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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.44 by root, Mon Jun 25 04:08:17 2007 UTC vs.
Revision 1.62 by root, Thu Oct 11 22:52:52 2007 UTC

…		…
		1	=encoding utf-8
		2
1	=head1 NAME	3	=head1 NAME
2		4
3	JSON::XS - JSON serialising/deserialising, done correctly and fast	5	JSON::XS - JSON serialising/deserialising, done correctly and fast
		6
		7	JSON::XS - 正しくて高速な JSON シリアライザ/デシリアライザ
		8	(http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html)
4		9
5	=head1 SYNOPSIS	10	=head1 SYNOPSIS
6		11
7	use JSON::XS;	12	use JSON::XS;
8		13
9	# exported functions, they croak on error	14	# exported functions, they croak on error
10	# and expect/generate UTF-8	15	# and expect/generate UTF-8
11		16
12	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;	17	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;
13	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;	18	$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		19
19	# OO-interface	20	# OO-interface
20		21
21	$coder = JSON::XS->new->ascii->pretty->allow_nonref;	22	$coder = JSON::XS->new->ascii->pretty->allow_nonref;
22	$pretty_printed_unencoded = $coder->encode ($perl_scalar);	23	$pretty_printed_unencoded = $coder->encode ($perl_scalar);
85		86
86	package JSON::XS;	87	package JSON::XS;
87		88
88	use strict;	89	use strict;
89		90
90	our $VERSION = '1.4';	91	our $VERSION = '1.5';
91	our @ISA = qw(Exporter);	92	our @ISA = qw(Exporter);
92		93
93	our @EXPORT = qw(to_json from_json objToJson jsonToObj);	94	our @EXPORT = qw(to_json from_json);
94		95
95	use Exporter;	96	use Exporter;
96	use XSLoader;	97	use XSLoader;
97		98
98	=head1 FUNCTIONAL INTERFACE	99	=head1 FUNCTIONAL INTERFACE
…		…
282		283
283	Example, space_before and indent disabled, space_after enabled:	284	Example, space_before and indent disabled, space_after enabled:
284		285
285	{"key": "value"}	286	{"key": "value"}
286		287
		288	=item $json = $json->relaxed ([$enable])
		289
		290	If C<$enable> is true (or missing), then C<decode> will accept some
		291	extensions to normal JSON syntax (see below). C<encode> will not be
		292	affected in anyway. I<Be aware that this option makes you accept invalid
		293	JSON texts as if they were valid!>. I suggest only to use this option to
		294	parse application-specific files written by humans (configuration files,
		295	resource files etc.)
		296
		297	If C<$enable> is false (the default), then C<decode> will only accept
		298	valid JSON texts.
		299
		300	Currently accepted extensions are:
		301
		302	=over 4
		303
		304	=item * list items can have an end-comma
		305
		306	JSON I<separates> array elements and key-value pairs with commas. This
		307	can be annoying if you write JSON texts manually and want to be able to
		308	quickly append elements, so this extension accepts comma at the end of
		309	such items not just between them:
		310
		311	[
		312	1,
		313	2, <- this comma not normally allowed
		314	]
		315	{
		316	"k1": "v1",
		317	"k2": "v2", <- this comma not normally allowed
		318	}
		319
		320	=item * shell-style '#'-comments
		321
		322	Whenever JSON allows whitespace, shell-style comments are additionally
		323	allowed. They are terminated by the first carriage-return or line-feed
		324	character, after which more white-space and comments are allowed.
		325
		326	[
		327	1, # this comment not allowed in JSON
		328	# neither this one...
		329	]
		330
		331	=back
		332
287	=item $json = $json->canonical ([$enable])	333	=item $json = $json->canonical ([$enable])
288		334
289	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects	335	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
290	by sorting their keys. This is adding a comparatively high overhead.	336	by sorting their keys. This is adding a comparatively high overhead.
291		337
…		…
341		387
342	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>	388	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	389	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	390	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	391	(== crash) in this case. The name of C<TO_JSON> was chosen because other
346	methods called by the Perl core (== not the user of the object) are	392	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>	393	usually in upper case letters and to avoid collisions with the C<to_json>
348	function.	394	function.
349		395
		396	This setting does not yet influence C<decode> in any way, but in the
		397	future, global hooks might get installed that influence C<decode> and are
		398	enabled by this setting.
		399
350	If C<$enable> is false, then the C<allow_blessed> setting will decide what	400	If C<$enable> is false, then the C<allow_blessed> setting will decide what
351	to do when a blessed object is found.	401	to do when a blessed object is found.
