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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.20 by root, Sun Mar 25 00:47:42 2007 UTC vs.
Revision 1.75 by root, Thu Nov 29 13:35:35 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;
8		11
9	# exported functions, croak on error	12	# exported functions, they croak on error
		13	# and expect/generate UTF-8
10		14
11	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;	15	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;
12	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;	16	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;
13		17
14	# oo-interface	18	# OO-interface
15		19
16	$coder = JSON::XS->new->ascii->pretty->allow_nonref;	20	$coder = JSON::XS->new->ascii->pretty->allow_nonref;
17	$pretty_printed_unencoded = $coder->encode ($perl_scalar);	21	$pretty_printed_unencoded = $coder->encode ($perl_scalar);
18	$perl_scalar = $coder->decode ($unicode_json_text);	22	$perl_scalar = $coder->decode ($unicode_json_text);
19		23
36		40
37	=head2 FEATURES	41	=head2 FEATURES
38		42
39	=over 4	43	=over 4
40		44
41	=item * correct handling of unicode issues	45	=item * correct Unicode handling
42		46
43	This module knows how to handle Unicode, and even documents how and when	47	This module knows how to handle Unicode, and even documents how and when
44	it does so.	48	it does so.
45		49
46	=item * round-trip integrity	50	=item * round-trip integrity
47		51
48	When you serialise a perl data structure using only datatypes supported	52	When you serialise a perl data structure using only datatypes supported
49	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.
50	(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).
51		56
52	=item * strict checking of JSON correctness	57	=item * strict checking of JSON correctness
53		58
54	There is no guessing, no generating of illegal JSON texts by default,	59	There is no guessing, no generating of illegal JSON texts by default,
55	and only JSON is accepted as input by default (the latter is a security	60	and only JSON is accepted as input by default (the latter is a security
…		…
65	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
66	interface.	71	interface.
67		72
68	=item * reasonably versatile output formats	73	=item * reasonably versatile output formats
69		74
70	You can choose between the most compact guarenteed single-line format	75	You can choose between the most compact guaranteed single-line format
71	possible (nice for simple line-based protocols), a pure-ascii format (for	76	possible (nice for simple line-based protocols), a pure-ascii format
72	when your transport is not 8-bit clean), or a pretty-printed format (for	77	(for when your transport is not 8-bit clean, still supports the whole
73	when you want to read that stuff). Or you can combine those features in	78	Unicode range), or a pretty-printed format (for when you want to read that
74	whatever way you like.	79	stuff). Or you can combine those features in whatever way you like.
75		80
76	=back	81	=back
77		82
78	=cut	83	=cut
79		84
80	package JSON::XS;	85	package JSON::XS;
81		86
82	use strict;	87	use strict;
83		88
84	BEGIN {
85	our $VERSION = '0.7';	89	our $VERSION = '2.0';
86	our @ISA = qw(Exporter);	90	our @ISA = qw(Exporter);
87		91
88	our @EXPORT = qw(to_json from_json);	92	our @EXPORT = qw(to_json from_json);
89	require Exporter;
90		93
91	require XSLoader;	94	use Exporter;
92	XSLoader::load JSON::XS::, $VERSION;	95	use XSLoader;
93	}
94		96
95	=head1 FUNCTIONAL INTERFACE	97	=head1 FUNCTIONAL INTERFACE
96		98
97	The following convinience methods are provided by this module. They are	99	The following convenience methods are provided by this module. They are
98	exported by default:	100	exported by default:
99		101
100	=over 4	102	=over 4
101		103
102	=item $json_text = to_json $perl_scalar	104	=item $json_text = to_json $perl_scalar
103		105
104	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
105	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.
106	octets only). Croaks on error.
107		108
108	This function call is functionally identical to:	109	This function call is functionally identical to:
109		110
110	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)	111	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)
111		112
112	except being faster.	113	except being faster.
113		114
114	=item $perl_scalar = from_json $json_text	115	=item $perl_scalar = from_json $json_text
115		116
116	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
117	parse that as an UTF-8 encoded JSON text, returning the resulting simple	118	to parse that as an UTF-8 encoded JSON text, returning the resulting
118	scalar or reference. Croaks on error.	119	reference. Croaks on error.
119		120
120	This function call is functionally identical to:	121	This function call is functionally identical to:
121		122
122	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)	123	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
123		124
124	except being faster.	125	except being faster.
125		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.
		135
126	=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
127		186
128	=head1 OBJECT-ORIENTED INTERFACE	187	=head1 OBJECT-ORIENTED INTERFACE
129		188
130	The object oriented interface lets you configure your own encoding or	189	The object oriented interface lets you configure your own encoding or
131	decoding style, within the limits of supported formats.	190	decoding style, within the limits of supported formats.
…		…
143	my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})	202	my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})
144	=> {"a": [1, 2]}	203	=> {"a": [1, 2]}
145		204
146	=item $json = $json->ascii ([$enable])	205	=item $json = $json->ascii ([$enable])
147		206
		207	=item $enabled = $json->get_ascii
		208
148	If C<$enable> is true (or missing), then the C<encode> method will not	209	If C<$enable> is true (or missing), then the C<encode> method will not
149	generate characters outside the code range C<0..127> (which is ASCII). Any	210	generate characters outside the code range C<0..127> (which is ASCII). Any
150	unicode characters outside that range will be escaped using either a	211	Unicode characters outside that range will be escaped using either a
151	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,	212	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
152	as per RFC4627.	213	as per RFC4627. The resulting encoded JSON text can be treated as a native
		214	Unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
		215	or any other superset of ASCII.
153		216
154	If C<$enable> is false, then the C<encode> method will not escape Unicode	217	If C<$enable> is false, then the C<encode> method will not escape Unicode
155	characters unless required by the JSON syntax. This results in a faster	218	characters unless required by the JSON syntax or other flags. This results
156	and more compact format.	219	in a faster and more compact format.
		220
		221	The main use for this flag is to produce JSON texts that can be
		222	transmitted over a 7-bit channel, as the encoded JSON texts will not
		223	contain any 8 bit characters.
