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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.21 by root, Sun Mar 25 02:32:40 2007 UTC vs.
Revision 1.48 by root, Mon Jun 25 22:11:39 2007 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use JSON::XS;	7	use JSON::XS;
8		8
9	# exported functions, croak on error	9	# exported functions, they croak on error
		10	# and expect/generate UTF-8
10		11
11	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;	12	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;
12	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;	13	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;
13		14
14	# objToJson and jsonToObj are exported for JSON	15	# objToJson and jsonToObj aliases to to_json and from_json
		16	# are exported for compatibility to the JSON module,
15	# compatibility, but should not be used in new code.	17	# but should not be used in new code.
16		18
17	# oo-interface	19	# OO-interface
18		20
19	$coder = JSON::XS->new->ascii->pretty->allow_nonref;	21	$coder = JSON::XS->new->ascii->pretty->allow_nonref;
20	$pretty_printed_unencoded = $coder->encode ($perl_scalar);	22	$pretty_printed_unencoded = $coder->encode ($perl_scalar);
21	$perl_scalar = $coder->decode ($unicode_json_text);	23	$perl_scalar = $coder->decode ($unicode_json_text);
22		24
…		…
83		85
84	package JSON::XS;	86	package JSON::XS;
85		87
86	use strict;	88	use strict;
87		89
88	BEGIN {
89	our $VERSION = '0.8';	90	our $VERSION = '1.4';
90	our @ISA = qw(Exporter);	91	our @ISA = qw(Exporter);
91		92
92	our @EXPORT = qw(to_json from_json objToJson jsonToObj);	93	our @EXPORT = qw(to_json from_json objToJson jsonToObj);
93	require Exporter;
94		94
95	require XSLoader;	95	use Exporter;
96	XSLoader::load JSON::XS::, $VERSION;	96	use XSLoader;
97	}
98		97
99	=head1 FUNCTIONAL INTERFACE	98	=head1 FUNCTIONAL INTERFACE
100		99
101	The following convinience methods are provided by this module. They are	100	The following convinience methods are provided by this module. They are
102	exported by default:	101	exported by default:
…		…
125		124
126	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)	125	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
127		126
128	except being faster.	127	except being faster.
129		128
		129	=item $is_boolean = JSON::XS::is_bool $scalar
		130
		131	Returns true if the passed scalar represents either JSON::XS::true or
		132	JSON::XS::false, two constants that act like C<1> and C<0>, respectively
		133	and are used to represent JSON C<true> and C<false> values in Perl.
		134
		135	See MAPPING, below, for more information on how JSON values are mapped to
		136	Perl.
		137
130	=back	138	=back
		139
131		140
132	=head1 OBJECT-ORIENTED INTERFACE	141	=head1 OBJECT-ORIENTED INTERFACE
133		142
134	The object oriented interface lets you configure your own encoding or	143	The object oriented interface lets you configure your own encoding or
135	decoding style, within the limits of supported formats.	144	decoding style, within the limits of supported formats.
…		…
151		160
152	If C<$enable> is true (or missing), then the C<encode> method will not	161	If C<$enable> is true (or missing), then the C<encode> method will not
153	generate characters outside the code range C<0..127> (which is ASCII). Any	162	generate characters outside the code range C<0..127> (which is ASCII). Any
154	unicode characters outside that range will be escaped using either a	163	unicode characters outside that range will be escaped using either a
155	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,	164	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
156	as per RFC4627.	165	as per RFC4627. The resulting encoded JSON text can be treated as a native
		166	unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
		167	or any other superset of ASCII.
157		168
158	If C<$enable> is false, then the C<encode> method will not escape Unicode	169	If C<$enable> is false, then the C<encode> method will not escape Unicode
159	characters unless required by the JSON syntax. This results in a faster	170	characters unless required by the JSON syntax or other flags. This results
160	and more compact format.	171	in a faster and more compact format.
