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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.66 by root, Sun Oct 14 20:02:57 2007 UTC vs.
Revision 1.139 by root, Thu May 23 09:31:32 2013 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 and Perl, the deserialised data structure is identical on the Perl
54	(e.g. the string "2.0" doesn't suddenly become "2" just because it looks	70	level. (e.g. the string "2.0" doesn't suddenly become "2" just because
55	like a number).	71	it looks like a number). There I<are> minor exceptions to this, read the
		72	MAPPING 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 guarenteed 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
87	use strict;	104	use common::sense;
88		105
89	our $VERSION = '1.51';	106	our $VERSION = 2.34;
90	our @ISA = qw(Exporter);	107	our @ISA = qw(Exporter);
91		108
92	our @EXPORT = qw(to_json from_json);	109	our @EXPORT = qw(encode_json decode_json to_json from_json);
		110
		111	sub to_json($) {
		112	require Carp;
		113	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");
		114	}
		115
		116	sub from_json($) {
		117	require Carp;
		118	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");
		119	}
93		120
94	use Exporter;	121	use Exporter;
95	use XSLoader;	122	use XSLoader;
96		123
97	=head1 FUNCTIONAL INTERFACE	124	=head1 FUNCTIONAL INTERFACE
98		125
99	The following convinience methods are provided by this module. They are	126	The following convenience methods are provided by this module. They are
100	exported by default:	127	exported by default:
101		128
102	=over 4	129	=over 4
103		130
104	=item $json_text = to_json $perl_scalar	131	=item $json_text = encode_json $perl_scalar
105		132
106	Converts the given Perl data structure to a UTF-8 encoded, binary string	133	Converts the given Perl data structure to a UTF-8 encoded, binary string
107	(that is, the string contains octets only). Croaks on error.	134	(that is, the string contains octets only). Croaks on error.
108		135
109	This function call is functionally identical to:	136	This function call is functionally identical to:
110		137
111	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)	138	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)
112		139
113	except being faster.	140	Except being faster.
114		141
115	=item $perl_scalar = from_json $json_text	142	=item $perl_scalar = decode_json $json_text
116		143
117	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries	144	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	145	to parse that as an UTF-8 encoded JSON text, returning the resulting
119	reference. Croaks on error.	146	reference. Croaks on error.
120		147
121	This function call is functionally identical to:	148	This function call is functionally identical to:
122		149
123	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)	150	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
124		151
125	except being faster.	152	Except being faster.
126		153
127	=item $is_boolean = JSON::XS::is_bool $scalar	154	=item $is_boolean = JSON::XS::is_bool $scalar
128		155
129	Returns true if the passed scalar represents either JSON::XS::true or	156	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	157	JSON::XS::false, two constants that act like C<1> and C<0>, respectively
…		…
143		170
144	=over 4	171	=over 4
145		172
146	=item 1. Perl strings can store characters with ordinal values > 255.	173	=item 1. Perl strings can store characters with ordinal values > 255.
147		174
148	This enables you to store unicode characters as single characters in a	175	This enables you to store Unicode characters as single characters in a
149	Perl string - very natural.	176	Perl string - very natural.
150		177
151	=item 2. Perl does I<not> associate an encoding with your strings.	178	=item 2. Perl does I<not> associate an encoding with your strings.
152		179
153	Unless you force it to, e.g. when matching it against a regex, or printing	180	... 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	181	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	182	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	183	on various settings. In no case is an encoding stored together with your
157	I<use> that decides encoding, not any magical metadata.	184	data, it is I<use> that decides encoding, not any magical meta data.
158		185
159	=item 3. The internal utf-8 flag has no meaning with regards to the	186	=item 3. The internal utf-8 flag has no meaning with regards to the
160	encoding of your string.	187	encoding of your string.
161		188
162	Just ignore that flag unless you debug a Perl bug, a module written in	189	Just ignore that flag unless you debug a Perl bug, a module written in
163	XS or want to dive into the internals of perl. Otherwise it will only	190	XS or want to dive into the internals of perl. Otherwise it will only
164	confuse you, as, despite the name, it says nothing about how your string	191	confuse you, as, despite the name, it says nothing about how your string
165	is encoded. You can have unicode strings with that flag set, with that	192	is encoded. You can have Unicode strings with that flag set, with that
166	flag clear, and you can have binary data with that flag set and that flag	193	flag clear, and you can have binary data with that flag set and that flag
167	clear. Other possibilities exist, too.	194	clear. Other possibilities exist, too.
168		195
169	If you didn't know about that flag, just the better, pretend it doesn't	196	If you didn't know about that flag, just the better, pretend it doesn't
170	exist.	197	exist.
171		198
172	=item 4. A "Unicode String" is simply a string where each character can be	199	=item 4. A "Unicode String" is simply a string where each character can be
173	validly interpreted as a Unicode codepoint.	200	validly interpreted as a Unicode code point.
174		201
175	If you have UTF-8 encoded data, it is no longer a Unicode string, but a	202	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.	203	Unicode string encoded in UTF-8, giving you a binary string.
177		204
178	=item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string.	205	=item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string.
179		206
180	Its a fact. Learn to live with it.	207	It's a fact. Learn to live with it.
181		208
182	=back	209	=back
183		210
184	I hope this helps :)	211	I hope this helps :)
185		212
…		…
202	my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})	229	my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})
203	=> {"a": [1, 2]}	230	=> {"a": [1, 2]}
204		231
205	=item $json = $json->ascii ([$enable])	232	=item $json = $json->ascii ([$enable])
206		233
		234	=item $enabled = $json->get_ascii
		235
207	If C<$enable> is true (or missing), then the C<encode> method will not	236	If C<$enable> is true (or missing), then the C<encode> method will not
208	generate characters outside the code range C<0..127> (which is ASCII). Any	237	generate characters outside the code range C<0..127> (which is ASCII). Any
209	unicode characters outside that range will be escaped using either a	238	Unicode characters outside that range will be escaped using either a
210	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,	239	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
211	as per RFC4627. The resulting encoded JSON text can be treated as a native	240	as per RFC4627. The resulting encoded JSON text can be treated as a native
212	unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,	241	Unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
213	or any other superset of ASCII.	242	or any other superset of ASCII.
214		243
215	If C<$enable> is false, then the C<encode> method will not escape Unicode	244	If C<$enable> is false, then the C<encode> method will not escape Unicode
216	characters unless required by the JSON syntax or other flags. This results	245	characters unless required by the JSON syntax or other flags. This results
217	in a faster and more compact format.	246	in a faster and more compact format.
218		247
		248	See also the section I<ENCODING/CODESET FLAG NOTES> later in this
		249	document.
		250
219	The main use for this flag is to produce JSON texts that can be	251	The main use for this flag is to produce JSON texts that can be
220	transmitted over a 7-bit channel, as the encoded JSON texts will not	252	transmitted over a 7-bit channel, as the encoded JSON texts will not
221	contain any 8 bit characters.	253	contain any 8 bit characters.
222		254
223	JSON::XS->new->ascii (1)->encode ([chr 0x10401])	255	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
224	=> ["\ud801\udc01"]	256	=> ["\ud801\udc01"]
225		257
226	=item $json = $json->latin1 ([$enable])	258	=item $json = $json->latin1 ([$enable])
227		259
		260	=item $enabled = $json->get_latin1
		261
228	If C<$enable> is true (or missing), then the C<encode> method will encode	262	If C<$enable> is true (or missing), then the C<encode> method will encode
229	the resulting JSON text as latin1 (or iso-8859-1), escaping any characters	263	the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
230	outside the code range C<0..255>. The resulting string can be treated as a	264	outside the code range C<0..255>. The resulting string can be treated as a
231	latin1-encoded JSON text or a native unicode string. The C<decode> method	265	latin1-encoded JSON text or a native Unicode string. The C<decode> method
232	will not be affected in any way by this flag, as C<decode> by default	266	will not be affected in any way by this flag, as C<decode> by default
233	expects unicode, which is a strict superset of latin1.	267	expects Unicode, which is a strict superset of latin1.
234		268
235	If C<$enable> is false, then the C<encode> method will not escape Unicode	269	If C<$enable> is false, then the C<encode> method will not escape Unicode
236	characters unless required by the JSON syntax or other flags.	270	characters unless required by the JSON syntax or other flags.
		271
		272	See also the section I<ENCODING/CODESET FLAG NOTES> later in this
		273	document.
237		274
238	The main use for this flag is efficiently encoding binary data as JSON	275	The main use for this flag is efficiently encoding binary data as JSON
239	text, as most octets will not be escaped, resulting in a smaller encoded	276	text, as most octets will not be escaped, resulting in a smaller encoded
240	size. The disadvantage is that the resulting JSON text is encoded	277	size. The disadvantage is that the resulting JSON text is encoded
241	in latin1 (and must correctly be treated as such when storing and	278	in latin1 (and must correctly be treated as such when storing and
242	transfering), a rare encoding for JSON. It is therefore most useful when	279	transferring), a rare encoding for JSON. It is therefore most useful when
243	you want to store data structures known to contain binary data efficiently	280	you want to store data structures known to contain binary data efficiently
244	in files or databases, not when talking to other JSON encoders/decoders.	281	in files or databases, not when talking to other JSON encoders/decoders.