157		224
158	JSON::XS->new->ascii (1)->encode ([chr 0x10401])	225	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
159	=> ["\ud801\udc01"]	226	=> ["\ud801\udc01"]
160		227
		228	=item $json = $json->latin1 ([$enable])
		229
		230	=item $enabled = $json->get_latin1
		231
		232	If C<$enable> is true (or missing), then the C<encode> method will encode
		233	the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
		234	outside the code range C<0..255>. The resulting string can be treated as a
		235	latin1-encoded JSON text or a native Unicode string. The C<decode> method
		236	will not be affected in any way by this flag, as C<decode> by default
		237	expects Unicode, which is a strict superset of latin1.
		238
		239	If C<$enable> is false, then the C<encode> method will not escape Unicode
		240	characters unless required by the JSON syntax or other flags.
		241
		242	The main use for this flag is efficiently encoding binary data as JSON
		243	text, as most octets will not be escaped, resulting in a smaller encoded
		244	size. The disadvantage is that the resulting JSON text is encoded
		245	in latin1 (and must correctly be treated as such when storing and
		246	transferring), a rare encoding for JSON. It is therefore most useful when
		247	you want to store data structures known to contain binary data efficiently
		248	in files or databases, not when talking to other JSON encoders/decoders.
		249
		250	JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
		251	=> ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
		252
161	=item $json = $json->utf8 ([$enable])	253	=item $json = $json->utf8 ([$enable])
		254
		255	=item $enabled = $json->get_utf8
162		256
163	If C<$enable> is true (or missing), then the C<encode> method will encode	257	If C<$enable> is true (or missing), then the C<encode> method will encode
164	the JSON result into UTF-8, as required by many protocols, while the	258	the JSON result into UTF-8, as required by many protocols, while the
165	C<decode> method expects to be handled an UTF-8-encoded string. Please	259	C<decode> method expects to be handled an UTF-8-encoded string. Please
166	note that UTF-8-encoded strings do not contain any characters outside the	260	note that UTF-8-encoded strings do not contain any characters outside the
167	range C<0..255>, they are thus useful for bytewise/binary I/O. In future	261	range C<0..255>, they are thus useful for bytewise/binary I/O. In future
168	versions, enabling this option might enable autodetection of the UTF-16	262	versions, enabling this option might enable autodetection of the UTF-16
169	and UTF-32 encoding families, as described in RFC4627.	263	and UTF-32 encoding families, as described in RFC4627.
170		264
171	If C<$enable> is false, then the C<encode> method will return the JSON	265	If C<$enable> is false, then the C<encode> method will return the JSON
172	string as a (non-encoded) unicode string, while C<decode> expects thus a	266	string as a (non-encoded) Unicode string, while C<decode> expects thus a
173	unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs	267	Unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs
174	to be done yourself, e.g. using the Encode module.	268	to be done yourself, e.g. using the Encode module.
175		269
176	Example, output UTF-16BE-encoded JSON:	270	Example, output UTF-16BE-encoded JSON:
177		271
178	use Encode;	272	use Encode;
…		…
200	]	294	]
201	}	295	}
202		296
203	=item $json = $json->indent ([$enable])	297	=item $json = $json->indent ([$enable])
204		298
		299	=item $enabled = $json->get_indent
		300
205	If C<$enable> is true (or missing), then the C<encode> method will use a multiline	301	If C<$enable> is true (or missing), then the C<encode> method will use a multiline
206	format as output, putting every array member or object/hash key-value pair	302	format as output, putting every array member or object/hash key-value pair
207	into its own line, identing them properly.	303	into its own line, indenting them properly.
208		304
209	If C<$enable> is false, no newlines or indenting will be produced, and the	305	If C<$enable> is false, no newlines or indenting will be produced, and the
210	resulting JSON text is guarenteed not to contain any C<newlines>.	306	resulting JSON text is guaranteed not to contain any C<newlines>.
211		307
212	This setting has no effect when decoding JSON texts.	308	This setting has no effect when decoding JSON texts.
213		309
214	=item $json = $json->space_before ([$enable])	310	=item $json = $json->space_before ([$enable])
		311
		312	=item $enabled = $json->get_space_before
215		313
216	If C<$enable> is true (or missing), then the C<encode> method will add an extra	314	If C<$enable> is true (or missing), then the C<encode> method will add an extra
217	optional space before the C<:> separating keys from values in JSON objects.	315	optional space before the C<:> separating keys from values in JSON objects.
218		316
219	If C<$enable> is false, then the C<encode> method will not add any extra	317	If C<$enable> is false, then the C<encode> method will not add any extra
…		…
225	Example, space_before enabled, space_after and indent disabled:	323	Example, space_before enabled, space_after and indent disabled:
226		324
227	{"key" :"value"}	325	{"key" :"value"}
228		326
229	=item $json = $json->space_after ([$enable])	327	=item $json = $json->space_after ([$enable])
		328
		329	=item $enabled = $json->get_space_after
230		330
231	If C<$enable> is true (or missing), then the C<encode> method will add an extra	331	If C<$enable> is true (or missing), then the C<encode> method will add an extra
232	optional space after the C<:> separating keys from values in JSON objects	332	optional space after the C<:> separating keys from values in JSON objects
233	and extra whitespace after the C<,> separating key-value pairs and array	333	and extra whitespace after the C<,> separating key-value pairs and array
234	members.	334	members.
…		…
240		340
241	Example, space_before and indent disabled, space_after enabled:	341	Example, space_before and indent disabled, space_after enabled:
242		342
243	{"key": "value"}	343	{"key": "value"}
244		344
		345	=item $json = $json->relaxed ([$enable])
		346
		347	=item $enabled = $json->get_relaxed
		348
		349	If C<$enable> is true (or missing), then C<decode> will accept some
		350	extensions to normal JSON syntax (see below). C<encode> will not be
		351	affected in anyway. I<Be aware that this option makes you accept invalid
		352	JSON texts as if they were valid!>. I suggest only to use this option to
		353	parse application-specific files written by humans (configuration files,
		354	resource files etc.)
