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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.62 by root, Thu Oct 11 22:52:52 2007 UTC vs.
Revision 1.131 by root, Thu Mar 11 19:31:37 2010 UTC

…		…
		1	=head1 NAME
		2
		3	JSON::XS - JSON serialising/deserialising, done correctly and fast
		4
1	=encoding utf-8	5	=encoding utf-8
2
3	=head1 NAME
4
5	JSON::XS - JSON serialising/deserialising, done correctly and fast
6		6
7	JSON::XS - 正しくて高速な JSON シリアライザ/デシリアライザ	7	JSON::XS - 正しくて高速な JSON シリアライザ/デシリアライザ
8	(http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html)	8	(http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html)
9		9
10	=head1 SYNOPSIS	10	=head1 SYNOPSIS
12	use JSON::XS;	12	use JSON::XS;
13		13
14	# exported functions, they croak on error	14	# exported functions, they croak on error
15	# and expect/generate UTF-8	15	# and expect/generate UTF-8
16		16
17	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;	17	$utf8_encoded_json_text = encode_json $perl_hash_or_arrayref;
18	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;	18	$perl_hash_or_arrayref = decode_json $utf8_encoded_json_text;
19		19
20	# OO-interface	20	# OO-interface
21		21
22	$coder = JSON::XS->new->ascii->pretty->allow_nonref;	22	$coder = JSON::XS->new->ascii->pretty->allow_nonref;
23	$pretty_printed_unencoded = $coder->encode ($perl_scalar);	23	$pretty_printed_unencoded = $coder->encode ($perl_scalar);
24	$perl_scalar = $coder->decode ($unicode_json_text);	24	$perl_scalar = $coder->decode ($unicode_json_text);
25		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
26	=head1 DESCRIPTION	34	=head1 DESCRIPTION
27		35
28	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
29	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
30	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.
31		47
32	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
33	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
34	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
35	their maintainers are unresponsive, gone missing, or not listening to bug	51	their maintainers are unresponsive, gone missing, or not listening to bug
36	reports for other reasons.	52	reports for other reasons.
37		53
38	See COMPARISON, below, for a comparison to some other JSON modules.
39
40	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
41	vice versa.	55	vice versa.
42		56
43	=head2 FEATURES	57	=head2 FEATURES
44		58
45	=over 4	59	=over 4
46		60
47	=item * correct unicode handling	61	=item * correct Unicode handling
48		62
49	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
50	it does so.	64	so, and even documents what "correct" means.
51		65
52	=item * round-trip integrity	66	=item * round-trip integrity
53		67
54	When you serialise a perl data structure using only datatypes supported	68	When you serialise a perl data structure using only data types supported
55	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
56	(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
57	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.
58		73
59	=item * strict checking of JSON correctness	74	=item * strict checking of JSON correctness
60		75
61	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,
62	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
63	feature).	78	feature).
64		79
65	=item * fast	80	=item * fast
66		81
67	Compared to other JSON modules, this module compares favourably in terms	82	Compared to other JSON modules and other serialisers such as Storable,
68	of speed, too.	83	this module usually compares favourably in terms of speed, too.
69		84
70	=item * simple to use	85	=item * simple to use
71		86
72	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
73	interface.	88	oriented interface interface.
74		89
75	=item * reasonably versatile output formats	90	=item * reasonably versatile output formats
76		91
77	You can choose between the most compact guarenteed single-line format	92	You can choose between the most compact guaranteed-single-line format
78	possible (nice for simple line-based protocols), a pure-ascii format	93	possible (nice for simple line-based protocols), a pure-ASCII format
79	(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
80	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
81	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.
82		97
83	=back	98	=back
84		99
85	=cut	100	=cut
86		101
87	package JSON::XS;	102	package JSON::XS;
88		103
89	use strict;	104	use common::sense;
90		105
91	our $VERSION = '1.5';	106	our $VERSION = '2.28';
92	our @ISA = qw(Exporter);	107	our @ISA = qw(Exporter);
93		108
94	our @EXPORT = qw(to_json from_json);	109	our @EXPORT = qw(encode_json decode_json to_json from_json);
		110
		111	sub to_json($) {
		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	}
95		120
96	use Exporter;	121	use Exporter;
97	use XSLoader;	122	use XSLoader;
98		123
99	=head1 FUNCTIONAL INTERFACE	124	=head1 FUNCTIONAL INTERFACE
100		125
101	The following convinience methods are provided by this module. They are	126	The following convenience methods are provided by this module. They are
102	exported by default:	127	exported by default:
103		128
104	=over 4	129	=over 4
105		130
106	=item $json_text = to_json $perl_scalar	131	=item $json_text = encode_json $perl_scalar
107		132
108	Converts the given Perl data structure (a simple scalar or a reference to	133	Converts the given Perl data structure to a UTF-8 encoded, binary string
109	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains	134	(that is, the string contains octets only). Croaks on error.
110	octets only). Croaks on error.
111		135
112	This function call is functionally identical to:	136	This function call is functionally identical to:
113		137
114	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)	138	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)
115		139
116	except being faster.	140	Except being faster.
117		141
118	=item $perl_scalar = from_json $json_text	142	=item $perl_scalar = decode_json $json_text
119		143
120	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to	144	The opposite of C<encode_json>: expects an UTF-8 (binary) string and tries
121	parse that as an UTF-8 encoded JSON text, returning the resulting simple	145	to parse that as an UTF-8 encoded JSON text, returning the resulting
122	scalar or reference. Croaks on error.	146	reference. Croaks on error.
123		147
124	This function call is functionally identical to:	148	This function call is functionally identical to:
125		149
126	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)	150	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
127		151
128	except being faster.	152	Except being faster.
129		153
130	=item $is_boolean = JSON::XS::is_bool $scalar	154	=item $is_boolean = JSON::XS::is_bool $scalar
131		155
132	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
133	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
…		…
137	Perl.	161	Perl.
138		162
139	=back	163	=back
140		164
141		165
		166	=head1 A FEW NOTES ON UNICODE AND PERL
		167
		168	Since this often leads to confusion, here are a few very clear words on
		169	how Unicode works in Perl, modulo bugs.
		170
		171	=over 4
		172
		173	=item 1. Perl strings can store characters with ordinal values > 255.
		174
		175	This enables you to store Unicode characters as single characters in a
		176	Perl string - very natural.
		177
		178	=item 2. Perl does I<not> associate an encoding with your strings.
		179
		180	... until you force it to, e.g. when matching it against a regex, or
		181	printing the scalar to a file, in which case Perl either interprets your
		182	string as locale-encoded text, octets/binary, or as Unicode, depending
		183	on various settings. In no case is an encoding stored together with your
		184	data, it is I<use> that decides encoding, not any magical meta data.
		185
		186	=item 3. The internal utf-8 flag has no meaning with regards to the
		187	encoding of your string.
		188
		189	Just ignore that flag unless you debug a Perl bug, a module written in
		190	XS or want to dive into the internals of perl. Otherwise it will only
		191	confuse you, as, despite the name, it says nothing about how your string
		192	is encoded. You can have Unicode strings with that flag set, with that
		193	flag clear, and you can have binary data with that flag set and that flag
		194	clear. Other possibilities exist, too.
		195
		196	If you didn't know about that flag, just the better, pretend it doesn't
		197	exist.
		198
		199	=item 4. A "Unicode String" is simply a string where each character can be
		200	validly interpreted as a Unicode code point.
		201
		202	If you have UTF-8 encoded data, it is no longer a Unicode string, but a
		203	Unicode string encoded in UTF-8, giving you a binary string.
		204
		205	=item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string.
		206
		207	It's a fact. Learn to live with it.
		208
		209	=back
		210
		211	I hope this helps :)
		212
		213
142	=head1 OBJECT-ORIENTED INTERFACE	214	=head1 OBJECT-ORIENTED INTERFACE
143		215
144	The object oriented interface lets you configure your own encoding or	216	The object oriented interface lets you configure your own encoding or
145	decoding style, within the limits of supported formats.	217	decoding style, within the limits of supported formats.
146		218
…		…
157	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]})
158	=> {"a": [1, 2]}	230	=> {"a": [1, 2]}
159		231
160	=item $json = $json->ascii ([$enable])	232	=item $json = $json->ascii ([$enable])
161		233
		234	=item $enabled = $json->get_ascii
		235
162	If C<$enable> is true (or missing), then the C<encode> method will not	236	If C<$enable> is true (or missing), then the C<encode> method will not
163	generate characters outside the code range C<0..127> (which is ASCII). Any	237	generate characters outside the code range C<0..127> (which is ASCII). Any
164	unicode characters outside that range will be escaped using either a	238	Unicode characters outside that range will be escaped using either a
165	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,	239	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
166	as per RFC4627. The resulting encoded JSON text can be treated as a native	240	as per RFC4627. The resulting encoded JSON text can be treated as a native
167	unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,	241	Unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
168	or any other superset of ASCII.	242	or any other superset of ASCII.
