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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.5 by root, Thu Mar 22 21:36:52 2007 UTC vs.
Revision 1.68 by root, Tue Oct 23 03:30:02 2007 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		4
		5	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)
		7
5	=head1 SYNOPSIS	8	=head1 SYNOPSIS
6		9
7	use JSON::XS;	10	use JSON::XS;
		11
		12	# exported functions, they croak on error
		13	# and expect/generate UTF-8
		14
		15	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;
		16	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;
		17
		18	# OO-interface
		19
		20	$coder = JSON::XS->new->ascii->pretty->allow_nonref;
		21	$pretty_printed_unencoded = $coder->encode ($perl_scalar);
		22	$perl_scalar = $coder->decode ($unicode_json_text);
8		23
9	=head1 DESCRIPTION	24	=head1 DESCRIPTION
10		25
11	This module converts Perl data structures to JSON and vice versa. Its	26	This module converts Perl data structures to JSON and vice versa. Its
12	primary goal is to be I<correct> and its secondary goal is to be	27	primary goal is to be I<correct> and its secondary goal is to be
18	their maintainers are unresponsive, gone missing, or not listening to bug	33	their maintainers are unresponsive, gone missing, or not listening to bug
19	reports for other reasons.	34	reports for other reasons.
20		35
21	See COMPARISON, below, for a comparison to some other JSON modules.	36	See COMPARISON, below, for a comparison to some other JSON modules.
22		37
		38	See MAPPING, below, on how JSON::XS maps perl values to JSON values and
		39	vice versa.
		40
23	=head2 FEATURES	41	=head2 FEATURES
24		42
25	=over 4	43	=over 4
26		44
27	=item * correct handling of unicode issues	45	=item * correct Unicode handling
28		46
29	This module knows how to handle Unicode, and even documents how it does so.	47	This module knows how to handle Unicode, and even documents how and when
		48	it does so.
30		49
31	=item * round-trip integrity	50	=item * round-trip integrity
32		51
33	When you serialise a perl data structure using only datatypes supported	52	When you serialise a perl data structure using only datatypes supported
34	by JSON, the deserialised data structure is identical on the Perl level.	53	by JSON, the deserialised data structure is identical on the Perl level.
35	(e.g. the string "2.0" doesn't suddenly become "2").	54	(e.g. the string "2.0" doesn't suddenly become "2" just because it looks
		55	like a number).
36		56
37	=item * strict checking of JSON correctness	57	=item * strict checking of JSON correctness
38		58
39	There is no guessing, no generating of illegal JSON strings by default,	59	There is no guessing, no generating of illegal JSON texts by default,
40	and only JSON is accepted as input (the latter is a security feature).	60	and only JSON is accepted as input by default (the latter is a security
		61	feature).
41		62
42	=item * fast	63	=item * fast
43		64
44	compared to other JSON modules, this module compares favourably.	65	Compared to other JSON modules, this module compares favourably in terms
		66	of speed, too.
45		67
46	=item * simple to use	68	=item * simple to use
47		69
48	This module has both a simple functional interface as well as an OO	70	This module has both a simple functional interface as well as an OO
49	interface.	71	interface.
50		72
51	=item * reasonably versatile output formats	73	=item * reasonably versatile output formats
52		74
53	You can choose between the most compact format possible, a pure-ascii	75	You can choose between the most compact guaranteed single-line format
54	format, or a pretty-printed format. Or you can combine those features in	76	possible (nice for simple line-based protocols), a pure-ascii format
55	whatever way you like.	77	(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
		79	stuff). Or you can combine those features in whatever way you like.
56		80
57	=back	81	=back
58		82
59	=cut	83	=cut
60		84
61	package JSON::XS;	85	package JSON::XS;
62		86
63	BEGIN {	87	use strict;
		88
64	$VERSION = '0.1';	89	our $VERSION = '1.52';
65	@ISA = qw(Exporter);	90	our @ISA = qw(Exporter);
66		91
67	@EXPORT = qw(to_json from_json);	92	our @EXPORT = qw(to_json from_json);
68	require Exporter;
69		93
70	require XSLoader;	94	use Exporter;
71	XSLoader::load JSON::XS::, $VERSION;	95	use XSLoader;
72	}
73		96
74	=head1 FUNCTIONAL INTERFACE	97	=head1 FUNCTIONAL INTERFACE
75		98
76	The following convinience methods are provided by this module. They are	99	The following convenience methods are provided by this module. They are
77	exported by default:	100	exported by default:
78		101
79	=over 4	102	=over 4
80		103
81	=item $json_string = to_json $perl_scalar	104	=item $json_text = to_json $perl_scalar
82		105
83	Converts the given Perl data structure (a simple scalar or a reference to	106	Converts the given Perl data structure to a UTF-8 encoded, binary string
84	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains	107	(that is, the string contains octets only). Croaks on error.
85	octets only). Croaks on error.
86		108
87	This function call is functionally identical to C<< JSON::XS->new->utf8	109	This function call is functionally identical to:
88	(1)->encode ($perl_scalar) >>.
89		110
		111	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)
		112
		113	except being faster.
		114
90	=item $perl_scalar = from_json $json_string	115	=item $perl_scalar = from_json $json_text
91		116
92	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to	117	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries
93	parse that as an UTF-8 encoded JSON string, returning the resulting simple	118	to parse that as an UTF-8 encoded JSON text, returning the resulting
94	scalar or reference. Croaks on error.	119	reference. Croaks on error.
95		120
96	This function call is functionally identical to C<< JSON::XS->new->utf8	121	This function call is functionally identical to:
97	(1)->decode ($json_string) >>.	122
		123	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
		124
		125	except being faster.
