> method
		182	will not be affected in any way by this flag, as C<decode> by default
		183	expects unicode, which is a strict superset of latin1.
		184
		185	If C<$enable> is false, then the C<encode> method will not escape Unicode
		186	characters unless required by the JSON syntax or other flags.
		187
		188	The main use for this flag is efficiently encoding binary data as JSON
		189	text, as most octets will not be escaped, resulting in a smaller encoded
		190	size. The disadvantage is that the resulting JSON text is encoded
		191	in latin1 (and must correctly be treated as such when storing and
		192	transfering), a rare encoding for JSON. It is therefore most useful when
		193	you want to store data structures known to contain binary data efficiently
		194	in files or databases, not when talking to other JSON encoders/decoders.
		195
		196	JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
		197	=> ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
166		198
167	=item $json = $json->utf8 ([$enable])	199	=item $json = $json->utf8 ([$enable])
168		200
169	If C<$enable> is true (or missing), then the C<encode> method will encode	201	If C<$enable> is true (or missing), then the C<encode> method will encode
170	the JSON result into UTF-8, as required by many protocols, while the	202	the JSON result into UTF-8, as required by many protocols, while the
…		…
280	resulting in an invalid JSON text:	312	resulting in an invalid JSON text:
281		313
282	JSON::XS->new->allow_nonref->encode ("Hello, World!")	314	JSON::XS->new->allow_nonref->encode ("Hello, World!")
283	=> "Hello, World!"	315	=> "Hello, World!"
284		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
285	=item $json = $json->shrink ([$enable])	353	=item $json = $json->shrink ([$enable])
286		354
287	Perl usually over-allocates memory a bit when allocating space for	355	Perl usually over-allocates memory a bit when allocating space for
288	strings. This flag optionally resizes strings generated by either	356	strings. This flag optionally resizes strings generated by either
289	C<encode> or C<decode> to their minimum size possible. This can save	357	C<encode> or C<decode> to their minimum size possible. This can save
290	memory when your JSON texts are either very very long or you have many	358	memory when your JSON texts are either very very long or you have many
291	short strings. It will also try to downgrade any strings to octet-form	359	short strings. It will also try to downgrade any strings to octet-form
292	if possible: perl stores strings internally either in an encoding called	360	if possible: perl stores strings internally either in an encoding called
293	UTF-X or in octet-form. The latter cannot store everything but uses less	361	UTF-X or in octet-form. The latter cannot store everything but uses less
294	space in general.	362	space in general (and some buggy Perl or C code might even rely on that
		363	internal representation being used).
295		364
		365	The actual definition of what shrink does might change in future versions,
		366	but it will always try to save space at the expense of time.
		367
296	If C<$enable> is true (or missing), the string returned by C<encode> will be shrunk-to-fit,	368	If C<$enable> is true (or missing), the string returned by C<encode> will
297	while all strings generated by C<decode> will also be shrunk-to-fit.	369	be shrunk-to-fit, while all strings generated by C<decode> will also be
		370	shrunk-to-fit.
298		371
299	If C<$enable> is false, then the normal perl allocation algorithms are used.	372	If C<$enable> is false, then the normal perl allocation algorithms are used.
300	If you work with your data, then this is likely to be faster.	373	If you work with your data, then this is likely to be faster.
301		374
302	In the future, this setting might control other things, such as converting	375	In the future, this setting might control other things, such as converting
303	strings that look like integers or floats into integers or floats	376	strings that look like integers or floats into integers or floats
304	internally (there is no difference on the Perl level), saving space.	377	internally (there is no difference on the Perl level), saving space.
		378
		379	=item $json = $json->max_depth ([$maximum_nesting_depth])
		380
		381	Sets the maximum nesting level (default C<512>) accepted while encoding
		382	or decoding. If the JSON text or Perl data structure has an equal or
		383	higher nesting level then this limit, then the encoder and decoder will
		384	stop and croak at that point.
		385
		386	Nesting level is defined by number of hash- or arrayrefs that the encoder
		387	needs to traverse to reach a given point or the number of C<{> or C<[>
		388	characters without their matching closing parenthesis crossed to reach a
		389	given character in a string.
		390
		391	Setting the maximum depth to one disallows any nesting, so that ensures
		392	that the object is only a single hash/object or array.
