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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.73 by root, Sun Nov 25 19:36:54 2007 UTC vs.
Revision 1.111 by root, Mon Jul 21 02:45:17 2008 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	JSON::XS - JSON serialising/deserialising, done correctly and fast	3	JSON::XS - JSON serialising/deserialising, done correctly and fast
		4
		5	=encoding utf-8
4		6
5	JSON::XS - 正しくて高速な JSON シリアライザ/デシリアライザ	7	JSON::XS - 正しくて高速な JSON シリアライザ/デシリアライザ
6	(http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html)	8	(http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html)
7		9
8	=head1 SYNOPSIS	10	=head1 SYNOPSIS
10	use JSON::XS;	12	use JSON::XS;
11		13
12	# exported functions, they croak on error	14	# exported functions, they croak on error
13	# and expect/generate UTF-8	15	# and expect/generate UTF-8
14		16
15	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;	17	$utf8_encoded_json_text = encode_json $perl_hash_or_arrayref;
16	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;	18	$perl_hash_or_arrayref = decode_json $utf8_encoded_json_text;
17		19
18	# OO-interface	20	# OO-interface
19		21
20	$coder = JSON::XS->new->ascii->pretty->allow_nonref;	22	$coder = JSON::XS->new->ascii->pretty->allow_nonref;
21	$pretty_printed_unencoded = $coder->encode ($perl_scalar);	23	$pretty_printed_unencoded = $coder->encode ($perl_scalar);
22	$perl_scalar = $coder->decode ($unicode_json_text);	24	$perl_scalar = $coder->decode ($unicode_json_text);
23		25
		26	# Note that JSON version 2.0 and above will automatically use JSON::XS
		27	# if available, at virtually no speed overhead either, so you should
		28	# be able to just:
		29
		30	use JSON;
		31
		32	# and do the same things, except that you have a pure-perl fallback now.
		33
24	=head1 DESCRIPTION	34	=head1 DESCRIPTION
25		35
26	This module converts Perl data structures to JSON and vice versa. Its	36	This module converts Perl data structures to JSON and vice versa. Its
27	primary goal is to be I<correct> and its secondary goal is to be	37	primary goal is to be I<correct> and its secondary goal is to be
28	I<fast>. To reach the latter goal it was written in C.	38	I<fast>. To reach the latter goal it was written in C.
		39
		40	Beginning with version 2.0 of the JSON module, when both JSON and
		41	JSON::XS are installed, then JSON will fall back on JSON::XS (this can be
		42	overridden) with no overhead due to emulation (by inheriting constructor
		43	and methods). If JSON::XS is not available, it will fall back to the
		44	compatible JSON::PP module as backend, so using JSON instead of JSON::XS
		45	gives you a portable JSON API that can be fast when you need and doesn't
		46	require a C compiler when that is a problem.
29		47
30	As this is the n-th-something JSON module on CPAN, what was the reason	48	As this is the n-th-something JSON module on CPAN, what was the reason
31	to write yet another JSON module? While it seems there are many JSON	49	to write yet another JSON module? While it seems there are many JSON
32	modules, none of them correctly handle all corner cases, and in most cases	50	modules, none of them correctly handle all corner cases, and in most cases
33	their maintainers are unresponsive, gone missing, or not listening to bug	51	their maintainers are unresponsive, gone missing, or not listening to bug
34	reports for other reasons.	52	reports for other reasons.
35		53
36	See COMPARISON, below, for a comparison to some other JSON modules.
37
38	See MAPPING, below, on how JSON::XS maps perl values to JSON values and	54	See MAPPING, below, on how JSON::XS maps perl values to JSON values and
39	vice versa.	55	vice versa.
40		56
41	=head2 FEATURES	57	=head2 FEATURES
42		58
43	=over 4	59	=over 4
44		60
45	=item * correct Unicode handling	61	=item * correct Unicode handling
46		62
47	This module knows how to handle Unicode, and even documents how and when	63	This module knows how to handle Unicode, documents how and when it does
48	it does so.	64	so, and even documents what "correct" means.
49		65
50	=item * round-trip integrity	66	=item * round-trip integrity
51		67
52	When you serialise a perl data structure using only datatypes supported	68	When you serialise a perl data structure using only data types supported
53	by JSON, the deserialised data structure is identical on the Perl level.	69	by JSON, the deserialised data structure is identical on the Perl level.
54	(e.g. the string "2.0" doesn't suddenly become "2" just because it looks	70	(e.g. the string "2.0" doesn't suddenly become "2" just because it looks
55	like a number).	71	like a number). There minor I<are> exceptions to this, read the MAPPING
		72	section below to learn about those.
56		73
57	=item * strict checking of JSON correctness	74	=item * strict checking of JSON correctness
58		75
59	There is no guessing, no generating of illegal JSON texts by default,	76	There is no guessing, no generating of illegal JSON texts by default,
60	and only JSON is accepted as input by default (the latter is a security	77	and only JSON is accepted as input by default (the latter is a security
61	feature).	78	feature).
62		79
63	=item * fast	80	=item * fast
64		81
65	Compared to other JSON modules, this module compares favourably in terms	82	Compared to other JSON modules and other serialisers such as Storable,
66	of speed, too.	83	this module usually compares favourably in terms of speed, too.
67		84
68	=item * simple to use	85	=item * simple to use
69		86
70	This module has both a simple functional interface as well as an OO	87	This module has both a simple functional interface as well as an object
71	interface.	88	oriented interface interface.
72		89
73	=item * reasonably versatile output formats	90	=item * reasonably versatile output formats
74		91
75	You can choose between the most compact guaranteed single-line format	92	You can choose between the most compact guaranteed-single-line format
76	possible (nice for simple line-based protocols), a pure-ascii format	93	possible (nice for simple line-based protocols), a pure-ASCII format
77	(for when your transport is not 8-bit clean, still supports the whole	94	(for when your transport is not 8-bit clean, still supports the whole
78	Unicode range), or a pretty-printed format (for when you want to read that	95	Unicode range), or a pretty-printed format (for when you want to read that
79	stuff). Or you can combine those features in whatever way you like.	96	stuff). Or you can combine those features in whatever way you like.