169		243
170	If C<$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
171	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
172	in a faster and more compact format.	246	in a faster and more compact format.
173		247
		248	See also the section I<ENCODING/CODESET FLAG NOTES> later in this
		249	document.
		250
174	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
175	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
176	contain any 8 bit characters.	253	contain any 8 bit characters.
177		254
178	JSON::XS->new->ascii (1)->encode ([chr 0x10401])	255	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
179	=> ["\ud801\udc01"]	256	=> ["\ud801\udc01"]
180		257
181	=item $json = $json->latin1 ([$enable])	258	=item $json = $json->latin1 ([$enable])
182		259
		260	=item $enabled = $json->get_latin1
		261
183	If C<$enable> is true (or missing), then the C<encode> method will encode	262	If C<$enable> is true (or missing), then the C<encode> method will encode
184	the resulting JSON text as latin1 (or iso-8859-1), escaping any characters	263	the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
185	outside the code range C<0..255>. The resulting string can be treated as a	264	outside the code range C<0..255>. The resulting string can be treated as a
186	latin1-encoded JSON text or a native unicode string. The C<decode> method	265	latin1-encoded JSON text or a native Unicode string. The C<decode> method
187	will not be affected in any way by this flag, as C<decode> by default	266	will not be affected in any way by this flag, as C<decode> by default
188	expects unicode, which is a strict superset of latin1.	267	expects Unicode, which is a strict superset of latin1.
189		268
190	If C<$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
191	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.
192		274
193	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
194	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
195	size. The disadvantage is that the resulting JSON text is encoded	277	size. The disadvantage is that the resulting JSON text is encoded
196	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
197	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
198	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
199	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.
200		282
201	JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]	283	JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
202	=> ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)	284	=> ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
203		285
204	=item $json = $json->utf8 ([$enable])	286	=item $json = $json->utf8 ([$enable])
		287
		288	=item $enabled = $json->get_utf8
205		289
206	If C<$enable> is true (or missing), then the C<encode> method will encode	290	If C<$enable> is true (or missing), then the C<encode> method will encode
207	the JSON result into UTF-8, as required by many protocols, while the	291	the JSON result into UTF-8, as required by many protocols, while the
208	C<decode> method expects to be handled an UTF-8-encoded string. Please	292	C<decode> method expects to be handled an UTF-8-encoded string. Please
209	note that UTF-8-encoded strings do not contain any characters outside the	293	note that UTF-8-encoded strings do not contain any characters outside the
210	range C<0..255>, they are thus useful for bytewise/binary I/O. In future	294	range C<0..255>, they are thus useful for bytewise/binary I/O. In future
211	versions, enabling this option might enable autodetection of the UTF-16	295	versions, enabling this option might enable autodetection of the UTF-16
212	and UTF-32 encoding families, as described in RFC4627.	296	and UTF-32 encoding families, as described in RFC4627.
213		297
214	If C<$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
215	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
216	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
217	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.
218		305
219	Example, output UTF-16BE-encoded JSON:	306	Example, output UTF-16BE-encoded JSON:
220		307
221	use Encode;	308	use Encode;
222	$jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);	309	$jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);
…		…
243	]	330	]
244	}	331	}
245		332
246	=item $json = $json->indent ([$enable])	333	=item $json = $json->indent ([$enable])
247		334
		335	=item $enabled = $json->get_indent
		336
248	If C<$enable> is true (or missing), then the C<encode> method will use a multiline	337	If C<$enable> is true (or missing), then the C<encode> method will use a multiline
249	format as output, putting every array member or object/hash key-value pair	338	format as output, putting every array member or object/hash key-value pair
250	into its own line, identing them properly.	339	into its own line, indenting them properly.
251		340
252	If C<$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
253	resulting JSON text is guarenteed not to contain any C<newlines>.	342	resulting JSON text is guaranteed not to contain any C<newlines>.
254		343
255	This setting has no effect when decoding JSON texts.	344	This setting has no effect when decoding JSON texts.
256		345
257	=item $json = $json->space_before ([$enable])	346	=item $json = $json->space_before ([$enable])
		347
		348	=item $enabled = $json->get_space_before
258		349
259	If C<$enable> is true (or missing), then the C<encode> method will add an extra	350	If C<$enable> is true (or missing), then the C<encode> method will add an extra
260	optional space before the C<:> separating keys from values in JSON objects.	351	optional space before the C<:> separating keys from values in JSON objects.
261		352
262	If C<$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
…		…
268	Example, space_before enabled, space_after and indent disabled:	359	Example, space_before enabled, space_after and indent disabled:
269		360
270	{"key" :"value"}	361	{"key" :"value"}
271		362
272	=item $json = $json->space_after ([$enable])	363	=item $json = $json->space_after ([$enable])
		364
		365	=item $enabled = $json->get_space_after
273		366
274	If C<$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
275	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
276	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
277	members.	370	members.
…		…
284	Example, space_before and indent disabled, space_after enabled:	377	Example, space_before and indent disabled, space_after enabled:
285		378
286	{"key": "value"}	379	{"key": "value"}
287		380
288	=item $json = $json->relaxed ([$enable])	381	=item $json = $json->relaxed ([$enable])
		382
		383	=item $enabled = $json->get_relaxed
289		384
290	If C<$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
291	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
292	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
293	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
…		…
330		425
331	=back	426	=back
332		427
333	=item $json = $json->canonical ([$enable])	428	=item $json = $json->canonical ([$enable])
334		429
		430	=item $enabled = $json->get_canonical
		431
335	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects	432	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
336	by sorting their keys. This is adding a comparatively high overhead.	433	by sorting their keys. This is adding a comparatively high overhead.
337		434
338	If C<$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
339	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
340	of the same script).	437	of the same script).
341		438
342	This option is useful if you want the same data structure to be encoded as	439	This option is useful if you want the same data structure to be encoded as
343	the same JSON text (given the same overall settings). If it is disabled,	440	the same JSON text (given the same overall settings). If it is disabled,
344	the same hash migh be encoded differently even if contains the same data,	441	the same hash might be encoded differently even if contains the same data,
345	as key-value pairs have no inherent ordering in Perl.	442	as key-value pairs have no inherent ordering in Perl.
346		443
347	This setting has no effect when decoding JSON texts.	444	This setting has no effect when decoding JSON texts.
348		445
		446	This setting has currently no effect on tied hashes.
		447
349	=item $json = $json->allow_nonref ([$enable])	448	=item $json = $json->allow_nonref ([$enable])
		449
		450	=item $enabled = $json->get_allow_nonref
350		451
351	If C<$enable> is true (or missing), then the C<encode> method can convert a	452	If C<$enable> is true (or missing), then the C<encode> method can convert a
352	non-reference into its corresponding string, number or null JSON value,	453	non-reference into its corresponding string, number or null JSON value,
353	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON	454	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
354	values instead of croaking.	455	values instead of croaking.
…		…
362	resulting in an invalid JSON text:	463	resulting in an invalid JSON text:
363		464
364	JSON::XS->new->allow_nonref->encode ("Hello, World!")	465	JSON::XS->new->allow_nonref->encode ("Hello, World!")
365	=> "Hello, World!"	466	=> "Hello, World!"
366		467
		468	=item $json = $json->allow_unknown ([$enable])
		469
		470	=item $enabled = $json->get_allow_unknown
		471
		472	If C<$enable> is true (or missing), then C<encode> will I<not> throw an
		473	exception when it encounters values it cannot represent in JSON (for
		474	example, filehandles) but instead will encode a JSON C<null> value. Note
		475	that blessed objects are not included here and are handled separately by
		476	c<allow_nonref>.
		477
		478	If C<$enable> is false (the default), then C<encode> will throw an
		479	exception when it encounters anything it cannot encode as JSON.
		480
		481	This option does not affect C<decode> in any way, and it is recommended to
		482	leave it off unless you know your communications partner.