		393
		394	The argument to C<max_depth> will be rounded up to the next highest power
		395	of two. If no argument is given, the highest possible setting will be
		396	used, which is rarely useful.
		397
		398	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
		399
		400	=item $json = $json->max_size ([$maximum_string_size])
		401
		402	Set the maximum length a JSON text may have (in bytes) where decoding is
		403	being attempted. The default is C<0>, meaning no limit. When C<decode>
		404	is called on a string longer then this number of characters it will not
		405	attempt to decode the string but throw an exception. This setting has no
		406	effect on C<encode> (yet).
		407
		408	The argument to C<max_size> will be rounded up to the next B<highest>
		409	power of two (so may be more than requested). If no argument is given, the
		410	limit check will be deactivated (same as when C<0> is specified).
		411
		412	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
305		413
306	=item $json_text = $json->encode ($perl_scalar)	414	=item $json_text = $json->encode ($perl_scalar)
307		415
308	Converts the given Perl data structure (a simple scalar or a reference	416	Converts the given Perl data structure (a simple scalar or a reference
309	to a hash or array) to its JSON representation. Simple scalars will be	417	to a hash or array) to its JSON representation. Simple scalars will be
…		…
319		427
320	JSON numbers and strings become simple Perl scalars. JSON arrays become	428	JSON numbers and strings become simple Perl scalars. JSON arrays become
321	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes	429	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
322	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.	430	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
323		431
		432	=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
		433
		434	This works like the C<decode> method, but instead of raising an exception
		435	when there is trailing garbage after the first JSON object, it will
		436	silently stop parsing there and return the number of characters consumed
		437	so far.
		438
		439	This is useful if your JSON texts are not delimited by an outer protocol
		440	(which is not the brightest thing to do in the first place) and you need
		441	to know where the JSON text ends.
		442
		443	JSON::XS->new->decode_prefix ("[1] the tail")
		444	=> ([], 3)
		445
324	=back	446	=back
		447
325		448
326	=head1 MAPPING	449	=head1 MAPPING
327		450
328	This section describes how JSON::XS maps Perl values to JSON values and	451	This section describes how JSON::XS maps Perl values to JSON values and
329	vice versa. These mappings are designed to "do the right thing" in most	452	vice versa. These mappings are designed to "do the right thing" in most
…		…
331	(what you put in comes out as something equivalent).	454	(what you put in comes out as something equivalent).
332		455
333	For the more enlightened: note that in the following descriptions,	456	For the more enlightened: note that in the following descriptions,
334	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>	457	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
335	refers to the abstract Perl language itself.	458	refers to the abstract Perl language itself.
		459
336		460
337	=head2 JSON -> PERL	461	=head2 JSON -> PERL
338		462
339	=over 4	463	=over 4
340		464
…		…
361	conversion details, but an integer may take slightly less memory and might	485	conversion details, but an integer may take slightly less memory and might
362	represent more values exactly than (floating point) numbers.	486	represent more values exactly than (floating point) numbers.
363		487
364	=item true, false	488	=item true, false
365		489
366	These JSON atoms become C<0>, C<1>, respectively. Information is lost in	490	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
367	this process. Future versions might represent those values differently,	491	respectively. They are overloaded to act almost exactly like the numbers
368	but they will be guarenteed to act like these integers would normally in	492	C<1> and C<0>. You can check wether a scalar is a JSON boolean by using