		126
		127	=item $is_boolean = JSON::XS::is_bool $scalar
		128
		129	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
		131	and are used to represent JSON C<true> and C<false> values in Perl.
		132
		133	See MAPPING, below, for more information on how JSON values are mapped to
		134	Perl.
98		135
99	=back	136	=back
		137
		138
		139	=head1 A FEW NOTES ON UNICODE AND PERL
		140
		141	Since this often leads to confusion, here are a few very clear words on
		142	how Unicode works in Perl, modulo bugs.
		143
		144	=over 4
		145
		146	=item 1. Perl strings can store characters with ordinal values > 255.
		147
		148	This enables you to store Unicode characters as single characters in a
		149	Perl string - very natural.
		150
		151	=item 2. Perl does I<not> associate an encoding with your strings.
		152
		153	Unless you force it to, e.g. when matching it against a regex, or printing
		154	the scalar to a file, in which case Perl either interprets your string as
		155	locale-encoded text, octets/binary, or as Unicode, depending on various
		156	settings. In no case is an encoding stored together with your data, it is
		157	I<use> that decides encoding, not any magical metadata.
		158
		159	=item 3. The internal utf-8 flag has no meaning with regards to the
		160	encoding of your string.
		161
		162	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
		164	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
		166	flag clear, and you can have binary data with that flag set and that flag
		167	clear. Other possibilities exist, too.
		168
		169	If you didn't know about that flag, just the better, pretend it doesn't
		170	exist.
		171
		172	=item 4. A "Unicode String" is simply a string where each character can be
		173	validly interpreted as a Unicode codepoint.
		174
		175	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.
		177
		178	=item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string.
		179
		180	It's a fact. Learn to live with it.
		181
		182	=back
		183
		184	I hope this helps :)
		185
100		186
101	=head1 OBJECT-ORIENTED INTERFACE	187	=head1 OBJECT-ORIENTED INTERFACE
102		188
103	The object oriented interface lets you configure your own encoding or	189	The object oriented interface lets you configure your own encoding or
104	decoding style, within the limits of supported formats.	190	decoding style, within the limits of supported formats.
…		…
111	strings. All boolean flags described below are by default I<disabled>.	197	strings. All boolean flags described below are by default I<disabled>.
112		198
113	The mutators for flags all return the JSON object again and thus calls can	199	The mutators for flags all return the JSON object again and thus calls can
114	be chained:	200	be chained:
115		201
116	my $json = JSON::XS->new->utf8(1)->space_after(1)->encode ({a => [1,2]})	202	my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})
117	=> {"a": [1, 2]}	203	=> {"a": [1, 2]}
118		204
119	=item $json = $json->ascii ($enable)	205	=item $json = $json->ascii ([$enable])
120		206
121	If C<$enable> is true, then the C<encode> method will not generate	207	If C<$enable> is true (or missing), then the C<encode> method will not
122	characters outside the code range C<0..127>. Any unicode characters	208	generate characters outside the code range C<0..127> (which is ASCII). Any
123	outside that range will be escaped using either a single \uXXXX (BMP	209	Unicode characters outside that range will be escaped using either a
124	characters) or a double \uHHHH\uLLLLL escape sequence, as per RFC4627.	210	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
		212	Unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
		213	or any other superset of ASCII.
125		214
126	If C<$enable> is false, then the C<encode> method will not escape Unicode	215	If C<$enable> is false, then the C<encode> method will not escape Unicode
127	characters unless necessary.	216	characters unless required by the JSON syntax or other flags. This results
		217	in a faster and more compact format.
128		218
		219	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
		221	contain any 8 bit characters.
		222
129	JSON::XS->new->ascii (1)->encode (chr 0x10401)	223	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
130	=> \ud801\udc01	224	=> ["\ud801\udc01"]
131		225
		226	=item $json = $json->latin1 ([$enable])
		227
		228	If C<$enable> is true (or missing), then the C<encode> method will encode
		229	the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
		230	outside the code range C<0..255>. The resulting string can be treated as a
		231	latin1-encoded JSON text or a native Unicode string. The C<decode> method
		232	will not be affected in any way by this flag, as C<decode> by default
		233	expects Unicode, which is a strict superset of latin1.
		234
		235	If C<$enable> is false, then the C<encode> method will not escape Unicode
		236	characters unless required by the JSON syntax or other flags.
		237
		238	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
		240	size. The disadvantage is that the resulting JSON text is encoded
		241	in latin1 (and must correctly be treated as such when storing and
		242	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
		244	in files or databases, not when talking to other JSON encoders/decoders.
		245
		246	JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
		247	=> ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
		248
132	=item $json = $json->utf8 ($enable)	249	=item $json = $json->utf8 ([$enable])
133		250
134	If C<$enable> is true, then the C<encode> method will encode the JSON	251	If C<$enable> is true (or missing), then the C<encode> method will encode
135	string into UTF-8, as required by many protocols, while the C<decode>	252	the JSON result into UTF-8, as required by many protocols, while the
136	method expects to be handled an UTF-8-encoded string. Please note that	253	C<decode> method expects to be handled an UTF-8-encoded string. Please
137	UTF-8-encoded strings do not contain any characters outside the range	254	note that UTF-8-encoded strings do not contain any characters outside the
138	C<0..255>, they are thus useful for bytewise/binary I/O.	255	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
		257	and UTF-32 encoding families, as described in RFC4627.
139		258
140	If C<$enable> is false, then the C<encode> method will return the JSON	259	If C<$enable> is false, then the C<encode> method will return the JSON
141	string as a (non-encoded) unicode string, while C<decode> expects thus a	260	string as a (non-encoded) Unicode string, while C<decode> expects thus a
142	unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs	261	Unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs
143	to be done yourself, e.g. using the Encode module.	262	to be done yourself, e.g. using the Encode module.