		355
		356	If C<$enable> is false (the default), then C<decode> will only accept
		357	valid JSON texts.
		358
		359	Currently accepted extensions are:
		360
		361	=over 4
		362
		363	=item * list items can have an end-comma
		364
		365	JSON I<separates> array elements and key-value pairs with commas. This
		366	can be annoying if you write JSON texts manually and want to be able to
		367	quickly append elements, so this extension accepts comma at the end of
		368	such items not just between them:
		369
		370	[
		371	1,
		372	2, <- this comma not normally allowed
		373	]
		374	{
		375	"k1": "v1",
		376	"k2": "v2", <- this comma not normally allowed
		377	}
		378
		379	=item * shell-style '#'-comments
		380
		381	Whenever JSON allows whitespace, shell-style comments are additionally
		382	allowed. They are terminated by the first carriage-return or line-feed
		383	character, after which more white-space and comments are allowed.
		384
		385	[
		386	1, # this comment not allowed in JSON
		387	# neither this one...
		388	]
		389
		390	=back
		391
245	=item $json = $json->canonical ([$enable])	392	=item $json = $json->canonical ([$enable])
		393
		394	=item $enabled = $json->get_canonical
246		395
247	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects	396	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
248	by sorting their keys. This is adding a comparatively high overhead.	397	by sorting their keys. This is adding a comparatively high overhead.
249		398
250	If C<$enable> is false, then the C<encode> method will output key-value	399	If C<$enable> is false, then the C<encode> method will output key-value
251	pairs in the order Perl stores them (which will likely change between runs	400	pairs in the order Perl stores them (which will likely change between runs
252	of the same script).	401	of the same script).
253		402
254	This option is useful if you want the same data structure to be encoded as	403	This option is useful if you want the same data structure to be encoded as
255	the same JSON text (given the same overall settings). If it is disabled,	404	the same JSON text (given the same overall settings). If it is disabled,
256	the same hash migh be encoded differently even if contains the same data,	405	the same hash might be encoded differently even if contains the same data,
257	as key-value pairs have no inherent ordering in Perl.	406	as key-value pairs have no inherent ordering in Perl.
258		407
259	This setting has no effect when decoding JSON texts.	408	This setting has no effect when decoding JSON texts.
260		409
261	=item $json = $json->allow_nonref ([$enable])	410	=item $json = $json->allow_nonref ([$enable])
		411
		412	=item $enabled = $json->get_allow_nonref
262		413
263	If C<$enable> is true (or missing), then the C<encode> method can convert a	414	If C<$enable> is true (or missing), then the C<encode> method can convert a
264	non-reference into its corresponding string, number or null JSON value,	415	non-reference into its corresponding string, number or null JSON value,
265	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON	416	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
266	values instead of croaking.	417	values instead of croaking.
…		…
274	resulting in an invalid JSON text:	425	resulting in an invalid JSON text:
275		426
276	JSON::XS->new->allow_nonref->encode ("Hello, World!")	427	JSON::XS->new->allow_nonref->encode ("Hello, World!")
277	=> "Hello, World!"	428	=> "Hello, World!"
278		429
		430	=item $json = $json->allow_blessed ([$enable])
		431
		432	=item $enabled = $json->get_allow_blessed
		433
		434	If C<$enable> is true (or missing), then the C<encode> method will not
		435	barf when it encounters a blessed reference. Instead, the value of the
		436	B<convert_blessed> option will decide whether C<null> (C<convert_blessed>
		437	disabled or no C<to_json> method found) or a representation of the
		438	object (C<convert_blessed> enabled and C<to_json> method found) is being
		439	encoded. Has no effect on C<decode>.
		440
		441	If C<$enable> is false (the default), then C<encode> will throw an
		442	exception when it encounters a blessed object.
		443
		444	=item $json = $json->convert_blessed ([$enable])
		445
		446	=item $enabled = $json->get_convert_blessed
		447
		448	If C<$enable> is true (or missing), then C<encode>, upon encountering a
		449	blessed object, will check for the availability of the C<TO_JSON> method
		450	on the object's class. If found, it will be called in scalar context
		451	and the resulting scalar will be encoded instead of the object. If no
		452	C<TO_JSON> method is found, the value of C<allow_blessed> will decide what
		453	to do.
		454
		455	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
		456	returns other blessed objects, those will be handled in the same
		457	way. C<TO_JSON> must take care of not causing an endless recursion cycle
		458	(== crash) in this case. The name of C<TO_JSON> was chosen because other
		459	methods called by the Perl core (== not by the user of the object) are
		460	usually in upper case letters and to avoid collisions with the C<to_json>
		461	function.
		462
		463	This setting does not yet influence C<decode> in any way, but in the
		464	future, global hooks might get installed that influence C<decode> and are
		465	enabled by this setting.
		466
		467	If C<$enable> is false, then the C<allow_blessed> setting will decide what
		468	to do when a blessed object is found.
		469
		470	=item $json = $json->filter_json_object ([$coderef->($hashref)])
		471
		472	When C<$coderef> is specified, it will be called from C<decode> each
		473	time it decodes a JSON object. The only argument is a reference to the
		474	newly-created hash. If the code references returns a single scalar (which
		475	need not be a reference), this value (i.e. a copy of that scalar to avoid
		476	aliasing) is inserted into the deserialised data structure. If it returns
		477	an empty list (NOTE: I<not> C<undef>, which is a valid scalar), the
		478	original deserialised hash will be inserted. This setting can slow down
		479	decoding considerably.
		480
		481	When C<$coderef> is omitted or undefined, any existing callback will
		482	be removed and C<decode> will not change the deserialised hash in any
		483	way.
		484
		485	Example, convert all JSON objects into the integer 5:
		486
		487	my $js = JSON::XS->new->filter_json_object (sub { 5 });
		488	# returns [5]
		489	$js->decode ('[{}]')
		490	# throw an exception because allow_nonref is not enabled
		491	# so a lone 5 is not allowed.