		483
367	=item $json = $json->allow_blessed ([$enable])	484	=item $json = $json->allow_blessed ([$enable])
		485
		486	=item $enabled = $json->get_allow_blessed
368		487
369	If C<$enable> is true (or missing), then the C<encode> method will not	488	If C<$enable> is true (or missing), then the C<encode> method will not
370	barf when it encounters a blessed reference. Instead, the value of the	489	barf when it encounters a blessed reference. Instead, the value of the
371	B<convert_blessed> option will decide wether C<null> (C<convert_blessed>	490	B<convert_blessed> option will decide whether C<null> (C<convert_blessed>
372	disabled or no C<to_json> method found) or a representation of the	491	disabled or no C<TO_JSON> method found) or a representation of the
373	object (C<convert_blessed> enabled and C<to_json> method found) is being	492	object (C<convert_blessed> enabled and C<TO_JSON> method found) is being
374	encoded. Has no effect on C<decode>.	493	encoded. Has no effect on C<decode>.
375		494
376	If C<$enable> is false (the default), then C<encode> will throw an	495	If C<$enable> is false (the default), then C<encode> will throw an
377	exception when it encounters a blessed object.	496	exception when it encounters a blessed object.
378		497
379	=item $json = $json->convert_blessed ([$enable])	498	=item $json = $json->convert_blessed ([$enable])
		499
		500	=item $enabled = $json->get_convert_blessed
380		501
381	If C<$enable> is true (or missing), then C<encode>, upon encountering a	502	If C<$enable> is true (or missing), then C<encode>, upon encountering a
382	blessed object, will check for the availability of the C<TO_JSON> method	503	blessed object, will check for the availability of the C<TO_JSON> method
383	on the object's class. If found, it will be called in scalar context	504	on the object's class. If found, it will be called in scalar context
384	and the resulting scalar will be encoded instead of the object. If no	505	and the resulting scalar will be encoded instead of the object. If no
…		…
388	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>	509	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
389	returns other blessed objects, those will be handled in the same	510	returns other blessed objects, those will be handled in the same
390	way. C<TO_JSON> must take care of not causing an endless recursion cycle	511	way. C<TO_JSON> must take care of not causing an endless recursion cycle
391	(== crash) in this case. The name of C<TO_JSON> was chosen because other	512	(== crash) in this case. The name of C<TO_JSON> was chosen because other
392	methods called by the Perl core (== not by the user of the object) are	513	methods called by the Perl core (== not by the user of the object) are
393	usually in upper case letters and to avoid collisions with the C<to_json>	514	usually in upper case letters and to avoid collisions with any C<to_json>
394	function.	515	function or method.
395		516
396	This setting does not yet influence C<decode> in any way, but in the	517	This setting does not yet influence C<decode> in any way, but in the
397	future, global hooks might get installed that influence C<decode> and are	518	future, global hooks might get installed that influence C<decode> and are
398	enabled by this setting.	519	enabled by this setting.
399		520
…		…
441		562
442	As this callback gets called less often then the C<filter_json_object>	563	As this callback gets called less often then the C<filter_json_object>
443	one, decoding speed will not usually suffer as much. Therefore, single-key	564	one, decoding speed will not usually suffer as much. Therefore, single-key
444	objects make excellent targets to serialise Perl objects into, especially	565	objects make excellent targets to serialise Perl objects into, especially
445	as single-key JSON objects are as close to the type-tagged value concept	566	as single-key JSON objects are as close to the type-tagged value concept
446	as JSON gets (its basically an ID/VALUE tuple). Of course, JSON does not	567	as JSON gets (it's basically an ID/VALUE tuple). Of course, JSON does not
447	support this in any way, so you need to make sure your data never looks	568	support this in any way, so you need to make sure your data never looks
448	like a serialised Perl hash.	569	like a serialised Perl hash.
449		570
450	Typical names for the single object key are C<__class_whatever__>, or	571	Typical names for the single object key are C<__class_whatever__>, or
451	C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even	572	C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even
…		…
475		596
476	{ __widget__ => $self->{id} }	597	{ __widget__ => $self->{id} }
477	}	598	}
478		599
479	=item $json = $json->shrink ([$enable])	600	=item $json = $json->shrink ([$enable])
		601
		602	=item $enabled = $json->get_shrink
480		603
481	Perl usually over-allocates memory a bit when allocating space for	604	Perl usually over-allocates memory a bit when allocating space for
482	strings. This flag optionally resizes strings generated by either	605	strings. This flag optionally resizes strings generated by either
483	C<encode> or C<decode> to their minimum size possible. This can save	606	C<encode> or C<decode> to their minimum size possible. This can save
484	memory when your JSON texts are either very very long or you have many	607	memory when your JSON texts are either very very long or you have many
…		…
502	strings that look like integers or floats into integers or floats	625	strings that look like integers or floats into integers or floats
503	internally (there is no difference on the Perl level), saving space.	626	internally (there is no difference on the Perl level), saving space.
504		627
505	=item $json = $json->max_depth ([$maximum_nesting_depth])	628	=item $json = $json->max_depth ([$maximum_nesting_depth])
506		629
		630	=item $max_depth = $json->get_max_depth
		631
507	Sets the maximum nesting level (default C<512>) accepted while encoding	632	Sets the maximum nesting level (default C<512>) accepted while encoding
508	or decoding. If the JSON text or Perl data structure has an equal or	633	or decoding. If a higher nesting level is detected in JSON text or a Perl
509	higher nesting level then this limit, then the encoder and decoder will	634	data structure, then the encoder and decoder will stop and croak at that
510	stop and croak at that point.	635	point.
511		636
512	Nesting level is defined by number of hash- or arrayrefs that the encoder	637	Nesting level is defined by number of hash- or arrayrefs that the encoder
513	needs to traverse to reach a given point or the number of C<{> or C<[>	638	needs to traverse to reach a given point or the number of C<{> or C<[>
514	characters without their matching closing parenthesis crossed to reach a	639	characters without their matching closing parenthesis crossed to reach a
515	given character in a string.	640	given character in a string.
516		641
517	Setting the maximum depth to one disallows any nesting, so that ensures	642	Setting the maximum depth to one disallows any nesting, so that ensures
518	that the object is only a single hash/object or array.	643	that the object is only a single hash/object or array.
519		644
520	The argument to C<max_depth> will be rounded up to the next highest power
521	of two. If no argument is given, the highest possible setting will be	645	If no argument is given, the highest possible setting will be used, which
522	used, which is rarely useful.	646	is rarely useful.
		647
		648	Note that nesting is implemented by recursion in C. The default value has
		649	been chosen to be as large as typical operating systems allow without
		650	crashing.
523		651
524	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	652	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
525		653
526	=item $json = $json->max_size ([$maximum_string_size])	654	=item $json = $json->max_size ([$maximum_string_size])
		655
		656	=item $max_size = $json->get_max_size
527		657
528	Set the maximum length a JSON text may have (in bytes) where decoding is	658	Set the maximum length a JSON text may have (in bytes) where decoding is
529	being attempted. The default is C<0>, meaning no limit. When C<decode>	659	being attempted. The default is C<0>, meaning no limit. When C<decode>
530	is called on a string longer then this number of characters it will not	660	is called on a string that is longer then this many bytes, it will not
531	attempt to decode the string but throw an exception. This setting has no	661	attempt to decode the string but throw an exception. This setting has no
532	effect on C<encode> (yet).	662	effect on C<encode> (yet).
533		663
534	The argument to C<max_size> will be rounded up to the next B<highest>	664	If no argument is given, the limit check will be deactivated (same as when
535	power of two (so may be more than requested). If no argument is given, the	665	C<0> is specified).
536	limit check will be deactivated (same as when C<0> is specified).
537		666
538	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	667	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
539		668
540	=item $json_text = $json->encode ($perl_scalar)	669	=item $json_text = $json->encode ($perl_scalar)
541		670
…		…
570	=> ([], 3)	699	=> ([], 3)
571		700
572	=back	701	=back
573		702
574		703
		704	=head1 INCREMENTAL PARSING
		705
		706	In some cases, there is the need for incremental parsing of JSON
		707	texts. While this module always has to keep both JSON text and resulting
		708	Perl data structure in memory at one time, it does allow you to parse a
		709	JSON stream incrementally. It does so by accumulating text until it has
		710	a full JSON object, which it then can decode. This process is similar to
		711	using C<decode_prefix> to see if a full JSON object is available, but
		712	is much more efficient (and can be implemented with a minimum of method
		713	calls).
		714
		715	JSON::XS will only attempt to parse the JSON text once it is sure it
		716	has enough text to get a decisive result, using a very simple but
		717	truly incremental parser. This means that it sometimes won't stop as
		718	early as the full parser, for example, it doesn't detect parenthese
		719	mismatches. The only thing it guarantees is that it starts decoding as
		720	soon as a syntactically valid JSON text has been seen. This means you need
		721	to set resource limits (e.g. C<max_size>) to ensure the parser will stop
		722	parsing in the presence if syntax errors.