144		263
		264	Example, output UTF-16BE-encoded JSON:
		265
		266	use Encode;
		267	$jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);
		268
		269	Example, decode UTF-32LE-encoded JSON:
		270
		271	use Encode;
		272	$object = JSON::XS->new->decode (decode "UTF-32LE", $jsontext);
		273
145	=item $json = $json->pretty ($enable)	274	=item $json = $json->pretty ([$enable])
146		275
147	This enables (or disables) all of the C<indent>, C<space_before> and	276	This enables (or disables) all of the C<indent>, C<space_before> and
148	C<space_after> (and in the future possibly more) flags in one call to	277	C<space_after> (and in the future possibly more) flags in one call to
149	generate the most readable (or most compact) form possible.	278	generate the most readable (or most compact) form possible.
		279
		280	Example, pretty-print some simple structure:
150		281
151	my $json = JSON::XS->new->pretty(1)->encode ({a => [1,2]})	282	my $json = JSON::XS->new->pretty(1)->encode ({a => [1,2]})
152	=>	283	=>
153	{	284	{
154	"a" : [	285	"a" : [
155	1,	286	1,
156	2	287	2
157	]	288	]
158	}	289	}
159		290
160	=item $json = $json->indent ($enable)	291	=item $json = $json->indent ([$enable])
161		292
162	If C<$enable> is true, then the C<encode> method will use a multiline	293	If C<$enable> is true (or missing), then the C<encode> method will use a multiline
163	format as output, putting every array member or object/hash key-value pair	294	format as output, putting every array member or object/hash key-value pair
164	into its own line, identing them properly.	295	into its own line, indenting them properly.
165		296
166	If C<$enable> is false, no newlines or indenting will be produced, and the	297	If C<$enable> is false, no newlines or indenting will be produced, and the
167	resulting JSON strings is guarenteed not to contain any C<newlines>.	298	resulting JSON text is guaranteed not to contain any C<newlines>.
168		299
169	This setting has no effect when decoding JSON strings.	300	This setting has no effect when decoding JSON texts.
170		301
171	=item $json = $json->space_before ($enable)	302	=item $json = $json->space_before ([$enable])
172		303
173	If C<$enable> is true, then the C<encode> method will add an extra	304	If C<$enable> is true (or missing), then the C<encode> method will add an extra
174	optional space before the C<:> separating keys from values in JSON objects.	305	optional space before the C<:> separating keys from values in JSON objects.
175		306
176	If C<$enable> is false, then the C<encode> method will not add any extra	307	If C<$enable> is false, then the C<encode> method will not add any extra
177	space at those places.	308	space at those places.
178		309
179	This setting has no effect when decoding JSON strings. You will also most	310	This setting has no effect when decoding JSON texts. You will also
180	likely combine this setting with C<space_after>.	311	most likely combine this setting with C<space_after>.
181		312
		313	Example, space_before enabled, space_after and indent disabled:
		314
		315	{"key" :"value"}
		316
182	=item $json = $json->space_after ($enable)	317	=item $json = $json->space_after ([$enable])
183		318
184	If C<$enable> is true, then the C<encode> method will add an extra	319	If C<$enable> is true (or missing), then the C<encode> method will add an extra
185	optional space after the C<:> separating keys from values in JSON objects	320	optional space after the C<:> separating keys from values in JSON objects
186	and extra whitespace after the C<,> separating key-value pairs and array	321	and extra whitespace after the C<,> separating key-value pairs and array
187	members.	322	members.
188		323
189	If C<$enable> is false, then the C<encode> method will not add any extra	324	If C<$enable> is false, then the C<encode> method will not add any extra
190	space at those places.	325	space at those places.
191		326
192	This setting has no effect when decoding JSON strings.	327	This setting has no effect when decoding JSON texts.
193		328
		329	Example, space_before and indent disabled, space_after enabled:
		330
		331	{"key": "value"}
		332
		333	=item $json = $json->relaxed ([$enable])
		334
		335	If C<$enable> is true (or missing), then C<decode> will accept some
		336	extensions to normal JSON syntax (see below). C<encode> will not be
		337	affected in anyway. I<Be aware that this option makes you accept invalid
		338	JSON texts as if they were valid!>. I suggest only to use this option to
		339	parse application-specific files written by humans (configuration files,
		340	resource files etc.)
		341
		342	If C<$enable> is false (the default), then C<decode> will only accept
		343	valid JSON texts.
		344
		345	Currently accepted extensions are:
		346
		347	=over 4
		348
		349	=item * list items can have an end-comma
		350
		351	JSON I<separates> array elements and key-value pairs with commas. This
		352	can be annoying if you write JSON texts manually and want to be able to
		353	quickly append elements, so this extension accepts comma at the end of
		354	such items not just between them:
		355
		356	[
		357	1,
		358	2, <- this comma not normally allowed
		359	]
		360	{
		361	"k1": "v1",
		362	"k2": "v2", <- this comma not normally allowed
		363	}
		364
		365	=item * shell-style '#'-comments
		366
		367	Whenever JSON allows whitespace, shell-style comments are additionally
		368	allowed. They are terminated by the first carriage-return or line-feed
		369	character, after which more white-space and comments are allowed.
		370
		371	[
		372	1, # this comment not allowed in JSON
		373	# neither this one...
		374	]
		375
		376	=back
		377
194	=item $json = $json->canonical ($enable)	378	=item $json = $json->canonical ([$enable])
195		379
196	If C<$enable> is true, then the C<encode> method will output JSON objects	380	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
197	by sorting their keys. This is adding a comparatively high overhead.	381	by sorting their keys. This is adding a comparatively high overhead.