		492	$js->decode ('{"a":1, "b":2}');
		493
		494	=item $json = $json->filter_json_single_key_object ($key [=> $coderef->($value)])
		495
		496	Works remotely similar to C<filter_json_object>, but is only called for
		497	JSON objects having a single key named C<$key>.
		498
		499	This C<$coderef> is called before the one specified via
		500	C<filter_json_object>, if any. It gets passed the single value in the JSON
		501	object. If it returns a single value, it will be inserted into the data
		502	structure. If it returns nothing (not even C<undef> but the empty list),
		503	the callback from C<filter_json_object> will be called next, as if no
		504	single-key callback were specified.
		505
		506	If C<$coderef> is omitted or undefined, the corresponding callback will be
		507	disabled. There can only ever be one callback for a given key.
		508
		509	As this callback gets called less often then the C<filter_json_object>
		510	one, decoding speed will not usually suffer as much. Therefore, single-key
		511	objects make excellent targets to serialise Perl objects into, especially
		512	as single-key JSON objects are as close to the type-tagged value concept
		513	as JSON gets (it's basically an ID/VALUE tuple). Of course, JSON does not
		514	support this in any way, so you need to make sure your data never looks
		515	like a serialised Perl hash.
		516
		517	Typical names for the single object key are C<__class_whatever__>, or
		518	C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even
		519	things like C<__class_md5sum(classname)__>, to reduce the risk of clashing
		520	with real hashes.
		521
		522	Example, decode JSON objects of the form C<< { "__widget__" => <id> } >>
		523	into the corresponding C<< $WIDGET{<id>} >> object:
		524
		525	# return whatever is in $WIDGET{5}:
		526	JSON::XS
		527	->new
		528	->filter_json_single_key_object (__widget__ => sub {
		529	$WIDGET{ $_[0] }
		530	})
		531	->decode ('{"__widget__": 5')
		532
		533	# this can be used with a TO_JSON method in some "widget" class
		534	# for serialisation to json:
		535	sub WidgetBase::TO_JSON {
		536	my ($self) = @_;
		537
		538	unless ($self->{id}) {
		539	$self->{id} = ..get..some..id..;
		540	$WIDGET{$self->{id}} = $self;
		541	}
		542
		543	{ __widget__ => $self->{id} }
		544	}
		545
279	=item $json = $json->shrink ([$enable])	546	=item $json = $json->shrink ([$enable])
280		547
		548	=item $enabled = $json->get_shrink
		549
281	Perl usually over-allocates memory a bit when allocating space for	550	Perl usually over-allocates memory a bit when allocating space for
282	strings. This flag optionally resizes strings generated by either	551	strings. This flag optionally resizes strings generated by either
283	C<encode> or C<decode> to their minimum size possible. This can save	552	C<encode> or C<decode> to their minimum size possible. This can save
284	memory when your JSON texts are either very very long or you have many	553	memory when your JSON texts are either very very long or you have many
285	short strings. It will also try to downgrade any strings to octet-form	554	short strings. It will also try to downgrade any strings to octet-form
286	if possible: perl stores strings internally either in an encoding called	555	if possible: perl stores strings internally either in an encoding called
287	UTF-X or in octet-form. The latter cannot store everything but uses less	556	UTF-X or in octet-form. The latter cannot store everything but uses less
288	space in general.	557	space in general (and some buggy Perl or C code might even rely on that
		558	internal representation being used).
289		559
		560	The actual definition of what shrink does might change in future versions,
		561	but it will always try to save space at the expense of time.
		562
290	If C<$enable> is true (or missing), the string returned by C<encode> will be shrunk-to-fit,	563	If C<$enable> is true (or missing), the string returned by C<encode> will
291	while all strings generated by C<decode> will also be shrunk-to-fit.	564	be shrunk-to-fit, while all strings generated by C<decode> will also be
		565	shrunk-to-fit.
292		566
293	If C<$enable> is false, then the normal perl allocation algorithms are used.	567	If C<$enable> is false, then the normal perl allocation algorithms are used.
294	If you work with your data, then this is likely to be faster.	568	If you work with your data, then this is likely to be faster.
295		569
296	In the future, this setting might control other things, such as converting	570	In the future, this setting might control other things, such as converting
297	strings that look like integers or floats into integers or floats	571	strings that look like integers or floats into integers or floats
298	internally (there is no difference on the Perl level), saving space.	572	internally (there is no difference on the Perl level), saving space.
		573
		574	=item $json = $json->max_depth ([$maximum_nesting_depth])
		575
		576	=item $max_depth = $json->get_max_depth
		577
		578	Sets the maximum nesting level (default C<512>) accepted while encoding
		579	or decoding. If the JSON text or Perl data structure has an equal or
		580	higher nesting level then this limit, then the encoder and decoder will
		581	stop and croak at that point.
		582
		583	Nesting level is defined by number of hash- or arrayrefs that the encoder
		584	needs to traverse to reach a given point or the number of C<{> or C<[>
		585	characters without their matching closing parenthesis crossed to reach a
		586	given character in a string.
		587
		588	Setting the maximum depth to one disallows any nesting, so that ensures
		589	that the object is only a single hash/object or array.
		590
		591	The argument to C<max_depth> will be rounded up to the next highest power
		592	of two. If no argument is given, the highest possible setting will be
		593	used, which is rarely useful.
		594
		595	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
		596
		597	=item $json = $json->max_size ([$maximum_string_size])
		598
		599	=item $max_size = $json->get_max_size
		600
		601	Set the maximum length a JSON text may have (in bytes) where decoding is
		602	being attempted. The default is C<0>, meaning no limit. When C<decode>
		603	is called on a string longer then this number of characters it will not
		604	attempt to decode the string but throw an exception. This setting has no
		605	effect on C<encode> (yet).
		606
		607	The argument to C<max_size> will be rounded up to the next B<highest>
		608	power of two (so may be more than requested). If no argument is given, the
		609	limit check will be deactivated (same as when C<0> is specified).