80		97
81	=back	98	=back
82		99
83	=cut	100	=cut
84		101
85	package JSON::XS;	102	package JSON::XS;
86		103
		104	no warnings;
87	use strict;	105	use strict;
88		106
89	our $VERSION = '1.6';	107	our $VERSION = '2.2222';
90	our @ISA = qw(Exporter);	108	our @ISA = qw(Exporter);
91		109
92	our @EXPORT = qw(to_json from_json);	110	our @EXPORT = qw(encode_json decode_json to_json from_json);
		111
		112	sub to_json($) {
		113	require Carp;
		114	Carp::croak ("JSON::XS::to_json has been renamed to encode_json, either downgrade to pre-2.0 versions of JSON::XS or rename the call");
		115	}
		116
		117	sub from_json($) {
		118	require Carp;
		119	Carp::croak ("JSON::XS::from_json has been renamed to decode_json, either downgrade to pre-2.0 versions of JSON::XS or rename the call");
		120	}
93		121
94	use Exporter;	122	use Exporter;
95	use XSLoader;	123	use XSLoader;
96		124
97	=head1 FUNCTIONAL INTERFACE	125	=head1 FUNCTIONAL INTERFACE
…		…
99	The following convenience methods are provided by this module. They are	127	The following convenience methods are provided by this module. They are
100	exported by default:	128	exported by default:
101		129
102	=over 4	130	=over 4
103		131
104	=item $json_text = to_json $perl_scalar	132	=item $json_text = encode_json $perl_scalar
105		133
106	Converts the given Perl data structure to a UTF-8 encoded, binary string	134	Converts the given Perl data structure to a UTF-8 encoded, binary string
107	(that is, the string contains octets only). Croaks on error.	135	(that is, the string contains octets only). Croaks on error.
108		136
109	This function call is functionally identical to:	137	This function call is functionally identical to:
110		138
111	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)	139	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)
112		140
113	except being faster.	141	Except being faster.
114		142
115	=item $perl_scalar = from_json $json_text	143	=item $perl_scalar = decode_json $json_text
116		144
117	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries	145	The opposite of C<encode_json>: expects an UTF-8 (binary) string and tries
118	to parse that as an UTF-8 encoded JSON text, returning the resulting	146	to parse that as an UTF-8 encoded JSON text, returning the resulting
119	reference. Croaks on error.	147	reference. Croaks on error.
120		148
121	This function call is functionally identical to:	149	This function call is functionally identical to:
122		150
123	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)	151	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
124		152
125	except being faster.	153	Except being faster.
126		154
127	=item $is_boolean = JSON::XS::is_bool $scalar	155	=item $is_boolean = JSON::XS::is_bool $scalar
128		156
129	Returns true if the passed scalar represents either JSON::XS::true or	157	Returns true if the passed scalar represents either JSON::XS::true or
130	JSON::XS::false, two constants that act like C<1> and C<0>, respectively	158	JSON::XS::false, two constants that act like C<1> and C<0>, respectively
…		…
148	This enables you to store Unicode characters as single characters in a	176	This enables you to store Unicode characters as single characters in a
149	Perl string - very natural.	177	Perl string - very natural.
150		178
151	=item 2. Perl does I<not> associate an encoding with your strings.	179	=item 2. Perl does I<not> associate an encoding with your strings.
152		180
153	Unless you force it to, e.g. when matching it against a regex, or printing	181	... until you force it to, e.g. when matching it against a regex, or
154	the scalar to a file, in which case Perl either interprets your string as	182	printing the scalar to a file, in which case Perl either interprets your
155	locale-encoded text, octets/binary, or as Unicode, depending on various	183	string as locale-encoded text, octets/binary, or as Unicode, depending
156	settings. In no case is an encoding stored together with your data, it is	184	on various settings. In no case is an encoding stored together with your
157	I<use> that decides encoding, not any magical metadata.	185	data, it is I<use> that decides encoding, not any magical meta data.
158		186
159	=item 3. The internal utf-8 flag has no meaning with regards to the	187	=item 3. The internal utf-8 flag has no meaning with regards to the
160	encoding of your string.	188	encoding of your string.
161		189
162	Just ignore that flag unless you debug a Perl bug, a module written in	190	Just ignore that flag unless you debug a Perl bug, a module written in
…		…
168		196
169	If you didn't know about that flag, just the better, pretend it doesn't	197	If you didn't know about that flag, just the better, pretend it doesn't
170	exist.	198	exist.
171		199
172	=item 4. A "Unicode String" is simply a string where each character can be	200	=item 4. A "Unicode String" is simply a string where each character can be
173	validly interpreted as a Unicode codepoint.	201	validly interpreted as a Unicode code point.
174		202
175	If you have UTF-8 encoded data, it is no longer a Unicode string, but a	203	If you have UTF-8 encoded data, it is no longer a Unicode string, but a
176	Unicode string encoded in UTF-8, giving you a binary string.	204	Unicode string encoded in UTF-8, giving you a binary string.
177		205
178	=item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string.	206	=item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string.
…		…
216		244
217	If C<$enable> is false, then the C<encode> method will not escape Unicode	245	If C<$enable> is false, then the C<encode> method will not escape Unicode
218	characters unless required by the JSON syntax or other flags. This results	246	characters unless required by the JSON syntax or other flags. This results
219	in a faster and more compact format.	247	in a faster and more compact format.
220		248
		249	See also the section I<ENCODING/CODESET FLAG NOTES> later in this
		250	document.
		251
221	The main use for this flag is to produce JSON texts that can be	252	The main use for this flag is to produce JSON texts that can be
222	transmitted over a 7-bit channel, as the encoded JSON texts will not	253	transmitted over a 7-bit channel, as the encoded JSON texts will not
223	contain any 8 bit characters.	254	contain any 8 bit characters.
224		255
225	JSON::XS->new->ascii (1)->encode ([chr 0x10401])	256	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
…		…
236	will not be affected in any way by this flag, as C<decode> by default	267	will not be affected in any way by this flag, as C<decode> by default
237	expects Unicode, which is a strict superset of latin1.	268	expects Unicode, which is a strict superset of latin1.
238		269
239	If C<$enable> is false, then the C<encode> method will not escape Unicode	270	If C<$enable> is false, then the C<encode> method will not escape Unicode
240	characters unless required by the JSON syntax or other flags.	271	characters unless required by the JSON syntax or other flags.
		272
		273	See also the section I<ENCODING/CODESET FLAG NOTES> later in this
		274	document.
241		275
242	The main use for this flag is efficiently encoding binary data as JSON	276	The main use for this flag is efficiently encoding binary data as JSON
243	text, as most octets will not be escaped, resulting in a smaller encoded	277	text, as most octets will not be escaped, resulting in a smaller encoded
244	size. The disadvantage is that the resulting JSON text is encoded	278	size. The disadvantage is that the resulting JSON text is encoded
245	in latin1 (and must correctly be treated as such when storing and	279	in latin1 (and must correctly be treated as such when storing and
…		…
265	If C<$enable> is false, then the C<encode> method will return the JSON	299	If C<$enable> is false, then the C<encode> method will return the JSON
266	string as a (non-encoded) Unicode string, while C<decode> expects thus a	300	string as a (non-encoded) Unicode string, while C<decode> expects thus a
267	Unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs	301	Unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs
268	to be done yourself, e.g. using the Encode module.	302	to be done yourself, e.g. using the Encode module.
269		303
		304	See also the section I<ENCODING/CODESET FLAG NOTES> later in this
		305	document.
