[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 1.62 by root, Thu Oct 11 22:52:52 2007 UTC

…		…
		1	=encoding utf-8
		2
1	=head1 NAME	3	=head1 NAME
2		4
3	JSON::XS - JSON serialising/deserialising, done correctly and fast	5	JSON::XS - JSON serialising/deserialising, done correctly and fast
4		6
		7	JSON::XS - 正しくて高速な JSON シリアライザ/デシリアライザ
		8	(http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html)
		9
5	=head1 SYNOPSIS	10	=head1 SYNOPSIS
6		11
7	use JSON::XS;	12	use JSON::XS;
		13
		14	# exported functions, they croak on error
		15	# and expect/generate UTF-8
		16
		17	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;
		18	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;
		19
		20	# OO-interface
		21
		22	$coder = JSON::XS->new->ascii->pretty->allow_nonref;
		23	$pretty_printed_unencoded = $coder->encode ($perl_scalar);
		24	$perl_scalar = $coder->decode ($unicode_json_text);
8		25
9	=head1 DESCRIPTION	26	=head1 DESCRIPTION
10		27
11	This module converts Perl data structures to JSON and vice versa. Its	28	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	29	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	35	their maintainers are unresponsive, gone missing, or not listening to bug
19	reports for other reasons.	36	reports for other reasons.
20		37
21	See COMPARISON, below, for a comparison to some other JSON modules.	38	See COMPARISON, below, for a comparison to some other JSON modules.
22		39
		40	See MAPPING, below, on how JSON::XS maps perl values to JSON values and
		41	vice versa.
		42
23	=head2 FEATURES	43	=head2 FEATURES
24		44
25	=over 4	45	=over 4
26		46
27	=item * correct handling of unicode issues	47	=item * correct unicode handling
28		48
29	This module knows how to handle Unicode, and even documents how it does so.	49	This module knows how to handle Unicode, and even documents how and when
		50	it does so.
30		51
31	=item * round-trip integrity	52	=item * round-trip integrity
32		53
33	When you serialise a perl data structure using only datatypes supported	54	When you serialise a perl data structure using only datatypes supported
34	by JSON, the deserialised data structure is identical on the Perl level.	55	by JSON, the deserialised data structure is identical on the Perl level.
35	(e.g. the string "2.0" doesn't suddenly become "2").	56	(e.g. the string "2.0" doesn't suddenly become "2" just because it looks
		57	like a number).
36		58
37	=item * strict checking of JSON correctness	59	=item * strict checking of JSON correctness
38		60
39	There is no guessing, no generating of illegal JSON strings by default,	61	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).	62	and only JSON is accepted as input by default (the latter is a security
		63	feature).
41		64
42	=item * fast	65	=item * fast
43		66
44	compared to other JSON modules, this module compares favourably.	67	Compared to other JSON modules, this module compares favourably in terms
		68	of speed, too.
45		69
46	=item * simple to use	70	=item * simple to use
47		71
48	This module has both a simple functional interface as well as an OO	72	This module has both a simple functional interface as well as an OO
49	interface.	73	interface.
50		74
51	=item * reasonably versatile output formats	75	=item * reasonably versatile output formats
52		76
53	You can choose between the most compact format possible, a pure-ascii	77	You can choose between the most compact guarenteed single-line format
54	format, or a pretty-printed format. Or you can combine those features in	78	possible (nice for simple line-based protocols), a pure-ascii format
55	whatever way you like.	79	(for when your transport is not 8-bit clean, still supports the whole
		80	unicode range), or a pretty-printed format (for when you want to read that
		81	stuff). Or you can combine those features in whatever way you like.
56		82
57	=back	83	=back
58		84
59	=cut	85	=cut
60		86
61	package JSON::XS;	87	package JSON::XS;
62		88
63	BEGIN {	89	use strict;
		90
64	$VERSION = '0.1';	91	our $VERSION = '1.5';
65	@ISA = qw(Exporter);	92	our @ISA = qw(Exporter);
66		93
67	@EXPORT = qw(to_json from_json);	94	our @EXPORT = qw(to_json from_json);
68	require Exporter;
69		95
70	require XSLoader;	96	use Exporter;
71	XSLoader::load JSON::XS::, $VERSION;	97	use XSLoader;
72	}
73		98
74	=head1 FUNCTIONAL INTERFACE	99	=head1 FUNCTIONAL INTERFACE
75		100
76	The following convinience methods are provided by this module. They are	101	The following convinience methods are provided by this module. They are
77	exported by default:	102	exported by default:
78		103
79	=over 4	104	=over 4
80		105
81	=item $json_string = to_json $perl_scalar	106	=item $json_text = to_json $perl_scalar
82		107
83	Converts the given Perl data structure (a simple scalar or a reference to	108	Converts the given Perl data structure (a simple scalar or a reference to
84	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains	109	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains
85	octets only). Croaks on error.	110	octets only). Croaks on error.
