[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 1.41 by root, Mon Jun 11 03:45:26 2007 UTC

…		…
86	package JSON::XS;	86	package JSON::XS;
87		87
88	use strict;	88	use strict;
89		89
90	BEGIN {	90	BEGIN {
91	our $VERSION = '0.8';	91	our $VERSION = '1.24';
92	our @ISA = qw(Exporter);	92	our @ISA = qw(Exporter);
93		93
94	our @EXPORT = qw(to_json from_json objToJson jsonToObj);	94	our @EXPORT = qw(to_json from_json objToJson jsonToObj);
95	require Exporter;	95	require Exporter;
96		96
…		…
128	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)	128	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
129		129
130	except being faster.	130	except being faster.
131		131
132	=back	132	=back
		133
133		134
134	=head1 OBJECT-ORIENTED INTERFACE	135	=head1 OBJECT-ORIENTED INTERFACE
135		136
136	The object oriented interface lets you configure your own encoding or	137	The object oriented interface lets you configure your own encoding or
137	decoding style, within the limits of supported formats.	138	decoding style, within the limits of supported formats.
…		…
153		154
154	If C<$enable> is true (or missing), then the C<encode> method will not	155	If C<$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	156	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	157	unicode characters outside that range will be escaped using either a
157	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,	158	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
158	as per RFC4627.	159	as per RFC4627. The resulting encoded JSON text can be treated as a native
		160	unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
		161	or any other superset of ASCII.
159		162
160	If C<$enable> is false, then the C<encode> method will not escape Unicode	163	If C<$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	164	characters unless required by the JSON syntax or other flags. This results
162	and more compact format.	165	in a faster and more compact format.
		166
		167	The main use for this flag is to produce JSON texts that can be
		168	transmitted over a 7-bit channel, as the encoded JSON texts will not
		169	contain any 8 bit characters.
163		170
164	JSON::XS->new->ascii (1)->encode ([chr 0x10401])	171	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
165	=> ["\ud801\udc01"]	172	=> ["\ud801\udc01"]
		173
		174	=item $json = $json->latin1 ([$enable])
		175
		176	If C<$enable> is true (or missing), then the C<encode> method will encode
		177	the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
		178	outside the code range C<0..255>. The resulting string can be treated as a
		179	latin1-encoded JSON text or a native unicode string. The C<decode> method
		180	will not be affected in any way by this flag, as C<decode> by default
		181	expects unicode, which is a strict superset of latin1.
		182
		183	If C<$enable> is false, then the C<encode> method will not escape Unicode
		184	characters unless required by the JSON syntax or other flags.
		185
		186	The main use for this flag is efficiently encoding binary data as JSON
		187	text, as most octets will not be escaped, resulting in a smaller encoded
		188	size. The disadvantage is that the resulting JSON text is encoded
		189	in latin1 (and must correctly be treated as such when storing and
		190	transfering), a rare encoding for JSON. It is therefore most useful when
		191	you want to store data structures known to contain binary data efficiently
		192	in files or databases, not when talking to other JSON encoders/decoders.
		193
		194	JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
		195	=> ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
166		196
167	=item $json = $json->utf8 ([$enable])	197	=item $json = $json->utf8 ([$enable])
168		198
169	If C<$enable> is true (or missing), then the C<encode> method will encode	199	If C<$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	200	the JSON result into UTF-8, as required by many protocols, while the
…		…
283	=> "Hello, World!"	313	=> "Hello, World!"
284		314
285	=item $json = $json->shrink ([$enable])	315	=item $json = $json->shrink ([$enable])
286		316
287	Perl usually over-allocates memory a bit when allocating space for	317	Perl usually over-allocates memory a bit when allocating space for
288	strings. This flag optionally resizes strings generated by either	318	strings. This flag optionally resizes strings generated by either
289	C<encode> or C<decode> to their minimum size possible. This can save	319	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	320	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	321	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	322	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	323	UTF-X or in octet-form. The latter cannot store everything but uses less
294	space in general.	324	space in general (and some buggy Perl or C code might even rely on that
		325	internal representation being used).
295		326
		327	The actual definition of what shrink does might change in future versions,
		328	but it will always try to save space at the expense of time.
		329
296	If C<$enable> is true (or missing), the string returned by C<encode> will be shrunk-to-fit,	330	If C<$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.	331	be shrunk-to-fit, while all strings generated by C<decode> will also be
		332	shrunk-to-fit.