		610
		611	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
299		612
300	=item $json_text = $json->encode ($perl_scalar)	613	=item $json_text = $json->encode ($perl_scalar)
301		614
302	Converts the given Perl data structure (a simple scalar or a reference	615	Converts the given Perl data structure (a simple scalar or a reference
303	to a hash or array) to its JSON representation. Simple scalars will be	616	to a hash or array) to its JSON representation. Simple scalars will be
…		…
313		626
314	JSON numbers and strings become simple Perl scalars. JSON arrays become	627	JSON numbers and strings become simple Perl scalars. JSON arrays become
315	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes	628	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
316	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.	629	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
317		630
		631	=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
		632
		633	This works like the C<decode> method, but instead of raising an exception
		634	when there is trailing garbage after the first JSON object, it will
		635	silently stop parsing there and return the number of characters consumed
		636	so far.
		637
		638	This is useful if your JSON texts are not delimited by an outer protocol
		639	(which is not the brightest thing to do in the first place) and you need
		640	to know where the JSON text ends.
		641
		642	JSON::XS->new->decode_prefix ("[1] the tail")
		643	=> ([], 3)
		644
318	=back	645	=back
		646
319		647
320	=head1 MAPPING	648	=head1 MAPPING
321		649
322	This section describes how JSON::XS maps Perl values to JSON values and	650	This section describes how JSON::XS maps Perl values to JSON values and
323	vice versa. These mappings are designed to "do the right thing" in most	651	vice versa. These mappings are designed to "do the right thing" in most
324	circumstances automatically, preserving round-tripping characteristics	652	circumstances automatically, preserving round-tripping characteristics
325	(what you put in comes out as something equivalent).	653	(what you put in comes out as something equivalent).
326		654
327	For the more enlightened: note that in the following descriptions,	655	For the more enlightened: note that in the following descriptions,
328	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>	656	lowercase I<perl> refers to the Perl interpreter, while uppercase I<Perl>
329	refers to the abstract Perl language itself.	657	refers to the abstract Perl language itself.
330		658
		659
331	=head2 JSON -> PERL	660	=head2 JSON -> PERL
332		661
333	=over 4	662	=over 4
334		663
335	=item object	664	=item object
336		665
337	A JSON object becomes a reference to a hash in Perl. No ordering of object	666	A JSON object becomes a reference to a hash in Perl. No ordering of object
338	keys is preserved (JSON does not preserver object key ordering itself).	667	keys is preserved (JSON does not preserve object key ordering itself).
339		668
340	=item array	669	=item array
341		670
342	A JSON array becomes a reference to an array in Perl.	671	A JSON array becomes a reference to an array in Perl.
343		672
…		…
347	are represented by the same codepoints in the Perl string, so no manual	676	are represented by the same codepoints in the Perl string, so no manual
348	decoding is necessary.	677	decoding is necessary.
349		678
350	=item number	679	=item number
351		680
352	A JSON number becomes either an integer or numeric (floating point)	681	A JSON number becomes either an integer, numeric (floating point) or
353	scalar in perl, depending on its range and any fractional parts. On the	682	string scalar in perl, depending on its range and any fractional parts. On
354	Perl level, there is no difference between those as Perl handles all the	683	the Perl level, there is no difference between those as Perl handles all
355	conversion details, but an integer may take slightly less memory and might	684	the conversion details, but an integer may take slightly less memory and
356	represent more values exactly than (floating point) numbers.	685	might represent more values exactly than (floating point) numbers.
		686
		687	If the number consists of digits only, JSON::XS will try to represent
		688	it as an integer value. If that fails, it will try to represent it as
		689	a numeric (floating point) value if that is possible without loss of
		690	precision. Otherwise it will preserve the number as a string value.
		691
		692	Numbers containing a fractional or exponential part will always be
		693	represented as numeric (floating point) values, possibly at a loss of
		694	precision.
		695
		696	This might create round-tripping problems as numbers might become strings,
		697	but as Perl is typeless there is no other way to do it.
357		698
358	=item true, false	699	=item true, false
359		700
360	These JSON atoms become C<0>, C<1>, respectively. Information is lost in	701	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
361	this process. Future versions might represent those values differently,	702	respectively. They are overloaded to act almost exactly like the numbers
362	but they will be guarenteed to act like these integers would normally in	703	C<1> and C<0>. You can check whether a scalar is a JSON boolean by using
363	Perl.	704	the C<JSON::XS::is_bool> function.
364		705
365	=item null	706	=item null
366		707
367	A JSON null atom becomes C<undef> in Perl.	708	A JSON null atom becomes C<undef> in Perl.
368		709
369	=back	710	=back
		711
370		712
371	=head2 PERL -> JSON	713	=head2 PERL -> JSON
372		714
373	The mapping from Perl to JSON is slightly more difficult, as Perl is a	715	The mapping from Perl to JSON is slightly more difficult, as Perl is a
374	truly typeless language, so we can only guess which JSON type is meant by	716	truly typeless language, so we can only guess which JSON type is meant by
…		…
377	=over 4	719	=over 4
378		720
379	=item hash references	721	=item hash references
380		722
381	Perl hash references become JSON objects. As there is no inherent ordering	723	Perl hash references become JSON objects. As there is no inherent ordering
382	in hash keys, they will usually be encoded in a pseudo-random order that	724	in hash keys (or JSON objects), they will usually be encoded in a
383	can change between runs of the same program but stays generally the same	725	pseudo-random order that can change between runs of the same program but
384	within a single run of a program. JSON::XS can optionally sort the hash	726	stays generally the same within a single run of a program. JSON::XS can
385	keys (determined by the I<canonical> flag), so the same datastructure	727	optionally sort the hash keys (determined by the I<canonical> flag), so
386	will serialise to the same JSON text (given same settings and version of	728	the same datastructure will serialise to the same JSON text (given same
387	JSON::XS), but this incurs a runtime overhead.	729	settings and version of JSON::XS), but this incurs a runtime overhead
		730	and is only rarely useful, e.g. when you want to compare some JSON text
		731	against another for equality.