245		282
246	JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]	283	JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
247	=> ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)	284	=> ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
248		285
249	=item $json = $json->utf8 ([$enable])	286	=item $json = $json->utf8 ([$enable])
		287
		288	=item $enabled = $json->get_utf8
250		289
251	If C<$enable> is true (or missing), then the C<encode> method will encode	290	If C<$enable> is true (or missing), then the C<encode> method will encode
252	the JSON result into UTF-8, as required by many protocols, while the	291	the JSON result into UTF-8, as required by many protocols, while the
253	C<decode> method expects to be handled an UTF-8-encoded string. Please	292	C<decode> method expects to be handled an UTF-8-encoded string. Please
254	note that UTF-8-encoded strings do not contain any characters outside the	293	note that UTF-8-encoded strings do not contain any characters outside the
255	range C<0..255>, they are thus useful for bytewise/binary I/O. In future	294	range C<0..255>, they are thus useful for bytewise/binary I/O. In future
256	versions, enabling this option might enable autodetection of the UTF-16	295	versions, enabling this option might enable autodetection of the UTF-16
257	and UTF-32 encoding families, as described in RFC4627.	296	and UTF-32 encoding families, as described in RFC4627.
258		297
259	If C<$enable> is false, then the C<encode> method will return the JSON	298	If C<$enable> is false, then the C<encode> method will return the JSON
260	string as a (non-encoded) unicode string, while C<decode> expects thus a	299	string as a (non-encoded) Unicode string, while C<decode> expects thus a
261	unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs	300	Unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs
262	to be done yourself, e.g. using the Encode module.	301	to be done yourself, e.g. using the Encode module.
		302
		303	See also the section I<ENCODING/CODESET FLAG NOTES> later in this
		304	document.
263		305
264	Example, output UTF-16BE-encoded JSON:	306	Example, output UTF-16BE-encoded JSON:
265		307
266	use Encode;	308	use Encode;
267	$jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);	309	$jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);
…		…
288	]	330	]
289	}	331	}
290		332
291	=item $json = $json->indent ([$enable])	333	=item $json = $json->indent ([$enable])
292		334
		335	=item $enabled = $json->get_indent
		336
293	If C<$enable> is true (or missing), then the C<encode> method will use a multiline	337	If C<$enable> is true (or missing), then the C<encode> method will use a multiline
294	format as output, putting every array member or object/hash key-value pair	338	format as output, putting every array member or object/hash key-value pair
295	into its own line, identing them properly.	339	into its own line, indenting them properly.
296		340
297	If C<$enable> is false, no newlines or indenting will be produced, and the	341	If C<$enable> is false, no newlines or indenting will be produced, and the
298	resulting JSON text is guarenteed not to contain any C<newlines>.	342	resulting JSON text is guaranteed not to contain any C<newlines>.
299		343
300	This setting has no effect when decoding JSON texts.	344	This setting has no effect when decoding JSON texts.
301		345
302	=item $json = $json->space_before ([$enable])	346	=item $json = $json->space_before ([$enable])
		347
		348	=item $enabled = $json->get_space_before
303		349
304	If C<$enable> is true (or missing), then the C<encode> method will add an extra	350	If C<$enable> is true (or missing), then the C<encode> method will add an extra
305	optional space before the C<:> separating keys from values in JSON objects.	351	optional space before the C<:> separating keys from values in JSON objects.
306		352
307	If C<$enable> is false, then the C<encode> method will not add any extra	353	If C<$enable> is false, then the C<encode> method will not add any extra
…		…
313	Example, space_before enabled, space_after and indent disabled:	359	Example, space_before enabled, space_after and indent disabled:
314		360
315	{"key" :"value"}	361	{"key" :"value"}
316		362
317	=item $json = $json->space_after ([$enable])	363	=item $json = $json->space_after ([$enable])
		364
		365	=item $enabled = $json->get_space_after
318		366
319	If C<$enable> is true (or missing), then the C<encode> method will add an extra	367	If C<$enable> is true (or missing), then the C<encode> method will add an extra
320	optional space after the C<:> separating keys from values in JSON objects	368	optional space after the C<:> separating keys from values in JSON objects
321	and extra whitespace after the C<,> separating key-value pairs and array	369	and extra whitespace after the C<,> separating key-value pairs and array
322	members.	370	members.
…		…
329	Example, space_before and indent disabled, space_after enabled:	377	Example, space_before and indent disabled, space_after enabled:
330		378
331	{"key": "value"}	379	{"key": "value"}
332		380
333	=item $json = $json->relaxed ([$enable])	381	=item $json = $json->relaxed ([$enable])
		382
		383	=item $enabled = $json->get_relaxed
334		384
335	If C<$enable> is true (or missing), then C<decode> will accept some	385	If C<$enable> is true (or missing), then C<decode> will accept some
336	extensions to normal JSON syntax (see below). C<encode> will not be	386	extensions to normal JSON syntax (see below). C<encode> will not be
337	affected in anyway. I<Be aware that this option makes you accept invalid	387	affected in anyway. I<Be aware that this option makes you accept invalid
338	JSON texts as if they were valid!>. I suggest only to use this option to	388	JSON texts as if they were valid!>. I suggest only to use this option to
…		…
375		425
376	=back	426	=back
377		427
378	=item $json = $json->canonical ([$enable])	428	=item $json = $json->canonical ([$enable])
379		429
		430	=item $enabled = $json->get_canonical
		431
380	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects	432	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
381	by sorting their keys. This is adding a comparatively high overhead.	433	by sorting their keys. This is adding a comparatively high overhead.
382		434
383	If C<$enable> is false, then the C<encode> method will output key-value	435	If C<$enable> is false, then the C<encode> method will output key-value
384	pairs in the order Perl stores them (which will likely change between runs	436	pairs in the order Perl stores them (which will likely change between runs
385	of the same script).	437	of the same script, and can change even within the same run from 5.18
		438	onwards).
386		439
387	This option is useful if you want the same data structure to be encoded as	440	This option is useful if you want the same data structure to be encoded as
388	the same JSON text (given the same overall settings). If it is disabled,	441	the same JSON text (given the same overall settings). If it is disabled,
389	the same hash migh be encoded differently even if contains the same data,	442	the same hash might be encoded differently even if contains the same data,
390	as key-value pairs have no inherent ordering in Perl.	443	as key-value pairs have no inherent ordering in Perl.
391		444
392	This setting has no effect when decoding JSON texts.	445	This setting has no effect when decoding JSON texts.
393		446
		447	This setting has currently no effect on tied hashes.
		448
394	=item $json = $json->allow_nonref ([$enable])	449	=item $json = $json->allow_nonref ([$enable])
		450
		451	=item $enabled = $json->get_allow_nonref
395		452
396	If C<$enable> is true (or missing), then the C<encode> method can convert a	453	If C<$enable> is true (or missing), then the C<encode> method can convert a
397	non-reference into its corresponding string, number or null JSON value,	454	non-reference into its corresponding string, number or null JSON value,
398	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON	455	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
399	values instead of croaking.	456	values instead of croaking.
…		…
407	resulting in an invalid JSON text:	464	resulting in an invalid JSON text:
408		465
409	JSON::XS->new->allow_nonref->encode ("Hello, World!")	466	JSON::XS->new->allow_nonref->encode ("Hello, World!")
410	=> "Hello, World!"	467	=> "Hello, World!"
411		468
		469	=item $json = $json->allow_unknown ([$enable])
		470
		471	=item $enabled = $json->get_allow_unknown
		472
		473	If C<$enable> is true (or missing), then C<encode> will I<not> throw an
		474	exception when it encounters values it cannot represent in JSON (for
		475	example, filehandles) but instead will encode a JSON C<null> value. Note
		476	that blessed objects are not included here and are handled separately by
		477	c<allow_nonref>.
		478
		479	If C<$enable> is false (the default), then C<encode> will throw an
		480	exception when it encounters anything it cannot encode as JSON.
		481
		482	This option does not affect C<decode> in any way, and it is recommended to
		483	leave it off unless you know your communications partner.