		723
		724	The following methods implement this incremental parser.
		725
		726	=over 4
		727
		728	=item [void, scalar or list context] = $json->incr_parse ([$string])
		729
		730	This is the central parsing function. It can both append new text and
		731	extract objects from the stream accumulated so far (both of these
		732	functions are optional).
		733
		734	If C<$string> is given, then this string is appended to the already
		735	existing JSON fragment stored in the C<$json> object.
		736
		737	After that, if the function is called in void context, it will simply
		738	return without doing anything further. This can be used to add more text
		739	in as many chunks as you want.
		740
		741	If the method is called in scalar context, then it will try to extract
		742	exactly I<one> JSON object. If that is successful, it will return this
		743	object, otherwise it will return C<undef>. If there is a parse error,
		744	this method will croak just as C<decode> would do (one can then use
		745	C<incr_skip> to skip the errornous part). This is the most common way of
		746	using the method.
		747
		748	And finally, in list context, it will try to extract as many objects
		749	from the stream as it can find and return them, or the empty list
		750	otherwise. For this to work, there must be no separators between the JSON
		751	objects or arrays, instead they must be concatenated back-to-back. If
		752	an error occurs, an exception will be raised as in the scalar context
		753	case. Note that in this case, any previously-parsed JSON texts will be
		754	lost.
		755
		756	Example: Parse some JSON arrays/objects in a given string and return
		757	them.
		758
		759	my @objs = JSON::XS->new->incr_parse ("[5][7][1,2]");
		760
		761	=item $lvalue_string = $json->incr_text
		762
		763	This method returns the currently stored JSON fragment as an lvalue, that
		764	is, you can manipulate it. This I<only> works when a preceding call to
		765	C<incr_parse> in I<scalar context> successfully returned an object. Under
		766	all other circumstances you must not call this function (I mean it.
		767	although in simple tests it might actually work, it I<will> fail under
		768	real world conditions). As a special exception, you can also call this
		769	method before having parsed anything.
		770
		771	This function is useful in two cases: a) finding the trailing text after a
		772	JSON object or b) parsing multiple JSON objects separated by non-JSON text
		773	(such as commas).
		774
		775	=item $json->incr_skip
		776
		777	This will reset the state of the incremental parser and will remove
		778	the parsed text from the input buffer so far. This is useful after
		779	C<incr_parse> died, in which case the input buffer and incremental parser
		780	state is left unchanged, to skip the text parsed so far and to reset the
		781	parse state.
		782
		783	The difference to C<incr_reset> is that only text until the parse error
		784	occured is removed.
		785
		786	=item $json->incr_reset
		787
		788	This completely resets the incremental parser, that is, after this call,
		789	it will be as if the parser had never parsed anything.
		790
		791	This is useful if you want to repeatedly parse JSON objects and want to
		792	ignore any trailing data, which means you have to reset the parser after
		793	each successful decode.
		794
		795	=back
		796
		797	=head2 LIMITATIONS
		798
		799	All options that affect decoding are supported, except
		800	C<allow_nonref>. The reason for this is that it cannot be made to
		801	work sensibly: JSON objects and arrays are self-delimited, i.e. you can concatenate
		802	them back to back and still decode them perfectly. This does not hold true
		803	for JSON numbers, however.
		804
		805	For example, is the string C<1> a single JSON number, or is it simply the
		806	start of C<12>? Or is C<12> a single JSON number, or the concatenation
		807	of C<1> and C<2>? In neither case you can tell, and this is why JSON::XS
		808	takes the conservative route and disallows this case.
		809
		810	=head2 EXAMPLES
		811
		812	Some examples will make all this clearer. First, a simple example that
		813	works similarly to C<decode_prefix>: We want to decode the JSON object at
		814	the start of a string and identify the portion after the JSON object:
		815
		816	my $text = "[1,2,3] hello";
		817
		818	my $json = new JSON::XS;
		819
		820	my $obj = $json->incr_parse ($text)
		821	or die "expected JSON object or array at beginning of string";
		822
		823	my $tail = $json->incr_text;
		824	# $tail now contains " hello"
		825
		826	Easy, isn't it?
		827
		828	Now for a more complicated example: Imagine a hypothetical protocol where
		829	you read some requests from a TCP stream, and each request is a JSON
		830	array, without any separation between them (in fact, it is often useful to
		831	use newlines as "separators", as these get interpreted as whitespace at
		832	the start of the JSON text, which makes it possible to test said protocol
		833	with C<telnet>...).
		834
		835	Here is how you'd do it (it is trivial to write this in an event-based
		836	manner):
		837
		838	my $json = new JSON::XS;
		839
		840	# read some data from the socket
		841	while (sysread $socket, my $buf, 4096) {
		842
		843	# split and decode as many requests as possible
		844	for my $request ($json->incr_parse ($buf)) {
		845	# act on the $request
		846	}
		847	}
		848
		849	Another complicated example: Assume you have a string with JSON objects
		850	or arrays, all separated by (optional) comma characters (e.g. C<[1],[2],
		851	[3]>). To parse them, we have to skip the commas between the JSON texts,
		852	and here is where the lvalue-ness of C<incr_text> comes in useful:
		853
		854	my $text = "[1],[2], [3]";
		855	my $json = new JSON::XS;
		856
		857	# void context, so no parsing done
		858	$json->incr_parse ($text);
		859
		860	# now extract as many objects as possible. note the
		861	# use of scalar context so incr_text can be called.
		862	while (my $obj = $json->incr_parse) {
		863	# do something with $obj
		864
		865	# now skip the optional comma
		866	$json->incr_text =~ s/^ \s* , //x;
		867	}
		868
		869	Now lets go for a very complex example: Assume that you have a gigantic
		870	JSON array-of-objects, many gigabytes in size, and you want to parse it,
		871	but you cannot load it into memory fully (this has actually happened in
		872	the real world :).
		873
		874	Well, you lost, you have to implement your own JSON parser. But JSON::XS
		875	can still help you: You implement a (very simple) array parser and let
		876	JSON decode the array elements, which are all full JSON objects on their
		877	own (this wouldn't work if the array elements could be JSON numbers, for
		878	example):
		879
		880	my $json = new JSON::XS;
		881
		882	# open the monster
		883	open my $fh, "<bigfile.json"
		884	or die "bigfile: $!";
		885
		886	# first parse the initial "["
		887	for (;;) {
		888	sysread $fh, my $buf, 65536
		889	or die "read error: $!";
		890	$json->incr_parse ($buf); # void context, so no parsing
		891
		892	# Exit the loop once we found and removed(!) the initial "[".
		893	# In essence, we are (ab-)using the $json object as a simple scalar
		894	# we append data to.
		895	last if $json->incr_text =~ s/^ \s* \[ //x;
		896	}
		897
		898	# now we have the skipped the initial "[", so continue
		899	# parsing all the elements.
		900	for (;;) {
		901	# in this loop we read data until we got a single JSON object
		902	for (;;) {
		903	if (my $obj = $json->incr_parse) {
		904	# do something with $obj
		905	last;
		906	}
		907
		908	# add more data
		909	sysread $fh, my $buf, 65536
		910	or die "read error: $!";
		911	$json->incr_parse ($buf); # void context, so no parsing
		912	}
		913
		914	# in this loop we read data until we either found and parsed the
		915	# separating "," between elements, or the final "]"
		916	for (;;) {
		917	# first skip whitespace
		918	$json->incr_text =~ s/^\s*//;
		919
		920	# if we find "]", we are done
		921	if ($json->incr_text =~ s/^\]//) {
		922	print "finished.\n";
		923	exit;
		924	}
		925
		926	# if we find ",", we can continue with the next element
		927	if ($json->incr_text =~ s/^,//) {
		928	last;
		929	}
		930
		931	# if we find anything else, we have a parse error!
		932	if (length $json->incr_text) {
		933	die "parse error near ", $json->incr_text;
		934	}
		935
		936	# else add more data
		937	sysread $fh, my $buf, 65536
		938	or die "read error: $!";
		939	$json->incr_parse ($buf); # void context, so no parsing
		940	}
		941
		942	This is a complex example, but most of the complexity comes from the fact
		943	that we are trying to be correct (bear with me if I am wrong, I never ran
		944	the above example :).
		945
		946
		947
575	=head1 MAPPING	948	=head1 MAPPING
576		949
577	This section describes how JSON::XS maps Perl values to JSON values and	950	This section describes how JSON::XS maps Perl values to JSON values and
578	vice versa. These mappings are designed to "do the right thing" in most	951	vice versa. These mappings are designed to "do the right thing" in most
579	circumstances automatically, preserving round-tripping characteristics	952	circumstances automatically, preserving round-tripping characteristics
580	(what you put in comes out as something equivalent).	953	(what you put in comes out as something equivalent).