		402
		403	=item $json = $json->filter_json_object ([$coderef->($hashref)])
		404
		405	When C<$coderef> is specified, it will be called from C<decode> each
		406	time it decodes a JSON object. The only argument is a reference to the
		407	newly-created hash. If the code references returns a single scalar (which
		408	need not be a reference), this value (i.e. a copy of that scalar to avoid
		409	aliasing) is inserted into the deserialised data structure. If it returns
		410	an empty list (NOTE: I<not> C<undef>, which is a valid scalar), the
		411	original deserialised hash will be inserted. This setting can slow down
		412	decoding considerably.
		413
		414	When C<$coderef> is omitted or undefined, any existing callback will
		415	be removed and C<decode> will not change the deserialised hash in any
		416	way.
		417
		418	Example, convert all JSON objects into the integer 5:
		419
		420	my $js = JSON::XS->new->filter_json_object (sub { 5 });
		421	# returns [5]
		422	$js->decode ('[{}]')
		423	# throw an exception because allow_nonref is not enabled
		424	# so a lone 5 is not allowed.
		425	$js->decode ('{"a":1, "b":2}');
		426
		427	=item $json = $json->filter_json_single_key_object ($key [=> $coderef->($value)])
		428
		429	Works remotely similar to C<filter_json_object>, but is only called for
		430	JSON objects having a single key named C<$key>.
		431
		432	This C<$coderef> is called before the one specified via
		433	C<filter_json_object>, if any. It gets passed the single value in the JSON
		434	object. If it returns a single value, it will be inserted into the data
		435	structure. If it returns nothing (not even C<undef> but the empty list),
		436	the callback from C<filter_json_object> will be called next, as if no
		437	single-key callback were specified.
		438
		439	If C<$coderef> is omitted or undefined, the corresponding callback will be
		440	disabled. There can only ever be one callback for a given key.
		441
		442	As this callback gets called less often then the C<filter_json_object>
		443	one, decoding speed will not usually suffer as much. Therefore, single-key
		444	objects make excellent targets to serialise Perl objects into, especially
		445	as single-key JSON objects are as close to the type-tagged value concept
		446	as JSON gets (its basically an ID/VALUE tuple). Of course, JSON does not
		447	support this in any way, so you need to make sure your data never looks
		448	like a serialised Perl hash.
		449
		450	Typical names for the single object key are C<__class_whatever__>, or
		451	C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even
		452	things like C<__class_md5sum(classname)__>, to reduce the risk of clashing
		453	with real hashes.
		454
		455	Example, decode JSON objects of the form C<< { "__widget__" => <id> } >>
		456	into the corresponding C<< $WIDGET{<id>} >> object:
		457
		458	# return whatever is in $WIDGET{5}:
		459	JSON::XS
		460	->new
		461	->filter_json_single_key_object (__widget__ => sub {
		462	$WIDGET{ $_[0] }
		463	})
		464	->decode ('{"__widget__": 5')
		465
		466	# this can be used with a TO_JSON method in some "widget" class
		467	# for serialisation to json:
		468	sub WidgetBase::TO_JSON {
		469	my ($self) = @_;
		470
		471	unless ($self->{id}) {
		472	$self->{id} = ..get..some..id..;
		473	$WIDGET{$self->{id}} = $self;
		474	}
		475
		476	{ __widget__ => $self->{id} }
		477	}
352		478
353	=item $json = $json->shrink ([$enable])	479	=item $json = $json->shrink ([$enable])
354		480
355	Perl usually over-allocates memory a bit when allocating space for	481	Perl usually over-allocates memory a bit when allocating space for
356	strings. This flag optionally resizes strings generated by either	482	strings. This flag optionally resizes strings generated by either
…		…
389	given character in a string.	515	given character in a string.
390		516
391	Setting the maximum depth to one disallows any nesting, so that ensures	517	Setting the maximum depth to one disallows any nesting, so that ensures
392	that the object is only a single hash/object or array.	518	that the object is only a single hash/object or array.
393		519
394	The argument to C<max_depth> will be rounded up to the next nearest power	520	The argument to C<max_depth> will be rounded up to the next highest power
395	of two.	521	of two. If no argument is given, the highest possible setting will be
		522	used, which is rarely useful.