		306
270	Example, output UTF-16BE-encoded JSON:	307	Example, output UTF-16BE-encoded JSON:
271		308
272	use Encode;	309	use Encode;
273	$jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);	310	$jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);
274		311
…		…
276		313
277	use Encode;	314	use Encode;
278	$object = JSON::XS->new->decode (decode "UTF-32LE", $jsontext);	315	$object = JSON::XS->new->decode (decode "UTF-32LE", $jsontext);
279		316
280	=item $json = $json->pretty ([$enable])	317	=item $json = $json->pretty ([$enable])
281
282	=item $enabled = $json->get_pretty
283		318
284	This enables (or disables) all of the C<indent>, C<space_before> and	319	This enables (or disables) all of the C<indent>, C<space_before> and
285	C<space_after> (and in the future possibly more) flags in one call to	320	C<space_after> (and in the future possibly more) flags in one call to
286	generate the most readable (or most compact) form possible.	321	generate the most readable (or most compact) form possible.
287		322
…		…
427	resulting in an invalid JSON text:	462	resulting in an invalid JSON text:
428		463
429	JSON::XS->new->allow_nonref->encode ("Hello, World!")	464	JSON::XS->new->allow_nonref->encode ("Hello, World!")
430	=> "Hello, World!"	465	=> "Hello, World!"
431		466
		467	=item $json = $json->allow_unknown ([$enable])
		468
		469	=item $enabled = $json->get_allow_unknown
		470
		471	If C<$enable> is true (or missing), then C<encode> will I<not> throw an
		472	exception when it encounters values it cannot represent in JSON (for
		473	example, filehandles) but instead will encode a JSON C<null> value. Note
		474	that blessed objects are not included here and are handled separately by
		475	c<allow_nonref>.
		476
		477	If C<$enable> is false (the default), then C<encode> will throw an
		478	exception when it encounters anything it cannot encode as JSON.
		479
		480	This option does not affect C<decode> in any way, and it is recommended to
		481	leave it off unless you know your communications partner.
		482
432	=item $json = $json->allow_blessed ([$enable])	483	=item $json = $json->allow_blessed ([$enable])
433		484
434	=item $enabled = $json->get_allow_bless	485	=item $enabled = $json->get_allow_blessed
435		486
436	If C<$enable> is true (or missing), then the C<encode> method will not	487	If C<$enable> is true (or missing), then the C<encode> method will not
437	barf when it encounters a blessed reference. Instead, the value of the	488	barf when it encounters a blessed reference. Instead, the value of the
438	B<convert_blessed> option will decide whether C<null> (C<convert_blessed>	489	B<convert_blessed> option will decide whether C<null> (C<convert_blessed>
439	disabled or no C<to_json> method found) or a representation of the	490	disabled or no C<TO_JSON> method found) or a representation of the
440	object (C<convert_blessed> enabled and C<to_json> method found) is being	491	object (C<convert_blessed> enabled and C<TO_JSON> method found) is being
441	encoded. Has no effect on C<decode>.	492	encoded. Has no effect on C<decode>.
442		493
443	If C<$enable> is false (the default), then C<encode> will throw an	494	If C<$enable> is false (the default), then C<encode> will throw an
444	exception when it encounters a blessed object.	495	exception when it encounters a blessed object.
445		496
…		…
457	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>	508	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
458	returns other blessed objects, those will be handled in the same	509	returns other blessed objects, those will be handled in the same
459	way. C<TO_JSON> must take care of not causing an endless recursion cycle	510	way. C<TO_JSON> must take care of not causing an endless recursion cycle
460	(== crash) in this case. The name of C<TO_JSON> was chosen because other	511	(== crash) in this case. The name of C<TO_JSON> was chosen because other
461	methods called by the Perl core (== not by the user of the object) are	512	methods called by the Perl core (== not by the user of the object) are
462	usually in upper case letters and to avoid collisions with the C<to_json>	513	usually in upper case letters and to avoid collisions with any C<to_json>
463	function.	514	function or method.
464		515
465	This setting does not yet influence C<decode> in any way, but in the	516	This setting does not yet influence C<decode> in any way, but in the
466	future, global hooks might get installed that influence C<decode> and are	517	future, global hooks might get installed that influence C<decode> and are
467	enabled by this setting.	518	enabled by this setting.
468		519
…		…
576	=item $json = $json->max_depth ([$maximum_nesting_depth])	627	=item $json = $json->max_depth ([$maximum_nesting_depth])
577		628
578	=item $max_depth = $json->get_max_depth	629	=item $max_depth = $json->get_max_depth
579		630
580	Sets the maximum nesting level (default C<512>) accepted while encoding	631	Sets the maximum nesting level (default C<512>) accepted while encoding
581	or decoding. If the JSON text or Perl data structure has an equal or	632	or decoding. If a higher nesting level is detected in JSON text or a Perl
582	higher nesting level then this limit, then the encoder and decoder will	633	data structure, then the encoder and decoder will stop and croak at that
583	stop and croak at that point.	634	point.
584		635
585	Nesting level is defined by number of hash- or arrayrefs that the encoder	636	Nesting level is defined by number of hash- or arrayrefs that the encoder
586	needs to traverse to reach a given point or the number of C<{> or C<[>	637	needs to traverse to reach a given point or the number of C<{> or C<[>
587	characters without their matching closing parenthesis crossed to reach a	638	characters without their matching closing parenthesis crossed to reach a
588	given character in a string.	639	given character in a string.
589		640
590	Setting the maximum depth to one disallows any nesting, so that ensures	641	Setting the maximum depth to one disallows any nesting, so that ensures
591	that the object is only a single hash/object or array.	642	that the object is only a single hash/object or array.
592		643
593	The argument to C<max_depth> will be rounded up to the next highest power
594	of two. If no argument is given, the highest possible setting will be	644	If no argument is given, the highest possible setting will be used, which
595	used, which is rarely useful.	645	is rarely useful.
		646
		647	Note that nesting is implemented by recursion in C. The default value has
		648	been chosen to be as large as typical operating systems allow without
		649	crashing.
596		650
597	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	651	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
598		652
599	=item $json = $json->max_size ([$maximum_string_size])	653	=item $json = $json->max_size ([$maximum_string_size])
600		654
601	=item $max_size = $json->get_max_size	655	=item $max_size = $json->get_max_size
602		656
603	Set the maximum length a JSON text may have (in bytes) where decoding is	657	Set the maximum length a JSON text may have (in bytes) where decoding is
604	being attempted. The default is C<0>, meaning no limit. When C<decode>	658	being attempted. The default is C<0>, meaning no limit. When C<decode>
605	is called on a string longer then this number of characters it will not	659	is called on a string that is longer then this many bytes, it will not
606	attempt to decode the string but throw an exception. This setting has no	660	attempt to decode the string but throw an exception. This setting has no
607	effect on C<encode> (yet).	661	effect on C<encode> (yet).