298		333
299	If C<$enable> is false, then the normal perl allocation algorithms are used.	334	If C<$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.	335	If you work with your data, then this is likely to be faster.
301		336
302	In the future, this setting might control other things, such as converting	337	In the future, this setting might control other things, such as converting
303	strings that look like integers or floats into integers or floats	338	strings that look like integers or floats into integers or floats
304	internally (there is no difference on the Perl level), saving space.	339	internally (there is no difference on the Perl level), saving space.
		340
		341	=item $json = $json->max_depth ([$maximum_nesting_depth])
		342
		343	Sets the maximum nesting level (default C<512>) accepted while encoding
		344	or decoding. If the JSON text or Perl data structure has an equal or
		345	higher nesting level then this limit, then the encoder and decoder will
		346	stop and croak at that point.
		347
		348	Nesting level is defined by number of hash- or arrayrefs that the encoder
		349	needs to traverse to reach a given point or the number of C<{> or C<[>
		350	characters without their matching closing parenthesis crossed to reach a
		351	given character in a string.
		352
		353	Setting the maximum depth to one disallows any nesting, so that ensures
		354	that the object is only a single hash/object or array.
		355
		356	The argument to C<max_depth> will be rounded up to the next nearest power
		357	of two.
		358
		359	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
305		360
306	=item $json_text = $json->encode ($perl_scalar)	361	=item $json_text = $json->encode ($perl_scalar)
307		362
308	Converts the given Perl data structure (a simple scalar or a reference	363	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	364	to a hash or array) to its JSON representation. Simple scalars will be
…		…
319		374
320	JSON numbers and strings become simple Perl scalars. JSON arrays become	375	JSON numbers and strings become simple Perl scalars. JSON arrays become
321	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes	376	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>.	377	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
323		378
		379	=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
		380
		381	This works like the C<decode> method, but instead of raising an exception
		382	when there is trailing garbage after the first JSON object, it will
		383	silently stop parsing there and return the number of characters consumed
		384	so far.
		385
		386	This is useful if your JSON texts are not delimited by an outer protocol
		387	(which is not the brightest thing to do in the first place) and you need
		388	to know where the JSON text ends.
		389
		390	JSON::XS->new->decode_prefix ("[1] the tail")
		391	=> ([], 3)
		392
324	=back	393	=back
		394
325		395
326	=head1 MAPPING	396	=head1 MAPPING
327		397
328	This section describes how JSON::XS maps Perl values to JSON values and	398	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	399	vice versa. These mappings are designed to "do the right thing" in most
…		…
331	(what you put in comes out as something equivalent).	401	(what you put in comes out as something equivalent).
332		402
333	For the more enlightened: note that in the following descriptions,	403	For the more enlightened: note that in the following descriptions,
334	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>	404	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
335	refers to the abstract Perl language itself.	405	refers to the abstract Perl language itself.
		406
336		407
337	=head2 JSON -> PERL	408	=head2 JSON -> PERL
338		409
339	=over 4	410	=over 4
340		411
…		…
372		443
373	A JSON null atom becomes C<undef> in Perl.	444	A JSON null atom becomes C<undef> in Perl.
374		445
375	=back	446	=back
376		447
		448
377	=head2 PERL -> JSON	449	=head2 PERL -> JSON
378		450
379	The mapping from Perl to JSON is slightly more difficult, as Perl is a	451	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	452	truly typeless language, so we can only guess which JSON type is meant by
381	a Perl value.	453	a Perl value.
…		…
383	=over 4	455	=over 4
384		456
385	=item hash references	457	=item hash references
386		458
387	Perl hash references become JSON objects. As there is no inherent ordering	459	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	460	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	461	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	462	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	463	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	464	the same datastructure will serialise to the same JSON text (given same
393	JSON::XS), but this incurs a runtime overhead.	465	settings and version of JSON::XS), but this incurs a runtime overhead
		466	and is only rarely useful, e.g. when you want to compare some JSON text
		467	against another for equality.