		484
412	=item $json = $json->allow_blessed ([$enable])	485	=item $json = $json->allow_blessed ([$enable])
		486
		487	=item $enabled = $json->get_allow_blessed
413		488
414	If C<$enable> is true (or missing), then the C<encode> method will not	489	If C<$enable> is true (or missing), then the C<encode> method will not
415	barf when it encounters a blessed reference. Instead, the value of the	490	barf when it encounters a blessed reference. Instead, the value of the
416	B<convert_blessed> option will decide wether C<null> (C<convert_blessed>	491	B<convert_blessed> option will decide whether C<null> (C<convert_blessed>
417	disabled or no C<to_json> method found) or a representation of the	492	disabled or no C<TO_JSON> method found) or a representation of the
418	object (C<convert_blessed> enabled and C<to_json> method found) is being	493	object (C<convert_blessed> enabled and C<TO_JSON> method found) is being
419	encoded. Has no effect on C<decode>.	494	encoded. Has no effect on C<decode>.
420		495
421	If C<$enable> is false (the default), then C<encode> will throw an	496	If C<$enable> is false (the default), then C<encode> will throw an
422	exception when it encounters a blessed object.	497	exception when it encounters a blessed object.
423		498
424	=item $json = $json->convert_blessed ([$enable])	499	=item $json = $json->convert_blessed ([$enable])
		500
		501	=item $enabled = $json->get_convert_blessed
425		502
426	If C<$enable> is true (or missing), then C<encode>, upon encountering a	503	If C<$enable> is true (or missing), then C<encode>, upon encountering a
427	blessed object, will check for the availability of the C<TO_JSON> method	504	blessed object, will check for the availability of the C<TO_JSON> method
428	on the object's class. If found, it will be called in scalar context	505	on the object's class. If found, it will be called in scalar context
429	and the resulting scalar will be encoded instead of the object. If no	506	and the resulting scalar will be encoded instead of the object. If no
…		…
433	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>	510	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
434	returns other blessed objects, those will be handled in the same	511	returns other blessed objects, those will be handled in the same
435	way. C<TO_JSON> must take care of not causing an endless recursion cycle	512	way. C<TO_JSON> must take care of not causing an endless recursion cycle
436	(== crash) in this case. The name of C<TO_JSON> was chosen because other	513	(== crash) in this case. The name of C<TO_JSON> was chosen because other
437	methods called by the Perl core (== not by the user of the object) are	514	methods called by the Perl core (== not by the user of the object) are
438	usually in upper case letters and to avoid collisions with the C<to_json>	515	usually in upper case letters and to avoid collisions with any C<to_json>
439	function.	516	function or method.
440		517
441	This setting does not yet influence C<decode> in any way, but in the	518	This setting does not yet influence C<decode> in any way, but in the
442	future, global hooks might get installed that influence C<decode> and are	519	future, global hooks might get installed that influence C<decode> and are
443	enabled by this setting.	520	enabled by this setting.
444		521
…		…
486		563
487	As this callback gets called less often then the C<filter_json_object>	564	As this callback gets called less often then the C<filter_json_object>
488	one, decoding speed will not usually suffer as much. Therefore, single-key	565	one, decoding speed will not usually suffer as much. Therefore, single-key
489	objects make excellent targets to serialise Perl objects into, especially	566	objects make excellent targets to serialise Perl objects into, especially
490	as single-key JSON objects are as close to the type-tagged value concept	567	as single-key JSON objects are as close to the type-tagged value concept
491	as JSON gets (its basically an ID/VALUE tuple). Of course, JSON does not	568	as JSON gets (it's basically an ID/VALUE tuple). Of course, JSON does not
492	support this in any way, so you need to make sure your data never looks	569	support this in any way, so you need to make sure your data never looks
493	like a serialised Perl hash.	570	like a serialised Perl hash.
494		571
495	Typical names for the single object key are C<__class_whatever__>, or	572	Typical names for the single object key are C<__class_whatever__>, or
496	C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even	573	C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even
…		…
520		597
521	{ __widget__ => $self->{id} }	598	{ __widget__ => $self->{id} }
522	}	599	}
523		600
524	=item $json = $json->shrink ([$enable])	601	=item $json = $json->shrink ([$enable])
		602
		603	=item $enabled = $json->get_shrink
525		604
526	Perl usually over-allocates memory a bit when allocating space for	605	Perl usually over-allocates memory a bit when allocating space for
527	strings. This flag optionally resizes strings generated by either	606	strings. This flag optionally resizes strings generated by either
528	C<encode> or C<decode> to their minimum size possible. This can save	607	C<encode> or C<decode> to their minimum size possible. This can save
529	memory when your JSON texts are either very very long or you have many	608	memory when your JSON texts are either very very long or you have many
…		…
547	strings that look like integers or floats into integers or floats	626	strings that look like integers or floats into integers or floats
548	internally (there is no difference on the Perl level), saving space.	627	internally (there is no difference on the Perl level), saving space.
549		628
550	=item $json = $json->max_depth ([$maximum_nesting_depth])	629	=item $json = $json->max_depth ([$maximum_nesting_depth])
551		630
		631	=item $max_depth = $json->get_max_depth
		632
552	Sets the maximum nesting level (default C<512>) accepted while encoding	633	Sets the maximum nesting level (default C<512>) accepted while encoding
553	or decoding. If the JSON text or Perl data structure has an equal or	634	or decoding. If a higher nesting level is detected in JSON text or a Perl
554	higher nesting level then this limit, then the encoder and decoder will	635	data structure, then the encoder and decoder will stop and croak at that
555	stop and croak at that point.	636	point.
556		637
557	Nesting level is defined by number of hash- or arrayrefs that the encoder	638	Nesting level is defined by number of hash- or arrayrefs that the encoder
558	needs to traverse to reach a given point or the number of C<{> or C<[>	639	needs to traverse to reach a given point or the number of C<{> or C<[>
559	characters without their matching closing parenthesis crossed to reach a	640	characters without their matching closing parenthesis crossed to reach a
560	given character in a string.	641	given character in a string.
561		642
562	Setting the maximum depth to one disallows any nesting, so that ensures	643	Setting the maximum depth to one disallows any nesting, so that ensures
563	that the object is only a single hash/object or array.	644	that the object is only a single hash/object or array.
564		645
565	The argument to C<max_depth> will be rounded up to the next highest power
566	of two. If no argument is given, the highest possible setting will be	646	If no argument is given, the highest possible setting will be used, which
567	used, which is rarely useful.	647	is rarely useful.
		648
		649	Note that nesting is implemented by recursion in C. The default value has
		650	been chosen to be as large as typical operating systems allow without
		651	crashing.
568		652
569	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	653	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
570		654
571	=item $json = $json->max_size ([$maximum_string_size])	655	=item $json = $json->max_size ([$maximum_string_size])
		656
		657	=item $max_size = $json->get_max_size
572		658
573	Set the maximum length a JSON text may have (in bytes) where decoding is	659	Set the maximum length a JSON text may have (in bytes) where decoding is
574	being attempted. The default is C<0>, meaning no limit. When C<decode>	660	being attempted. The default is C<0>, meaning no limit. When C<decode>
575	is called on a string longer then this number of characters it will not	661	is called on a string that is longer then this many bytes, it will not
576	attempt to decode the string but throw an exception. This setting has no	662	attempt to decode the string but throw an exception. This setting has no
577	effect on C<encode> (yet).	663	effect on C<encode> (yet).
578		664
579	The argument to C<max_size> will be rounded up to the next B<highest>	665	If no argument is given, the limit check will be deactivated (same as when
580	power of two (so may be more than requested). If no argument is given, the	666	C<0> is specified).
581	limit check will be deactivated (same as when C<0> is specified).
582		667
583	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	668	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
584		669
585	=item $json_text = $json->encode ($perl_scalar)	670	=item $json_text = $json->encode ($perl_scalar)
586		671
…		…
615	=> ([], 3)	700	=> ([], 3)
616		701
617	=back	702	=back
618		703
619		704
		705	=head1 INCREMENTAL PARSING
		706
		707	In some cases, there is the need for incremental parsing of JSON
		708	texts. While this module always has to keep both JSON text and resulting
		709	Perl data structure in memory at one time, it does allow you to parse a
		710	JSON stream incrementally. It does so by accumulating text until it has
		711	a full JSON object, which it then can decode. This process is similar to
		712	using C<decode_prefix> to see if a full JSON object is available, but
		713	is much more efficient (and can be implemented with a minimum of method
		714	calls).
		715
		716	JSON::XS will only attempt to parse the JSON text once it is sure it
		717	has enough text to get a decisive result, using a very simple but
		718	truly incremental parser. This means that it sometimes won't stop as
		719	early as the full parser, for example, it doesn't detect mismatched
		720	parentheses. The only thing it guarantees is that it starts decoding as
		721	soon as a syntactically valid JSON text has been seen. This means you need
		722	to set resource limits (e.g. C<max_size>) to ensure the parser will stop
		723	parsing in the presence if syntax errors.
		724
		725	The following methods implement this incremental parser.
		726
		727	=over 4
		728
		729	=item [void, scalar or list context] = $json->incr_parse ([$string])
		730
		731	This is the central parsing function. It can both append new text and
		732	extract objects from the stream accumulated so far (both of these
		733	functions are optional).