581		954
582	For the more enlightened: note that in the following descriptions,	955	For the more enlightened: note that in the following descriptions,
583	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>	956	lowercase I<perl> refers to the Perl interpreter, while uppercase I<Perl>
584	refers to the abstract Perl language itself.	957	refers to the abstract Perl language itself.
585		958
586		959
587	=head2 JSON -> PERL	960	=head2 JSON -> PERL
588		961
589	=over 4	962	=over 4
590		963
591	=item object	964	=item object
592		965
593	A JSON object becomes a reference to a hash in Perl. No ordering of object	966	A JSON object becomes a reference to a hash in Perl. No ordering of object
594	keys is preserved (JSON does not preserver object key ordering itself).	967	keys is preserved (JSON does not preserve object key ordering itself).
595		968
596	=item array	969	=item array
597		970
598	A JSON array becomes a reference to an array in Perl.	971	A JSON array becomes a reference to an array in Perl.
599		972
…		…
607		980
608	A JSON number becomes either an integer, numeric (floating point) or	981	A JSON number becomes either an integer, numeric (floating point) or
609	string scalar in perl, depending on its range and any fractional parts. On	982	string scalar in perl, depending on its range and any fractional parts. On
610	the Perl level, there is no difference between those as Perl handles all	983	the Perl level, there is no difference between those as Perl handles all
611	the conversion details, but an integer may take slightly less memory and	984	the conversion details, but an integer may take slightly less memory and
612	might represent more values exactly than (floating point) numbers.	985	might represent more values exactly than floating point numbers.
613		986
614	If the number consists of digits only, JSON::XS will try to represent	987	If the number consists of digits only, JSON::XS will try to represent
615	it as an integer value. If that fails, it will try to represent it as	988	it as an integer value. If that fails, it will try to represent it as
616	a numeric (floating point) value if that is possible without loss of	989	a numeric (floating point) value if that is possible without loss of
617	precision. Otherwise it will preserve the number as a string value.	990	precision. Otherwise it will preserve the number as a string value (in
		991	which case you lose roundtripping ability, as the JSON number will be
		992	re-encoded toa JSON string).
618		993
619	Numbers containing a fractional or exponential part will always be	994	Numbers containing a fractional or exponential part will always be
620	represented as numeric (floating point) values, possibly at a loss of	995	represented as numeric (floating point) values, possibly at a loss of
621	precision.	996	precision (in which case you might lose perfect roundtripping ability, but
		997	the JSON number will still be re-encoded as a JSON number).
622		998
623	This might create round-tripping problems as numbers might become strings,	999	Note that precision is not accuracy - binary floating point values cannot
624	but as Perl is typeless there is no other way to do it.	1000	represent most decimal fractions exactly, and when converting from and to
		1001	floating point, JSON::XS only guarantees precision up to but not including
		1002	the leats significant bit.
625		1003
626	=item true, false	1004	=item true, false
627		1005
628	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,	1006	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
629	respectively. They are overloaded to act almost exactly like the numbers	1007	respectively. They are overloaded to act almost exactly like the numbers
630	C<1> and C<0>. You can check wether a scalar is a JSON boolean by using	1008	C<1> and C<0>. You can check whether a scalar is a JSON boolean by using
631	the C<JSON::XS::is_bool> function.	1009	the C<JSON::XS::is_bool> function.
632		1010
633	=item null	1011	=item null
634		1012
635	A JSON null atom becomes C<undef> in Perl.	1013	A JSON null atom becomes C<undef> in Perl.
…		…
666	Other unblessed references are generally not allowed and will cause an	1044	Other unblessed references are generally not allowed and will cause an
667	exception to be thrown, except for references to the integers C<0> and	1045	exception to be thrown, except for references to the integers C<0> and
668	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can	1046	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
669	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.	1047	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
670		1048
671	to_json [\0,JSON::XS::true] # yields [false,true]	1049	encode_json [\0, JSON::XS::true] # yields [false,true]
672		1050
673	=item JSON::XS::true, JSON::XS::false	1051	=item JSON::XS::true, JSON::XS::false
674		1052
675	These special values become JSON true and JSON false values,	1053	These special values become JSON true and JSON false values,
676	respectively. You can also use C<\1> and C<\0> directly if you want.	1054	respectively. You can also use C<\1> and C<\0> directly if you want.
677		1055
678	=item blessed objects	1056	=item blessed objects
679		1057
680	Blessed objects are not allowed. JSON::XS currently tries to encode their	1058	Blessed objects are not directly representable in JSON. See the
681	underlying representation (hash- or arrayref), but this behaviour might	1059	C<allow_blessed> and C<convert_blessed> methods on various options on
682	change in future versions.	1060	how to deal with this: basically, you can choose between throwing an
		1061	exception, encoding the reference as if it weren't blessed, or provide
		1062	your own serialiser method.
683		1063
684	=item simple scalars	1064	=item simple scalars
685		1065
686	Simple Perl scalars (any scalar that is not a reference) are the most	1066	Simple Perl scalars (any scalar that is not a reference) are the most
687	difficult objects to encode: JSON::XS will encode undefined scalars as	1067	difficult objects to encode: JSON::XS will encode undefined scalars as
688	JSON null value, scalars that have last been used in a string context	1068	JSON C<null> values, scalars that have last been used in a string context
689	before encoding as JSON strings and anything else as number value:	1069	before encoding as JSON strings, and anything else as number value:
690		1070
691	# dump as number	1071	# dump as number
692	to_json [2] # yields [2]	1072	encode_json [2] # yields [2]
693	to_json [-3.0e17] # yields [-3e+17]	1073	encode_json [-3.0e17] # yields [-3e+17]
694	my $value = 5; to_json [$value] # yields [5]	1074	my $value = 5; encode_json [$value] # yields [5]
695		1075
696	# used as string, so dump as string	1076	# used as string, so dump as string
697	print $value;	1077	print $value;
698	to_json [$value] # yields ["5"]	1078	encode_json [$value] # yields ["5"]
699		1079
700	# undef becomes null	1080	# undef becomes null
701	to_json [undef] # yields [null]	1081	encode_json [undef] # yields [null]
702		1082
703	You can force the type to be a string by stringifying it:	1083	You can force the type to be a JSON string by stringifying it:
704		1084
705	my $x = 3.1; # some variable containing a number	1085	my $x = 3.1; # some variable containing a number
706	"$x"; # stringified	1086	"$x"; # stringified
707	$x .= ""; # another, more awkward way to stringify	1087	$x .= ""; # another, more awkward way to stringify
708	print $x; # perl does it for you, too, quite often	1088	print $x; # perl does it for you, too, quite often
709		1089
710	You can force the type to be a number by numifying it:	1090	You can force the type to be a JSON number by numifying it:
711		1091
712	my $x = "3"; # some variable containing a string	1092	my $x = "3"; # some variable containing a string
713	$x += 0; # numify it, ensuring it will be dumped as a number	1093	$x += 0; # numify it, ensuring it will be dumped as a number
714	$x *= 1; # same thing, the choise is yours.	1094	$x *= 1; # same thing, the choice is yours.
715		1095
716	You can not currently output JSON booleans or force the type in other,	1096	You can not currently force the type in other, less obscure, ways. Tell me
717	less obscure, ways. Tell me if you need this capability.	1097	if you need this capability (but don't forget to explain why it's needed
		1098	:).
		1099
		1100	Note that numerical precision has the same meaning as under Perl (so
		1101	binary to decimal conversion follows the same rules as in Perl, which
		1102	can differ to other languages). Also, your perl interpreter might expose
		1103	extensions to the floating point numbers of your platform, such as
		1104	infinities or NaN's - these cannot be represented in JSON, and it is an
		1105	error to pass those in.
718		1106
719	=back	1107	=back
720		1108
721		1109
722	=head1 COMPARISON	1110	=head1 ENCODING/CODESET FLAG NOTES
723		1111
724	As already mentioned, this module was created because none of the existing	1112	The interested reader might have seen a number of flags that signify
725	JSON modules could be made to work correctly. First I will describe the	1113	encodings or codesets - C<utf8>, C<latin1> and C<ascii>. There seems to be
726	problems (or pleasures) I encountered with various existing JSON modules,	1114	some confusion on what these do, so here is a short comparison:
727	followed by some benchmark values. JSON::XS was designed not to suffer	1115
728	from any of these problems or limitations.	1116	C<utf8> controls whether the JSON text created by C<encode> (and expected
		1117	by C<decode>) is UTF-8 encoded or not, while C<latin1> and C<ascii> only
		1118	control whether C<encode> escapes character values outside their respective
		1119	codeset range. Neither of these flags conflict with each other, although
		1120	some combinations make less sense than others.