608		662
609	The argument to C<max_size> will be rounded up to the next B<highest>	663	If no argument is given, the limit check will be deactivated (same as when
610	power of two (so may be more than requested). If no argument is given, the	664	C<0> is specified).
611	limit check will be deactivated (same as when C<0> is specified).
612		665
613	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	666	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
614		667
615	=item $json_text = $json->encode ($perl_scalar)	668	=item $json_text = $json->encode ($perl_scalar)
616		669
…		…
645	=> ([], 3)	698	=> ([], 3)
646		699
647	=back	700	=back
648		701
649		702
		703	=head1 INCREMENTAL PARSING
		704
		705	In some cases, there is the need for incremental parsing of JSON
		706	texts. While this module always has to keep both JSON text and resulting
		707	Perl data structure in memory at one time, it does allow you to parse a
		708	JSON stream incrementally. It does so by accumulating text until it has
		709	a full JSON object, which it then can decode. This process is similar to
		710	using C<decode_prefix> to see if a full JSON object is available, but
		711	is much more efficient (and can be implemented with a minimum of method
		712	calls).
		713
		714	JSON::XS will only attempt to parse the JSON text once it is sure it
		715	has enough text to get a decisive result, using a very simple but
		716	truly incremental parser. This means that it sometimes won't stop as
		717	early as the full parser, for example, it doesn't detect parenthese
		718	mismatches. The only thing it guarantees is that it starts decoding as
		719	soon as a syntactically valid JSON text has been seen. This means you need
		720	to set resource limits (e.g. C<max_size>) to ensure the parser will stop
		721	parsing in the presence if syntax errors.
		722
		723	The following methods implement this incremental parser.
		724
		725	=over 4
		726
		727	=item [void, scalar or list context] = $json->incr_parse ([$string])
		728
		729	This is the central parsing function. It can both append new text and
		730	extract objects from the stream accumulated so far (both of these
		731	functions are optional).
		732
		733	If C<$string> is given, then this string is appended to the already
		734	existing JSON fragment stored in the C<$json> object.
		735
		736	After that, if the function is called in void context, it will simply
		737	return without doing anything further. This can be used to add more text
		738	in as many chunks as you want.
		739
		740	If the method is called in scalar context, then it will try to extract
		741	exactly I<one> JSON object. If that is successful, it will return this
		742	object, otherwise it will return C<undef>. If there is a parse error,
		743	this method will croak just as C<decode> would do (one can then use
		744	C<incr_skip> to skip the errornous part). This is the most common way of
		745	using the method.
		746
		747	And finally, in list context, it will try to extract as many objects
		748	from the stream as it can find and return them, or the empty list
		749	otherwise. For this to work, there must be no separators between the JSON
		750	objects or arrays, instead they must be concatenated back-to-back. If
		751	an error occurs, an exception will be raised as in the scalar context
		752	case. Note that in this case, any previously-parsed JSON texts will be
		753	lost.
		754
		755	=item $lvalue_string = $json->incr_text
		756
		757	This method returns the currently stored JSON fragment as an lvalue, that
		758	is, you can manipulate it. This I<only> works when a preceding call to
		759	C<incr_parse> in I<scalar context> successfully returned an object. Under
		760	all other circumstances you must not call this function (I mean it.
		761	although in simple tests it might actually work, it I<will> fail under
		762	real world conditions). As a special exception, you can also call this
		763	method before having parsed anything.
		764
		765	This function is useful in two cases: a) finding the trailing text after a
		766	JSON object or b) parsing multiple JSON objects separated by non-JSON text
		767	(such as commas).
		768
		769	=item $json->incr_skip
		770
		771	This will reset the state of the incremental parser and will remove the
		772	parsed text from the input buffer. This is useful after C<incr_parse>
		773	died, in which case the input buffer and incremental parser state is left
		774	unchanged, to skip the text parsed so far and to reset the parse state.
		775
		776	=item $json->incr_reset
		777
		778	This completely resets the incremental parser, that is, after this call,
		779	it will be as if the parser had never parsed anything.
		780
		781	This is useful if you want ot repeatedly parse JSON objects and want to
		782	ignore any trailing data, which means you have to reset the parser after
		783	each successful decode.
		784
		785	=back
		786
		787	=head2 LIMITATIONS
		788
		789	All options that affect decoding are supported, except
		790	C<allow_nonref>. The reason for this is that it cannot be made to
		791	work sensibly: JSON objects and arrays are self-delimited, i.e. you can concatenate
		792	them back to back and still decode them perfectly. This does not hold true
		793	for JSON numbers, however.
		794
		795	For example, is the string C<1> a single JSON number, or is it simply the
		796	start of C<12>? Or is C<12> a single JSON number, or the concatenation
		797	of C<1> and C<2>? In neither case you can tell, and this is why JSON::XS
		798	takes the conservative route and disallows this case.
		799
		800	=head2 EXAMPLES
		801
		802	Some examples will make all this clearer. First, a simple example that
		803	works similarly to C<decode_prefix>: We want to decode the JSON object at
		804	the start of a string and identify the portion after the JSON object:
		805
		806	my $text = "[1,2,3] hello";
		807
		808	my $json = new JSON::XS;
		809
		810	my $obj = $json->incr_parse ($text)
		811	or die "expected JSON object or array at beginning of string";
		812
		813	my $tail = $json->incr_text;
		814	# $tail now contains " hello"
		815
		816	Easy, isn't it?
		817
		818	Now for a more complicated example: Imagine a hypothetical protocol where
		819	you read some requests from a TCP stream, and each request is a JSON
		820	array, without any separation between them (in fact, it is often useful to
		821	use newlines as "separators", as these get interpreted as whitespace at
		822	the start of the JSON text, which makes it possible to test said protocol
		823	with C<telnet>...).
		824
		825	Here is how you'd do it (it is trivial to write this in an event-based
		826	manner):
		827
		828	my $json = new JSON::XS;
		829
		830	# read some data from the socket
		831	while (sysread $socket, my $buf, 4096) {
		832
		833	# split and decode as many requests as possible
		834	for my $request ($json->incr_parse ($buf)) {
		835	# act on the $request
		836	}
		837	}
		838
		839	Another complicated example: Assume you have a string with JSON objects
		840	or arrays, all separated by (optional) comma characters (e.g. C<[1],[2],
		841	[3]>). To parse them, we have to skip the commas between the JSON texts,
		842	and here is where the lvalue-ness of C<incr_text> comes in useful:
		843
		844	my $text = "[1],[2], [3]";
		845	my $json = new JSON::XS;
		846
		847	# void context, so no parsing done
		848	$json->incr_parse ($text);
		849
		850	# now extract as many objects as possible. note the
		851	# use of scalar context so incr_text can be called.