198		382
199	If C<$enable> is false, then the C<encode> method will output key-value	383	If C<$enable> is false, then the C<encode> method will output key-value
200	pairs in the order Perl stores them (which will likely change between runs	384	pairs in the order Perl stores them (which will likely change between runs
201	of the same script).	385	of the same script).
202		386
203	This option is useful if you want the same data structure to be encoded as	387	This option is useful if you want the same data structure to be encoded as
204	the same JSON string (given the same overall settings). If it is disabled,	388	the same JSON text (given the same overall settings). If it is disabled,
205	the same hash migh be encoded differently even if contains the same data,	389	the same hash might be encoded differently even if contains the same data,
206	as key-value pairs have no inherent ordering in Perl.	390	as key-value pairs have no inherent ordering in Perl.
207		391
208	This setting has no effect when decoding JSON strings.	392	This setting has no effect when decoding JSON texts.
209		393
210	=item $json = $json->allow_nonref ($enable)	394	=item $json = $json->allow_nonref ([$enable])
211		395
212	If C<$enable> is true, then the C<encode> method can convert a	396	If C<$enable> is true (or missing), then the C<encode> method can convert a
213	non-reference into its corresponding string, number or null JSON value,	397	non-reference into its corresponding string, number or null JSON value,
214	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON	398	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
215	values instead of croaking.	399	values instead of croaking.
216		400
217	If C<$enable> is false, then the C<encode> method will croak if it isn't	401	If C<$enable> is false, then the C<encode> method will croak if it isn't
218	passed an arrayref or hashref, as JSON strings must either be an object	402	passed an arrayref or hashref, as JSON texts must either be an object
219	or array. Likewise, C<decode> will croak if given something that is not a	403	or array. Likewise, C<decode> will croak if given something that is not a
220	JSON object or array.	404	JSON object or array.
221		405
		406	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,
		407	resulting in an invalid JSON text:
		408
		409	JSON::XS->new->allow_nonref->encode ("Hello, World!")
		410	=> "Hello, World!"
		411
		412	=item $json = $json->allow_blessed ([$enable])
		413
		414	If C<$enable> is true (or missing), then the C<encode> method will not
		415	barf when it encounters a blessed reference. Instead, the value of the
		416	B<convert_blessed> option will decide whether C<null> (C<convert_blessed>
		417	disabled or no C<to_json> method found) or a representation of the
		418	object (C<convert_blessed> enabled and C<to_json> method found) is being
		419	encoded. Has no effect on C<decode>.
		420
		421	If C<$enable> is false (the default), then C<encode> will throw an
		422	exception when it encounters a blessed object.
		423
		424	=item $json = $json->convert_blessed ([$enable])
		425
		426	If C<$enable> is true (or missing), then C<encode>, upon encountering a
		427	blessed object, will check for the availability of the C<TO_JSON> method
		428	on the object's class. If found, it will be called in scalar context
		429	and the resulting scalar will be encoded instead of the object. If no
		430	C<TO_JSON> method is found, the value of C<allow_blessed> will decide what
		431	to do.
		432
		433	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
		434	returns other blessed objects, those will be handled in the same
		435	way. C<TO_JSON> must take care of not causing an endless recursion cycle
		436	(== crash) in this case. The name of C<TO_JSON> was chosen because other
		437	methods called by the Perl core (== not by the user of the object) are
		438	usually in upper case letters and to avoid collisions with the C<to_json>
		439	function.
		440
		441	This setting does not yet influence C<decode> in any way, but in the
		442	future, global hooks might get installed that influence C<decode> and are
		443	enabled by this setting.
		444
		445	If C<$enable> is false, then the C<allow_blessed> setting will decide what
		446	to do when a blessed object is found.
		447
		448	=item $json = $json->filter_json_object ([$coderef->($hashref)])
		449
		450	When C<$coderef> is specified, it will be called from C<decode> each
		451	time it decodes a JSON object. The only argument is a reference to the
		452	newly-created hash. If the code references returns a single scalar (which
		453	need not be a reference), this value (i.e. a copy of that scalar to avoid
		454	aliasing) is inserted into the deserialised data structure. If it returns
		455	an empty list (NOTE: I<not> C<undef>, which is a valid scalar), the
		456	original deserialised hash will be inserted. This setting can slow down
		457	decoding considerably.
		458
		459	When C<$coderef> is omitted or undefined, any existing callback will
		460	be removed and C<decode> will not change the deserialised hash in any
		461	way.
		462
		463	Example, convert all JSON objects into the integer 5:
		464
		465	my $js = JSON::XS->new->filter_json_object (sub { 5 });
		466	# returns [5]
		467	$js->decode ('[{}]')
		468	# throw an exception because allow_nonref is not enabled
		469	# so a lone 5 is not allowed.
		470	$js->decode ('{"a":1, "b":2}');
		471
		472	=item $json = $json->filter_json_single_key_object ($key [=> $coderef->($value)])
		473
		474	Works remotely similar to C<filter_json_object>, but is only called for
		475	JSON objects having a single key named C<$key>.
		476
		477	This C<$coderef> is called before the one specified via
		478	C<filter_json_object>, if any. It gets passed the single value in the JSON
		479	object. If it returns a single value, it will be inserted into the data
		480	structure. If it returns nothing (not even C<undef> but the empty list),
		481	the callback from C<filter_json_object> will be called next, as if no
		482	single-key callback were specified.
		483
		484	If C<$coderef> is omitted or undefined, the corresponding callback will be
		485	disabled. There can only ever be one callback for a given key.
		486
		487	As this callback gets called less often then the C<filter_json_object>
		488	one, decoding speed will not usually suffer as much. Therefore, single-key
		489	objects make excellent targets to serialise Perl objects into, especially
		490	as single-key JSON objects are as close to the type-tagged value concept
		491	as JSON gets (it's basically an ID/VALUE tuple). Of course, JSON does not
		492	support this in any way, so you need to make sure your data never looks
		493	like a serialised Perl hash.