86		111
87	This function call is functionally identical to C<< JSON::XS->new->utf8	112	This function call is functionally identical to:
88	(1)->encode ($perl_scalar) >>.
89		113
		114	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)
		115
		116	except being faster.
		117
90	=item $perl_scalar = from_json $json_string	118	=item $perl_scalar = from_json $json_text
91		119
92	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to	120	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to
93	parse that as an UTF-8 encoded JSON string, returning the resulting simple	121	parse that as an UTF-8 encoded JSON text, returning the resulting simple
94	scalar or reference. Croaks on error.	122	scalar or reference. Croaks on error.
95		123
96	This function call is functionally identical to C<< JSON::XS->new->utf8	124	This function call is functionally identical to:
97	(1)->decode ($json_string) >>.	125
		126	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
		127
		128	except being faster.
		129
		130	=item $is_boolean = JSON::XS::is_bool $scalar
		131
		132	Returns true if the passed scalar represents either JSON::XS::true or
		133	JSON::XS::false, two constants that act like C<1> and C<0>, respectively
		134	and are used to represent JSON C<true> and C<false> values in Perl.
		135
		136	See MAPPING, below, for more information on how JSON values are mapped to
		137	Perl.
98		138
99	=back	139	=back
		140
100		141
101	=head1 OBJECT-ORIENTED INTERFACE	142	=head1 OBJECT-ORIENTED INTERFACE
102		143
103	The object oriented interface lets you configure your own encoding or	144	The object oriented interface lets you configure your own encoding or
104	decoding style, within the limits of supported formats.	145	decoding style, within the limits of supported formats.
…		…
111	strings. All boolean flags described below are by default I<disabled>.	152	strings. All boolean flags described below are by default I<disabled>.
112		153
113	The mutators for flags all return the JSON object again and thus calls can	154	The mutators for flags all return the JSON object again and thus calls can
114	be chained:	155	be chained:
115		156
116	my $json = JSON::XS->new->utf8(1)->space_after(1)->encode ({a => [1,2]})	157	my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})
117	=> {"a": [1, 2]}	158	=> {"a": [1, 2]}
118		159
119	=item $json = $json->ascii ($enable)	160	=item $json = $json->ascii ([$enable])
120		161
121	If C<$enable> is true, then the C<encode> method will not generate	162	If C<$enable> is true (or missing), then the C<encode> method will not
122	characters outside the code range C<0..127>. Any unicode characters	163	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	164	unicode characters outside that range will be escaped using either a
124	characters) or a double \uHHHH\uLLLLL escape sequence, as per RFC4627.	165	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
		166	as per RFC4627. The resulting encoded JSON text can be treated as a native
		167	unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
		168	or any other superset of ASCII.
125		169
126	If C<$enable> is false, then the C<encode> method will not escape Unicode	170	If C<$enable> is false, then the C<encode> method will not escape Unicode
127	characters unless necessary.	171	characters unless required by the JSON syntax or other flags. This results
		172	in a faster and more compact format.
128		173
		174	The main use for this flag is to produce JSON texts that can be
		175	transmitted over a 7-bit channel, as the encoded JSON texts will not
		176	contain any 8 bit characters.
		177
129	JSON::XS->new->ascii (1)->encode (chr 0x10401)	178	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
130	=> \ud801\udc01	179	=> ["\ud801\udc01"]
131		180
		181	=item $json = $json->latin1 ([$enable])
		182
		183	If C<$enable> is true (or missing), then the C<encode> method will encode
		184	the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
		185	outside the code range C<0..255>. The resulting string can be treated as a
		186	latin1-encoded JSON text or a native unicode string. The C<decode> method
		187	will not be affected in any way by this flag, as C<decode> by default
		188	expects unicode, which is a strict superset of latin1.