		852	while (my $obj = $json->incr_parse) {
		853	# do something with $obj
		854
		855	# now skip the optional comma
		856	$json->incr_text =~ s/^ \s* , //x;
		857	}
		858
		859	Now lets go for a very complex example: Assume that you have a gigantic
		860	JSON array-of-objects, many gigabytes in size, and you want to parse it,
		861	but you cannot load it into memory fully (this has actually happened in
		862	the real world :).
		863
		864	Well, you lost, you have to implement your own JSON parser. But JSON::XS
		865	can still help you: You implement a (very simple) array parser and let
		866	JSON decode the array elements, which are all full JSON objects on their
		867	own (this wouldn't work if the array elements could be JSON numbers, for
		868	example):
		869
		870	my $json = new JSON::XS;
		871
		872	# open the monster
		873	open my $fh, "<bigfile.json"
		874	or die "bigfile: $!";
		875
		876	# first parse the initial "["
		877	for (;;) {
		878	sysread $fh, my $buf, 65536
		879	or die "read error: $!";
		880	$json->incr_parse ($buf); # void context, so no parsing
		881
		882	# Exit the loop once we found and removed(!) the initial "[".
		883	# In essence, we are (ab-)using the $json object as a simple scalar
		884	# we append data to.
		885	last if $json->incr_text =~ s/^ \s* \[ //x;
		886	}
		887
		888	# now we have the skipped the initial "[", so continue
		889	# parsing all the elements.
		890	for (;;) {
		891	# in this loop we read data until we got a single JSON object
		892	for (;;) {
		893	if (my $obj = $json->incr_parse) {
		894	# do something with $obj
		895	last;
		896	}
		897
		898	# add more data
		899	sysread $fh, my $buf, 65536
		900	or die "read error: $!";
		901	$json->incr_parse ($buf); # void context, so no parsing
		902	}
		903
		904	# in this loop we read data until we either found and parsed the
		905	# separating "," between elements, or the final "]"
		906	for (;;) {
		907	# first skip whitespace
		908	$json->incr_text =~ s/^\s*//;
		909
		910	# if we find "]", we are done
		911	if ($json->incr_text =~ s/^\]//) {
		912	print "finished.\n";
		913	exit;
		914	}
		915
		916	# if we find ",", we can continue with the next element
		917	if ($json->incr_text =~ s/^,//) {
		918	last;
		919	}
		920
		921	# if we find anything else, we have a parse error!
		922	if (length $json->incr_text) {
		923	die "parse error near ", $json->incr_text;
		924	}
		925
		926	# else add more data
		927	sysread $fh, my $buf, 65536
		928	or die "read error: $!";
		929	$json->incr_parse ($buf); # void context, so no parsing
		930	}
		931
		932	This is a complex example, but most of the complexity comes from the fact
		933	that we are trying to be correct (bear with me if I am wrong, I never ran
		934	the above example :).
		935
		936
		937
650	=head1 MAPPING	938	=head1 MAPPING
651		939
652	This section describes how JSON::XS maps Perl values to JSON values and	940	This section describes how JSON::XS maps Perl values to JSON values and
653	vice versa. These mappings are designed to "do the right thing" in most	941	vice versa. These mappings are designed to "do the right thing" in most
654	circumstances automatically, preserving round-tripping characteristics	942	circumstances automatically, preserving round-tripping characteristics
…		…
682		970
683	A JSON number becomes either an integer, numeric (floating point) or	971	A JSON number becomes either an integer, numeric (floating point) or
684	string scalar in perl, depending on its range and any fractional parts. On	972	string scalar in perl, depending on its range and any fractional parts. On
685	the Perl level, there is no difference between those as Perl handles all	973	the Perl level, there is no difference between those as Perl handles all
686	the conversion details, but an integer may take slightly less memory and	974	the conversion details, but an integer may take slightly less memory and
687	might represent more values exactly than (floating point) numbers.	975	might represent more values exactly than floating point numbers.
688		976
689	If the number consists of digits only, JSON::XS will try to represent	977	If the number consists of digits only, JSON::XS will try to represent
690	it as an integer value. If that fails, it will try to represent it as	978	it as an integer value. If that fails, it will try to represent it as
691	a numeric (floating point) value if that is possible without loss of	979	a numeric (floating point) value if that is possible without loss of
692	precision. Otherwise it will preserve the number as a string value.	980	precision. Otherwise it will preserve the number as a string value (in
		981	which case you lose roundtripping ability, as the JSON number will be
		982	re-encoded toa JSON string).
693		983
694	Numbers containing a fractional or exponential part will always be	984	Numbers containing a fractional or exponential part will always be
695	represented as numeric (floating point) values, possibly at a loss of	985	represented as numeric (floating point) values, possibly at a loss of
696	precision.	986	precision (in which case you might lose perfect roundtripping ability, but
697		987	the JSON number will still be re-encoded as a JSON number).
698	This might create round-tripping problems as numbers might become strings,
699	but as Perl is typeless there is no other way to do it.
700		988
701	=item true, false	989	=item true, false
702		990
703	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,	991	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
704	respectively. They are overloaded to act almost exactly like the numbers	992	respectively. They are overloaded to act almost exactly like the numbers
…		…
741	Other unblessed references are generally not allowed and will cause an	1029	Other unblessed references are generally not allowed and will cause an
742	exception to be thrown, except for references to the integers C<0> and	1030	exception to be thrown, except for references to the integers C<0> and
743	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can	1031	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
744	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.	1032	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
745		1033
746	to_json [\0,JSON::XS::true] # yields [false,true]	1034	encode_json [\0, JSON::XS::true] # yields [false,true]
747		1035
748	=item JSON::XS::true, JSON::XS::false	1036	=item JSON::XS::true, JSON::XS::false
749		1037
750	These special values become JSON true and JSON false values,	1038	These special values become JSON true and JSON false values,
751	respectively. You can also use C<\1> and C<\0> directly if you want.	1039	respectively. You can also use C<\1> and C<\0> directly if you want.
752		1040
753	=item blessed objects	1041	=item blessed objects
754		1042
755	Blessed objects are not allowed. JSON::XS currently tries to encode their	1043	Blessed objects are not directly representable in JSON. See the
756	underlying representation (hash- or arrayref), but this behaviour might	1044	C<allow_blessed> and C<convert_blessed> methods on various options on
757	change in future versions.	1045	how to deal with this: basically, you can choose between throwing an
		1046	exception, encoding the reference as if it weren't blessed, or provide
		1047	your own serialiser method.