		494
		495	Typical names for the single object key are C<__class_whatever__>, or
		496	C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even
		497	things like C<__class_md5sum(classname)__>, to reduce the risk of clashing
		498	with real hashes.
		499
		500	Example, decode JSON objects of the form C<< { "__widget__" => <id> } >>
		501	into the corresponding C<< $WIDGET{<id>} >> object:
		502
		503	# return whatever is in $WIDGET{5}:
		504	JSON::XS
		505	->new
		506	->filter_json_single_key_object (__widget__ => sub {
		507	$WIDGET{ $_[0] }
		508	})
		509	->decode ('{"__widget__": 5')
		510
		511	# this can be used with a TO_JSON method in some "widget" class
		512	# for serialisation to json:
		513	sub WidgetBase::TO_JSON {
		514	my ($self) = @_;
		515
		516	unless ($self->{id}) {
		517	$self->{id} = ..get..some..id..;
		518	$WIDGET{$self->{id}} = $self;
		519	}
		520
		521	{ __widget__ => $self->{id} }
		522	}
		523
		524	=item $json = $json->shrink ([$enable])
		525
		526	Perl usually over-allocates memory a bit when allocating space for
		527	strings. This flag optionally resizes strings generated by either
		528	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
		530	short strings. It will also try to downgrade any strings to octet-form
		531	if possible: perl stores strings internally either in an encoding called
		532	UTF-X or in octet-form. The latter cannot store everything but uses less
		533	space in general (and some buggy Perl or C code might even rely on that
		534	internal representation being used).
		535
		536	The actual definition of what shrink does might change in future versions,
		537	but it will always try to save space at the expense of time.
		538
		539	If C<$enable> is true (or missing), the string returned by C<encode> will
		540	be shrunk-to-fit, while all strings generated by C<decode> will also be
		541	shrunk-to-fit.
		542
		543	If C<$enable> is false, then the normal perl allocation algorithms are used.
		544	If you work with your data, then this is likely to be faster.
		545
		546	In the future, this setting might control other things, such as converting
		547	strings that look like integers or floats into integers or floats
		548	internally (there is no difference on the Perl level), saving space.
		549
		550	=item $json = $json->max_depth ([$maximum_nesting_depth])
		551
		552	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
		554	higher nesting level then this limit, then the encoder and decoder will
		555	stop and croak at that point.
		556
		557	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<[>
		559	characters without their matching closing parenthesis crossed to reach a
		560	given character in a string.
		561
		562	Setting the maximum depth to one disallows any nesting, so that ensures
		563	that the object is only a single hash/object or array.
		564
		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
		567	used, which is rarely useful.
		568
		569	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
		570
		571	=item $json = $json->max_size ([$maximum_string_size])
		572
		573	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>
		575	is called on a string longer then this number of characters it will not
		576	attempt to decode the string but throw an exception. This setting has no
		577	effect on C<encode> (yet).
		578
		579	The argument to C<max_size> will be rounded up to the next B<highest>
		580	power of two (so may be more than requested). If no argument is given, the
		581	limit check will be deactivated (same as when C<0> is specified).
		582
		583	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
		584
222	=item $json_string = $json->encode ($perl_scalar)	585	=item $json_text = $json->encode ($perl_scalar)
223		586
224	Converts the given Perl data structure (a simple scalar or a reference	587	Converts the given Perl data structure (a simple scalar or a reference
225	to a hash or array) to its JSON representation. Simple scalars will be	588	to a hash or array) to its JSON representation. Simple scalars will be
226	converted into JSON string or number sequences, while references to arrays	589	converted into JSON string or number sequences, while references to arrays
227	become JSON arrays and references to hashes become JSON objects. Undefined	590	become JSON arrays and references to hashes become JSON objects. Undefined
228	Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>	591	Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>
229	nor C<false> values will be generated.	592	nor C<false> values will be generated.
230		593
231	=item $perl_scalar = $json->decode ($json_string)	594	=item $perl_scalar = $json->decode ($json_text)
232		595
233	The opposite of C<encode>: expects a JSON string and tries to parse it,	596	The opposite of C<encode>: expects a JSON text and tries to parse it,
234	returning the resulting simple scalar or reference. Croaks on error.	597	returning the resulting simple scalar or reference. Croaks on error.
235		598
236	JSON numbers and strings become simple Perl scalars. JSON arrays become	599	JSON numbers and strings become simple Perl scalars. JSON arrays become
237	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes	600	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
238	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.	601	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
239		602
		603	=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
		604
		605	This works like the C<decode> method, but instead of raising an exception
		606	when there is trailing garbage after the first JSON object, it will
		607	silently stop parsing there and return the number of characters consumed
		608	so far.
		609
		610	This is useful if your JSON texts are not delimited by an outer protocol
		611	(which is not the brightest thing to do in the first place) and you need
		612	to know where the JSON text ends.
		613
		614	JSON::XS->new->decode_prefix ("[1] the tail")
		615	=> ([], 3)
		616
240	=back	617	=back
		618
		619
		620	=head1 MAPPING
		621
		622	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
		624	circumstances automatically, preserving round-tripping characteristics
		625	(what you put in comes out as something equivalent).
		626
		627	For the more enlightened: note that in the following descriptions,
		628	lowercase I<perl> refers to the Perl interpreter, while uppercase I<Perl>
		629	refers to the abstract Perl language itself.
		630
		631
		632	=head2 JSON -> PERL
		633
		634	=over 4
		635
		636	=item object
		637
		638	A JSON object becomes a reference to a hash in Perl. No ordering of object
		639	keys is preserved (JSON does not preserve object key ordering itself).