		1121
		1122	Care has been taken to make all flags symmetrical with respect to
		1123	C<encode> and C<decode>, that is, texts encoded with any combination of
		1124	these flag values will be correctly decoded when the same flags are used
		1125	- in general, if you use different flag settings while encoding vs. when
		1126	decoding you likely have a bug somewhere.
		1127
		1128	Below comes a verbose discussion of these flags. Note that a "codeset" is
		1129	simply an abstract set of character-codepoint pairs, while an encoding
		1130	takes those codepoint numbers and I<encodes> them, in our case into
		1131	octets. Unicode is (among other things) a codeset, UTF-8 is an encoding,
		1132	and ISO-8859-1 (= latin 1) and ASCII are both codesets I<and> encodings at
		1133	the same time, which can be confusing.
729		1134
730	=over 4	1135	=over 4
731		1136
732	=item JSON 1.07	1137	=item C<utf8> flag disabled
733		1138
734	Slow (but very portable, as it is written in pure Perl).	1139	When C<utf8> is disabled (the default), then C<encode>/C<decode> generate
		1140	and expect Unicode strings, that is, characters with high ordinal Unicode
		1141	values (> 255) will be encoded as such characters, and likewise such
		1142	characters are decoded as-is, no canges to them will be done, except
		1143	"(re-)interpreting" them as Unicode codepoints or Unicode characters,
		1144	respectively (to Perl, these are the same thing in strings unless you do
		1145	funny/weird/dumb stuff).
735		1146
736	Undocumented/buggy Unicode handling (how JSON handles unicode values is	1147	This is useful when you want to do the encoding yourself (e.g. when you
737	undocumented. One can get far by feeding it unicode strings and doing	1148	want to have UTF-16 encoded JSON texts) or when some other layer does
738	en-/decoding oneself, but unicode escapes are not working properly).	1149	the encoding for you (for example, when printing to a terminal using a
		1150	filehandle that transparently encodes to UTF-8 you certainly do NOT want
		1151	to UTF-8 encode your data first and have Perl encode it another time).
739		1152
740	No roundtripping (strings get clobbered if they look like numbers, e.g.	1153	=item C<utf8> flag enabled
741	the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will
742	decode into the number 2.
743		1154
744	=item JSON::PC 0.01	1155	If the C<utf8>-flag is enabled, C<encode>/C<decode> will encode all
		1156	characters using the corresponding UTF-8 multi-byte sequence, and will
		1157	expect your input strings to be encoded as UTF-8, that is, no "character"
		1158	of the input string must have any value > 255, as UTF-8 does not allow
		1159	that.
745		1160
746	Very fast.	1161	The C<utf8> flag therefore switches between two modes: disabled means you
		1162	will get a Unicode string in Perl, enabled means you get an UTF-8 encoded
		1163	octet/binary string in Perl.
747		1164
748	Undocumented/buggy Unicode handling.	1165	=item C<latin1> or C<ascii> flags enabled
749		1166
750	No roundtripping.	1167	With C<latin1> (or C<ascii>) enabled, C<encode> will escape characters
		1168	with ordinal values > 255 (> 127 with C<ascii>) and encode the remaining
		1169	characters as specified by the C<utf8> flag.
751		1170
752	Has problems handling many Perl values (e.g. regex results and other magic	1171	If C<utf8> is disabled, then the result is also correctly encoded in those
753	values will make it croak).	1172	character sets (as both are proper subsets of Unicode, meaning that a
		1173	Unicode string with all character values < 256 is the same thing as a
		1174	ISO-8859-1 string, and a Unicode string with all character values < 128 is
		1175	the same thing as an ASCII string in Perl).
754		1176
755	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>	1177	If C<utf8> is enabled, you still get a correct UTF-8-encoded string,
756	which is not a valid JSON text.	1178	regardless of these flags, just some more characters will be escaped using
		1179	C<\uXXXX> then before.
757		1180
758	Unmaintained (maintainer unresponsive for many months, bugs are not	1181	Note that ISO-8859-1-I<encoded> strings are not compatible with UTF-8
759	getting fixed).	1182	encoding, while ASCII-encoded strings are. That is because the ISO-8859-1
		1183	encoding is NOT a subset of UTF-8 (despite the ISO-8859-1 I<codeset> being
		1184	a subset of Unicode), while ASCII is.
760		1185
761	=item JSON::Syck 0.21	1186	Surprisingly, C<decode> will ignore these flags and so treat all input
		1187	values as governed by the C<utf8> flag. If it is disabled, this allows you
		1188	to decode ISO-8859-1- and ASCII-encoded strings, as both strict subsets of
		1189	Unicode. If it is enabled, you can correctly decode UTF-8 encoded strings.
762		1190
763	Very buggy (often crashes).	1191	So neither C<latin1> nor C<ascii> are incompatible with the C<utf8> flag -
		1192	they only govern when the JSON output engine escapes a character or not.
764		1193
765	Very inflexible (no human-readable format supported, format pretty much	1194	The main use for C<latin1> is to relatively efficiently store binary data
766	undocumented. I need at least a format for easy reading by humans and a	1195	as JSON, at the expense of breaking compatibility with most JSON decoders.
767	single-line compact format for use in a protocol, and preferably a way to
768	generate ASCII-only JSON texts).
769		1196
770	Completely broken (and confusingly documented) Unicode handling (unicode	1197	The main use for C<ascii> is to force the output to not contain characters
771	escapes are not working properly, you need to set ImplicitUnicode to	1198	with values > 127, which means you can interpret the resulting string
772	I<different> values on en- and decoding to get symmetric behaviour).	1199	as UTF-8, ISO-8859-1, ASCII, KOI8-R or most about any character set and
773		1200	8-bit-encoding, and still get the same data structure back. This is useful
774	No roundtripping (simple cases work, but this depends on wether the scalar	1201	when your channel for JSON transfer is not 8-bit clean or the encoding
775	value was used in a numeric context or not).	1202	might be mangled in between (e.g. in mail), and works because ASCII is a
776		1203	proper subset of most 8-bit and multibyte encodings in use in the world.
777	Dumping hashes may skip hash values depending on iterator state.
778
779	Unmaintained (maintainer unresponsive for many months, bugs are not
780	getting fixed).
781
782	Does not check input for validity (i.e. will accept non-JSON input and
783	return "something" instead of raising an exception. This is a security
784	issue: imagine two banks transfering money between each other using
785	JSON. One bank might parse a given non-JSON request and deduct money,
786	while the other might reject the transaction with a syntax error. While a
787	good protocol will at least recover, that is extra unnecessary work and
788	the transaction will still not succeed).
789
790	=item JSON::DWIW 0.04
791
792	Very fast. Very natural. Very nice.
793
794	Undocumented unicode handling (but the best of the pack. Unicode escapes
795	still don't get parsed properly).
796
797	Very inflexible.
798
799	No roundtripping.
800
801	Does not generate valid JSON texts (key strings are often unquoted, empty keys
802	result in nothing being output)
803
804	Does not check input for validity.
805		1204
806	=back	1205	=back
807		1206
808		1207
		1208	=head2 JSON and ECMAscript
		1209
		1210	JSON syntax is based on how literals are represented in javascript (the
		1211	not-standardised predecessor of ECMAscript) which is presumably why it is
		1212	called "JavaScript Object Notation".
		1213
		1214	However, JSON is not a subset (and also not a superset of course) of
		1215	ECMAscript (the standard) or javascript (whatever browsers actually
		1216	implement).
		1217
		1218	If you want to use javascript's C<eval> function to "parse" JSON, you
		1219	might run into parse errors for valid JSON texts, or the resulting data
		1220	structure might not be queryable:
		1221
		1222	One of the problems is that U+2028 and U+2029 are valid characters inside
		1223	JSON strings, but are not allowed in ECMAscript string literals, so the
		1224	following Perl fragment will not output something that can be guaranteed
		1225	to be parsable by javascript's C<eval>:
		1226
		1227	use JSON::XS;
		1228
		1229	print encode_json [chr 0x2028];
		1230
		1231	The right fix for this is to use a proper JSON parser in your javascript
		1232	programs, and not rely on C<eval> (see for example Douglas Crockford's
		1233	F<json2.js> parser).
		1234
		1235	If this is not an option, you can, as a stop-gap measure, simply encode to
		1236	ASCII-only JSON:
		1237
		1238	use JSON::XS;
		1239
		1240	print JSON::XS->new->ascii->encode ([chr 0x2028]);
		1241
		1242	Note that this will enlarge the resulting JSON text quite a bit if you
		1243	have many non-ASCII characters. You might be tempted to run some regexes
		1244	to only escape U+2028 and U+2029, e.g.:
		1245
		1246	# DO NOT USE THIS!