758		1048
759	=item simple scalars	1049	=item simple scalars
760		1050
761	Simple Perl scalars (any scalar that is not a reference) are the most	1051	Simple Perl scalars (any scalar that is not a reference) are the most
762	difficult objects to encode: JSON::XS will encode undefined scalars as	1052	difficult objects to encode: JSON::XS will encode undefined scalars as
763	JSON null value, scalars that have last been used in a string context	1053	JSON C<null> values, scalars that have last been used in a string context
764	before encoding as JSON strings and anything else as number value:	1054	before encoding as JSON strings, and anything else as number value:
765		1055
766	# dump as number	1056	# dump as number
767	to_json [2] # yields [2]	1057	encode_json [2] # yields [2]
768	to_json [-3.0e17] # yields [-3e+17]	1058	encode_json [-3.0e17] # yields [-3e+17]
769	my $value = 5; to_json [$value] # yields [5]	1059	my $value = 5; encode_json [$value] # yields [5]
770		1060
771	# used as string, so dump as string	1061	# used as string, so dump as string
772	print $value;	1062	print $value;
773	to_json [$value] # yields ["5"]	1063	encode_json [$value] # yields ["5"]
774		1064
775	# undef becomes null	1065	# undef becomes null
776	to_json [undef] # yields [null]	1066	encode_json [undef] # yields [null]
777		1067
778	You can force the type to be a JSON string by stringifying it:	1068	You can force the type to be a JSON string by stringifying it:
779		1069
780	my $x = 3.1; # some variable containing a number	1070	my $x = 3.1; # some variable containing a number
781	"$x"; # stringified	1071	"$x"; # stringified
…		…
787	my $x = "3"; # some variable containing a string	1077	my $x = "3"; # some variable containing a string
788	$x += 0; # numify it, ensuring it will be dumped as a number	1078	$x += 0; # numify it, ensuring it will be dumped as a number
789	$x *= 1; # same thing, the choice is yours.	1079	$x *= 1; # same thing, the choice is yours.
790		1080
791	You can not currently force the type in other, less obscure, ways. Tell me	1081	You can not currently force the type in other, less obscure, ways. Tell me
792	if you need this capability.	1082	if you need this capability (but don't forget to explain why it's needed
		1083	:).
793		1084
794	=back	1085	=back
795		1086
796		1087
797	=head1 COMPARISON	1088	=head1 ENCODING/CODESET FLAG NOTES
798		1089
799	As already mentioned, this module was created because none of the existing	1090	The interested reader might have seen a number of flags that signify
800	JSON modules could be made to work correctly. First I will describe the	1091	encodings or codesets - C<utf8>, C<latin1> and C<ascii>. There seems to be
801	problems (or pleasures) I encountered with various existing JSON modules,	1092	some confusion on what these do, so here is a short comparison:
802	followed by some benchmark values. JSON::XS was designed not to suffer	1093
803	from any of these problems or limitations.	1094	C<utf8> controls whether the JSON text created by C<encode> (and expected
		1095	by C<decode>) is UTF-8 encoded or not, while C<latin1> and C<ascii> only
		1096	control whether C<encode> escapes character values outside their respective
		1097	codeset range. Neither of these flags conflict with each other, although
		1098	some combinations make less sense than others.
		1099
		1100	Care has been taken to make all flags symmetrical with respect to
		1101	C<encode> and C<decode>, that is, texts encoded with any combination of
		1102	these flag values will be correctly decoded when the same flags are used
		1103	- in general, if you use different flag settings while encoding vs. when
		1104	decoding you likely have a bug somewhere.
		1105
		1106	Below comes a verbose discussion of these flags. Note that a "codeset" is
		1107	simply an abstract set of character-codepoint pairs, while an encoding
		1108	takes those codepoint numbers and I<encodes> them, in our case into
		1109	octets. Unicode is (among other things) a codeset, UTF-8 is an encoding,
		1110	and ISO-8859-1 (= latin 1) and ASCII are both codesets I<and> encodings at
		1111	the same time, which can be confusing.
804		1112
805	=over 4	1113	=over 4
806		1114
807	=item JSON 1.07	1115	=item C<utf8> flag disabled
808		1116
809	Slow (but very portable, as it is written in pure Perl).	1117	When C<utf8> is disabled (the default), then C<encode>/C<decode> generate
		1118	and expect Unicode strings, that is, characters with high ordinal Unicode
		1119	values (> 255) will be encoded as such characters, and likewise such
		1120	characters are decoded as-is, no canges to them will be done, except
		1121	"(re-)interpreting" them as Unicode codepoints or Unicode characters,
		1122	respectively (to Perl, these are the same thing in strings unless you do
		1123	funny/weird/dumb stuff).
810		1124
811	Undocumented/buggy Unicode handling (how JSON handles Unicode values is	1125	This is useful when you want to do the encoding yourself (e.g. when you
812	undocumented. One can get far by feeding it Unicode strings and doing	1126	want to have UTF-16 encoded JSON texts) or when some other layer does
813	en-/decoding oneself, but Unicode escapes are not working properly).	1127	the encoding for you (for example, when printing to a terminal using a
		1128	filehandle that transparently encodes to UTF-8 you certainly do NOT want
		1129	to UTF-8 encode your data first and have Perl encode it another time).
814		1130
815	No round-tripping (strings get clobbered if they look like numbers, e.g.	1131	=item C<utf8> flag enabled
816	the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will
817	decode into the number 2.
818		1132
819	=item JSON::PC 0.01	1133	If the C<utf8>-flag is enabled, C<encode>/C<decode> will encode all
		1134	characters using the corresponding UTF-8 multi-byte sequence, and will
		1135	expect your input strings to be encoded as UTF-8, that is, no "character"
		1136	of the input string must have any value > 255, as UTF-8 does not allow
		1137	that.
820		1138
821	Very fast.	1139	The C<utf8> flag therefore switches between two modes: disabled means you
		1140	will get a Unicode string in Perl, enabled means you get an UTF-8 encoded
		1141	octet/binary string in Perl.
822		1142
823	Undocumented/buggy Unicode handling.	1143	=item C<latin1> or C<ascii> flags enabled
824		1144
825	No round-tripping.	1145	With C<latin1> (or C<ascii>) enabled, C<encode> will escape characters
		1146	with ordinal values > 255 (> 127 with C<ascii>) and encode the remaining
		1147	characters as specified by the C<utf8> flag.
826		1148
827	Has problems handling many Perl values (e.g. regex results and other magic	1149	If C<utf8> is disabled, then the result is also correctly encoded in those
828	values will make it croak).	1150	character sets (as both are proper subsets of Unicode, meaning that a
		1151	Unicode string with all character values < 256 is the same thing as a
		1152	ISO-8859-1 string, and a Unicode string with all character values < 128 is
		1153	the same thing as an ASCII string in Perl).
829		1154
830	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>	1155	If C<utf8> is enabled, you still get a correct UTF-8-encoded string,
831	which is not a valid JSON text.	1156	regardless of these flags, just some more characters will be escaped using
		1157	C<\uXXXX> then before.
832		1158
833	Unmaintained (maintainer unresponsive for many months, bugs are not	1159	Note that ISO-8859-1-I<encoded> strings are not compatible with UTF-8
834	getting fixed).	1160	encoding, while ASCII-encoded strings are. That is because the ISO-8859-1
		1161	encoding is NOT a subset of UTF-8 (despite the ISO-8859-1 I<codeset> being
		1162	a subset of Unicode), while ASCII is.