		640
		641	=item array
		642
		643	A JSON array becomes a reference to an array in Perl.
		644
		645	=item string
		646
		647	A JSON string becomes a string scalar in Perl - Unicode codepoints in JSON
		648	are represented by the same codepoints in the Perl string, so no manual
		649	decoding is necessary.
		650
		651	=item number
		652
		653	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
		655	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
		657	might represent more values exactly than (floating point) numbers.
		658
		659	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
		661	a numeric (floating point) value if that is possible without loss of
		662	precision. Otherwise it will preserve the number as a string value.
		663
		664	Numbers containing a fractional or exponential part will always be
		665	represented as numeric (floating point) values, possibly at a loss of
		666	precision.
		667
		668	This might create round-tripping problems as numbers might become strings,
		669	but as Perl is typeless there is no other way to do it.
		670
		671	=item true, false
		672
		673	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
		675	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.
		677
		678	=item null
		679
		680	A JSON null atom becomes C<undef> in Perl.
		681
		682	=back
		683
		684
		685	=head2 PERL -> JSON
		686
		687	The mapping from Perl to JSON is slightly more difficult, as Perl is a
		688	truly typeless language, so we can only guess which JSON type is meant by
		689	a Perl value.
		690
		691	=over 4
		692
		693	=item hash references
		694
		695	Perl hash references become JSON objects. As there is no inherent ordering
		696	in hash keys (or JSON objects), they will usually be encoded in a
		697	pseudo-random order that can change between runs of the same program but
		698	stays generally the same within a single run of a program. JSON::XS can
		699	optionally sort the hash keys (determined by the I<canonical> flag), so
		700	the same datastructure will serialise to the same JSON text (given same
		701	settings and version of JSON::XS), but this incurs a runtime overhead
		702	and is only rarely useful, e.g. when you want to compare some JSON text
		703	against another for equality.
		704
		705	=item array references
		706
		707	Perl array references become JSON arrays.
		708
		709	=item other references
		710
		711	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
		713	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.
		715
		716	to_json [\0,JSON::XS::true] # yields [false,true]
		717
		718	=item JSON::XS::true, JSON::XS::false
		719
		720	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.
		722
		723	=item blessed objects
		724
		725	Blessed objects are not allowed. JSON::XS currently tries to encode their
		726	underlying representation (hash- or arrayref), but this behaviour might
		727	change in future versions.
		728
		729	=item simple scalars
		730
		731	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
		733	JSON null value, scalars that have last been used in a string context
		734	before encoding as JSON strings and anything else as number value:
		735
		736	# dump as number
		737	to_json [2] # yields [2]
		738	to_json [-3.0e17] # yields [-3e+17]
		739	my $value = 5; to_json [$value] # yields [5]
		740
		741	# used as string, so dump as string
		742	print $value;
		743	to_json [$value] # yields ["5"]
		744
		745	# undef becomes null
		746	to_json [undef] # yields [null]
		747
		748	You can force the type to be a JSON string by stringifying it:
		749
		750	my $x = 3.1; # some variable containing a number
		751	"$x"; # stringified
		752	$x .= ""; # another, more awkward way to stringify
		753	print $x; # perl does it for you, too, quite often
		754
		755	You can force the type to be a JSON number by numifying it:
		756
		757	my $x = "3"; # some variable containing a string
		758	$x += 0; # numify it, ensuring it will be dumped as a number
		759	$x *= 1; # same thing, the choice is yours.
		760
		761	You can not currently force the type in other, less obscure, ways. Tell me
		762	if you need this capability.
		763
		764	=back
		765
241		766
242	=head1 COMPARISON	767	=head1 COMPARISON
243		768
244	As already mentioned, this module was created because none of the existing	769	As already mentioned, this module was created because none of the existing
245	JSON modules could be made to work correctly. First I will describe the	770	JSON modules could be made to work correctly. First I will describe the
…		…
251		776
252	=item JSON 1.07	777	=item JSON 1.07
253		778
254	Slow (but very portable, as it is written in pure Perl).	779	Slow (but very portable, as it is written in pure Perl).
255		780
256	Undocumented/buggy Unicode handling (how JSON handles unicode values is	781	Undocumented/buggy Unicode handling (how JSON handles Unicode values is
257	undocumented. One can get far by feeding it unicode strings and doing	782	undocumented. One can get far by feeding it Unicode strings and doing
258	en-/decoding oneself, but unicode escapes are not working properly).	783	en-/decoding oneself, but Unicode escapes are not working properly).
259		784
260	No roundtripping (strings get clobbered if they look like numbers, e.g.	785	No roundtripping (strings get clobbered if they look like numbers, e.g.
261	the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will	786	the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will
262	decode into the number 2.	787	decode into the number 2.
263		788
…		…
271		796
272	Has problems handling many Perl values (e.g. regex results and other magic	797	Has problems handling many Perl values (e.g. regex results and other magic
273	values will make it croak).	798	values will make it croak).
274		799
275	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>	800	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>
276	which is not a valid JSON string.	801	which is not a valid JSON text.
277		802
278	Unmaintained (maintainer unresponsive for many months, bugs are not	803	Unmaintained (maintainer unresponsive for many months, bugs are not
279	getting fixed).	804	getting fixed).
280		805
281	=item JSON::Syck 0.21	806	=item JSON::Syck 0.21
…		…
283	Very buggy (often crashes).	808	Very buggy (often crashes).
284		809
285	Very inflexible (no human-readable format supported, format pretty much	810	Very inflexible (no human-readable format supported, format pretty much
286	undocumented. I need at least a format for easy reading by humans and a	811	undocumented. I need at least a format for easy reading by humans and a
287	single-line compact format for use in a protocol, and preferably a way to	812	single-line compact format for use in a protocol, and preferably a way to
288	generate ASCII-only JSON strings).	813	generate ASCII-only JSON texts).