369	Perl.	493	the C<JSON::XS::is_bool> function.
370		494
371	=item null	495	=item null
372		496
373	A JSON null atom becomes C<undef> in Perl.	497	A JSON null atom becomes C<undef> in Perl.
374		498
375	=back	499	=back
		500
376		501
377	=head2 PERL -> JSON	502	=head2 PERL -> JSON
378		503
379	The mapping from Perl to JSON is slightly more difficult, as Perl is a	504	The mapping from Perl to JSON is slightly more difficult, as Perl is a
380	truly typeless language, so we can only guess which JSON type is meant by	505	truly typeless language, so we can only guess which JSON type is meant by
…		…
383	=over 4	508	=over 4
384		509
385	=item hash references	510	=item hash references
386		511
387	Perl hash references become JSON objects. As there is no inherent ordering	512	Perl hash references become JSON objects. As there is no inherent ordering
388	in hash keys, they will usually be encoded in a pseudo-random order that	513	in hash keys (or JSON objects), they will usually be encoded in a
389	can change between runs of the same program but stays generally the same	514	pseudo-random order that can change between runs of the same program but
390	within a single run of a program. JSON::XS can optionally sort the hash	515	stays generally the same within a single run of a program. JSON::XS can
391	keys (determined by the I<canonical> flag), so the same datastructure	516	optionally sort the hash keys (determined by the I<canonical> flag), so
392	will serialise to the same JSON text (given same settings and version of	517	the same datastructure will serialise to the same JSON text (given same
393	JSON::XS), but this incurs a runtime overhead.	518	settings and version of JSON::XS), but this incurs a runtime overhead
		519	and is only rarely useful, e.g. when you want to compare some JSON text
		520	against another for equality.
394		521
395	=item array references	522	=item array references
396		523
397	Perl array references become JSON arrays.	524	Perl array references become JSON arrays.
		525
		526	=item other references
		527
		528	Other unblessed references are generally not allowed and will cause an
		529	exception to be thrown, except for references to the integers C<0> and
		530	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
		531	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
		532
		533	to_json [\0,JSON::XS::true] # yields [false,true]
		534
		535	=item JSON::XS::true, JSON::XS::false
		536
		537	These special values become JSON true and JSON false values,
		538	respectively. You cna alos use C<\1> and C<\0> directly if you want.
398		539
399	=item blessed objects	540	=item blessed objects
400		541
401	Blessed objects are not allowed. JSON::XS currently tries to encode their	542	Blessed objects are not allowed. JSON::XS currently tries to encode their
402	underlying representation (hash- or arrayref), but this behaviour might	543	underlying representation (hash- or arrayref), but this behaviour might
…		…
435	$x *= 1; # same thing, the choise is yours.	576	$x *= 1; # same thing, the choise is yours.
436		577
437	You can not currently output JSON booleans or force the type in other,	578	You can not currently output JSON booleans or force the type in other,
438	less obscure, ways. Tell me if you need this capability.	579	less obscure, ways. Tell me if you need this capability.
439		580
440	=item circular data structures
441
442	Those will be encoded until memory or stackspace runs out.
443
444	=back	581	=back
		582
445		583
446	=head1 COMPARISON	584	=head1 COMPARISON
447		585
448	As already mentioned, this module was created because none of the existing	586	As already mentioned, this module was created because none of the existing
449	JSON modules could be made to work correctly. First I will describe the	587	JSON modules could be made to work correctly. First I will describe the
…		…
527		665
528	Does not check input for validity.	666	Does not check input for validity.
529		667
530	=back	668	=back
531		669
		670
		671	=head2 JSON and YAML
		672
		673	You often hear that JSON is a subset (or a close subset) of YAML. This is,
		674	however, a mass hysteria and very far from the truth. In general, there is
		675	no way to configure JSON::XS to output a data structure as valid YAML.
		676
		677	If you really must use JSON::XS to generate YAML, you should use this
		678	algorithm (subject to change in future versions):
		679
		680	my $to_yaml = JSON::XS->new->utf8->space_after (1);
		681	my $yaml = $to_yaml->encode ($ref) . "\n";
		682
		683	This will usually generate JSON texts that also parse as valid
		684	YAML. Please note that YAML has hardcoded limits on (simple) object key
		685	lengths that JSON doesn't have, so you should make sure that your hash
		686	keys are noticably shorter than the 1024 characters YAML allows.
		687
		688	There might be other incompatibilities that I am not aware of. In general
		689	you should not try to generate YAML with a JSON generator or vice versa,
		690	or try to parse JSON with a YAML parser or vice versa: chances are high
		691	that you will run into severe interoperability problems.
		692
		693
532	=head2 SPEED	694	=head2 SPEED
533		695
534	It seems that JSON::XS is surprisingly fast, as shown in the following	696	It seems that JSON::XS is surprisingly fast, as shown in the following
535	tables. They have been generated with the help of the C<eg/bench> program	697	tables. They have been generated with the help of the C<eg/bench> program
536	in the JSON::XS distribution, to make it easy to compare on your own	698	in the JSON::XS distribution, to make it easy to compare on your own
537	system.	699	system.