835		1163
836	=item JSON::Syck 0.21	1164	Surprisingly, C<decode> will ignore these flags and so treat all input
		1165	values as governed by the C<utf8> flag. If it is disabled, this allows you
		1166	to decode ISO-8859-1- and ASCII-encoded strings, as both strict subsets of
		1167	Unicode. If it is enabled, you can correctly decode UTF-8 encoded strings.
837		1168
838	Very buggy (often crashes).	1169	So neither C<latin1> nor C<ascii> are incompatible with the C<utf8> flag -
		1170	they only govern when the JSON output engine escapes a character or not.
839		1171
840	Very inflexible (no human-readable format supported, format pretty much	1172	The main use for C<latin1> is to relatively efficiently store binary data
841	undocumented. I need at least a format for easy reading by humans and a	1173	as JSON, at the expense of breaking compatibility with most JSON decoders.
842	single-line compact format for use in a protocol, and preferably a way to
843	generate ASCII-only JSON texts).
844		1174
845	Completely broken (and confusingly documented) Unicode handling (Unicode	1175	The main use for C<ascii> is to force the output to not contain characters
846	escapes are not working properly, you need to set ImplicitUnicode to	1176	with values > 127, which means you can interpret the resulting string
847	I<different> values on en- and decoding to get symmetric behaviour).	1177	as UTF-8, ISO-8859-1, ASCII, KOI8-R or most about any character set and
848		1178	8-bit-encoding, and still get the same data structure back. This is useful
849	No round-tripping (simple cases work, but this depends on whether the scalar	1179	when your channel for JSON transfer is not 8-bit clean or the encoding
850	value was used in a numeric context or not).	1180	might be mangled in between (e.g. in mail), and works because ASCII is a
851		1181	proper subset of most 8-bit and multibyte encodings in use in the world.
852	Dumping hashes may skip hash values depending on iterator state.
853
854	Unmaintained (maintainer unresponsive for many months, bugs are not
855	getting fixed).
856
857	Does not check input for validity (i.e. will accept non-JSON input and
858	return "something" instead of raising an exception. This is a security
859	issue: imagine two banks transferring money between each other using
860	JSON. One bank might parse a given non-JSON request and deduct money,
861	while the other might reject the transaction with a syntax error. While a
862	good protocol will at least recover, that is extra unnecessary work and
863	the transaction will still not succeed).
864
865	=item JSON::DWIW 0.04
866
867	Very fast. Very natural. Very nice.
868
869	Undocumented Unicode handling (but the best of the pack. Unicode escapes
870	still don't get parsed properly).
871
872	Very inflexible.
873
874	No round-tripping.
875
876	Does not generate valid JSON texts (key strings are often unquoted, empty keys
877	result in nothing being output)
878
879	Does not check input for validity.
880		1182
881	=back	1183	=back
882		1184
883		1185
884	=head2 JSON and YAML	1186	=head2 JSON and YAML
885		1187
886	You often hear that JSON is a subset (or a close subset) of YAML. This is,	1188	You often hear that JSON is a subset of YAML. This is, however, a mass
887	however, a mass hysteria and very far from the truth. In general, there is	1189	hysteria(*) and very far from the truth (as of the time of this writing),
888	no way to configure JSON::XS to output a data structure as valid YAML.	1190	so let me state it clearly: I<in general, there is no way to configure
		1191	JSON::XS to output a data structure as valid YAML> that works in all
		1192	cases.
889		1193
890	If you really must use JSON::XS to generate YAML, you should use this	1194	If you really must use JSON::XS to generate YAML, you should use this
891	algorithm (subject to change in future versions):	1195	algorithm (subject to change in future versions):
892		1196
893	my $to_yaml = JSON::XS->new->utf8->space_after (1);	1197	my $to_yaml = JSON::XS->new->utf8->space_after (1);
894	my $yaml = $to_yaml->encode ($ref) . "\n";	1198	my $yaml = $to_yaml->encode ($ref) . "\n";
895		1199
896	This will usually generate JSON texts that also parse as valid	1200	This will I<usually> generate JSON texts that also parse as valid
897	YAML. Please note that YAML has hardcoded limits on (simple) object key	1201	YAML. Please note that YAML has hardcoded limits on (simple) object key
898	lengths that JSON doesn't have, so you should make sure that your hash	1202	lengths that JSON doesn't have and also has different and incompatible
		1203	unicode handling, so you should make sure that your hash keys are
899	keys are noticeably shorter than the 1024 characters YAML allows.	1204	noticeably shorter than the 1024 "stream characters" YAML allows and that
		1205	you do not have characters with codepoint values outside the Unicode BMP
		1206	(basic multilingual page). YAML also does not allow C<\/> sequences in
		1207	strings (which JSON::XS does not I<currently> generate, but other JSON
		1208	generators might).
900		1209
901	There might be other incompatibilities that I am not aware of. In general	1210	There might be other incompatibilities that I am not aware of (or the YAML
		1211	specification has been changed yet again - it does so quite often). In
902	you should not try to generate YAML with a JSON generator or vice versa,	1212	general you should not try to generate YAML with a JSON generator or vice
903	or try to parse JSON with a YAML parser or vice versa: chances are high	1213	versa, or try to parse JSON with a YAML parser or vice versa: chances are
904	that you will run into severe interoperability problems.	1214	high that you will run into severe interoperability problems when you
		1215	least expect it.
		1216
		1217	=over 4
		1218
		1219	=item (*)
		1220
		1221	I have been pressured multiple times by Brian Ingerson (one of the
		1222	authors of the YAML specification) to remove this paragraph, despite him
		1223	acknowledging that the actual incompatibilities exist. As I was personally
		1224	bitten by this "JSON is YAML" lie, I refused and said I will continue to
		1225	educate people about these issues, so others do not run into the same
		1226	problem again and again. After this, Brian called me a (quote)I<complete
		1227	and worthless idiot>(unquote).
		1228
		1229	In my opinion, instead of pressuring and insulting people who actually
		1230	clarify issues with YAML and the wrong statements of some of its
		1231	proponents, I would kindly suggest reading the JSON spec (which is not
		1232	that difficult or long) and finally make YAML compatible to it, and
		1233	educating users about the changes, instead of spreading lies about the
		1234	real compatibility for many I<years> and trying to silence people who
		1235	point out that it isn't true.
		1236
		1237	=back
905		1238
906		1239
907	=head2 SPEED	1240	=head2 SPEED
908		1241
909	It seems that JSON::XS is surprisingly fast, as shown in the following	1242	It seems that JSON::XS is surprisingly fast, as shown in the following
910	tables. They have been generated with the help of the C<eg/bench> program	1243	tables. They have been generated with the help of the C<eg/bench> program
911	in the JSON::XS distribution, to make it easy to compare on your own	1244	in the JSON::XS distribution, to make it easy to compare on your own
912	system.	1245	system.