		734
		735	If C<$string> is given, then this string is appended to the already
		736	existing JSON fragment stored in the C<$json> object.
		737
		738	After that, if the function is called in void context, it will simply
		739	return without doing anything further. This can be used to add more text
		740	in as many chunks as you want.
		741
		742	If the method is called in scalar context, then it will try to extract
		743	exactly I<one> JSON object. If that is successful, it will return this
		744	object, otherwise it will return C<undef>. If there is a parse error,
		745	this method will croak just as C<decode> would do (one can then use
		746	C<incr_skip> to skip the errornous part). This is the most common way of
		747	using the method.
		748
		749	And finally, in list context, it will try to extract as many objects
		750	from the stream as it can find and return them, or the empty list
		751	otherwise. For this to work, there must be no separators between the JSON
		752	objects or arrays, instead they must be concatenated back-to-back. If
		753	an error occurs, an exception will be raised as in the scalar context
		754	case. Note that in this case, any previously-parsed JSON texts will be
		755	lost.
		756
		757	Example: Parse some JSON arrays/objects in a given string and return
		758	them.
		759
		760	my @objs = JSON::XS->new->incr_parse ("[5][7][1,2]");
		761
		762	=item $lvalue_string = $json->incr_text
		763
		764	This method returns the currently stored JSON fragment as an lvalue, that
		765	is, you can manipulate it. This I<only> works when a preceding call to
		766	C<incr_parse> in I<scalar context> successfully returned an object. Under
		767	all other circumstances you must not call this function (I mean it.
		768	although in simple tests it might actually work, it I<will> fail under
		769	real world conditions). As a special exception, you can also call this
		770	method before having parsed anything.
		771
		772	This function is useful in two cases: a) finding the trailing text after a
		773	JSON object or b) parsing multiple JSON objects separated by non-JSON text
		774	(such as commas).
		775
		776	=item $json->incr_skip
		777
		778	This will reset the state of the incremental parser and will remove
		779	the parsed text from the input buffer so far. This is useful after
		780	C<incr_parse> died, in which case the input buffer and incremental parser
		781	state is left unchanged, to skip the text parsed so far and to reset the
		782	parse state.
		783
		784	The difference to C<incr_reset> is that only text until the parse error
		785	occured is removed.
		786
		787	=item $json->incr_reset
		788
		789	This completely resets the incremental parser, that is, after this call,
		790	it will be as if the parser had never parsed anything.
		791
		792	This is useful if you want to repeatedly parse JSON objects and want to
		793	ignore any trailing data, which means you have to reset the parser after
		794	each successful decode.
		795
		796	=back
		797
		798	=head2 LIMITATIONS
		799
		800	All options that affect decoding are supported, except
		801	C<allow_nonref>. The reason for this is that it cannot be made to
		802	work sensibly: JSON objects and arrays are self-delimited, i.e. you can concatenate
		803	them back to back and still decode them perfectly. This does not hold true
		804	for JSON numbers, however.
		805
		806	For example, is the string C<1> a single JSON number, or is it simply the
		807	start of C<12>? Or is C<12> a single JSON number, or the concatenation
		808	of C<1> and C<2>? In neither case you can tell, and this is why JSON::XS
		809	takes the conservative route and disallows this case.
		810
		811	=head2 EXAMPLES
		812
		813	Some examples will make all this clearer. First, a simple example that
		814	works similarly to C<decode_prefix>: We want to decode the JSON object at
		815	the start of a string and identify the portion after the JSON object:
		816
		817	my $text = "[1,2,3] hello";
		818
		819	my $json = new JSON::XS;
		820
		821	my $obj = $json->incr_parse ($text)
		822	or die "expected JSON object or array at beginning of string";
		823
		824	my $tail = $json->incr_text;
		825	# $tail now contains " hello"
		826
		827	Easy, isn't it?
		828
		829	Now for a more complicated example: Imagine a hypothetical protocol where
		830	you read some requests from a TCP stream, and each request is a JSON
		831	array, without any separation between them (in fact, it is often useful to
		832	use newlines as "separators", as these get interpreted as whitespace at
		833	the start of the JSON text, which makes it possible to test said protocol
		834	with C<telnet>...).
		835
		836	Here is how you'd do it (it is trivial to write this in an event-based
		837	manner):
		838
		839	my $json = new JSON::XS;
		840
		841	# read some data from the socket
		842	while (sysread $socket, my $buf, 4096) {
		843
		844	# split and decode as many requests as possible
		845	for my $request ($json->incr_parse ($buf)) {
		846	# act on the $request
		847	}
		848	}
		849
		850	Another complicated example: Assume you have a string with JSON objects
		851	or arrays, all separated by (optional) comma characters (e.g. C<[1],[2],
		852	[3]>). To parse them, we have to skip the commas between the JSON texts,
		853	and here is where the lvalue-ness of C<incr_text> comes in useful:
		854
		855	my $text = "[1],[2], [3]";
		856	my $json = new JSON::XS;
		857
		858	# void context, so no parsing done
		859	$json->incr_parse ($text);
		860
		861	# now extract as many objects as possible. note the
		862	# use of scalar context so incr_text can be called.
		863	while (my $obj = $json->incr_parse) {
		864	# do something with $obj
		865
		866	# now skip the optional comma
		867	$json->incr_text =~ s/^ \s* , //x;
		868	}
		869
		870	Now lets go for a very complex example: Assume that you have a gigantic
		871	JSON array-of-objects, many gigabytes in size, and you want to parse it,
		872	but you cannot load it into memory fully (this has actually happened in
		873	the real world :).
		874
		875	Well, you lost, you have to implement your own JSON parser. But JSON::XS
		876	can still help you: You implement a (very simple) array parser and let
		877	JSON decode the array elements, which are all full JSON objects on their
		878	own (this wouldn't work if the array elements could be JSON numbers, for
		879	example):
		880
		881	my $json = new JSON::XS;
		882
		883	# open the monster
		884	open my $fh, "<bigfile.json"
		885	or die "bigfile: $!";
		886
		887	# first parse the initial "["
		888	for (;;) {
		889	sysread $fh, my $buf, 65536
		890	or die "read error: $!";
		891	$json->incr_parse ($buf); # void context, so no parsing
		892
		893	# Exit the loop once we found and removed(!) the initial "[".
		894	# In essence, we are (ab-)using the $json object as a simple scalar
		895	# we append data to.
		896	last if $json->incr_text =~ s/^ \s* \[ //x;
		897	}
		898
		899	# now we have the skipped the initial "[", so continue
		900	# parsing all the elements.
		901	for (;;) {
		902	# in this loop we read data until we got a single JSON object
		903	for (;;) {
		904	if (my $obj = $json->incr_parse) {
		905	# do something with $obj
		906	last;
		907	}
		908
		909	# add more data
		910	sysread $fh, my $buf, 65536
		911	or die "read error: $!";
		912	$json->incr_parse ($buf); # void context, so no parsing
		913	}
		914
		915	# in this loop we read data until we either found and parsed the
		916	# separating "," between elements, or the final "]"
		917	for (;;) {
		918	# first skip whitespace
		919	$json->incr_text =~ s/^\s*//;
		920
		921	# if we find "]", we are done
		922	if ($json->incr_text =~ s/^\]//) {
		923	print "finished.\n";
		924	exit;
		925	}
		926
		927	# if we find ",", we can continue with the next element
		928	if ($json->incr_text =~ s/^,//) {
		929	last;
		930	}
		931
		932	# if we find anything else, we have a parse error!
		933	if (length $json->incr_text) {
		934	die "parse error near ", $json->incr_text;
		935	}
		936
		937	# else add more data
		938	sysread $fh, my $buf, 65536
		939	or die "read error: $!";
		940	$json->incr_parse ($buf); # void context, so no parsing
		941	}
		942
		943	This is a complex example, but most of the complexity comes from the fact
		944	that we are trying to be correct (bear with me if I am wrong, I never ran
		945	the above example :).
		946
		947
		948
620	=head1 MAPPING	949	=head1 MAPPING
621		950
622	This section describes how JSON::XS maps Perl values to JSON values and	951	This section describes how JSON::XS maps Perl values to JSON values and
623	vice versa. These mappings are designed to "do the right thing" in most	952	vice versa. These mappings are designed to "do the right thing" in most
624	circumstances automatically, preserving round-tripping characteristics	953	circumstances automatically, preserving round-tripping characteristics
625	(what you put in comes out as something equivalent).	954	(what you put in comes out as something equivalent).
626		955
627	For the more enlightened: note that in the following descriptions,	956	For the more enlightened: note that in the following descriptions,
628	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>	957	lowercase I<perl> refers to the Perl interpreter, while uppercase I<Perl>
629	refers to the abstract Perl language itself.	958	refers to the abstract Perl language itself.