		172
		173	The main use for this flag is to produce JSON texts that can be
		174	transmitted over a 7-bit channel, as the encoded JSON texts will not
		175	contain any 8 bit characters.
161		176
162	JSON::XS->new->ascii (1)->encode ([chr 0x10401])	177	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
163	=> ["\ud801\udc01"]	178	=> ["\ud801\udc01"]
		179
		180	=item $json = $json->latin1 ([$enable])
		181
		182	If C<$enable> is true (or missing), then the C<encode> method will encode
		183	the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
		184	outside the code range C<0..255>. The resulting string can be treated as a
		185	latin1-encoded JSON text or a native unicode string. The C<decode> method
		186	will not be affected in any way by this flag, as C<decode> by default
		187	expects unicode, which is a strict superset of latin1.
		188
		189	If C<$enable> is false, then the C<encode> method will not escape Unicode
		190	characters unless required by the JSON syntax or other flags.
		191
		192	The main use for this flag is efficiently encoding binary data as JSON
		193	text, as most octets will not be escaped, resulting in a smaller encoded
		194	size. The disadvantage is that the resulting JSON text is encoded
		195	in latin1 (and must correctly be treated as such when storing and
		196	transfering), a rare encoding for JSON. It is therefore most useful when
		197	you want to store data structures known to contain binary data efficiently
		198	in files or databases, not when talking to other JSON encoders/decoders.
		199
		200	JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
		201	=> ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
164		202
165	=item $json = $json->utf8 ([$enable])	203	=item $json = $json->utf8 ([$enable])
166		204
167	If C<$enable> is true (or missing), then the C<encode> method will encode	205	If C<$enable> is true (or missing), then the C<encode> method will encode
168	the JSON result into UTF-8, as required by many protocols, while the	206	the JSON result into UTF-8, as required by many protocols, while the
…		…
278	resulting in an invalid JSON text:	316	resulting in an invalid JSON text:
279		317
280	JSON::XS->new->allow_nonref->encode ("Hello, World!")	318	JSON::XS->new->allow_nonref->encode ("Hello, World!")
281	=> "Hello, World!"	319	=> "Hello, World!"
282		320
		321	=item $json = $json->allow_blessed ([$enable])
		322
		323	If C<$enable> is true (or missing), then the C<encode> method will not
		324	barf when it encounters a blessed reference. Instead, the value of the
		325	B<convert_blessed> option will decide wether C<null> (C<convert_blessed>
		326	disabled or no C<to_json> method found) or a representation of the
		327	object (C<convert_blessed> enabled and C<to_json> method found) is being
		328	encoded. Has no effect on C<decode>.
		329
		330	If C<$enable> is false (the default), then C<encode> will throw an
		331	exception when it encounters a blessed object.
		332
		333	=item $json = $json->convert_blessed ([$enable])
		334
		335	If C<$enable> is true (or missing), then C<encode>, upon encountering a
		336	blessed object, will check for the availability of the C<TO_JSON> method
		337	on the object's class. If found, it will be called in scalar context
		338	and the resulting scalar will be encoded instead of the object. If no
		339	C<TO_JSON> method is found, the value of C<allow_blessed> will decide what
		340	to do.
		341
		342	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
		343	returns other blessed objects, those will be handled in the same
		344	way. C<TO_JSON> must take care of not causing an endless recursion cycle
		345	(== crash) in this case. The name of C<TO_JSON> was chosen because other
		346	methods called by the Perl core (== not by the user of the object) are
		347	usually in upper case letters and to avoid collisions with the C<to_json>
		348	function.
		349
		350	This setting does not yet influence C<decode> in any way, but in the
		351	future, global hooks might get installed that influence C<decode> and are
		352	enabled by this setting.
		353
		354	If C<$enable> is false, then the C<allow_blessed> setting will decide what
		355	to do when a blessed object is found.