913		1246
914	First comes a comparison between various modules using a very short	1247	First comes a comparison between various modules using
915	single-line JSON string:	1248	a very short single-line JSON string (also available at
		1249	L<http://dist.schmorp.de/misc/json/short.json>).
916		1250
917	{"method": "handleMessage", "params": ["user1", "we were just talking"], \	1251	{"method": "handleMessage", "params": ["user1",
918	"id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}	1252	"we were just talking"], "id": null, "array":[1,11,234,-5,1e5,1e7,
		1253	true, false]}
919		1254
920	It shows the number of encodes/decodes per second (JSON::XS uses	1255	It shows the number of encodes/decodes per second (JSON::XS uses
921	the functional interface, while JSON::XS/2 uses the OO interface	1256	the functional interface, while JSON::XS/2 uses the OO interface
922	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables	1257	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
923	shrink). Higher is better:	1258	shrink). Higher is better:
…		…
939	about three times faster on decoding, and over forty times faster	1274	about three times faster on decoding, and over forty times faster
940	than JSON, even with pretty-printing and key sorting. It also compares	1275	than JSON, even with pretty-printing and key sorting. It also compares
941	favourably to Storable for small amounts of data.	1276	favourably to Storable for small amounts of data.
942		1277
943	Using a longer test string (roughly 18KB, generated from Yahoo! Locals	1278	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
944	search API (http://nanoref.com/yahooapis/mgPdGg):	1279	search API (L<http://dist.schmorp.de/misc/json/long.json>).
945		1280
946	module \| encode \| decode \|	1281	module \| encode \| decode \|
947	-----------\|------------\|------------\|	1282	-----------\|------------\|------------\|
948	JSON 1.x \| 55.260 \| 34.971 \|	1283	JSON 1.x \| 55.260 \| 34.971 \|
949	JSON::DWIW \| 825.228 \| 1082.513 \|	1284	JSON::DWIW \| 825.228 \| 1082.513 \|
…		…
986		1321
987	Third, JSON::XS recurses using the C stack when decoding objects and	1322	Third, JSON::XS recurses using the C stack when decoding objects and
988	arrays. The C stack is a limited resource: for instance, on my amd64	1323	arrays. The C stack is a limited resource: for instance, on my amd64
989	machine with 8MB of stack size I can decode around 180k nested arrays but	1324	machine with 8MB of stack size I can decode around 180k nested arrays but
990	only 14k nested JSON objects (due to perl itself recursing deeply on croak	1325	only 14k nested JSON objects (due to perl itself recursing deeply on croak
991	to free the temporary). If that is exceeded, the program crashes. to be	1326	to free the temporary). If that is exceeded, the program crashes. To be
992	conservative, the default nesting limit is set to 512. If your process	1327	conservative, the default nesting limit is set to 512. If your process
993	has a smaller stack, you should adjust this setting accordingly with the	1328	has a smaller stack, you should adjust this setting accordingly with the
994	C<max_depth> method.	1329	C<max_depth> method.
995		1330
996	And last but least, something else could bomb you that I forgot to think	1331	Something else could bomb you, too, that I forgot to think of. In that
997	of. In that case, you get to keep the pieces. I am always open for hints,	1332	case, you get to keep the pieces. I am always open for hints, though...
998	though...	1333
		1334	Also keep in mind that JSON::XS might leak contents of your Perl data
		1335	structures in its error messages, so when you serialise sensitive
		1336	information you might want to make sure that exceptions thrown by JSON::XS
		1337	will not end up in front of untrusted eyes.
999		1338
1000	If you are using JSON::XS to return packets to consumption	1339	If you are using JSON::XS to return packets to consumption
1001	by JavaScript scripts in a browser you should have a look at	1340	by JavaScript scripts in a browser you should have a look at
1002	L<http://jpsykes.com/47/practical-csrf-and-json-security> to see whether	1341	L<http://jpsykes.com/47/practical-csrf-and-json-security> to see whether
1003	you are vulnerable to some common attack vectors (which really are browser	1342	you are vulnerable to some common attack vectors (which really are browser
1004	design bugs, but it is still you who will have to deal with it, as major	1343	design bugs, but it is still you who will have to deal with it, as major
1005	browser developers care only for features, not about doing security	1344	browser developers care only for features, not about getting security
1006	right).	1345	right).
1007		1346
1008		1347
1009	=head1 THREADS	1348	=head1 THREADS
1010		1349
1011	This module is I<not> guaranteed to be thread safe and there are no	1350	This module is I<not> guaranteed to be thread safe and there are no
1012	plans to change this until Perl gets thread support (as opposed to the	1351	plans to change this until Perl gets thread support (as opposed to the
1013	horribly slow so-called "threads" which are simply slow and bloated	1352	horribly slow so-called "threads" which are simply slow and bloated
1014	process simulations - use fork, its I<much> faster, cheaper, better).	1353	process simulations - use fork, it's I<much> faster, cheaper, better).
1015		1354
1016	(It might actually work, but you have been warned).	1355	(It might actually work, but you have been warned).
1017		1356
1018		1357
1019	=head1 BUGS	1358	=head1 BUGS
1020		1359
1021	While the goal of this module is to be correct, that unfortunately does	1360	While the goal of this module is to be correct, that unfortunately does
1022	not mean its bug-free, only that I think its design is bug-free. It is	1361	not mean it's bug-free, only that I think its design is bug-free. If you
1023	still relatively early in its development. If you keep reporting bugs they	1362	keep reporting bugs they will be fixed swiftly, though.
1024	will be fixed swiftly, though.
1025		1363
1026	Please refrain from using rt.cpan.org or any other bug reporting	1364	Please refrain from using rt.cpan.org or any other bug reporting
1027	service. I put the contact address into my modules for a reason.	1365	service. I put the contact address into my modules for a reason.
1028		1366
1029	=cut	1367	=cut
…		…
1049	"--" => sub { $_[0] = ${$_[0]} - 1 },	1387	"--" => sub { $_[0] = ${$_[0]} - 1 },
1050	fallback => 1;	1388	fallback => 1;
1051		1389
1052	1;	1390	1;
1053		1391
		1392	=head1 SEE ALSO
		1393
		1394	The F<json_xs> command line utility for quick experiments.
		1395
1054	=head1 AUTHOR	1396	=head1 AUTHOR
1055		1397
1056	Marc Lehmann <schmorp@schmorp.de>	1398	Marc Lehmann <schmorp@schmorp.de>
1057	http://home.schmorp.de/	1399	http://home.schmorp.de/
1058		1400

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Revision 1.73 by root, Sun Nov 25 19:36:54 2007 UTC vs.
Revision 1.111 by root, Mon Jul 21 02:45:17 2008 UTC