630		959
631		960
632	=head2 JSON -> PERL	961	=head2 JSON -> PERL
633		962
634	=over 4	963	=over 4
635		964
636	=item object	965	=item object
637		966
638	A JSON object becomes a reference to a hash in Perl. No ordering of object	967	A JSON object becomes a reference to a hash in Perl. No ordering of object
639	keys is preserved (JSON does not preserver object key ordering itself).	968	keys is preserved (JSON does not preserve object key ordering itself).
640		969
641	=item array	970	=item array
642		971
643	A JSON array becomes a reference to an array in Perl.	972	A JSON array becomes a reference to an array in Perl.
644		973
…		…
652		981
653	A JSON number becomes either an integer, numeric (floating point) or	982	A JSON number becomes either an integer, numeric (floating point) or
654	string scalar in perl, depending on its range and any fractional parts. On	983	string scalar in perl, depending on its range and any fractional parts. On
655	the Perl level, there is no difference between those as Perl handles all	984	the Perl level, there is no difference between those as Perl handles all
656	the conversion details, but an integer may take slightly less memory and	985	the conversion details, but an integer may take slightly less memory and
657	might represent more values exactly than (floating point) numbers.	986	might represent more values exactly than floating point numbers.
658		987
659	If the number consists of digits only, JSON::XS will try to represent	988	If the number consists of digits only, JSON::XS will try to represent
660	it as an integer value. If that fails, it will try to represent it as	989	it as an integer value. If that fails, it will try to represent it as
661	a numeric (floating point) value if that is possible without loss of	990	a numeric (floating point) value if that is possible without loss of
662	precision. Otherwise it will preserve the number as a string value.	991	precision. Otherwise it will preserve the number as a string value (in
		992	which case you lose roundtripping ability, as the JSON number will be
		993	re-encoded toa JSON string).
663		994
664	Numbers containing a fractional or exponential part will always be	995	Numbers containing a fractional or exponential part will always be
665	represented as numeric (floating point) values, possibly at a loss of	996	represented as numeric (floating point) values, possibly at a loss of
666	precision.	997	precision (in which case you might lose perfect roundtripping ability, but
		998	the JSON number will still be re-encoded as a JSON number).
667		999
668	This might create round-tripping problems as numbers might become strings,	1000	Note that precision is not accuracy - binary floating point values cannot
669	but as Perl is typeless there is no other way to do it.	1001	represent most decimal fractions exactly, and when converting from and to
		1002	floating point, JSON::XS only guarantees precision up to but not including
		1003	the leats significant bit.
670		1004
671	=item true, false	1005	=item true, false
672		1006
673	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,	1007	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
674	respectively. They are overloaded to act almost exactly like the numbers	1008	respectively. They are overloaded to act almost exactly like the numbers
675	C<1> and C<0>. You can check wether a scalar is a JSON boolean by using	1009	C<1> and C<0>. You can check whether a scalar is a JSON boolean by using
676	the C<JSON::XS::is_bool> function.	1010	the C<JSON::XS::is_bool> function.
677		1011
678	=item null	1012	=item null
679		1013
680	A JSON null atom becomes C<undef> in Perl.	1014	A JSON null atom becomes C<undef> in Perl.
…		…
711	Other unblessed references are generally not allowed and will cause an	1045	Other unblessed references are generally not allowed and will cause an
712	exception to be thrown, except for references to the integers C<0> and	1046	exception to be thrown, except for references to the integers C<0> and
713	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can	1047	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
714	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.	1048	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
715		1049
716	to_json [\0,JSON::XS::true] # yields [false,true]	1050	encode_json [\0, JSON::XS::true] # yields [false,true]
717		1051
718	=item JSON::XS::true, JSON::XS::false	1052	=item JSON::XS::true, JSON::XS::false
719		1053
720	These special values become JSON true and JSON false values,	1054	These special values become JSON true and JSON false values,
721	respectively. You can also use C<\1> and C<\0> directly if you want.	1055	respectively. You can also use C<\1> and C<\0> directly if you want.
722		1056
723	=item blessed objects	1057	=item blessed objects
724		1058
725	Blessed objects are not allowed. JSON::XS currently tries to encode their	1059	Blessed objects are not directly representable in JSON. See the
726	underlying representation (hash- or arrayref), but this behaviour might	1060	C<allow_blessed> and C<convert_blessed> methods on various options on
727	change in future versions.	1061	how to deal with this: basically, you can choose between throwing an
		1062	exception, encoding the reference as if it weren't blessed, or provide
		1063	your own serialiser method.
728		1064
729	=item simple scalars	1065	=item simple scalars
730		1066
731	Simple Perl scalars (any scalar that is not a reference) are the most	1067	Simple Perl scalars (any scalar that is not a reference) are the most
732	difficult objects to encode: JSON::XS will encode undefined scalars as	1068	difficult objects to encode: JSON::XS will encode undefined scalars as
733	JSON null value, scalars that have last been used in a string context	1069	JSON C<null> values, scalars that have last been used in a string context
734	before encoding as JSON strings and anything else as number value:	1070	before encoding as JSON strings, and anything else as number value:
735		1071
736	# dump as number	1072	# dump as number
737	to_json [2] # yields [2]	1073	encode_json [2] # yields [2]
738	to_json [-3.0e17] # yields [-3e+17]	1074	encode_json [-3.0e17] # yields [-3e+17]
739	my $value = 5; to_json [$value] # yields [5]	1075	my $value = 5; encode_json [$value] # yields [5]
740		1076
741	# used as string, so dump as string	1077	# used as string, so dump as string
742	print $value;	1078	print $value;
743	to_json [$value] # yields ["5"]	1079	encode_json [$value] # yields ["5"]
744		1080
745	# undef becomes null	1081	# undef becomes null
746	to_json [undef] # yields [null]	1082	encode_json [undef] # yields [null]
747		1083
748	You can force the type to be a string by stringifying it:	1084	You can force the type to be a JSON string by stringifying it:
749		1085
750	my $x = 3.1; # some variable containing a number	1086	my $x = 3.1; # some variable containing a number
751	"$x"; # stringified	1087	"$x"; # stringified
752	$x .= ""; # another, more awkward way to stringify	1088	$x .= ""; # another, more awkward way to stringify
753	print $x; # perl does it for you, too, quite often	1089	print $x; # perl does it for you, too, quite often
754		1090
755	You can force the type to be a number by numifying it:	1091	You can force the type to be a JSON number by numifying it:
756		1092
757	my $x = "3"; # some variable containing a string	1093	my $x = "3"; # some variable containing a string
758	$x += 0; # numify it, ensuring it will be dumped as a number	1094	$x += 0; # numify it, ensuring it will be dumped as a number
759	$x *= 1; # same thing, the choise is yours.	1095	$x *= 1; # same thing, the choice is yours.
760		1096
761	You can not currently output JSON booleans or force the type in other,	1097	You can not currently force the type in other, less obscure, ways. Tell me
762	less obscure, ways. Tell me if you need this capability.	1098	if you need this capability (but don't forget to explain why it's needed
		1099	:).
		1100
		1101	Note that numerical precision has the same meaning as under Perl (so
		1102	binary to decimal conversion follows the same rules as in Perl, which
		1103	can differ to other languages). Also, your perl interpreter might expose
		1104	extensions to the floating point numbers of your platform, such as
		1105	infinities or NaN's - these cannot be represented in JSON, and it is an
		1106	error to pass those in.
763		1107
764	=back	1108	=back
765		1109
766		1110
767	=head1 COMPARISON	1111	=head1 ENCODING/CODESET FLAG NOTES
768		1112
769	As already mentioned, this module was created because none of the existing	1113	The interested reader might have seen a number of flags that signify
770	JSON modules could be made to work correctly. First I will describe the	1114	encodings or codesets - C<utf8>, C<latin1> and C<ascii>. There seems to be
771	problems (or pleasures) I encountered with various existing JSON modules,	1115	some confusion on what these do, so here is a short comparison:
772	followed by some benchmark values. JSON::XS was designed not to suffer	1116
773	from any of these problems or limitations.	1117	C<utf8> controls whether the JSON text created by C<encode> (and expected
		1118	by C<decode>) is UTF-8 encoded or not, while C<latin1> and C<ascii> only
		1119	control whether C<encode> escapes character values outside their respective
		1120	codeset range. Neither of these flags conflict with each other, although
		1121	some combinations make less sense than others.
		1122
		1123	Care has been taken to make all flags symmetrical with respect to
		1124	C<encode> and C<decode>, that is, texts encoded with any combination of
		1125	these flag values will be correctly decoded when the same flags are used
		1126	- in general, if you use different flag settings while encoding vs. when
		1127	decoding you likely have a bug somewhere.