		189
		190	If C<$enable> is false, then the C<encode> method will not escape Unicode
		191	characters unless required by the JSON syntax or other flags.
		192
		193	The main use for this flag is efficiently encoding binary data as JSON
		194	text, as most octets will not be escaped, resulting in a smaller encoded
		195	size. The disadvantage is that the resulting JSON text is encoded
		196	in latin1 (and must correctly be treated as such when storing and
		197	transfering), a rare encoding for JSON. It is therefore most useful when
		198	you want to store data structures known to contain binary data efficiently
		199	in files or databases, not when talking to other JSON encoders/decoders.
		200
		201	JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
		202	=> ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
		203
132	=item $json = $json->utf8 ($enable)	204	=item $json = $json->utf8 ([$enable])
133		205
134	If C<$enable> is true, then the C<encode> method will encode the JSON	206	If C<$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>	207	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	208	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	209	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.	210	range C<0..255>, they are thus useful for bytewise/binary I/O. In future
		211	versions, enabling this option might enable autodetection of the UTF-16
		212	and UTF-32 encoding families, as described in RFC4627.
139		213
140	If C<$enable> is false, then the C<encode> method will return the JSON	214	If C<$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	215	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	216	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.	217	to be done yourself, e.g. using the Encode module.
144		218
		219	Example, output UTF-16BE-encoded JSON:
		220
		221	use Encode;
		222	$jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);
		223
		224	Example, decode UTF-32LE-encoded JSON:
		225
		226	use Encode;
		227	$object = JSON::XS->new->decode (decode "UTF-32LE", $jsontext);
		228
145	=item $json = $json->pretty ($enable)	229	=item $json = $json->pretty ([$enable])
146		230
147	This enables (or disables) all of the C<indent>, C<space_before> and	231	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	232	C<space_after> (and in the future possibly more) flags in one call to
149	generate the most readable (or most compact) form possible.	233	generate the most readable (or most compact) form possible.
		234
		235	Example, pretty-print some simple structure:
150		236
151	my $json = JSON::XS->new->pretty(1)->encode ({a => [1,2]})	237	my $json = JSON::XS->new->pretty(1)->encode ({a => [1,2]})
152	=>	238	=>
153	{	239	{
154	"a" : [	240	"a" : [
155	1,	241	1,
156	2	242	2
157	]	243	]
158	}	244	}
159		245
160	=item $json = $json->indent ($enable)	246	=item $json = $json->indent ([$enable])
161		247
162	If C<$enable> is true, then the C<encode> method will use a multiline	248	If C<$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	249	format as output, putting every array member or object/hash key-value pair
164	into its own line, identing them properly.	250	into its own line, identing them properly.
165		251
166	If C<$enable> is false, no newlines or indenting will be produced, and the	252	If C<$enable> is false, no newlines or indenting will be produced, and the
167	resulting JSON strings is guarenteed not to contain any C<newlines>.	253	resulting JSON text is guarenteed not to contain any C<newlines>.
168		254
169	This setting has no effect when decoding JSON strings.	255	This setting has no effect when decoding JSON texts.
170		256
171	=item $json = $json->space_before ($enable)	257	=item $json = $json->space_before ([$enable])
172		258
173	If C<$enable> is true, then the C<encode> method will add an extra	259	If C<$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.	260	optional space before the C<:> separating keys from values in JSON objects.
175		261
176	If C<$enable> is false, then the C<encode> method will not add any extra	262	If C<$enable> is false, then the C<encode> method will not add any extra
177	space at those places.	263	space at those places.
178		264
179	This setting has no effect when decoding JSON strings. You will also most	265	This setting has no effect when decoding JSON texts. You will also
180	likely combine this setting with C<space_after>.	266	most likely combine this setting with C<space_after>.
181		267
		268	Example, space_before enabled, space_after and indent disabled:
		269
		270	{"key" :"value"}
		271
182	=item $json = $json->space_after ($enable)	272	=item $json = $json->space_after ([$enable])
183		273
184	If C<$enable> is true, then the C<encode> method will add an extra	274	If C<$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	275	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	276	and extra whitespace after the C<,> separating key-value pairs and array
187	members.	277	members.
188		278
189	If C<$enable> is false, then the C<encode> method will not add any extra	279	If C<$enable> is false, then the C<encode> method will not add any extra
190	space at those places.	280	space at those places.