		356
283	=item $json = $json->shrink ([$enable])	357	=item $json = $json->shrink ([$enable])
284		358
285	Perl usually over-allocates memory a bit when allocating space for	359	Perl usually over-allocates memory a bit when allocating space for
286	strings. This flag optionally resizes strings generated by either	360	strings. This flag optionally resizes strings generated by either
287	C<encode> or C<decode> to their minimum size possible. This can save	361	C<encode> or C<decode> to their minimum size possible. This can save
288	memory when your JSON texts are either very very long or you have many	362	memory when your JSON texts are either very very long or you have many
289	short strings. It will also try to downgrade any strings to octet-form	363	short strings. It will also try to downgrade any strings to octet-form
290	if possible: perl stores strings internally either in an encoding called	364	if possible: perl stores strings internally either in an encoding called
291	UTF-X or in octet-form. The latter cannot store everything but uses less	365	UTF-X or in octet-form. The latter cannot store everything but uses less
292	space in general.	366	space in general (and some buggy Perl or C code might even rely on that
		367	internal representation being used).
293		368
		369	The actual definition of what shrink does might change in future versions,
		370	but it will always try to save space at the expense of time.
		371
294	If C<$enable> is true (or missing), the string returned by C<encode> will be shrunk-to-fit,	372	If C<$enable> is true (or missing), the string returned by C<encode> will
295	while all strings generated by C<decode> will also be shrunk-to-fit.	373	be shrunk-to-fit, while all strings generated by C<decode> will also be
		374	shrunk-to-fit.
296		375
297	If C<$enable> is false, then the normal perl allocation algorithms are used.	376	If C<$enable> is false, then the normal perl allocation algorithms are used.
298	If you work with your data, then this is likely to be faster.	377	If you work with your data, then this is likely to be faster.
299		378
300	In the future, this setting might control other things, such as converting	379	In the future, this setting might control other things, such as converting
301	strings that look like integers or floats into integers or floats	380	strings that look like integers or floats into integers or floats
302	internally (there is no difference on the Perl level), saving space.	381	internally (there is no difference on the Perl level), saving space.
		382
		383	=item $json = $json->max_depth ([$maximum_nesting_depth])
		384
		385	Sets the maximum nesting level (default C<512>) accepted while encoding
		386	or decoding. If the JSON text or Perl data structure has an equal or
		387	higher nesting level then this limit, then the encoder and decoder will
		388	stop and croak at that point.
		389
		390	Nesting level is defined by number of hash- or arrayrefs that the encoder
		391	needs to traverse to reach a given point or the number of C<{> or C<[>
		392	characters without their matching closing parenthesis crossed to reach a
		393	given character in a string.
		394
		395	Setting the maximum depth to one disallows any nesting, so that ensures
		396	that the object is only a single hash/object or array.
		397
		398	The argument to C<max_depth> will be rounded up to the next highest power
		399	of two. If no argument is given, the highest possible setting will be
		400	used, which is rarely useful.
		401
		402	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
		403
		404	=item $json = $json->max_size ([$maximum_string_size])
		405
		406	Set the maximum length a JSON text may have (in bytes) where decoding is
		407	being attempted. The default is C<0>, meaning no limit. When C<decode>
		408	is called on a string longer then this number of characters it will not
		409	attempt to decode the string but throw an exception. This setting has no
		410	effect on C<encode> (yet).
		411
		412	The argument to C<max_size> will be rounded up to the next B<highest>
		413	power of two (so may be more than requested). If no argument is given, the
		414	limit check will be deactivated (same as when C<0> is specified).
		415
		416	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
303		417
304	=item $json_text = $json->encode ($perl_scalar)	418	=item $json_text = $json->encode ($perl_scalar)
305		419
306	Converts the given Perl data structure (a simple scalar or a reference	420	Converts the given Perl data structure (a simple scalar or a reference
307	to a hash or array) to its JSON representation. Simple scalars will be	421	to a hash or array) to its JSON representation. Simple scalars will be
…		…
317		431
318	JSON numbers and strings become simple Perl scalars. JSON arrays become	432	JSON numbers and strings become simple Perl scalars. JSON arrays become
319	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes	433	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
320	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.	434	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
321		435
		436	=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
		437
		438	This works like the C<decode> method, but instead of raising an exception
		439	when there is trailing garbage after the first JSON object, it will
		440	silently stop parsing there and return the number of characters consumed
		441	so far.