		1128
		1129	Below comes a verbose discussion of these flags. Note that a "codeset" is
		1130	simply an abstract set of character-codepoint pairs, while an encoding
		1131	takes those codepoint numbers and I<encodes> them, in our case into
		1132	octets. Unicode is (among other things) a codeset, UTF-8 is an encoding,
		1133	and ISO-8859-1 (= latin 1) and ASCII are both codesets I<and> encodings at
		1134	the same time, which can be confusing.
774		1135
775	=over 4	1136	=over 4
776		1137
777	=item JSON 1.07	1138	=item C<utf8> flag disabled
778		1139
779	Slow (but very portable, as it is written in pure Perl).	1140	When C<utf8> is disabled (the default), then C<encode>/C<decode> generate
		1141	and expect Unicode strings, that is, characters with high ordinal Unicode
		1142	values (> 255) will be encoded as such characters, and likewise such
		1143	characters are decoded as-is, no canges to them will be done, except
		1144	"(re-)interpreting" them as Unicode codepoints or Unicode characters,
		1145	respectively (to Perl, these are the same thing in strings unless you do
		1146	funny/weird/dumb stuff).
780		1147
781	Undocumented/buggy Unicode handling (how JSON handles unicode values is	1148	This is useful when you want to do the encoding yourself (e.g. when you
782	undocumented. One can get far by feeding it unicode strings and doing	1149	want to have UTF-16 encoded JSON texts) or when some other layer does
783	en-/decoding oneself, but unicode escapes are not working properly).	1150	the encoding for you (for example, when printing to a terminal using a
		1151	filehandle that transparently encodes to UTF-8 you certainly do NOT want
		1152	to UTF-8 encode your data first and have Perl encode it another time).
784		1153
785	No roundtripping (strings get clobbered if they look like numbers, e.g.	1154	=item C<utf8> flag enabled
786	the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will
787	decode into the number 2.
788		1155
789	=item JSON::PC 0.01	1156	If the C<utf8>-flag is enabled, C<encode>/C<decode> will encode all
		1157	characters using the corresponding UTF-8 multi-byte sequence, and will
		1158	expect your input strings to be encoded as UTF-8, that is, no "character"
		1159	of the input string must have any value > 255, as UTF-8 does not allow
		1160	that.
790		1161
791	Very fast.	1162	The C<utf8> flag therefore switches between two modes: disabled means you
		1163	will get a Unicode string in Perl, enabled means you get an UTF-8 encoded
		1164	octet/binary string in Perl.
792		1165
793	Undocumented/buggy Unicode handling.	1166	=item C<latin1> or C<ascii> flags enabled
794		1167
795	No roundtripping.	1168	With C<latin1> (or C<ascii>) enabled, C<encode> will escape characters
		1169	with ordinal values > 255 (> 127 with C<ascii>) and encode the remaining
		1170	characters as specified by the C<utf8> flag.
796		1171
797	Has problems handling many Perl values (e.g. regex results and other magic	1172	If C<utf8> is disabled, then the result is also correctly encoded in those
798	values will make it croak).	1173	character sets (as both are proper subsets of Unicode, meaning that a
		1174	Unicode string with all character values < 256 is the same thing as a
		1175	ISO-8859-1 string, and a Unicode string with all character values < 128 is
		1176	the same thing as an ASCII string in Perl).
799		1177
800	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>	1178	If C<utf8> is enabled, you still get a correct UTF-8-encoded string,
801	which is not a valid JSON text.	1179	regardless of these flags, just some more characters will be escaped using
		1180	C<\uXXXX> then before.
802		1181
803	Unmaintained (maintainer unresponsive for many months, bugs are not	1182	Note that ISO-8859-1-I<encoded> strings are not compatible with UTF-8
804	getting fixed).	1183	encoding, while ASCII-encoded strings are. That is because the ISO-8859-1
		1184	encoding is NOT a subset of UTF-8 (despite the ISO-8859-1 I<codeset> being
		1185	a subset of Unicode), while ASCII is.
805		1186
806	=item JSON::Syck 0.21	1187	Surprisingly, C<decode> will ignore these flags and so treat all input
		1188	values as governed by the C<utf8> flag. If it is disabled, this allows you
		1189	to decode ISO-8859-1- and ASCII-encoded strings, as both strict subsets of
		1190	Unicode. If it is enabled, you can correctly decode UTF-8 encoded strings.
807		1191
808	Very buggy (often crashes).	1192	So neither C<latin1> nor C<ascii> are incompatible with the C<utf8> flag -
		1193	they only govern when the JSON output engine escapes a character or not.
809		1194
810	Very inflexible (no human-readable format supported, format pretty much	1195	The main use for C<latin1> is to relatively efficiently store binary data
811	undocumented. I need at least a format for easy reading by humans and a	1196	as JSON, at the expense of breaking compatibility with most JSON decoders.
812	single-line compact format for use in a protocol, and preferably a way to
813	generate ASCII-only JSON texts).
814		1197
815	Completely broken (and confusingly documented) Unicode handling (unicode	1198	The main use for C<ascii> is to force the output to not contain characters
816	escapes are not working properly, you need to set ImplicitUnicode to	1199	with values > 127, which means you can interpret the resulting string
817	I<different> values on en- and decoding to get symmetric behaviour).	1200	as UTF-8, ISO-8859-1, ASCII, KOI8-R or most about any character set and
818		1201	8-bit-encoding, and still get the same data structure back. This is useful
819	No roundtripping (simple cases work, but this depends on wether the scalar	1202	when your channel for JSON transfer is not 8-bit clean or the encoding
820	value was used in a numeric context or not).	1203	might be mangled in between (e.g. in mail), and works because ASCII is a
821		1204	proper subset of most 8-bit and multibyte encodings in use in the world.
822	Dumping hashes may skip hash values depending on iterator state.
823
824	Unmaintained (maintainer unresponsive for many months, bugs are not
825	getting fixed).
826
827	Does not check input for validity (i.e. will accept non-JSON input and
828	return "something" instead of raising an exception. This is a security
829	issue: imagine two banks transfering money between each other using
830	JSON. One bank might parse a given non-JSON request and deduct money,
831	while the other might reject the transaction with a syntax error. While a
832	good protocol will at least recover, that is extra unnecessary work and
833	the transaction will still not succeed).
834
835	=item JSON::DWIW 0.04
836
837	Very fast. Very natural. Very nice.
838
839	Undocumented unicode handling (but the best of the pack. Unicode escapes
840	still don't get parsed properly).
841
842	Very inflexible.
843
844	No roundtripping.
845
846	Does not generate valid JSON texts (key strings are often unquoted, empty keys
847	result in nothing being output)
848
849	Does not check input for validity.
850		1205
851	=back	1206	=back
852		1207
853		1208
		1209	=head2 JSON and ECMAscript
		1210
		1211	JSON syntax is based on how literals are represented in javascript (the
		1212	not-standardised predecessor of ECMAscript) which is presumably why it is
		1213	called "JavaScript Object Notation".
		1214
		1215	However, JSON is not a subset (and also not a superset of course) of
		1216	ECMAscript (the standard) or javascript (whatever browsers actually
		1217	implement).
		1218
		1219	If you want to use javascript's C<eval> function to "parse" JSON, you
		1220	might run into parse errors for valid JSON texts, or the resulting data
		1221	structure might not be queryable:
		1222
		1223	One of the problems is that U+2028 and U+2029 are valid characters inside
		1224	JSON strings, but are not allowed in ECMAscript string literals, so the
		1225	following Perl fragment will not output something that can be guaranteed
		1226	to be parsable by javascript's C<eval>:
		1227
		1228	use JSON::XS;
		1229
		1230	print encode_json [chr 0x2028];
		1231
		1232	The right fix for this is to use a proper JSON parser in your javascript
		1233	programs, and not rely on C<eval> (see for example Douglas Crockford's
		1234	F<json2.js> parser).
		1235
		1236	If this is not an option, you can, as a stop-gap measure, simply encode to
		1237	ASCII-only JSON:
		1238
		1239	use JSON::XS;
		1240
		1241	print JSON::XS->new->ascii->encode ([chr 0x2028]);
		1242
		1243	Note that this will enlarge the resulting JSON text quite a bit if you
		1244	have many non-ASCII characters. You might be tempted to run some regexes
		1245	to only escape U+2028 and U+2029, e.g.:
		1246
		1247	# DO NOT USE THIS!
		1248	my $json = JSON::XS->new->utf8->encode ([chr 0x2028]);
		1249	$json =~ s/\xe2\x80\xa8/\\u2028/g; # escape U+2028
		1250	$json =~ s/\xe2\x80\xa9/\\u2029/g; # escape U+2029
		1251	print $json;
		1252
		1253	Note that I<this is a bad idea>: the above only works for U+2028 and
		1254	U+2029 and thus only for fully ECMAscript-compliant parsers. Many existing
		1255	javascript implementations, however, have issues with other characters as
		1256	well - using C<eval> naively simply I<will> cause problems.