		1247	my $json = JSON::XS->new->utf8->encode ([chr 0x2028]);
		1248	$json =~ s/\xe2\x80\xa8/\\u2028/g; # escape U+2028
		1249	$json =~ s/\xe2\x80\xa9/\\u2029/g; # escape U+2029
		1250	print $json;
		1251
		1252	Note that I<this is a bad idea>: the above only works for U+2028 and
		1253	U+2029 and thus only for fully ECMAscript-compliant parsers. Many existing
		1254	javascript implementations, however, have issues with other characters as
		1255	well - using C<eval> naively simply I<will> cause problems.
		1256
		1257	Another problem is that some javascript implementations reserve
		1258	some property names for their own purposes (which probably makes
		1259	them non-ECMAscript-compliant). For example, Iceweasel reserves the
		1260	C<__proto__> property name for it's own purposes.
		1261
		1262	If that is a problem, you could parse try to filter the resulting JSON
		1263	output for these property strings, e.g.:
		1264
		1265	$json =~ s/"__proto__"\s*:/"__proto__renamed":/g;
		1266
		1267	This works because C<__proto__> is not valid outside of strings, so every
		1268	occurence of C<"__proto__"\s*:> must be a string used as property name.
		1269
		1270	If you know of other incompatibilities, please let me know.
		1271
		1272
809	=head2 JSON and YAML	1273	=head2 JSON and YAML
810		1274
811	You often hear that JSON is a subset (or a close subset) of YAML. This is,	1275	You often hear that JSON is a subset of YAML. This is, however, a mass
812	however, a mass hysteria and very far from the truth. In general, there is	1276	hysteria(*) and very far from the truth (as of the time of this writing),
813	no way to configure JSON::XS to output a data structure as valid YAML.	1277	so let me state it clearly: I<in general, there is no way to configure
		1278	JSON::XS to output a data structure as valid YAML> that works in all
		1279	cases.
814		1280
815	If you really must use JSON::XS to generate YAML, you should use this	1281	If you really must use JSON::XS to generate YAML, you should use this
816	algorithm (subject to change in future versions):	1282	algorithm (subject to change in future versions):
817		1283
818	my $to_yaml = JSON::XS->new->utf8->space_after (1);	1284	my $to_yaml = JSON::XS->new->utf8->space_after (1);
819	my $yaml = $to_yaml->encode ($ref) . "\n";	1285	my $yaml = $to_yaml->encode ($ref) . "\n";
820		1286
821	This will usually generate JSON texts that also parse as valid	1287	This will I<usually> generate JSON texts that also parse as valid
822	YAML. Please note that YAML has hardcoded limits on (simple) object key	1288	YAML. Please note that YAML has hardcoded limits on (simple) object key
823	lengths that JSON doesn't have, so you should make sure that your hash	1289	lengths that JSON doesn't have and also has different and incompatible
		1290	unicode character escape syntax, so you should make sure that your hash
824	keys are noticably shorter than the 1024 characters YAML allows.	1291	keys are noticeably shorter than the 1024 "stream characters" YAML allows
		1292	and that you do not have characters with codepoint values outside the
		1293	Unicode BMP (basic multilingual page). YAML also does not allow C<\/>
		1294	sequences in strings (which JSON::XS does not I<currently> generate, but
		1295	other JSON generators might).
825		1296
826	There might be other incompatibilities that I am not aware of. In general	1297	There might be other incompatibilities that I am not aware of (or the YAML
		1298	specification has been changed yet again - it does so quite often). In
827	you should not try to generate YAML with a JSON generator or vice versa,	1299	general you should not try to generate YAML with a JSON generator or vice
828	or try to parse JSON with a YAML parser or vice versa: chances are high	1300	versa, or try to parse JSON with a YAML parser or vice versa: chances are
829	that you will run into severe interoperability problems.	1301	high that you will run into severe interoperability problems when you
		1302	least expect it.
		1303
		1304	=over 4
		1305
		1306	=item (*)
		1307
		1308	I have been pressured multiple times by Brian Ingerson (one of the
		1309	authors of the YAML specification) to remove this paragraph, despite him
		1310	acknowledging that the actual incompatibilities exist. As I was personally
		1311	bitten by this "JSON is YAML" lie, I refused and said I will continue to
		1312	educate people about these issues, so others do not run into the same
		1313	problem again and again. After this, Brian called me a (quote)I<complete
		1314	and worthless idiot>(unquote).
		1315
		1316	In my opinion, instead of pressuring and insulting people who actually
		1317	clarify issues with YAML and the wrong statements of some of its
		1318	proponents, I would kindly suggest reading the JSON spec (which is not
		1319	that difficult or long) and finally make YAML compatible to it, and
		1320	educating users about the changes, instead of spreading lies about the
		1321	real compatibility for many I<years> and trying to silence people who
		1322	point out that it isn't true.
		1323
		1324	Addendum/2009: the YAML 1.2 spec is still incomaptible with JSON, even
		1325	though the incompatibilities have been documented (and are known to
		1326	Brian) for many years and the spec makes explicit claims that YAML is a
		1327	superset of JSON. It would be so easy to fix, but apparently, bullying and
		1328	corrupting userdata is so much easier.
		1329
		1330	=back
830		1331
831		1332
832	=head2 SPEED	1333	=head2 SPEED
833		1334
834	It seems that JSON::XS is surprisingly fast, as shown in the following	1335	It seems that JSON::XS is surprisingly fast, as shown in the following
835	tables. They have been generated with the help of the C<eg/bench> program	1336	tables. They have been generated with the help of the C<eg/bench> program
836	in the JSON::XS distribution, to make it easy to compare on your own	1337	in the JSON::XS distribution, to make it easy to compare on your own
837	system.	1338	system.
838		1339
839	First comes a comparison between various modules using a very short	1340	First comes a comparison between various modules using
840	single-line JSON string:	1341	a very short single-line JSON string (also available at
		1342	L<http://dist.schmorp.de/misc/json/short.json>).
841		1343
842	{"method": "handleMessage", "params": ["user1", "we were just talking"], \	1344	{"method": "handleMessage", "params": ["user1",
843	"id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}	1345	"we were just talking"], "id": null, "array":[1,11,234,-5,1e5,1e7,
		1346	1, 0]}
844		1347
845	It shows the number of encodes/decodes per second (JSON::XS uses	1348	It shows the number of encodes/decodes per second (JSON::XS uses
846	the functional interface, while JSON::XS/2 uses the OO interface	1349	the functional interface, while JSON::XS/2 uses the OO interface
847	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables	1350	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
848	shrink). Higher is better:	1351	shrink. JSON::DWIW/DS uses the deserialise function, while JSON::DWIW::FJ
		1352	uses the from_json method). Higher is better:
849		1353
850	Storable \| 15779.925 \| 14169.946 \|
851	-----------+------------+------------+
852	module \| encode \| decode \|	1354	module \| encode \| decode \|
853	-----------\|------------\|------------\|	1355	--------------\|------------\|------------\|
854	JSON \| 4990.842 \| 4088.813 \|	1356	JSON::DWIW/DS \| 86302.551 \| 102300.098 \|
855	JSON::DWIW \| 51653.990 \| 71575.154 \|	1357	JSON::DWIW/FJ \| 86302.551 \| 75983.768 \|
856	JSON::PC \| 65948.176 \| 74631.744 \|	1358	JSON::PP \| 15827.562 \| 6638.658 \|
857	JSON::PP \| 8931.652 \| 3817.168 \|	1359	JSON::Syck \| 63358.066 \| 47662.545 \|
858	JSON::Syck \| 24877.248 \| 27776.848 \|	1360	JSON::XS \| 511500.488 \| 511500.488 \|
859	JSON::XS \| 388361.481 \| 227951.304 \|	1361	JSON::XS/2 \| 291271.111 \| 388361.481 \|
860	JSON::XS/2 \| 227951.304 \| 218453.333 \|	1362	JSON::XS/3 \| 361577.931 \| 361577.931 \|
861	JSON::XS/3 \| 338250.323 \| 218453.333 \|	1363	Storable \| 66788.280 \| 265462.278 \|
862	Storable \| 16500.016 \| 135300.129 \|
863	-----------+------------+------------+	1364	--------------+------------+------------+
864		1365
865	That is, JSON::XS is about five times faster than JSON::DWIW on encoding,	1366	That is, JSON::XS is almost six times faster than JSON::DWIW on encoding,
866	about three times faster on decoding, and over fourty times faster	1367	about five times faster on decoding, and over thirty to seventy times
867	than JSON, even with pretty-printing and key sorting. It also compares	1368	faster than JSON's pure perl implementation. It also compares favourably
868	favourably to Storable for small amounts of data.	1369	to Storable for small amounts of data.