		442
		443	This is useful if your JSON texts are not delimited by an outer protocol
		444	(which is not the brightest thing to do in the first place) and you need
		445	to know where the JSON text ends.
		446
		447	JSON::XS->new->decode_prefix ("[1] the tail")
		448	=> ([], 3)
		449
322	=back	450	=back
		451
323		452
324	=head1 MAPPING	453	=head1 MAPPING
325		454
326	This section describes how JSON::XS maps Perl values to JSON values and	455	This section describes how JSON::XS maps Perl values to JSON values and
327	vice versa. These mappings are designed to "do the right thing" in most	456	vice versa. These mappings are designed to "do the right thing" in most
…		…
329	(what you put in comes out as something equivalent).	458	(what you put in comes out as something equivalent).
330		459
331	For the more enlightened: note that in the following descriptions,	460	For the more enlightened: note that in the following descriptions,
332	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>	461	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
333	refers to the abstract Perl language itself.	462	refers to the abstract Perl language itself.
		463
334		464
335	=head2 JSON -> PERL	465	=head2 JSON -> PERL
336		466
337	=over 4	467	=over 4
338		468
…		…
359	conversion details, but an integer may take slightly less memory and might	489	conversion details, but an integer may take slightly less memory and might
360	represent more values exactly than (floating point) numbers.	490	represent more values exactly than (floating point) numbers.
361		491
362	=item true, false	492	=item true, false
363		493
364	These JSON atoms become C<0>, C<1>, respectively. Information is lost in	494	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
365	this process. Future versions might represent those values differently,	495	respectively. They are overloaded to act almost exactly like the numbers
366	but they will be guarenteed to act like these integers would normally in	496	C<1> and C<0>. You can check wether a scalar is a JSON boolean by using
367	Perl.	497	the C<JSON::XS::is_bool> function.
368		498
369	=item null	499	=item null
370		500
371	A JSON null atom becomes C<undef> in Perl.	501	A JSON null atom becomes C<undef> in Perl.
372		502
373	=back	503	=back
		504
374		505
375	=head2 PERL -> JSON	506	=head2 PERL -> JSON
376		507
377	The mapping from Perl to JSON is slightly more difficult, as Perl is a	508	The mapping from Perl to JSON is slightly more difficult, as Perl is a
378	truly typeless language, so we can only guess which JSON type is meant by	509	truly typeless language, so we can only guess which JSON type is meant by
…		…
381	=over 4	512	=over 4
382		513
383	=item hash references	514	=item hash references
384		515
385	Perl hash references become JSON objects. As there is no inherent ordering	516	Perl hash references become JSON objects. As there is no inherent ordering
386	in hash keys, they will usually be encoded in a pseudo-random order that	517	in hash keys (or JSON objects), they will usually be encoded in a
387	can change between runs of the same program but stays generally the same	518	pseudo-random order that can change between runs of the same program but
388	within a single run of a program. JSON::XS can optionally sort the hash	519	stays generally the same within a single run of a program. JSON::XS can
389	keys (determined by the I<canonical> flag), so the same datastructure	520	optionally sort the hash keys (determined by the I<canonical> flag), so
390	will serialise to the same JSON text (given same settings and version of	521	the same datastructure will serialise to the same JSON text (given same
391	JSON::XS), but this incurs a runtime overhead.	522	settings and version of JSON::XS), but this incurs a runtime overhead
		523	and is only rarely useful, e.g. when you want to compare some JSON text
		524	against another for equality.