289		814
290	Completely broken (and confusingly documented) Unicode handling (unicode	815	Completely broken (and confusingly documented) Unicode handling (Unicode
291	escapes are not working properly, you need to set ImplicitUnicode to	816	escapes are not working properly, you need to set ImplicitUnicode to
292	I<different> values on en- and decoding to get symmetric behaviour).	817	I<different> values on en- and decoding to get symmetric behaviour).
293		818
294	No roundtripping (simple cases work, but this depends on wether the scalar	819	No roundtripping (simple cases work, but this depends on whether the scalar
295	value was used in a numeric context or not).	820	value was used in a numeric context or not).
296		821
297	Dumping hashes may skip hash values depending on iterator state.	822	Dumping hashes may skip hash values depending on iterator state.
298		823
299	Unmaintained (maintainer unresponsive for many months, bugs are not	824	Unmaintained (maintainer unresponsive for many months, bugs are not
300	getting fixed).	825	getting fixed).
301		826
302	Does not check input for validity (i.e. will accept non-JSON input and	827	Does not check input for validity (i.e. will accept non-JSON input and
303	return "something" instead of raising an exception. This is a security	828	return "something" instead of raising an exception. This is a security
304	issue: imagine two banks transfering money between each other using	829	issue: imagine two banks transferring money between each other using
305	JSON. One bank might parse a given non-JSON request and deduct money,	830	JSON. One bank might parse a given non-JSON request and deduct money,
306	while the other might reject the transaction with a syntax error. While a	831	while the other might reject the transaction with a syntax error. While a
307	good protocol will at least recover, that is extra unnecessary work and	832	good protocol will at least recover, that is extra unnecessary work and
308	the transaction will still not succeed).	833	the transaction will still not succeed).
309		834
310	=item JSON::DWIW 0.04	835	=item JSON::DWIW 0.04
311		836
312	Very fast. Very natural. Very nice.	837	Very fast. Very natural. Very nice.
313		838
314	Undocumented unicode handling (but the best of the pack. Unicode escapes	839	Undocumented Unicode handling (but the best of the pack. Unicode escapes
315	still don't get parsed properly).	840	still don't get parsed properly).
316		841
317	Very inflexible.	842	Very inflexible.
318		843
319	No roundtripping.	844	No roundtripping.
320		845
321	Does not generate valid JSON (key strings are often unquoted, empty keys	846	Does not generate valid JSON texts (key strings are often unquoted, empty keys
322	result in nothing being output)	847	result in nothing being output)
323		848
324	Does not check input for validity.	849	Does not check input for validity.
325		850
326	=back	851	=back
		852
		853
		854	=head2 JSON and YAML
		855
		856	You often hear that JSON is a subset (or a close subset) of YAML. This is,
		857	however, a mass hysteria and very far from the truth. In general, there is
		858	no way to configure JSON::XS to output a data structure as valid YAML.
		859
		860	If you really must use JSON::XS to generate YAML, you should use this
		861	algorithm (subject to change in future versions):
		862
		863	my $to_yaml = JSON::XS->new->utf8->space_after (1);
		864	my $yaml = $to_yaml->encode ($ref) . "\n";
		865
		866	This will usually generate JSON texts that also parse as valid
		867	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
		869	keys are noticeably shorter than the 1024 characters YAML allows.
		870
		871	There might be other incompatibilities that I am not aware of. In general
		872	you should not try to generate YAML with a JSON generator or vice versa,
		873	or try to parse JSON with a YAML parser or vice versa: chances are high
		874	that you will run into severe interoperability problems.
		875
327		876
328	=head2 SPEED	877	=head2 SPEED
329		878
330	It seems that JSON::XS is surprisingly fast, as shown in the following	879	It seems that JSON::XS is surprisingly fast, as shown in the following
331	tables. They have been generated with the help of the C<eg/bench> program	880	tables. They have been generated with the help of the C<eg/bench> program
332	in the JSON::XS distribution, to make it easy to compare on your own	881	in the JSON::XS distribution, to make it easy to compare on your own
333	system.	882	system.
334		883
335	First is a comparison between various modules using a very simple JSON	884	First comes a comparison between various modules using a very short
		885	single-line JSON string:
		886
		887	{"method": "handleMessage", "params": ["user1", "we were just talking"], \
		888	"id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
		889
336	string, showing the number of encodes/decodes per second (JSON::XS is	890	It shows the number of encodes/decodes per second (JSON::XS uses
337	the functional interface, while JSON::XS/2 is the OO interface with	891	the functional interface, while JSON::XS/2 uses the OO interface
338	pretty-printing and hashkey sorting enabled).	892	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
		893	shrink). Higher is better:
339		894
		895	Storable \| 15779.925 \| 14169.946 \|
		896	-----------+------------+------------+
340	module \| encode \| decode \|	897	module \| encode \| decode \|
341	-----------\|------------\|------------\|	898	-----------\|------------\|------------\|
342	JSON \| 14006 \| 6820 \|	899	JSON \| 4990.842 \| 4088.813 \|
343	JSON::DWIW \| 200937 \| 120386 \|	900	JSON::DWIW \| 51653.990 \| 71575.154 \|
344	JSON::PC \| 85065 \| 129366 \|	901	JSON::PC \| 65948.176 \| 74631.744 \|
345	JSON::Syck \| 59898 \| 44232 \|	902	JSON::PP \| 8931.652 \| 3817.168 \|
346	JSON::XS \| 1171478 \| 342435 \|	903	JSON::Syck \| 24877.248 \| 27776.848 \|
347	JSON::XS/2 \| 730760 \| 328714 \|	904	JSON::XS \| 388361.481 \| 227951.304 \|
		905	JSON::XS/2 \| 227951.304 \| 218453.333 \|
		906	JSON::XS/3 \| 338250.323 \| 218453.333 \|
		907	Storable \| 16500.016 \| 135300.129 \|
348	-----------+------------+------------+	908	-----------+------------+------------+
349		909
350	That is, JSON::XS is 6 times faster than than JSON::DWIW and about 80	910	That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
		911	about three times faster on decoding, and over forty times faster
351	times faster than JSON, even with pretty-printing and key sorting.	912	than JSON, even with pretty-printing and key sorting. It also compares
		913	favourably to Storable for small amounts of data.