394		468
395	=item array references	469	=item array references
396		470
397	Perl array references become JSON arrays.	471	Perl array references become JSON arrays.
		472
		473	=item other references
		474
		475	Other unblessed references are generally not allowed and will cause an
		476	exception to be thrown, except for references to the integers C<0> and
		477	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
		478	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
		479
		480	to_json [\0,JSON::XS::true] # yields [false,true]
398		481
399	=item blessed objects	482	=item blessed objects
400		483
401	Blessed objects are not allowed. JSON::XS currently tries to encode their	484	Blessed objects are not allowed. JSON::XS currently tries to encode their
402	underlying representation (hash- or arrayref), but this behaviour might	485	underlying representation (hash- or arrayref), but this behaviour might
…		…
435	$x *= 1; # same thing, the choise is yours.	518	$x *= 1; # same thing, the choise is yours.
436		519
437	You can not currently output JSON booleans or force the type in other,	520	You can not currently output JSON booleans or force the type in other,
438	less obscure, ways. Tell me if you need this capability.	521	less obscure, ways. Tell me if you need this capability.
439		522
440	=item circular data structures
441
442	Those will be encoded until memory or stackspace runs out.
443
444	=back	523	=back
		524
445		525
446	=head1 COMPARISON	526	=head1 COMPARISON
447		527
448	As already mentioned, this module was created because none of the existing	528	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	529	JSON modules could be made to work correctly. First I will describe the
…		…
527		607
528	Does not check input for validity.	608	Does not check input for validity.
529		609
530	=back	610	=back
531		611
		612
		613	=head2 JSON and YAML
		614
		615	You often hear that JSON is a subset (or a close subset) of YAML. This is,
		616	however, a mass hysteria and very far from the truth. In general, there is
		617	no way to configure JSON::XS to output a data structure as valid YAML.
		618
		619	If you really must use JSON::XS to generate YAML, you should use this
		620	algorithm (subject to change in future versions):
		621
		622	my $to_yaml = JSON::XS->new->utf8->space_after (1);
		623	my $yaml = $to_yaml->encode ($ref) . "\n";
		624
		625	This will usually generate JSON texts that also parse as valid
		626	YAML. Please note that YAML has hardcoded limits on (simple) object key
		627	lengths that JSON doesn't have, so you should make sure that your hash
		628	keys are noticably shorter than the 1024 characters YAML allows.
		629
		630	There might be other incompatibilities that I am not aware of. In general
		631	you should not try to generate YAML with a JSON generator or vice versa,
		632	or try to parse JSON with a YAML parser or vice versa: chances are high
		633	that you will run into severe interoperability problems.
		634
		635
532	=head2 SPEED	636	=head2 SPEED
533		637
534	It seems that JSON::XS is surprisingly fast, as shown in the following	638	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	639	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	640	in the JSON::XS distribution, to make it easy to compare on your own
537	system.	641	system.
538		642
539	First comes a comparison between various modules using a very short JSON	643	First comes a comparison between various modules using a very short
540	string:	644	single-line JSON string:
541		645
542	{"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null}	646	{"method": "handleMessage", "params": ["user1", "we were just talking"], \
		647	"id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
543		648
544	It shows the number of encodes/decodes per second (JSON::XS uses the	649	It shows the number of encodes/decodes per second (JSON::XS uses
545	functional interface, while JSON::XS/2 uses the OO interface with	650	the functional interface, while JSON::XS/2 uses the OO interface
546	pretty-printing and hashkey sorting enabled). Higher is better:	651	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
		652	shrink). Higher is better:
547		653
548	module \| encode \| decode \|	654	module \| encode \| decode \|
549	-----------\|------------\|------------\|	655	-----------\|------------\|------------\|
550	JSON \| 11488.516 \| 7823.035 \|	656	JSON \| 7645.468 \| 4208.613 \|
551	JSON::DWIW \| 94708.054 \| 129094.260 \|	657	JSON::DWIW \| 40721.398 \| 77101.176 \|
552	JSON::PC \| 63884.157 \| 128528.212 \|	658	JSON::PC \| 65948.176 \| 78251.940 \|
553	JSON::Syck \| 34898.677 \| 42096.911 \|	659	JSON::Syck \| 22844.793 \| 26479.192 \|
554	JSON::XS \| 654027.064 \| 396423.669 \|	660	JSON::XS \| 388361.481 \| 199728.762 \|
555	JSON::XS/2 \| 371564.190 \| 371725.613 \|	661	JSON::XS/2 \| 218453.333 \| 192399.266 \|
		662	JSON::XS/3 \| 338250.323 \| 192399.266 \|
		663	Storable \| 15779.925 \| 14169.946 \|
556	-----------+------------+------------+	664	-----------+------------+------------+
557		665
558	That is, JSON::XS is more than six times faster than JSON::DWIW on	666	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	667	about three times faster on decoding, and over fourty times faster
560	faster than JSON, even with pretty-printing and key sorting.	668	than JSON, even with pretty-printing and key sorting. It also compares
		669	favourably to Storable for small amounts of data.