191		281
192	This setting has no effect when decoding JSON strings.	282	This setting has no effect when decoding JSON texts.
193		283
		284	Example, space_before and indent disabled, space_after enabled:
		285
		286	{"key": "value"}
		287
		288	=item $json = $json->relaxed ([$enable])
		289
		290	If C<$enable> is true (or missing), then C<decode> will accept some
		291	extensions to normal JSON syntax (see below). C<encode> will not be
		292	affected in anyway. I<Be aware that this option makes you accept invalid
		293	JSON texts as if they were valid!>. I suggest only to use this option to
		294	parse application-specific files written by humans (configuration files,
		295	resource files etc.)
		296
		297	If C<$enable> is false (the default), then C<decode> will only accept
		298	valid JSON texts.
		299
		300	Currently accepted extensions are:
		301
		302	=over 4
		303
		304	=item * list items can have an end-comma
		305
		306	JSON I<separates> array elements and key-value pairs with commas. This
		307	can be annoying if you write JSON texts manually and want to be able to
		308	quickly append elements, so this extension accepts comma at the end of
		309	such items not just between them:
		310
		311	[
		312	1,
		313	2, <- this comma not normally allowed
		314	]
		315	{
		316	"k1": "v1",
		317	"k2": "v2", <- this comma not normally allowed
		318	}
		319
		320	=item * shell-style '#'-comments
		321
		322	Whenever JSON allows whitespace, shell-style comments are additionally
		323	allowed. They are terminated by the first carriage-return or line-feed
		324	character, after which more white-space and comments are allowed.
		325
		326	[
		327	1, # this comment not allowed in JSON
		328	# neither this one...
		329	]
		330
		331	=back
		332
194	=item $json = $json->canonical ($enable)	333	=item $json = $json->canonical ([$enable])
195		334
196	If C<$enable> is true, then the C<encode> method will output JSON objects	335	If C<$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.	336	by sorting their keys. This is adding a comparatively high overhead.
198		337
199	If C<$enable> is false, then the C<encode> method will output key-value	338	If C<$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	339	pairs in the order Perl stores them (which will likely change between runs
201	of the same script).	340	of the same script).
202		341
203	This option is useful if you want the same data structure to be encoded as	342	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,	343	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,	344	the same hash migh be encoded differently even if contains the same data,
206	as key-value pairs have no inherent ordering in Perl.	345	as key-value pairs have no inherent ordering in Perl.
207		346
208	This setting has no effect when decoding JSON strings.	347	This setting has no effect when decoding JSON texts.
209		348
210	=item $json = $json->allow_nonref ($enable)	349	=item $json = $json->allow_nonref ([$enable])
211		350
212	If C<$enable> is true, then the C<encode> method can convert a	351	If C<$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,	352	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	353	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
215	values instead of croaking.	354	values instead of croaking.
216		355
217	If C<$enable> is false, then the C<encode> method will croak if it isn't	356	If C<$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	357	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	358	or array. Likewise, C<decode> will croak if given something that is not a
220	JSON object or array.	359	JSON object or array.
221		360
		361	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,
		362	resulting in an invalid JSON text:
		363
		364	JSON::XS->new->allow_nonref->encode ("Hello, World!")
		365	=> "Hello, World!"
		366
		367	=item $json = $json->allow_blessed ([$enable])
		368
		369	If C<$enable> is true (or missing), then the C<encode> method will not
		370	barf when it encounters a blessed reference. Instead, the value of the
		371	B<convert_blessed> option will decide wether C<null> (C<convert_blessed>
		372	disabled or no C<to_json> method found) or a representation of the
		373	object (C<convert_blessed> enabled and C<to_json> method found) is being
		374	encoded. Has no effect on C<decode>.
		375
		376	If C<$enable> is false (the default), then C<encode> will throw an
		377	exception when it encounters a blessed object.
		378
		379	=item $json = $json->convert_blessed ([$enable])
		380
		381	If C<$enable> is true (or missing), then C<encode>, upon encountering a
		382	blessed object, will check for the availability of the C<TO_JSON> method
		383	on the object's class. If found, it will be called in scalar context
		384	and the resulting scalar will be encoded instead of the object. If no
		385	C<TO_JSON> method is found, the value of C<allow_blessed> will decide what
		386	to do.