388		732
389	=item array references	733	=item array references
390		734
391	Perl array references become JSON arrays.	735	Perl array references become JSON arrays.
		736
		737	=item other references
		738
		739	Other unblessed references are generally not allowed and will cause an
		740	exception to be thrown, except for references to the integers C<0> and
		741	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
		742	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
		743
		744	to_json [\0,JSON::XS::true] # yields [false,true]
		745
		746	=item JSON::XS::true, JSON::XS::false
		747
		748	These special values become JSON true and JSON false values,
		749	respectively. You can also use C<\1> and C<\0> directly if you want.
392		750
393	=item blessed objects	751	=item blessed objects
394		752
395	Blessed objects are not allowed. JSON::XS currently tries to encode their	753	Blessed objects are not allowed. JSON::XS currently tries to encode their
396	underlying representation (hash- or arrayref), but this behaviour might	754	underlying representation (hash- or arrayref), but this behaviour might
…		…
413	to_json [$value] # yields ["5"]	771	to_json [$value] # yields ["5"]
414		772
415	# undef becomes null	773	# undef becomes null
416	to_json [undef] # yields [null]	774	to_json [undef] # yields [null]
417		775
418	You can force the type to be a string by stringifying it:	776	You can force the type to be a JSON string by stringifying it:
419		777
420	my $x = 3.1; # some variable containing a number	778	my $x = 3.1; # some variable containing a number
421	"$x"; # stringified	779	"$x"; # stringified
422	$x .= ""; # another, more awkward way to stringify	780	$x .= ""; # another, more awkward way to stringify
423	print $x; # perl does it for you, too, quite often	781	print $x; # perl does it for you, too, quite often
424		782
425	You can force the type to be a number by numifying it:	783	You can force the type to be a JSON number by numifying it:
426		784
427	my $x = "3"; # some variable containing a string	785	my $x = "3"; # some variable containing a string
428	$x += 0; # numify it, ensuring it will be dumped as a number	786	$x += 0; # numify it, ensuring it will be dumped as a number
429	$x *= 1; # same thing, the choise is yours.	787	$x *= 1; # same thing, the choice is yours.
430		788
431	You can not currently output JSON booleans or force the type in other,	789	You can not currently force the type in other, less obscure, ways. Tell me
432	less obscure, ways. Tell me if you need this capability.	790	if you need this capability.
433
434	=item circular data structures
435
436	Those will be encoded until memory or stackspace runs out.
437		791
438	=back	792	=back
		793
439		794
440	=head1 COMPARISON	795	=head1 COMPARISON
441		796
442	As already mentioned, this module was created because none of the existing	797	As already mentioned, this module was created because none of the existing
443	JSON modules could be made to work correctly. First I will describe the	798	JSON modules could be made to work correctly. First I will describe the
…		…
449		804
450	=item JSON 1.07	805	=item JSON 1.07
451		806
452	Slow (but very portable, as it is written in pure Perl).	807	Slow (but very portable, as it is written in pure Perl).
453		808
454	Undocumented/buggy Unicode handling (how JSON handles unicode values is	809	Undocumented/buggy Unicode handling (how JSON handles Unicode values is
455	undocumented. One can get far by feeding it unicode strings and doing	810	undocumented. One can get far by feeding it Unicode strings and doing
456	en-/decoding oneself, but unicode escapes are not working properly).	811	en-/decoding oneself, but Unicode escapes are not working properly).
457		812
458	No roundtripping (strings get clobbered if they look like numbers, e.g.	813	No round-tripping (strings get clobbered if they look like numbers, e.g.
459	the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will	814	the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will
460	decode into the number 2.	815	decode into the number 2.
461		816
462	=item JSON::PC 0.01	817	=item JSON::PC 0.01
463		818
464	Very fast.	819	Very fast.
465		820
466	Undocumented/buggy Unicode handling.	821	Undocumented/buggy Unicode handling.
467		822
468	No roundtripping.	823	No round-tripping.
469		824
470	Has problems handling many Perl values (e.g. regex results and other magic	825	Has problems handling many Perl values (e.g. regex results and other magic
471	values will make it croak).	826	values will make it croak).
472		827
473	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>	828	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>
…		…
483	Very inflexible (no human-readable format supported, format pretty much	838	Very inflexible (no human-readable format supported, format pretty much
484	undocumented. I need at least a format for easy reading by humans and a	839	undocumented. I need at least a format for easy reading by humans and a
485	single-line compact format for use in a protocol, and preferably a way to	840	single-line compact format for use in a protocol, and preferably a way to
486	generate ASCII-only JSON texts).	841	generate ASCII-only JSON texts).
487		842
488	Completely broken (and confusingly documented) Unicode handling (unicode	843	Completely broken (and confusingly documented) Unicode handling (Unicode
489	escapes are not working properly, you need to set ImplicitUnicode to	844	escapes are not working properly, you need to set ImplicitUnicode to
490	I<different> values on en- and decoding to get symmetric behaviour).	845	I<different> values on en- and decoding to get symmetric behaviour).
491		846
492	No roundtripping (simple cases work, but this depends on wether the scalar	847	No round-tripping (simple cases work, but this depends on whether the scalar
493	value was used in a numeric context or not).	848	value was used in a numeric context or not).
494		849
495	Dumping hashes may skip hash values depending on iterator state.	850	Dumping hashes may skip hash values depending on iterator state.
496		851
497	Unmaintained (maintainer unresponsive for many months, bugs are not	852	Unmaintained (maintainer unresponsive for many months, bugs are not
498	getting fixed).	853	getting fixed).