		1257
		1258	Another problem is that some javascript implementations reserve
		1259	some property names for their own purposes (which probably makes
		1260	them non-ECMAscript-compliant). For example, Iceweasel reserves the
		1261	C<__proto__> property name for its own purposes.
		1262
		1263	If that is a problem, you could parse try to filter the resulting JSON
		1264	output for these property strings, e.g.:
		1265
		1266	$json =~ s/"__proto__"\s*:/"__proto__renamed":/g;
		1267
		1268	This works because C<__proto__> is not valid outside of strings, so every
		1269	occurence of C<"__proto__"\s*:> must be a string used as property name.
		1270
		1271	If you know of other incompatibilities, please let me know.
		1272
		1273
854	=head2 JSON and YAML	1274	=head2 JSON and YAML
855		1275
856	You often hear that JSON is a subset (or a close subset) of YAML. This is,	1276	You often hear that JSON is a subset of YAML. This is, however, a mass
857	however, a mass hysteria and very far from the truth. In general, there is	1277	hysteria(*) and very far from the truth (as of the time of this writing),
858	no way to configure JSON::XS to output a data structure as valid YAML.	1278	so let me state it clearly: I<in general, there is no way to configure
		1279	JSON::XS to output a data structure as valid YAML> that works in all
		1280	cases.
859		1281
860	If you really must use JSON::XS to generate YAML, you should use this	1282	If you really must use JSON::XS to generate YAML, you should use this
861	algorithm (subject to change in future versions):	1283	algorithm (subject to change in future versions):
862		1284
863	my $to_yaml = JSON::XS->new->utf8->space_after (1);	1285	my $to_yaml = JSON::XS->new->utf8->space_after (1);
864	my $yaml = $to_yaml->encode ($ref) . "\n";	1286	my $yaml = $to_yaml->encode ($ref) . "\n";
865		1287
866	This will usually generate JSON texts that also parse as valid	1288	This will I<usually> generate JSON texts that also parse as valid
867	YAML. Please note that YAML has hardcoded limits on (simple) object key	1289	YAML. Please note that YAML has hardcoded limits on (simple) object key
868	lengths that JSON doesn't have, so you should make sure that your hash	1290	lengths that JSON doesn't have and also has different and incompatible
		1291	unicode character escape syntax, so you should make sure that your hash
869	keys are noticably shorter than the 1024 characters YAML allows.	1292	keys are noticeably shorter than the 1024 "stream characters" YAML allows
		1293	and that you do not have characters with codepoint values outside the
		1294	Unicode BMP (basic multilingual page). YAML also does not allow C<\/>
		1295	sequences in strings (which JSON::XS does not I<currently> generate, but
		1296	other JSON generators might).
870		1297
871	There might be other incompatibilities that I am not aware of. In general	1298	There might be other incompatibilities that I am not aware of (or the YAML
		1299	specification has been changed yet again - it does so quite often). In
872	you should not try to generate YAML with a JSON generator or vice versa,	1300	general you should not try to generate YAML with a JSON generator or vice
873	or try to parse JSON with a YAML parser or vice versa: chances are high	1301	versa, or try to parse JSON with a YAML parser or vice versa: chances are
874	that you will run into severe interoperability problems.	1302	high that you will run into severe interoperability problems when you
		1303	least expect it.
		1304
		1305	=over 4
		1306
		1307	=item (*)
		1308
		1309	I have been pressured multiple times by Brian Ingerson (one of the
		1310	authors of the YAML specification) to remove this paragraph, despite him
		1311	acknowledging that the actual incompatibilities exist. As I was personally
		1312	bitten by this "JSON is YAML" lie, I refused and said I will continue to
		1313	educate people about these issues, so others do not run into the same
		1314	problem again and again. After this, Brian called me a (quote)I<complete
		1315	and worthless idiot>(unquote).
		1316
		1317	In my opinion, instead of pressuring and insulting people who actually
		1318	clarify issues with YAML and the wrong statements of some of its
		1319	proponents, I would kindly suggest reading the JSON spec (which is not
		1320	that difficult or long) and finally make YAML compatible to it, and
		1321	educating users about the changes, instead of spreading lies about the
		1322	real compatibility for many I<years> and trying to silence people who
		1323	point out that it isn't true.
		1324
		1325	Addendum/2009: the YAML 1.2 spec is still incompatible with JSON, even
		1326	though the incompatibilities have been documented (and are known to Brian)
		1327	for many years and the spec makes explicit claims that YAML is a superset
		1328	of JSON. It would be so easy to fix, but apparently, bullying people and
		1329	corrupting userdata is so much easier.
		1330
		1331	=back
875		1332
876		1333
877	=head2 SPEED	1334	=head2 SPEED
878		1335
879	It seems that JSON::XS is surprisingly fast, as shown in the following	1336	It seems that JSON::XS is surprisingly fast, as shown in the following
880	tables. They have been generated with the help of the C<eg/bench> program	1337	tables. They have been generated with the help of the C<eg/bench> program
881	in the JSON::XS distribution, to make it easy to compare on your own	1338	in the JSON::XS distribution, to make it easy to compare on your own
882	system.	1339	system.
883		1340
884	First comes a comparison between various modules using a very short	1341	First comes a comparison between various modules using
885	single-line JSON string:	1342	a very short single-line JSON string (also available at
		1343	L<http://dist.schmorp.de/misc/json/short.json>).
886		1344
887	{"method": "handleMessage", "params": ["user1", "we were just talking"], \	1345	{"method": "handleMessage", "params": ["user1",
888	"id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}	1346	"we were just talking"], "id": null, "array":[1,11,234,-5,1e5,1e7,
		1347	1, 0]}
889		1348
890	It shows the number of encodes/decodes per second (JSON::XS uses	1349	It shows the number of encodes/decodes per second (JSON::XS uses
891	the functional interface, while JSON::XS/2 uses the OO interface	1350	the functional interface, while JSON::XS/2 uses the OO interface
892	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables	1351	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
893	shrink). Higher is better:	1352	shrink. JSON::DWIW/DS uses the deserialise function, while JSON::DWIW::FJ
		1353	uses the from_json method). Higher is better:
894		1354
895	Storable \| 15779.925 \| 14169.946 \|
896	-----------+------------+------------+
897	module \| encode \| decode \|	1355	module \| encode \| decode \|
898	-----------\|------------\|------------\|	1356	--------------\|------------\|------------\|
899	JSON \| 4990.842 \| 4088.813 \|	1357	JSON::DWIW/DS \| 86302.551 \| 102300.098 \|
900	JSON::DWIW \| 51653.990 \| 71575.154 \|	1358	JSON::DWIW/FJ \| 86302.551 \| 75983.768 \|
901	JSON::PC \| 65948.176 \| 74631.744 \|	1359	JSON::PP \| 15827.562 \| 6638.658 \|
902	JSON::PP \| 8931.652 \| 3817.168 \|	1360	JSON::Syck \| 63358.066 \| 47662.545 \|
903	JSON::Syck \| 24877.248 \| 27776.848 \|	1361	JSON::XS \| 511500.488 \| 511500.488 \|
904	JSON::XS \| 388361.481 \| 227951.304 \|	1362	JSON::XS/2 \| 291271.111 \| 388361.481 \|
905	JSON::XS/2 \| 227951.304 \| 218453.333 \|	1363	JSON::XS/3 \| 361577.931 \| 361577.931 \|
906	JSON::XS/3 \| 338250.323 \| 218453.333 \|	1364	Storable \| 66788.280 \| 265462.278 \|
907	Storable \| 16500.016 \| 135300.129 \|
908	-----------+------------+------------+	1365	--------------+------------+------------+
909		1366
910	That is, JSON::XS is about five times faster than JSON::DWIW on encoding,	1367	That is, JSON::XS is almost six times faster than JSON::DWIW on encoding,
911	about three times faster on decoding, and over fourty times faster	1368	about five times faster on decoding, and over thirty to seventy times
912	than JSON, even with pretty-printing and key sorting. It also compares	1369	faster than JSON's pure perl implementation. It also compares favourably
913	favourably to Storable for small amounts of data.	1370	to Storable for small amounts of data.
914		1371
915	Using a longer test string (roughly 18KB, generated from Yahoo! Locals	1372	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
916	search API (http://nanoref.com/yahooapis/mgPdGg):	1373	search API (L<http://dist.schmorp.de/misc/json/long.json>).