538		700
539	First comes a comparison between various modules using a very short JSON	701	First comes a comparison between various modules using a very short
540	string:	702	single-line JSON string:
541		703
542	{"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null}	704	{"method": "handleMessage", "params": ["user1", "we were just talking"], \
		705	"id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
543		706
544	It shows the number of encodes/decodes per second (JSON::XS uses the	707	It shows the number of encodes/decodes per second (JSON::XS uses
545	functional interface, while JSON::XS/2 uses the OO interface with	708	the functional interface, while JSON::XS/2 uses the OO interface
546	pretty-printing and hashkey sorting enabled). Higher is better:	709	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
		710	shrink). Higher is better:
547		711
		712	Storable \| 15779.925 \| 14169.946 \|
		713	-----------+------------+------------+
548	module \| encode \| decode \|	714	module \| encode \| decode \|
549	-----------\|------------\|------------\|	715	-----------\|------------\|------------\|
550	JSON \| 11488.516 \| 7823.035 \|	716	JSON \| 4990.842 \| 4088.813 \|
551	JSON::DWIW \| 94708.054 \| 129094.260 \|	717	JSON::DWIW \| 51653.990 \| 71575.154 \|
552	JSON::PC \| 63884.157 \| 128528.212 \|	718	JSON::PC \| 65948.176 \| 74631.744 \|
553	JSON::Syck \| 34898.677 \| 42096.911 \|	719	JSON::PP \| 8931.652 \| 3817.168 \|
554	JSON::XS \| 654027.064 \| 396423.669 \|	720	JSON::Syck \| 24877.248 \| 27776.848 \|
555	JSON::XS/2 \| 371564.190 \| 371725.613 \|	721	JSON::XS \| 388361.481 \| 227951.304 \|
		722	JSON::XS/2 \| 227951.304 \| 218453.333 \|
		723	JSON::XS/3 \| 338250.323 \| 218453.333 \|
		724	Storable \| 16500.016 \| 135300.129 \|
556	-----------+------------+------------+	725	-----------+------------+------------+
557		726
558	That is, JSON::XS is more than six times faster than JSON::DWIW on	727	That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
559	encoding, more than three times faster on decoding, and about thirty times	728	about three times faster on decoding, and over fourty times faster
560	faster than JSON, even with pretty-printing and key sorting.	729	than JSON, even with pretty-printing and key sorting. It also compares
		730	favourably to Storable for small amounts of data.
561		731
562	Using a longer test string (roughly 18KB, generated from Yahoo! Locals	732	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
563	search API (http://nanoref.com/yahooapis/mgPdGg):	733	search API (http://nanoref.com/yahooapis/mgPdGg):
564		734
565	module \| encode \| decode \|	735	module \| encode \| decode \|
566	-----------\|------------\|------------\|	736	-----------\|------------\|------------\|
567	JSON \| 273.023 \| 44.674 \|	737	JSON \| 55.260 \| 34.971 \|
568	JSON::DWIW \| 1089.383 \| 1145.704 \|	738	JSON::DWIW \| 825.228 \| 1082.513 \|
569	JSON::PC \| 3097.419 \| 2393.921 \|	739	JSON::PC \| 3571.444 \| 2394.829 \|
570	JSON::Syck \| 514.060 \| 843.053 \|	740	JSON::PP \| 210.987 \| 32.574 \|
571	JSON::XS \| 6479.668 \| 3636.364 \|	741	JSON::Syck \| 552.551 \| 787.544 \|
572	JSON::XS/2 \| 3774.221 \| 3599.124 \|	742	JSON::XS \| 5780.463 \| 4854.519 \|
		743	JSON::XS/2 \| 3869.998 \| 4798.975 \|
		744	JSON::XS/3 \| 5862.880 \| 4798.975 \|
		745	Storable \| 4445.002 \| 5235.027 \|
573	-----------+------------+------------+	746	-----------+------------+------------+
574		747
575	Again, JSON::XS leads by far.	748	Again, JSON::XS leads by far (except for Storable which non-surprisingly
		749	decodes faster).
576		750
577	On large strings containing lots of high unicode characters, some modules	751	On large strings containing lots of high unicode characters, some modules
578	(such as JSON::PC) seem to decode faster than JSON::XS, but the result	752	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
579	will be broken due to missing (or wrong) unicode handling. Others refuse	753	will be broken due to missing (or wrong) unicode handling. Others refuse
580	to decode or encode properly, so it was impossible to prepare a fair	754	to decode or encode properly, so it was impossible to prepare a fair
581	comparison table for that case.	755	comparison table for that case.