		387
		388	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
		389	returns other blessed objects, those will be handled in the same
		390	way. C<TO_JSON> must take care of not causing an endless recursion cycle
		391	(== crash) in this case. The name of C<TO_JSON> was chosen because other
		392	methods called by the Perl core (== not by the user of the object) are
		393	usually in upper case letters and to avoid collisions with the C<to_json>
		394	function.
		395
		396	This setting does not yet influence C<decode> in any way, but in the
		397	future, global hooks might get installed that influence C<decode> and are
		398	enabled by this setting.
		399
		400	If C<$enable> is false, then the C<allow_blessed> setting will decide what
		401	to do when a blessed object is found.
		402
		403	=item $json = $json->filter_json_object ([$coderef->($hashref)])
		404
		405	When C<$coderef> is specified, it will be called from C<decode> each
		406	time it decodes a JSON object. The only argument is a reference to the
		407	newly-created hash. If the code references returns a single scalar (which
		408	need not be a reference), this value (i.e. a copy of that scalar to avoid
		409	aliasing) is inserted into the deserialised data structure. If it returns
		410	an empty list (NOTE: I<not> C<undef>, which is a valid scalar), the
		411	original deserialised hash will be inserted. This setting can slow down
		412	decoding considerably.
		413
		414	When C<$coderef> is omitted or undefined, any existing callback will
		415	be removed and C<decode> will not change the deserialised hash in any
		416	way.
		417
		418	Example, convert all JSON objects into the integer 5:
		419
		420	my $js = JSON::XS->new->filter_json_object (sub { 5 });
		421	# returns [5]
		422	$js->decode ('[{}]')
		423	# throw an exception because allow_nonref is not enabled
		424	# so a lone 5 is not allowed.
		425	$js->decode ('{"a":1, "b":2}');
		426
		427	=item $json = $json->filter_json_single_key_object ($key [=> $coderef->($value)])
		428
		429	Works remotely similar to C<filter_json_object>, but is only called for
		430	JSON objects having a single key named C<$key>.
		431
		432	This C<$coderef> is called before the one specified via
		433	C<filter_json_object>, if any. It gets passed the single value in the JSON
		434	object. If it returns a single value, it will be inserted into the data
		435	structure. If it returns nothing (not even C<undef> but the empty list),
		436	the callback from C<filter_json_object> will be called next, as if no
		437	single-key callback were specified.
		438
		439	If C<$coderef> is omitted or undefined, the corresponding callback will be
		440	disabled. There can only ever be one callback for a given key.
		441
		442	As this callback gets called less often then the C<filter_json_object>
		443	one, decoding speed will not usually suffer as much. Therefore, single-key
		444	objects make excellent targets to serialise Perl objects into, especially
		445	as single-key JSON objects are as close to the type-tagged value concept
		446	as JSON gets (its basically an ID/VALUE tuple). Of course, JSON does not
		447	support this in any way, so you need to make sure your data never looks
		448	like a serialised Perl hash.
		449
		450	Typical names for the single object key are C<__class_whatever__>, or
		451	C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even
		452	things like C<__class_md5sum(classname)__>, to reduce the risk of clashing
		453	with real hashes.
		454
		455	Example, decode JSON objects of the form C<< { "__widget__" => <id> } >>
		456	into the corresponding C<< $WIDGET{<id>} >> object:
		457
		458	# return whatever is in $WIDGET{5}:
		459	JSON::XS
		460	->new
		461	->filter_json_single_key_object (__widget__ => sub {
		462	$WIDGET{ $_[0] }
		463	})
		464	->decode ('{"__widget__": 5')
		465
		466	# this can be used with a TO_JSON method in some "widget" class
		467	# for serialisation to json:
		468	sub WidgetBase::TO_JSON {
		469	my ($self) = @_;
		470
		471	unless ($self->{id}) {
		472	$self->{id} = ..get..some..id..;
		473	$WIDGET{$self->{id}} = $self;
		474	}
		475
		476	{ __widget__ => $self->{id} }
		477	}
		478
		479	=item $json = $json->shrink ([$enable])
		480
		481	Perl usually over-allocates memory a bit when allocating space for
		482	strings. This flag optionally resizes strings generated by either
		483	C<encode> or C<decode> to their minimum size possible. This can save
		484	memory when your JSON texts are either very very long or you have many
		485	short strings. It will also try to downgrade any strings to octet-form
		486	if possible: perl stores strings internally either in an encoding called
		487	UTF-X or in octet-form. The latter cannot store everything but uses less
		488	space in general (and some buggy Perl or C code might even rely on that
		489	internal representation being used).