392		525
393	=item array references	526	=item array references
394		527
395	Perl array references become JSON arrays.	528	Perl array references become JSON arrays.
		529
		530	=item other references
		531
		532	Other unblessed references are generally not allowed and will cause an
		533	exception to be thrown, except for references to the integers C<0> and
		534	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
		535	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
		536
		537	to_json [\0,JSON::XS::true] # yields [false,true]
		538
		539	=item JSON::XS::true, JSON::XS::false
		540
		541	These special values become JSON true and JSON false values,
		542	respectively. You cna alos use C<\1> and C<\0> directly if you want.
396		543
397	=item blessed objects	544	=item blessed objects
398		545
399	Blessed objects are not allowed. JSON::XS currently tries to encode their	546	Blessed objects are not allowed. JSON::XS currently tries to encode their
400	underlying representation (hash- or arrayref), but this behaviour might	547	underlying representation (hash- or arrayref), but this behaviour might
…		…
433	$x *= 1; # same thing, the choise is yours.	580	$x *= 1; # same thing, the choise is yours.
434		581
435	You can not currently output JSON booleans or force the type in other,	582	You can not currently output JSON booleans or force the type in other,
436	less obscure, ways. Tell me if you need this capability.	583	less obscure, ways. Tell me if you need this capability.
437		584
438	=item circular data structures
439
440	Those will be encoded until memory or stackspace runs out.
441
442	=back	585	=back
		586
443		587
444	=head1 COMPARISON	588	=head1 COMPARISON
445		589
446	As already mentioned, this module was created because none of the existing	590	As already mentioned, this module was created because none of the existing
447	JSON modules could be made to work correctly. First I will describe the	591	JSON modules could be made to work correctly. First I will describe the
…		…
525		669
526	Does not check input for validity.	670	Does not check input for validity.
527		671
528	=back	672	=back
529		673
		674
		675	=head2 JSON and YAML
		676
		677	You often hear that JSON is a subset (or a close subset) of YAML. This is,
		678	however, a mass hysteria and very far from the truth. In general, there is
		679	no way to configure JSON::XS to output a data structure as valid YAML.
		680
		681	If you really must use JSON::XS to generate YAML, you should use this
		682	algorithm (subject to change in future versions):
		683
		684	my $to_yaml = JSON::XS->new->utf8->space_after (1);
		685	my $yaml = $to_yaml->encode ($ref) . "\n";
		686
		687	This will usually generate JSON texts that also parse as valid
		688	YAML. Please note that YAML has hardcoded limits on (simple) object key
		689	lengths that JSON doesn't have, so you should make sure that your hash
		690	keys are noticably shorter than the 1024 characters YAML allows.
		691
		692	There might be other incompatibilities that I am not aware of. In general
		693	you should not try to generate YAML with a JSON generator or vice versa,
		694	or try to parse JSON with a YAML parser or vice versa: chances are high
		695	that you will run into severe interoperability problems.
		696
		697
530	=head2 SPEED	698	=head2 SPEED
531		699
532	It seems that JSON::XS is surprisingly fast, as shown in the following	700	It seems that JSON::XS is surprisingly fast, as shown in the following
533	tables. They have been generated with the help of the C<eg/bench> program	701	tables. They have been generated with the help of the C<eg/bench> program
534	in the JSON::XS distribution, to make it easy to compare on your own	702	in the JSON::XS distribution, to make it easy to compare on your own
535	system.	703	system.