561		670
562	Using a longer test string (roughly 18KB, generated from Yahoo! Locals	671	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
563	search API (http://nanoref.com/yahooapis/mgPdGg):	672	search API (http://nanoref.com/yahooapis/mgPdGg):
564		673
565	module \| encode \| decode \|	674	module \| encode \| decode \|
566	-----------\|------------\|------------\|	675	-----------\|------------\|------------\|
567	JSON \| 273.023 \| 44.674 \|	676	JSON \| 254.685 \| 37.665 \|
568	JSON::DWIW \| 1089.383 \| 1145.704 \|	677	JSON::DWIW \| 843.343 \| 1049.731 \|
569	JSON::PC \| 3097.419 \| 2393.921 \|	678	JSON::PC \| 3602.116 \| 2307.352 \|
570	JSON::Syck \| 514.060 \| 843.053 \|	679	JSON::Syck \| 505.107 \| 787.899 \|
571	JSON::XS \| 6479.668 \| 3636.364 \|	680	JSON::XS \| 5747.196 \| 3690.220 \|
572	JSON::XS/2 \| 3774.221 \| 3599.124 \|	681	JSON::XS/2 \| 3968.121 \| 3676.634 \|
		682	JSON::XS/3 \| 6105.246 \| 3662.508 \|
		683	Storable \| 4417.337 \| 5285.161 \|
573	-----------+------------+------------+	684	-----------+------------+------------+
574		685
575	Again, JSON::XS leads by far.	686	Again, JSON::XS leads by far (except for Storable which non-surprisingly
		687	decodes faster).
576		688
577	On large strings containing lots of high unicode characters, some modules	689	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	690	(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	691	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	692	to decode or encode properly, so it was impossible to prepare a fair
581	comparison table for that case.	693	comparison table for that case.
582		694
583	=head1 RESOURCE LIMITS
584		695
585	JSON::XS does not impose any limits on the size of JSON texts or Perl	696	=head1 SECURITY CONSIDERATIONS
586	values they represent - if your machine can handle it, JSON::XS will	697
587	encode or decode it. Future versions might optionally impose structure	698	When you are using JSON in a protocol, talking to untrusted potentially
588	depth and memory use resource limits.	699	hostile creatures requires relatively few measures.
		700
		701	First of all, your JSON decoder should be secure, that is, should not have
		702	any buffer overflows. Obviously, this module should ensure that and I am
		703	trying hard on making that true, but you never know.
		704
		705	Second, you need to avoid resource-starving attacks. That means you should
		706	limit the size of JSON texts you accept, or make sure then when your
		707	resources run out, thats just fine (e.g. by using a separate process that
		708	can crash safely). The size of a JSON text in octets or characters is
		709	usually a good indication of the size of the resources required to decode
		710	it into a Perl structure.
		711
		712	Third, JSON::XS recurses using the C stack when decoding objects and
		713	arrays. The C stack is a limited resource: for instance, on my amd64
		714	machine with 8MB of stack size I can decode around 180k nested arrays but
		715	only 14k nested JSON objects (due to perl itself recursing deeply on croak
		716	to free the temporary). If that is exceeded, the program crashes. to be
		717	conservative, the default nesting limit is set to 512. If your process
		718	has a smaller stack, you should adjust this setting accordingly with the
		719	C<max_depth> method.
		720
		721	And last but least, something else could bomb you that I forgot to think
		722	of. In that case, you get to keep the pieces. I am always open for hints,
		723	though...
		724
589		725
590	=head1 BUGS	726	=head1 BUGS
591		727
592	While the goal of this module is to be correct, that unfortunately does	728	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	729	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	730	still relatively early in its development. If you keep reporting bugs they
595	be fixed swiftly, though.	731	will be fixed swiftly, though.
596		732
597	=cut	733	=cut
		734
		735	sub true() { \1 }
		736	sub false() { \0 }
598		737
599	1;	738	1;
600		739
601	=head1 AUTHOR	740	=head1 AUTHOR
602		741

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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 1.41 by root, Mon Jun 11 03:45:26 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 1.41 by root, Mon Jun 11 03:45:26 2007 UTC