499		854
500	Does not check input for validity (i.e. will accept non-JSON input and	855	Does not check input for validity (i.e. will accept non-JSON input and
501	return "something" instead of raising an exception. This is a security	856	return "something" instead of raising an exception. This is a security
502	issue: imagine two banks transfering money between each other using	857	issue: imagine two banks transferring money between each other using
503	JSON. One bank might parse a given non-JSON request and deduct money,	858	JSON. One bank might parse a given non-JSON request and deduct money,
504	while the other might reject the transaction with a syntax error. While a	859	while the other might reject the transaction with a syntax error. While a
505	good protocol will at least recover, that is extra unnecessary work and	860	good protocol will at least recover, that is extra unnecessary work and
506	the transaction will still not succeed).	861	the transaction will still not succeed).
507		862
508	=item JSON::DWIW 0.04	863	=item JSON::DWIW 0.04
509		864
510	Very fast. Very natural. Very nice.	865	Very fast. Very natural. Very nice.
511		866
512	Undocumented unicode handling (but the best of the pack. Unicode escapes	867	Undocumented Unicode handling (but the best of the pack. Unicode escapes
513	still don't get parsed properly).	868	still don't get parsed properly).
514		869
515	Very inflexible.	870	Very inflexible.
516		871
517	No roundtripping.	872	No round-tripping.
518		873
519	Does not generate valid JSON texts (key strings are often unquoted, empty keys	874	Does not generate valid JSON texts (key strings are often unquoted, empty keys
520	result in nothing being output)	875	result in nothing being output)
521		876
522	Does not check input for validity.	877	Does not check input for validity.
523		878
524	=back	879	=back
		880
		881
		882	=head2 JSON and YAML
		883
		884	You often hear that JSON is a subset (or a close subset) of YAML. This is,
		885	however, a mass hysteria and very far from the truth. In general, there is
		886	no way to configure JSON::XS to output a data structure as valid YAML.
		887
		888	If you really must use JSON::XS to generate YAML, you should use this
		889	algorithm (subject to change in future versions):
		890
		891	my $to_yaml = JSON::XS->new->utf8->space_after (1);
		892	my $yaml = $to_yaml->encode ($ref) . "\n";
		893
		894	This will usually generate JSON texts that also parse as valid
		895	YAML. Please note that YAML has hardcoded limits on (simple) object key
		896	lengths that JSON doesn't have, so you should make sure that your hash
		897	keys are noticeably shorter than the 1024 characters YAML allows.
		898
		899	There might be other incompatibilities that I am not aware of. In general
		900	you should not try to generate YAML with a JSON generator or vice versa,
		901	or try to parse JSON with a YAML parser or vice versa: chances are high
		902	that you will run into severe interoperability problems.
		903
525		904
526	=head2 SPEED	905	=head2 SPEED
527		906
528	It seems that JSON::XS is surprisingly fast, as shown in the following	907	It seems that JSON::XS is surprisingly fast, as shown in the following
529	tables. They have been generated with the help of the C<eg/bench> program	908	tables. They have been generated with the help of the C<eg/bench> program
530	in the JSON::XS distribution, to make it easy to compare on your own	909	in the JSON::XS distribution, to make it easy to compare on your own
531	system.	910	system.
532		911
533	First comes a comparison between various modules using a very short JSON	912	First comes a comparison between various modules using a very short
534	string:	913	single-line JSON string:
535		914
536	{"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null}	915	{"method": "handleMessage", "params": ["user1", "we were just talking"], \
		916	"id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
537		917
538	It shows the number of encodes/decodes per second (JSON::XS uses the	918	It shows the number of encodes/decodes per second (JSON::XS uses
539	functional interface, while JSON::XS/2 uses the OO interface with	919	the functional interface, while JSON::XS/2 uses the OO interface
540	pretty-printing and hashkey sorting enabled). Higher is better:	920	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
		921	shrink). Higher is better:
541		922
542	module \| encode \| decode \|	923	module \| encode \| decode \|
543	-----------\|------------\|------------\|	924	-----------\|------------\|------------\|
544	JSON \| 11488.516 \| 7823.035 \|	925	JSON 1.x \| 4990.842 \| 4088.813 \|
545	JSON::DWIW \| 94708.054 \| 129094.260 \|	926	JSON::DWIW \| 51653.990 \| 71575.154 \|
546	JSON::PC \| 63884.157 \| 128528.212 \|	927	JSON::PC \| 65948.176 \| 74631.744 \|
547	JSON::Syck \| 34898.677 \| 42096.911 \|	928	JSON::PP \| 8931.652 \| 3817.168 \|
548	JSON::XS \| 654027.064 \| 396423.669 \|	929	JSON::Syck \| 24877.248 \| 27776.848 \|
549	JSON::XS/2 \| 371564.190 \| 371725.613 \|	930	JSON::XS \| 388361.481 \| 227951.304 \|
		931	JSON::XS/2 \| 227951.304 \| 218453.333 \|
		932	JSON::XS/3 \| 338250.323 \| 218453.333 \|
		933	Storable \| 16500.016 \| 135300.129 \|
550	-----------+------------+------------+	934	-----------+------------+------------+
551		935
552	That is, JSON::XS is more than six times faster than JSON::DWIW on	936	That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
553	encoding, more than three times faster on decoding, and about thirty times	937	about three times faster on decoding, and over forty times faster
554	faster than JSON, even with pretty-printing and key sorting.	938	than JSON, even with pretty-printing and key sorting. It also compares
		939	favourably to Storable for small amounts of data.