		523
		524	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
		525
		526	=item $json = $json->max_size ([$maximum_string_size])
		527
		528	Set the maximum length a JSON text may have (in bytes) where decoding is
		529	being attempted. The default is C<0>, meaning no limit. When C<decode>
		530	is called on a string longer then this number of characters it will not
		531	attempt to decode the string but throw an exception. This setting has no
		532	effect on C<encode> (yet).
		533
		534	The argument to C<max_size> will be rounded up to the next B<highest>
		535	power of two (so may be more than requested). If no argument is given, the
		536	limit check will be deactivated (same as when C<0> is specified).
396		537
397	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	538	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
398		539
399	=item $json_text = $json->encode ($perl_scalar)	540	=item $json_text = $json->encode ($perl_scalar)
400		541
…		…
462	are represented by the same codepoints in the Perl string, so no manual	603	are represented by the same codepoints in the Perl string, so no manual
463	decoding is necessary.	604	decoding is necessary.
464		605
465	=item number	606	=item number
466		607
467	A JSON number becomes either an integer or numeric (floating point)	608	A JSON number becomes either an integer, numeric (floating point) or
468	scalar in perl, depending on its range and any fractional parts. On the	609	string scalar in perl, depending on its range and any fractional parts. On
469	Perl level, there is no difference between those as Perl handles all the	610	the Perl level, there is no difference between those as Perl handles all
470	conversion details, but an integer may take slightly less memory and might	611	the conversion details, but an integer may take slightly less memory and
471	represent more values exactly than (floating point) numbers.	612	might represent more values exactly than (floating point) numbers.
		613
		614	If the number consists of digits only, JSON::XS will try to represent
		615	it as an integer value. If that fails, it will try to represent it as
		616	a numeric (floating point) value if that is possible without loss of
		617	precision. Otherwise it will preserve the number as a string value.
		618
		619	Numbers containing a fractional or exponential part will always be
		620	represented as numeric (floating point) values, possibly at a loss of
		621	precision.
		622
		623	This might create round-tripping problems as numbers might become strings,
		624	but as Perl is typeless there is no other way to do it.
472		625
473	=item true, false	626	=item true, false
474		627
475	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,	628	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
476	respectively. They are overloaded to act almost exactly like the numbers	629	respectively. They are overloaded to act almost exactly like the numbers
…		…
518	to_json [\0,JSON::XS::true] # yields [false,true]	671	to_json [\0,JSON::XS::true] # yields [false,true]
519		672
520	=item JSON::XS::true, JSON::XS::false	673	=item JSON::XS::true, JSON::XS::false
521		674
522	These special values become JSON true and JSON false values,	675	These special values become JSON true and JSON false values,
523	respectively. You cna alos use C<\1> and C<\0> directly if you want.	676	respectively. You can also use C<\1> and C<\0> directly if you want.
524		677
525	=item blessed objects	678	=item blessed objects
526		679
527	Blessed objects are not allowed. JSON::XS currently tries to encode their	680	Blessed objects are not allowed. JSON::XS currently tries to encode their
528	underlying representation (hash- or arrayref), but this behaviour might	681	underlying representation (hash- or arrayref), but this behaviour might
…		…
692	It shows the number of encodes/decodes per second (JSON::XS uses	845	It shows the number of encodes/decodes per second (JSON::XS uses
693	the functional interface, while JSON::XS/2 uses the OO interface	846	the functional interface, while JSON::XS/2 uses the OO interface
694	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables	847	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
695	shrink). Higher is better:	848	shrink). Higher is better:
696		849
		850	Storable \| 15779.925 \| 14169.946 \|
		851	-----------+------------+------------+
697	module \| encode \| decode \|	852	module \| encode \| decode \|
698	-----------\|------------\|------------\|	853	-----------\|------------\|------------\|
699	JSON \| 7645.468 \| 4208.613 \|	854	JSON \| 4990.842 \| 4088.813 \|