582		756
583	=head1 RESOURCE LIMITS
584		757
585	JSON::XS does not impose any limits on the size of JSON texts or Perl	758	=head1 SECURITY CONSIDERATIONS
586	values they represent - if your machine can handle it, JSON::XS will	759
587	encode or decode it. Future versions might optionally impose structure	760	When you are using JSON in a protocol, talking to untrusted potentially
588	depth and memory use resource limits.	761	hostile creatures requires relatively few measures.
		762
		763	First of all, your JSON decoder should be secure, that is, should not have
		764	any buffer overflows. Obviously, this module should ensure that and I am
		765	trying hard on making that true, but you never know.
		766
		767	Second, you need to avoid resource-starving attacks. That means you should
		768	limit the size of JSON texts you accept, or make sure then when your
		769	resources run out, thats just fine (e.g. by using a separate process that
		770	can crash safely). The size of a JSON text in octets or characters is
		771	usually a good indication of the size of the resources required to decode
		772	it into a Perl structure. While JSON::XS can check the size of the JSON
		773	text, it might be too late when you already have it in memory, so you
		774	might want to check the size before you accept the string.
		775
		776	Third, JSON::XS recurses using the C stack when decoding objects and
		777	arrays. The C stack is a limited resource: for instance, on my amd64
		778	machine with 8MB of stack size I can decode around 180k nested arrays but
		779	only 14k nested JSON objects (due to perl itself recursing deeply on croak
		780	to free the temporary). If that is exceeded, the program crashes. to be
		781	conservative, the default nesting limit is set to 512. If your process
		782	has a smaller stack, you should adjust this setting accordingly with the
		783	C<max_depth> method.
		784
		785	And last but least, something else could bomb you that I forgot to think
		786	of. In that case, you get to keep the pieces. I am always open for hints,
		787	though...
		788
		789	If you are using JSON::XS to return packets to consumption
		790	by javascript scripts in a browser you should have a look at
		791	L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether
		792	you are vulnerable to some common attack vectors (which really are browser
		793	design bugs, but it is still you who will have to deal with it, as major
		794	browser developers care only for features, not about doing security
		795	right).
		796
589		797
590	=head1 BUGS	798	=head1 BUGS
591		799
592	While the goal of this module is to be correct, that unfortunately does	800	While the goal of this module is to be correct, that unfortunately does
593	not mean its bug-free, only that I think its design is bug-free. It is	801	not mean its bug-free, only that I think its design is bug-free. It is
594	still very young and not well-tested. If you keep reporting bugs they will	802	still relatively early in its development. If you keep reporting bugs they
595	be fixed swiftly, though.	803	will be fixed swiftly, though.
596		804
597	=cut	805	=cut
		806
		807	our $true = do { bless \(my $dummy = "1"), "JSON::XS::Boolean" };
		808	our $false = do { bless \(my $dummy = "0"), "JSON::XS::Boolean" };
		809
		810	sub true() { $true }
		811	sub false() { $false }
		812
		813	sub is_bool($) {
		814	UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
		815	# or UNIVERSAL::isa $_[0], "JSON::Literal"
		816	}
		817
		818	XSLoader::load "JSON::XS", $VERSION;
		819
		820	package JSON::XS::Boolean;
		821
		822	use overload
		823	"0+" => sub { ${$_[0]} },
		824	"++" => sub { $_[0] = ${$_[0]} + 1 },
		825	"--" => sub { $_[0] = ${$_[0]} - 1 },
		826	fallback => 1;
598		827
599	1;	828	1;
600		829
601	=head1 AUTHOR	830	=head1 AUTHOR
602		831

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Comparing JSON-XS/XS.pm (file contents): Revision 1.22 by root, Sun Mar 25 02:37:00 2007 UTC vs. Revision 1.50 by root, Mon Jul 2 00:29:38 2007 UTC

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Comparing JSON-XS/XS.pm (file contents):
Revision 1.22 by root, Sun Mar 25 02:37:00 2007 UTC vs.
Revision 1.50 by root, Mon Jul 2 00:29:38 2007 UTC