555		940
556	Using a longer test string (roughly 18KB, generated from Yahoo! Locals	941	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
557	search API (http://nanoref.com/yahooapis/mgPdGg):	942	search API (http://nanoref.com/yahooapis/mgPdGg):
558		943
559	module \| encode \| decode \|	944	module \| encode \| decode \|
560	-----------\|------------\|------------\|	945	-----------\|------------\|------------\|
561	JSON \| 273.023 \| 44.674 \|	946	JSON 1.x \| 55.260 \| 34.971 \|
562	JSON::DWIW \| 1089.383 \| 1145.704 \|	947	JSON::DWIW \| 825.228 \| 1082.513 \|
563	JSON::PC \| 3097.419 \| 2393.921 \|	948	JSON::PC \| 3571.444 \| 2394.829 \|
564	JSON::Syck \| 514.060 \| 843.053 \|	949	JSON::PP \| 210.987 \| 32.574 \|
565	JSON::XS \| 6479.668 \| 3636.364 \|	950	JSON::Syck \| 552.551 \| 787.544 \|
566	JSON::XS/2 \| 3774.221 \| 3599.124 \|	951	JSON::XS \| 5780.463 \| 4854.519 \|
		952	JSON::XS/2 \| 3869.998 \| 4798.975 \|
		953	JSON::XS/3 \| 5862.880 \| 4798.975 \|
		954	Storable \| 4445.002 \| 5235.027 \|
567	-----------+------------+------------+	955	-----------+------------+------------+
568		956
569	Again, JSON::XS leads by far.	957	Again, JSON::XS leads by far (except for Storable which non-surprisingly
		958	decodes faster).
570		959
571	On large strings containing lots of high unicode characters, some modules	960	On large strings containing lots of high Unicode characters, some modules
572	(such as JSON::PC) seem to decode faster than JSON::XS, but the result	961	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
573	will be broken due to missing (or wrong) unicode handling. Others refuse	962	will be broken due to missing (or wrong) Unicode handling. Others refuse
574	to decode or encode properly, so it was impossible to prepare a fair	963	to decode or encode properly, so it was impossible to prepare a fair
575	comparison table for that case.	964	comparison table for that case.
576		965
577	=head1 RESOURCE LIMITS
578		966
579	JSON::XS does not impose any limits on the size of JSON texts or Perl	967	=head1 SECURITY CONSIDERATIONS
580	values they represent - if your machine can handle it, JSON::XS will	968
581	encode or decode it. Future versions might optionally impose structure	969	When you are using JSON in a protocol, talking to untrusted potentially
582	depth and memory use resource limits.	970	hostile creatures requires relatively few measures.
		971
		972	First of all, your JSON decoder should be secure, that is, should not have
		973	any buffer overflows. Obviously, this module should ensure that and I am
		974	trying hard on making that true, but you never know.
		975
		976	Second, you need to avoid resource-starving attacks. That means you should
		977	limit the size of JSON texts you accept, or make sure then when your
		978	resources run out, that's just fine (e.g. by using a separate process that
		979	can crash safely). The size of a JSON text in octets or characters is
		980	usually a good indication of the size of the resources required to decode
		981	it into a Perl structure. While JSON::XS can check the size of the JSON
		982	text, it might be too late when you already have it in memory, so you
		983	might want to check the size before you accept the string.
		984
		985	Third, JSON::XS recurses using the C stack when decoding objects and
		986	arrays. The C stack is a limited resource: for instance, on my amd64
		987	machine with 8MB of stack size I can decode around 180k nested arrays but
		988	only 14k nested JSON objects (due to perl itself recursing deeply on croak
		989	to free the temporary). If that is exceeded, the program crashes. to be
		990	conservative, the default nesting limit is set to 512. If your process
		991	has a smaller stack, you should adjust this setting accordingly with the
		992	C<max_depth> method.
		993
		994	And last but least, something else could bomb you that I forgot to think
		995	of. In that case, you get to keep the pieces. I am always open for hints,
		996	though...
		997
		998	If you are using JSON::XS to return packets to consumption
		999	by JavaScript scripts in a browser you should have a look at
		1000	L<http://jpsykes.com/47/practical-csrf-and-json-security> to see whether
		1001	you are vulnerable to some common attack vectors (which really are browser
		1002	design bugs, but it is still you who will have to deal with it, as major
		1003	browser developers care only for features, not about doing security
		1004	right).
		1005
		1006
		1007	=head1 THREADS
		1008
		1009	This module is I<not> guaranteed to be thread safe and there are no
		1010	plans to change this until Perl gets thread support (as opposed to the
		1011	horribly slow so-called "threads" which are simply slow and bloated
		1012	process simulations - use fork, its I<much> faster, cheaper, better).
		1013
		1014	(It might actually work, but you have been warned).
		1015
583		1016
584	=head1 BUGS	1017	=head1 BUGS
585		1018
586	While the goal of this module is to be correct, that unfortunately does	1019	While the goal of this module is to be correct, that unfortunately does
587	not mean its bug-free, only that I think its design is bug-free. It is	1020	not mean its bug-free, only that I think its design is bug-free. It is
588	still very young and not well-tested. If you keep reporting bugs they will	1021	still relatively early in its development. If you keep reporting bugs they
589	be fixed swiftly, though.	1022	will be fixed swiftly, though.
		1023
		1024	Please refrain from using rt.cpan.org or any other bug reporting
		1025	service. I put the contact address into my modules for a reason.
590		1026
591	=cut	1027	=cut
		1028
		1029	our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
		1030	our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };
		1031
		1032	sub true() { $true }
		1033	sub false() { $false }
		1034
		1035	sub is_bool($) {
		1036	UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
		1037	# or UNIVERSAL::isa $_[0], "JSON::Literal"
		1038	}
		1039
		1040	XSLoader::load "JSON::XS", $VERSION;
		1041
		1042	package JSON::XS::Boolean;
		1043
		1044	use overload
		1045	"0+" => sub { ${$_[0]} },
		1046	"++" => sub { $_[0] = ${$_[0]} + 1 },
		1047	"--" => sub { $_[0] = ${$_[0]} - 1 },
		1048	fallback => 1;
592		1049
593	1;	1050	1;
594		1051
595	=head1 AUTHOR	1052	=head1 AUTHOR
596		1053

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Comparing JSON-XS/XS.pm (file contents): Revision 1.20 by root, Sun Mar 25 00:47:42 2007 UTC vs. Revision 1.75 by root, Thu Nov 29 13:35:35 2007 UTC

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Comparing JSON-XS/XS.pm (file contents):
Revision 1.20 by root, Sun Mar 25 00:47:42 2007 UTC vs.
Revision 1.75 by root, Thu Nov 29 13:35:35 2007 UTC