700	JSON::DWIW \| 40721.398 \| 77101.176 \|	855	JSON::DWIW \| 51653.990 \| 71575.154 \|
701	JSON::PC \| 65948.176 \| 78251.940 \|	856	JSON::PC \| 65948.176 \| 74631.744 \|
702	JSON::Syck \| 22844.793 \| 26479.192 \|	857	JSON::PP \| 8931.652 \| 3817.168 \|
		858	JSON::Syck \| 24877.248 \| 27776.848 \|
703	JSON::XS \| 388361.481 \| 199728.762 \|	859	JSON::XS \| 388361.481 \| 227951.304 \|
704	JSON::XS/2 \| 218453.333 \| 192399.266 \|	860	JSON::XS/2 \| 227951.304 \| 218453.333 \|
705	JSON::XS/3 \| 338250.323 \| 192399.266 \|	861	JSON::XS/3 \| 338250.323 \| 218453.333 \|
706	Storable \| 15779.925 \| 14169.946 \|	862	Storable \| 16500.016 \| 135300.129 \|
707	-----------+------------+------------+	863	-----------+------------+------------+
708		864
709	That is, JSON::XS is about five times faster than JSON::DWIW on encoding,	865	That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
710	about three times faster on decoding, and over fourty times faster	866	about three times faster on decoding, and over fourty times faster
711	than JSON, even with pretty-printing and key sorting. It also compares	867	than JSON, even with pretty-printing and key sorting. It also compares
…		…
714	Using a longer test string (roughly 18KB, generated from Yahoo! Locals	870	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
715	search API (http://nanoref.com/yahooapis/mgPdGg):	871	search API (http://nanoref.com/yahooapis/mgPdGg):
716		872
717	module \| encode \| decode \|	873	module \| encode \| decode \|
718	-----------\|------------\|------------\|	874	-----------\|------------\|------------\|
719	JSON \| 254.685 \| 37.665 \|	875	JSON \| 55.260 \| 34.971 \|
720	JSON::DWIW \| 843.343 \| 1049.731 \|	876	JSON::DWIW \| 825.228 \| 1082.513 \|
721	JSON::PC \| 3602.116 \| 2307.352 \|	877	JSON::PC \| 3571.444 \| 2394.829 \|
		878	JSON::PP \| 210.987 \| 32.574 \|
722	JSON::Syck \| 505.107 \| 787.899 \|	879	JSON::Syck \| 552.551 \| 787.544 \|
723	JSON::XS \| 5747.196 \| 3690.220 \|	880	JSON::XS \| 5780.463 \| 4854.519 \|
724	JSON::XS/2 \| 3968.121 \| 3676.634 \|	881	JSON::XS/2 \| 3869.998 \| 4798.975 \|
725	JSON::XS/3 \| 6105.246 \| 3662.508 \|	882	JSON::XS/3 \| 5862.880 \| 4798.975 \|
726	Storable \| 4417.337 \| 5285.161 \|	883	Storable \| 4445.002 \| 5235.027 \|
727	-----------+------------+------------+	884	-----------+------------+------------+
728		885
729	Again, JSON::XS leads by far (except for Storable which non-surprisingly	886	Again, JSON::XS leads by far (except for Storable which non-surprisingly
730	decodes faster).	887	decodes faster).
731		888
…		…
748	Second, you need to avoid resource-starving attacks. That means you should	905	Second, you need to avoid resource-starving attacks. That means you should
749	limit the size of JSON texts you accept, or make sure then when your	906	limit the size of JSON texts you accept, or make sure then when your
750	resources run out, thats just fine (e.g. by using a separate process that	907	resources run out, thats just fine (e.g. by using a separate process that
751	can crash safely). The size of a JSON text in octets or characters is	908	can crash safely). The size of a JSON text in octets or characters is
752	usually a good indication of the size of the resources required to decode	909	usually a good indication of the size of the resources required to decode
753	it into a Perl structure.	910	it into a Perl structure. While JSON::XS can check the size of the JSON
		911	text, it might be too late when you already have it in memory, so you
		912	might want to check the size before you accept the string.
754		913
755	Third, JSON::XS recurses using the C stack when decoding objects and	914	Third, JSON::XS recurses using the C stack when decoding objects and
756	arrays. The C stack is a limited resource: for instance, on my amd64	915	arrays. The C stack is a limited resource: for instance, on my amd64
757	machine with 8MB of stack size I can decode around 180k nested arrays but	916	machine with 8MB of stack size I can decode around 180k nested arrays but
758	only 14k nested JSON objects (due to perl itself recursing deeply on croak	917	only 14k nested JSON objects (due to perl itself recursing deeply on croak

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Comparing JSON-XS/XS.pm (file contents): Revision 1.44 by root, Mon Jun 25 04:08:17 2007 UTC vs. Revision 1.62 by root, Thu Oct 11 22:52:52 2007 UTC

Diff Legend

Comparing JSON-XS/XS.pm (file contents):
Revision 1.44 by root, Mon Jun 25 04:08:17 2007 UTC vs.
Revision 1.62 by root, Thu Oct 11 22:52:52 2007 UTC