		490
		491	The actual definition of what shrink does might change in future versions,
		492	but it will always try to save space at the expense of time.
		493
		494	If C<$enable> is true (or missing), the string returned by C<encode> will
		495	be shrunk-to-fit, while all strings generated by C<decode> will also be
		496	shrunk-to-fit.
		497
		498	If C<$enable> is false, then the normal perl allocation algorithms are used.
		499	If you work with your data, then this is likely to be faster.
		500
		501	In the future, this setting might control other things, such as converting
		502	strings that look like integers or floats into integers or floats
		503	internally (there is no difference on the Perl level), saving space.
		504
		505	=item $json = $json->max_depth ([$maximum_nesting_depth])
		506
		507	Sets the maximum nesting level (default C<512>) accepted while encoding
		508	or decoding. If the JSON text or Perl data structure has an equal or
		509	higher nesting level then this limit, then the encoder and decoder will
		510	stop and croak at that point.
		511
		512	Nesting level is defined by number of hash- or arrayrefs that the encoder
		513	needs to traverse to reach a given point or the number of C<{> or C<[>
		514	characters without their matching closing parenthesis crossed to reach a
		515	given character in a string.
		516
		517	Setting the maximum depth to one disallows any nesting, so that ensures
		518	that the object is only a single hash/object or array.
		519
		520	The argument to C<max_depth> will be rounded up to the next highest power
		521	of two. If no argument is given, the highest possible setting will be
		522	used, which is rarely useful.
		523
		524	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
		525
		526	=item $json = $json->max_size ([$maximum_string_size])
		527
		528	Set the maximum length a JSON text may have (in bytes) where decoding is
		529	being attempted. The default is C<0>, meaning no limit. When C<decode>
		530	is called on a string longer then this number of characters it will not
		531	attempt to decode the string but throw an exception. This setting has no
		532	effect on C<encode> (yet).
		533
		534	The argument to C<max_size> will be rounded up to the next B<highest>
		535	power of two (so may be more than requested). If no argument is given, the
		536	limit check will be deactivated (same as when C<0> is specified).
		537
		538	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
		539
222	=item $json_string = $json->encode ($perl_scalar)	540	=item $json_text = $json->encode ($perl_scalar)
223		541
224	Converts the given Perl data structure (a simple scalar or a reference	542	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	543	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	544	converted into JSON string or number sequences, while references to arrays
227	become JSON arrays and references to hashes become JSON objects. Undefined	545	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>	546	Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>
229	nor C<false> values will be generated.	547	nor C<false> values will be generated.
230		548
231	=item $perl_scalar = $json->decode ($json_string)	549	=item $perl_scalar = $json->decode ($json_text)
232		550
233	The opposite of C<encode>: expects a JSON string and tries to parse it,	551	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.	552	returning the resulting simple scalar or reference. Croaks on error.
235		553
236	JSON numbers and strings become simple Perl scalars. JSON arrays become	554	JSON numbers and strings become simple Perl scalars. JSON arrays become
237	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes	555	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>.	556	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
239		557
		558	=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
		559
		560	This works like the C<decode> method, but instead of raising an exception
		561	when there is trailing garbage after the first JSON object, it will
		562	silently stop parsing there and return the number of characters consumed
		563	so far.
		564
		565	This is useful if your JSON texts are not delimited by an outer protocol
		566	(which is not the brightest thing to do in the first place) and you need
		567	to know where the JSON text ends.
		568
		569	JSON::XS->new->decode_prefix ("[1] the tail")
		570	=> ([], 3)
		571
240	=back	572	=back
		573
		574
		575	=head1 MAPPING
		576
		577	This section describes how JSON::XS maps Perl values to JSON values and
		578	vice versa. These mappings are designed to "do the right thing" in most
		579	circumstances automatically, preserving round-tripping characteristics
		580	(what you put in comes out as something equivalent).
		581
		582	For the more enlightened: note that in the following descriptions,
		583	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
		584	refers to the abstract Perl language itself.
		585
		586
		587	=head2 JSON -> PERL
		588
		589	=over 4
		590
		591	=item object
		592
		593	A JSON object becomes a reference to a hash in Perl. No ordering of object
		594	keys is preserved (JSON does not preserver object key ordering itself).