536		704
537	First comes a comparison between various modules using a very short JSON	705	First comes a comparison between various modules using a very short
538	string:	706	single-line JSON string:
539		707
540	{"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null}	708	{"method": "handleMessage", "params": ["user1", "we were just talking"], \
		709	"id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
541		710
542	It shows the number of encodes/decodes per second (JSON::XS uses the	711	It shows the number of encodes/decodes per second (JSON::XS uses
543	functional interface, while JSON::XS/2 uses the OO interface with	712	the functional interface, while JSON::XS/2 uses the OO interface
544	pretty-printing and hashkey sorting enabled). Higher is better:	713	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
		714	shrink). Higher is better:
545		715
		716	Storable \| 15779.925 \| 14169.946 \|
		717	-----------+------------+------------+
546	module \| encode \| decode \|	718	module \| encode \| decode \|
547	-----------\|------------\|------------\|	719	-----------\|------------\|------------\|
548	JSON \| 11488.516 \| 7823.035 \|	720	JSON \| 4990.842 \| 4088.813 \|
549	JSON::DWIW \| 94708.054 \| 129094.260 \|	721	JSON::DWIW \| 51653.990 \| 71575.154 \|
550	JSON::PC \| 63884.157 \| 128528.212 \|	722	JSON::PC \| 65948.176 \| 74631.744 \|
551	JSON::Syck \| 34898.677 \| 42096.911 \|	723	JSON::PP \| 8931.652 \| 3817.168 \|
552	JSON::XS \| 654027.064 \| 396423.669 \|	724	JSON::Syck \| 24877.248 \| 27776.848 \|
553	JSON::XS/2 \| 371564.190 \| 371725.613 \|	725	JSON::XS \| 388361.481 \| 227951.304 \|
		726	JSON::XS/2 \| 227951.304 \| 218453.333 \|
		727	JSON::XS/3 \| 338250.323 \| 218453.333 \|
		728	Storable \| 16500.016 \| 135300.129 \|
554	-----------+------------+------------+	729	-----------+------------+------------+
555		730
556	That is, JSON::XS is more than six times faster than JSON::DWIW on	731	That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
557	encoding, more than three times faster on decoding, and about thirty times	732	about three times faster on decoding, and over fourty times faster
558	faster than JSON, even with pretty-printing and key sorting.	733	than JSON, even with pretty-printing and key sorting. It also compares
		734	favourably to Storable for small amounts of data.
559		735
560	Using a longer test string (roughly 18KB, generated from Yahoo! Locals	736	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
561	search API (http://nanoref.com/yahooapis/mgPdGg):	737	search API (http://nanoref.com/yahooapis/mgPdGg):
562		738
563	module \| encode \| decode \|	739	module \| encode \| decode \|
564	-----------\|------------\|------------\|	740	-----------\|------------\|------------\|
565	JSON \| 273.023 \| 44.674 \|	741	JSON \| 55.260 \| 34.971 \|
566	JSON::DWIW \| 1089.383 \| 1145.704 \|	742	JSON::DWIW \| 825.228 \| 1082.513 \|
567	JSON::PC \| 3097.419 \| 2393.921 \|	743	JSON::PC \| 3571.444 \| 2394.829 \|
568	JSON::Syck \| 514.060 \| 843.053 \|	744	JSON::PP \| 210.987 \| 32.574 \|
569	JSON::XS \| 6479.668 \| 3636.364 \|	745	JSON::Syck \| 552.551 \| 787.544 \|
570	JSON::XS/2 \| 3774.221 \| 3599.124 \|	746	JSON::XS \| 5780.463 \| 4854.519 \|
		747	JSON::XS/2 \| 3869.998 \| 4798.975 \|
		748	JSON::XS/3 \| 5862.880 \| 4798.975 \|
		749	Storable \| 4445.002 \| 5235.027 \|
571	-----------+------------+------------+	750	-----------+------------+------------+
572		751
573	Again, JSON::XS leads by far.	752	Again, JSON::XS leads by far (except for Storable which non-surprisingly
		753	decodes faster).
574		754
575	On large strings containing lots of high unicode characters, some modules	755	On large strings containing lots of high unicode characters, some modules
576	(such as JSON::PC) seem to decode faster than JSON::XS, but the result	756	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
577	will be broken due to missing (or wrong) unicode handling. Others refuse	757	will be broken due to missing (or wrong) unicode handling. Others refuse
578	to decode or encode properly, so it was impossible to prepare a fair	758	to decode or encode properly, so it was impossible to prepare a fair
579	comparison table for that case.	759	comparison table for that case.