352		914
353	Using a longer test string (roughly 8KB, generated from Yahoo! Locals	915	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
354	search API (http://nanoref.com/yahooapis/mgPdGg):	916	search API (http://nanoref.com/yahooapis/mgPdGg):
355		917
356	module \| encode \| decode \|	918	module \| encode \| decode \|
357	-----------\|------------\|------------\|	919	-----------\|------------\|------------\|
358	JSON \| 673 \| 38 \|	920	JSON \| 55.260 \| 34.971 \|
359	JSON::DWIW \| 5271 \| 770 \|	921	JSON::DWIW \| 825.228 \| 1082.513 \|
360	JSON::PC \| 9901 \| 2491 \|	922	JSON::PC \| 3571.444 \| 2394.829 \|
361	JSON::Syck \| 2360 \| 786 \|	923	JSON::PP \| 210.987 \| 32.574 \|
362	JSON::XS \| 37398 \| 3202 \|	924	JSON::Syck \| 552.551 \| 787.544 \|
363	JSON::XS/2 \| 13765 \| 3153 \|	925	JSON::XS \| 5780.463 \| 4854.519 \|
		926	JSON::XS/2 \| 3869.998 \| 4798.975 \|
		927	JSON::XS/3 \| 5862.880 \| 4798.975 \|
		928	Storable \| 4445.002 \| 5235.027 \|
364	-----------+------------+------------+	929	-----------+------------+------------+
365		930
366	Again, JSON::XS leads by far in the encoding case, while still beating	931	Again, JSON::XS leads by far (except for Storable which non-surprisingly
367	every other module in the decoding case.	932	decodes faster).
368		933
369	Last example is an almost 8MB large hash with many large binary values	934	On large strings containing lots of high Unicode characters, some modules
370	(PNG files), resulting in a lot of escaping:	935	(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
		937	to decode or encode properly, so it was impossible to prepare a fair
		938	comparison table for that case.
		939
		940
		941	=head1 SECURITY CONSIDERATIONS
		942
		943	When you are using JSON in a protocol, talking to untrusted potentially
		944	hostile creatures requires relatively few measures.
		945
		946	First of all, your JSON decoder should be secure, that is, should not have
		947	any buffer overflows. Obviously, this module should ensure that and I am
		948	trying hard on making that true, but you never know.
		949
		950	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
		952	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
		954	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
		956	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.
		958
		959	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
		961	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
		963	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
		965	has a smaller stack, you should adjust this setting accordingly with the
		966	C<max_depth> method.
		967
		968	And last but least, something else could bomb you that I forgot to think
		969	of. In that case, you get to keep the pieces. I am always open for hints,
		970	though...
		971
		972	If you are using JSON::XS to return packets to consumption
		973	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 whether
		975	you are vulnerable to some common attack vectors (which really are browser
		976	design bugs, but it is still you who will have to deal with it, as major
		977	browser developers care only for features, not about doing security
		978	right).
		979
		980
		981	=head1 THREADS
		982
		983	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
		985	horribly slow so-called "threads" which are simply slow and bloated
		986	process simulations - use fork, its I<much> faster, cheaper, better).
		987
		988	(It might actually work, but you have been warned).
		989
371		990
372	=head1 BUGS	991	=head1 BUGS
373		992
374	While the goal of this module is to be correct, that unfortunately does	993	While the goal of this module is to be correct, that unfortunately does
375	not mean its bug-free, only that I think its design is bug-free. It is	994	not mean its bug-free, only that I think its design is bug-free. It is
376	still very young and not well-tested. If you keep reporting bugs they will	995	still relatively early in its development. If you keep reporting bugs they
377	be fixed swiftly, though.	996	will be fixed swiftly, though.
		997
		998	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.
378		1000
379	=cut	1001	=cut
		1002
		1003	our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
		1004	our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };
		1005
		1006	sub true() { $true }
		1007	sub false() { $false }
		1008
		1009	sub is_bool($) {
		1010	UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
		1011	# or UNIVERSAL::isa $_[0], "JSON::Literal"
		1012	}
		1013
		1014	XSLoader::load "JSON::XS", $VERSION;
		1015
		1016	package JSON::XS::Boolean;
		1017
		1018	use overload
		1019	"0+" => sub { ${$_[0]} },
		1020	"++" => sub { $_[0] = ${$_[0]} + 1 },
		1021	"--" => sub { $_[0] = ${$_[0]} - 1 },
		1022	fallback => 1;
380		1023
381	1;	1024	1;
382		1025
383	=head1 AUTHOR	1026	=head1 AUTHOR
384		1027

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Comparing JSON-XS/XS.pm (file contents): Revision 1.5 by root, Thu Mar 22 21:36:52 2007 UTC vs. Revision 1.68 by root, Tue Oct 23 03:30:02 2007 UTC

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Comparing JSON-XS/XS.pm (file contents):
Revision 1.5 by root, Thu Mar 22 21:36:52 2007 UTC vs.
Revision 1.68 by root, Tue Oct 23 03:30:02 2007 UTC