		595
		596	=item array
		597
		598	A JSON array becomes a reference to an array in Perl.
		599
		600	=item string
		601
		602	A JSON string becomes a string scalar in Perl - Unicode codepoints in JSON
		603	are represented by the same codepoints in the Perl string, so no manual
		604	decoding is necessary.
		605
		606	=item number
		607
		608	A JSON number becomes either an integer, numeric (floating point) or
		609	string scalar in perl, depending on its range and any fractional parts. On
		610	the Perl level, there is no difference between those as Perl handles all
		611	the conversion details, but an integer may take slightly less memory and
		612	might represent more values exactly than (floating point) numbers.
		613
		614	If the number consists of digits only, JSON::XS will try to represent
		615	it as an integer value. If that fails, it will try to represent it as
		616	a numeric (floating point) value if that is possible without loss of
		617	precision. Otherwise it will preserve the number as a string value.
		618
		619	Numbers containing a fractional or exponential part will always be
		620	represented as numeric (floating point) values, possibly at a loss of
		621	precision.
		622
		623	This might create round-tripping problems as numbers might become strings,
		624	but as Perl is typeless there is no other way to do it.
		625
		626	=item true, false
		627
		628	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
		629	respectively. They are overloaded to act almost exactly like the numbers
		630	C<1> and C<0>. You can check wether a scalar is a JSON boolean by using
		631	the C<JSON::XS::is_bool> function.
		632
		633	=item null
		634
		635	A JSON null atom becomes C<undef> in Perl.
		636
		637	=back
		638
		639
		640	=head2 PERL -> JSON
		641
		642	The mapping from Perl to JSON is slightly more difficult, as Perl is a
		643	truly typeless language, so we can only guess which JSON type is meant by
		644	a Perl value.
		645
		646	=over 4
		647
		648	=item hash references
		649
		650	Perl hash references become JSON objects. As there is no inherent ordering
		651	in hash keys (or JSON objects), they will usually be encoded in a
		652	pseudo-random order that can change between runs of the same program but
		653	stays generally the same within a single run of a program. JSON::XS can
		654	optionally sort the hash keys (determined by the I<canonical> flag), so
		655	the same datastructure will serialise to the same JSON text (given same
		656	settings and version of JSON::XS), but this incurs a runtime overhead
		657	and is only rarely useful, e.g. when you want to compare some JSON text
		658	against another for equality.
		659
		660	=item array references
		661
		662	Perl array references become JSON arrays.
		663
		664	=item other references
		665
		666	Other unblessed references are generally not allowed and will cause an
		667	exception to be thrown, except for references to the integers C<0> and
		668	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
		669	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
		670
		671	to_json [\0,JSON::XS::true] # yields [false,true]
		672
		673	=item JSON::XS::true, JSON::XS::false
		674
		675	These special values become JSON true and JSON false values,
		676	respectively. You can also use C<\1> and C<\0> directly if you want.
		677
		678	=item blessed objects
		679
		680	Blessed objects are not allowed. JSON::XS currently tries to encode their
		681	underlying representation (hash- or arrayref), but this behaviour might
		682	change in future versions.
		683
		684	=item simple scalars
		685
		686	Simple Perl scalars (any scalar that is not a reference) are the most
		687	difficult objects to encode: JSON::XS will encode undefined scalars as
		688	JSON null value, scalars that have last been used in a string context
		689	before encoding as JSON strings and anything else as number value:
		690
		691	# dump as number
		692	to_json [2] # yields [2]
		693	to_json [-3.0e17] # yields [-3e+17]
		694	my $value = 5; to_json [$value] # yields [5]
		695
		696	# used as string, so dump as string
		697	print $value;
		698	to_json [$value] # yields ["5"]
		699
		700	# undef becomes null
		701	to_json [undef] # yields [null]
		702
		703	You can force the type to be a string by stringifying it:
		704
		705	my $x = 3.1; # some variable containing a number
		706	"$x"; # stringified
		707	$x .= ""; # another, more awkward way to stringify
		708	print $x; # perl does it for you, too, quite often
		709
		710	You can force the type to be a number by numifying it:
		711
		712	my $x = "3"; # some variable containing a string
		713	$x += 0; # numify it, ensuring it will be dumped as a number
		714	$x *= 1; # same thing, the choise is yours.
		715
		716	You can not currently output JSON booleans or force the type in other,
		717	less obscure, ways. Tell me if you need this capability.