580		760
581	=head1 RESOURCE LIMITS
582		761
583	JSON::XS does not impose any limits on the size of JSON texts or Perl	762	=head1 SECURITY CONSIDERATIONS
584	values they represent - if your machine can handle it, JSON::XS will	763
585	encode or decode it. Future versions might optionally impose structure	764	When you are using JSON in a protocol, talking to untrusted potentially
586	depth and memory use resource limits.	765	hostile creatures requires relatively few measures.
		766
		767	First of all, your JSON decoder should be secure, that is, should not have
		768	any buffer overflows. Obviously, this module should ensure that and I am
		769	trying hard on making that true, but you never know.
		770
		771	Second, you need to avoid resource-starving attacks. That means you should
		772	limit the size of JSON texts you accept, or make sure then when your
		773	resources run out, thats just fine (e.g. by using a separate process that
		774	can crash safely). The size of a JSON text in octets or characters is
		775	usually a good indication of the size of the resources required to decode
		776	it into a Perl structure. While JSON::XS can check the size of the JSON
		777	text, it might be too late when you already have it in memory, so you
		778	might want to check the size before you accept the string.
		779
		780	Third, JSON::XS recurses using the C stack when decoding objects and
		781	arrays. The C stack is a limited resource: for instance, on my amd64
		782	machine with 8MB of stack size I can decode around 180k nested arrays but
		783	only 14k nested JSON objects (due to perl itself recursing deeply on croak
		784	to free the temporary). If that is exceeded, the program crashes. to be
		785	conservative, the default nesting limit is set to 512. If your process
		786	has a smaller stack, you should adjust this setting accordingly with the
		787	C<max_depth> method.
		788
		789	And last but least, something else could bomb you that I forgot to think
		790	of. In that case, you get to keep the pieces. I am always open for hints,
		791	though...
		792
		793	If you are using JSON::XS to return packets to consumption
		794	by javascript scripts in a browser you should have a look at
		795	L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether
		796	you are vulnerable to some common attack vectors (which really are browser
		797	design bugs, but it is still you who will have to deal with it, as major
		798	browser developers care only for features, not about doing security
		799	right).
		800
587		801
588	=head1 BUGS	802	=head1 BUGS
589		803
590	While the goal of this module is to be correct, that unfortunately does	804	While the goal of this module is to be correct, that unfortunately does
591	not mean its bug-free, only that I think its design is bug-free. It is	805	not mean its bug-free, only that I think its design is bug-free. It is
592	still very young and not well-tested. If you keep reporting bugs they will	806	still relatively early in its development. If you keep reporting bugs they
593	be fixed swiftly, though.	807	will be fixed swiftly, though.
594		808
595	=cut	809	=cut
		810
		811	our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
		812	our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };
		813
		814	sub true() { $true }
		815	sub false() { $false }
		816
		817	sub is_bool($) {
		818	UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
		819	# or UNIVERSAL::isa $_[0], "JSON::Literal"
		820	}
		821
		822	XSLoader::load "JSON::XS", $VERSION;
		823
		824	package JSON::XS::Boolean;
		825
		826	use overload
		827	"0+" => sub { ${$_[0]} },
		828	"++" => sub { $_[0] = ${$_[0]} + 1 },
		829	"--" => sub { $_[0] = ${$_[0]} - 1 },
		830	fallback => 1;
596		831
597	1;	832	1;
598		833
599	=head1 AUTHOR	834	=head1 AUTHOR
600		835

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Comparing JSON-XS/XS.pm (file contents): Revision 1.21 by root, Sun Mar 25 02:32:40 2007 UTC vs. Revision 1.48 by root, Mon Jun 25 22:11:39 2007 UTC

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Comparing JSON-XS/XS.pm (file contents):
Revision 1.21 by root, Sun Mar 25 02:32:40 2007 UTC vs.
Revision 1.48 by root, Mon Jun 25 22:11:39 2007 UTC