869		1370
870	Using a longer test string (roughly 18KB, generated from Yahoo! Locals	1371	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
871	search API (http://nanoref.com/yahooapis/mgPdGg):	1372	search API (L<http://dist.schmorp.de/misc/json/long.json>).
872		1373
873	module \| encode \| decode \|	1374	module \| encode \| decode \|
874	-----------\|------------\|------------\|	1375	--------------\|------------\|------------\|
875	JSON \| 55.260 \| 34.971 \|	1376	JSON::DWIW/DS \| 1647.927 \| 2673.916 \|
876	JSON::DWIW \| 825.228 \| 1082.513 \|	1377	JSON::DWIW/FJ \| 1630.249 \| 2596.128 \|
877	JSON::PC \| 3571.444 \| 2394.829 \|
878	JSON::PP \| 210.987 \| 32.574 \|	1378	JSON::PP \| 400.640 \| 62.311 \|
879	JSON::Syck \| 552.551 \| 787.544 \|	1379	JSON::Syck \| 1481.040 \| 1524.869 \|
880	JSON::XS \| 5780.463 \| 4854.519 \|	1380	JSON::XS \| 20661.596 \| 9541.183 \|
881	JSON::XS/2 \| 3869.998 \| 4798.975 \|	1381	JSON::XS/2 \| 10683.403 \| 9416.938 \|
882	JSON::XS/3 \| 5862.880 \| 4798.975 \|	1382	JSON::XS/3 \| 20661.596 \| 9400.054 \|
883	Storable \| 4445.002 \| 5235.027 \|	1383	Storable \| 19765.806 \| 10000.725 \|
884	-----------+------------+------------+	1384	--------------+------------+------------+
885		1385
886	Again, JSON::XS leads by far (except for Storable which non-surprisingly	1386	Again, JSON::XS leads by far (except for Storable which non-surprisingly
887	decodes faster).	1387	decodes a bit faster).
888		1388
889	On large strings containing lots of high unicode characters, some modules	1389	On large strings containing lots of high Unicode characters, some modules
890	(such as JSON::PC) seem to decode faster than JSON::XS, but the result	1390	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
891	will be broken due to missing (or wrong) unicode handling. Others refuse	1391	will be broken due to missing (or wrong) Unicode handling. Others refuse
892	to decode or encode properly, so it was impossible to prepare a fair	1392	to decode or encode properly, so it was impossible to prepare a fair
893	comparison table for that case.	1393	comparison table for that case.
894		1394
895		1395
896	=head1 SECURITY CONSIDERATIONS	1396	=head1 SECURITY CONSIDERATIONS
…		…
902	any buffer overflows. Obviously, this module should ensure that and I am	1402	any buffer overflows. Obviously, this module should ensure that and I am
903	trying hard on making that true, but you never know.	1403	trying hard on making that true, but you never know.
904		1404
905	Second, you need to avoid resource-starving attacks. That means you should	1405	Second, you need to avoid resource-starving attacks. That means you should
906	limit the size of JSON texts you accept, or make sure then when your	1406	limit the size of JSON texts you accept, or make sure then when your
907	resources run out, thats just fine (e.g. by using a separate process that	1407	resources run out, that's just fine (e.g. by using a separate process that
908	can crash safely). The size of a JSON text in octets or characters is	1408	can crash safely). The size of a JSON text in octets or characters is
909	usually a good indication of the size of the resources required to decode	1409	usually a good indication of the size of the resources required to decode
910	it into a Perl structure. While JSON::XS can check the size of the JSON	1410	it into a Perl structure. While JSON::XS can check the size of the JSON
911	text, it might be too late when you already have it in memory, so you	1411	text, it might be too late when you already have it in memory, so you
912	might want to check the size before you accept the string.	1412	might want to check the size before you accept the string.
913		1413
914	Third, JSON::XS recurses using the C stack when decoding objects and	1414	Third, JSON::XS recurses using the C stack when decoding objects and
915	arrays. The C stack is a limited resource: for instance, on my amd64	1415	arrays. The C stack is a limited resource: for instance, on my amd64
916	machine with 8MB of stack size I can decode around 180k nested arrays but	1416	machine with 8MB of stack size I can decode around 180k nested arrays but
917	only 14k nested JSON objects (due to perl itself recursing deeply on croak	1417	only 14k nested JSON objects (due to perl itself recursing deeply on croak
918	to free the temporary). If that is exceeded, the program crashes. to be	1418	to free the temporary). If that is exceeded, the program crashes. To be
919	conservative, the default nesting limit is set to 512. If your process	1419	conservative, the default nesting limit is set to 512. If your process
920	has a smaller stack, you should adjust this setting accordingly with the	1420	has a smaller stack, you should adjust this setting accordingly with the
921	C<max_depth> method.	1421	C<max_depth> method.
922		1422
923	And last but least, something else could bomb you that I forgot to think	1423	Something else could bomb you, too, that I forgot to think of. In that
924	of. In that case, you get to keep the pieces. I am always open for hints,	1424	case, you get to keep the pieces. I am always open for hints, though...
925	though...	1425
		1426	Also keep in mind that JSON::XS might leak contents of your Perl data
		1427	structures in its error messages, so when you serialise sensitive
		1428	information you might want to make sure that exceptions thrown by JSON::XS
		1429	will not end up in front of untrusted eyes.
926		1430
927	If you are using JSON::XS to return packets to consumption	1431	If you are using JSON::XS to return packets to consumption
928	by javascript scripts in a browser you should have a look at	1432	by JavaScript scripts in a browser you should have a look at
929	L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether	1433	L<http://blog.archive.jpsykes.com/47/practical-csrf-and-json-security/> to
930	you are vulnerable to some common attack vectors (which really are browser	1434	see whether you are vulnerable to some common attack vectors (which really
931	design bugs, but it is still you who will have to deal with it, as major	1435	are browser design bugs, but it is still you who will have to deal with
932	browser developers care only for features, not about doing security	1436	it, as major browser developers care only for features, not about getting
933	right).	1437	security right).
		1438
		1439
		1440	=head1 THREADS
		1441
		1442	This module is I<not> guaranteed to be thread safe and there are no
		1443	plans to change this until Perl gets thread support (as opposed to the
		1444	horribly slow so-called "threads" which are simply slow and bloated
		1445	process simulations - use fork, it's I<much> faster, cheaper, better).
		1446
		1447	(It might actually work, but you have been warned).
934		1448
935		1449
936	=head1 BUGS	1450	=head1 BUGS
937		1451
938	While the goal of this module is to be correct, that unfortunately does	1452	While the goal of this module is to be correct, that unfortunately does
939	not mean its bug-free, only that I think its design is bug-free. It is	1453	not mean it's bug-free, only that I think its design is bug-free. If you
940	still relatively early in its development. If you keep reporting bugs they	1454	keep reporting bugs they will be fixed swiftly, though.
941	will be fixed swiftly, though.	1455
		1456	Please refrain from using rt.cpan.org or any other bug reporting
		1457	service. I put the contact address into my modules for a reason.
942		1458
943	=cut	1459	=cut
944		1460
945	our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };	1461	our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
946	our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };	1462	our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };
…		…
963	"--" => sub { $_[0] = ${$_[0]} - 1 },	1479	"--" => sub { $_[0] = ${$_[0]} - 1 },
964	fallback => 1;	1480	fallback => 1;
965		1481
966	1;	1482	1;
967		1483
		1484	=head1 SEE ALSO
		1485
		1486	The F<json_xs> command line utility for quick experiments.
		1487
968	=head1 AUTHOR	1488	=head1 AUTHOR
969		1489
970	Marc Lehmann <schmorp@schmorp.de>	1490	Marc Lehmann <schmorp@schmorp.de>
971	http://home.schmorp.de/	1491	http://home.schmorp.de/
972		1492

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Comparing JSON-XS/XS.pm (file contents): Revision 1.62 by root, Thu Oct 11 22:52:52 2007 UTC vs. Revision 1.131 by root, Thu Mar 11 19:31:37 2010 UTC

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Comparing JSON-XS/XS.pm (file contents):
Revision 1.62 by root, Thu Oct 11 22:52:52 2007 UTC vs.
Revision 1.131 by root, Thu Mar 11 19:31:37 2010 UTC