917		1374
918	module \| encode \| decode \|	1375	module \| encode \| decode \|
919	-----------\|------------\|------------\|	1376	--------------\|------------\|------------\|
920	JSON \| 55.260 \| 34.971 \|	1377	JSON::DWIW/DS \| 1647.927 \| 2673.916 \|
921	JSON::DWIW \| 825.228 \| 1082.513 \|	1378	JSON::DWIW/FJ \| 1630.249 \| 2596.128 \|
922	JSON::PC \| 3571.444 \| 2394.829 \|
923	JSON::PP \| 210.987 \| 32.574 \|	1379	JSON::PP \| 400.640 \| 62.311 \|
924	JSON::Syck \| 552.551 \| 787.544 \|	1380	JSON::Syck \| 1481.040 \| 1524.869 \|
925	JSON::XS \| 5780.463 \| 4854.519 \|	1381	JSON::XS \| 20661.596 \| 9541.183 \|
926	JSON::XS/2 \| 3869.998 \| 4798.975 \|	1382	JSON::XS/2 \| 10683.403 \| 9416.938 \|
927	JSON::XS/3 \| 5862.880 \| 4798.975 \|	1383	JSON::XS/3 \| 20661.596 \| 9400.054 \|
928	Storable \| 4445.002 \| 5235.027 \|	1384	Storable \| 19765.806 \| 10000.725 \|
929	-----------+------------+------------+	1385	--------------+------------+------------+
930		1386
931	Again, JSON::XS leads by far (except for Storable which non-surprisingly	1387	Again, JSON::XS leads by far (except for Storable which non-surprisingly
932	decodes faster).	1388	decodes a bit faster).
933		1389
934	On large strings containing lots of high unicode characters, some modules	1390	On large strings containing lots of high Unicode characters, some modules
935	(such as JSON::PC) seem to decode faster than JSON::XS, but the result	1391	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
936	will be broken due to missing (or wrong) unicode handling. Others refuse	1392	will be broken due to missing (or wrong) Unicode handling. Others refuse
937	to decode or encode properly, so it was impossible to prepare a fair	1393	to decode or encode properly, so it was impossible to prepare a fair
938	comparison table for that case.	1394	comparison table for that case.
939		1395
940		1396
941	=head1 SECURITY CONSIDERATIONS	1397	=head1 SECURITY CONSIDERATIONS
…		…
947	any buffer overflows. Obviously, this module should ensure that and I am	1403	any buffer overflows. Obviously, this module should ensure that and I am
948	trying hard on making that true, but you never know.	1404	trying hard on making that true, but you never know.
949		1405
950	Second, you need to avoid resource-starving attacks. That means you should	1406	Second, you need to avoid resource-starving attacks. That means you should
951	limit the size of JSON texts you accept, or make sure then when your	1407	limit the size of JSON texts you accept, or make sure then when your
952	resources run out, thats just fine (e.g. by using a separate process that	1408	resources run out, that's just fine (e.g. by using a separate process that
953	can crash safely). The size of a JSON text in octets or characters is	1409	can crash safely). The size of a JSON text in octets or characters is
954	usually a good indication of the size of the resources required to decode	1410	usually a good indication of the size of the resources required to decode
955	it into a Perl structure. While JSON::XS can check the size of the JSON	1411	it into a Perl structure. While JSON::XS can check the size of the JSON
956	text, it might be too late when you already have it in memory, so you	1412	text, it might be too late when you already have it in memory, so you
957	might want to check the size before you accept the string.	1413	might want to check the size before you accept the string.
958		1414
959	Third, JSON::XS recurses using the C stack when decoding objects and	1415	Third, JSON::XS recurses using the C stack when decoding objects and
960	arrays. The C stack is a limited resource: for instance, on my amd64	1416	arrays. The C stack is a limited resource: for instance, on my amd64
961	machine with 8MB of stack size I can decode around 180k nested arrays but	1417	machine with 8MB of stack size I can decode around 180k nested arrays but
962	only 14k nested JSON objects (due to perl itself recursing deeply on croak	1418	only 14k nested JSON objects (due to perl itself recursing deeply on croak
963	to free the temporary). If that is exceeded, the program crashes. to be	1419	to free the temporary). If that is exceeded, the program crashes. To be
964	conservative, the default nesting limit is set to 512. If your process	1420	conservative, the default nesting limit is set to 512. If your process
965	has a smaller stack, you should adjust this setting accordingly with the	1421	has a smaller stack, you should adjust this setting accordingly with the
966	C<max_depth> method.	1422	C<max_depth> method.
967		1423
968	And last but least, something else could bomb you that I forgot to think	1424	Something else could bomb you, too, that I forgot to think of. In that
969	of. In that case, you get to keep the pieces. I am always open for hints,	1425	case, you get to keep the pieces. I am always open for hints, though...
970	though...	1426
		1427	Also keep in mind that JSON::XS might leak contents of your Perl data
		1428	structures in its error messages, so when you serialise sensitive
		1429	information you might want to make sure that exceptions thrown by JSON::XS
		1430	will not end up in front of untrusted eyes.
971		1431
972	If you are using JSON::XS to return packets to consumption	1432	If you are using JSON::XS to return packets to consumption
973	by javascript scripts in a browser you should have a look at	1433	by JavaScript scripts in a browser you should have a look at
974	L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether	1434	L<http://blog.archive.jpsykes.com/47/practical-csrf-and-json-security/> to
975	you are vulnerable to some common attack vectors (which really are browser	1435	see whether you are vulnerable to some common attack vectors (which really
976	design bugs, but it is still you who will have to deal with it, as major	1436	are browser design bugs, but it is still you who will have to deal with
977	browser developers care only for features, not about doing security	1437	it, as major browser developers care only for features, not about getting
978	right).	1438	security right).
979		1439
980		1440
981	=head1 THREADS	1441	=head1 THREADS
982		1442
983	This module is I<not> guarenteed to be thread safe and there are no	1443	This module is I<not> guaranteed to be thread safe and there are no
984	plans to change this until Perl gets thread support (as opposed to the	1444	plans to change this until Perl gets thread support (as opposed to the
985	horribly slow so-called "threads" which are simply slow and bloated	1445	horribly slow so-called "threads" which are simply slow and bloated
986	process simulations - use fork, its I<much> faster, cheaper, better).	1446	process simulations - use fork, it's I<much> faster, cheaper, better).
987		1447
988	(It might actually work, but you ahve ben warned).	1448	(It might actually work, but you have been warned).
		1449
		1450
		1451	=head1 THE PERILS OF SETLOCALE
		1452
		1453	Sometimes people avoid the Perl locale support and directly call the
		1454	system's setlocale function with C<LC_ALL>.
		1455
		1456	This breaks both perl and modules such as JSON::XS, as stringification of
		1457	numbers no longer works correcly (e.g. C<$x = 0.1; print "$x"+1> might
		1458	print C<1>, and JSON::XS might output illegal JSON as JSON::XS relies on
		1459	perl to stringify numbers).
		1460
		1461	The solution is simple: don't call C<setlocale>, or use it for only those
		1462	categories you need, such as C<LC_MESSAGES> or C<LC_CTYPE>.
		1463
		1464	If you need C<LC_NUMERIC>, you should enable it only around the code that
		1465	actually needs it (avoiding stringification of numbers), and restore it
		1466	afterwards.
989		1467
990		1468
991	=head1 BUGS	1469	=head1 BUGS
992		1470
993	While the goal of this module is to be correct, that unfortunately does	1471	While the goal of this module is to be correct, that unfortunately does
994	not mean its bug-free, only that I think its design is bug-free. It is	1472	not mean it's bug-free, only that I think its design is bug-free. If you
995	still relatively early in its development. If you keep reporting bugs they	1473	keep reporting bugs they will be fixed swiftly, though.
996	will be fixed swiftly, though.
997		1474
998	Please refrain from using rt.cpan.org or any other bug reporting	1475	Please refrain from using rt.cpan.org or any other bug reporting
999	service. I put the contact address into my modules for a reason.	1476	service. I put the contact address into my modules for a reason.
1000		1477
1001	=cut	1478	=cut
…		…
1021	"--" => sub { $_[0] = ${$_[0]} - 1 },	1498	"--" => sub { $_[0] = ${$_[0]} - 1 },
1022	fallback => 1;	1499	fallback => 1;
1023		1500
1024	1;	1501	1;
1025		1502
		1503	=head1 SEE ALSO
		1504
		1505	The F<json_xs> command line utility for quick experiments.
		1506
1026	=head1 AUTHOR	1507	=head1 AUTHOR
1027		1508
1028	Marc Lehmann <schmorp@schmorp.de>	1509	Marc Lehmann <schmorp@schmorp.de>
1029	http://home.schmorp.de/	1510	http://home.schmorp.de/
1030		1511

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Comparing JSON-XS/XS.pm (file contents): Revision 1.66 by root, Sun Oct 14 20:02:57 2007 UTC vs. Revision 1.139 by root, Thu May 23 09:31:32 2013 UTC

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Comparing JSON-XS/XS.pm (file contents):
Revision 1.66 by root, Sun Oct 14 20:02:57 2007 UTC vs.
Revision 1.139 by root, Thu May 23 09:31:32 2013 UTC