		718
		719	=back
		720
241		721
242	=head1 COMPARISON	722	=head1 COMPARISON
243		723
244	As already mentioned, this module was created because none of the existing	724	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	725	JSON modules could be made to work correctly. First I will describe the
…		…
271		751
272	Has problems handling many Perl values (e.g. regex results and other magic	752	Has problems handling many Perl values (e.g. regex results and other magic
273	values will make it croak).	753	values will make it croak).
274		754
275	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>	755	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>
276	which is not a valid JSON string.	756	which is not a valid JSON text.
277		757
278	Unmaintained (maintainer unresponsive for many months, bugs are not	758	Unmaintained (maintainer unresponsive for many months, bugs are not
279	getting fixed).	759	getting fixed).
280		760
281	=item JSON::Syck 0.21	761	=item JSON::Syck 0.21
…		…
283	Very buggy (often crashes).	763	Very buggy (often crashes).
284		764
285	Very inflexible (no human-readable format supported, format pretty much	765	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	766	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	767	single-line compact format for use in a protocol, and preferably a way to
288	generate ASCII-only JSON strings).	768	generate ASCII-only JSON texts).
289		769
290	Completely broken (and confusingly documented) Unicode handling (unicode	770	Completely broken (and confusingly documented) Unicode handling (unicode
291	escapes are not working properly, you need to set ImplicitUnicode to	771	escapes are not working properly, you need to set ImplicitUnicode to
292	I<different> values on en- and decoding to get symmetric behaviour).	772	I<different> values on en- and decoding to get symmetric behaviour).
293		773
…		…
316		796
317	Very inflexible.	797	Very inflexible.
318		798
319	No roundtripping.	799	No roundtripping.
320		800
321	Does not generate valid JSON (key strings are often unquoted, empty keys	801	Does not generate valid JSON texts (key strings are often unquoted, empty keys
322	result in nothing being output)	802	result in nothing being output)
323		803
324	Does not check input for validity.	804	Does not check input for validity.
325		805
326	=back	806	=back
		807
		808
		809	=head2 JSON and YAML
		810
		811	You often hear that JSON is a subset (or a close subset) of YAML. This is,
		812	however, a mass hysteria and very far from the truth. In general, there is
		813	no way to configure JSON::XS to output a data structure as valid YAML.
		814
		815	If you really must use JSON::XS to generate YAML, you should use this
		816	algorithm (subject to change in future versions):
		817
		818	my $to_yaml = JSON::XS->new->utf8->space_after (1);
		819	my $yaml = $to_yaml->encode ($ref) . "\n";
		820
		821	This will usually generate JSON texts that also parse as valid
		822	YAML. Please note that YAML has hardcoded limits on (simple) object key
		823	lengths that JSON doesn't have, so you should make sure that your hash
		824	keys are noticably shorter than the 1024 characters YAML allows.
		825
		826	There might be other incompatibilities that I am not aware of. In general
		827	you should not try to generate YAML with a JSON generator or vice versa,
		828	or try to parse JSON with a YAML parser or vice versa: chances are high
		829	that you will run into severe interoperability problems.
		830
327		831
328	=head2 SPEED	832	=head2 SPEED
329		833
330	It seems that JSON::XS is surprisingly fast, as shown in the following	834	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	835	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	836	in the JSON::XS distribution, to make it easy to compare on your own
333	system.	837	system.
334		838
335	First is a comparison between various modules using a very simple JSON	839	First comes a comparison between various modules using a very short
		840	single-line JSON string:
		841
		842	{"method": "handleMessage", "params": ["user1", "we were just talking"], \
		843	"id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
		844
336	string, showing the number of encodes/decodes per second (JSON::XS is	845	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	846	the functional interface, while JSON::XS/2 uses the OO interface
338	pretty-printing and hashkey sorting enabled).	847	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
		848	shrink). Higher is better:
339		849
		850	Storable \| 15779.925 \| 14169.946 \|
		851	-----------+------------+------------+
340	module \| encode \| decode \|	852	module \| encode \| decode \|
341	-----------\|------------\|------------\|	853	-----------\|------------\|------------\|
342	JSON \| 14006 \| 6820 \|	854	JSON \| 4990.842 \| 4088.813 \|
343	JSON::DWIW \| 200937 \| 120386 \|	855	JSON::DWIW \| 51653.990 \| 71575.154 \|
344	JSON::PC \| 85065 \| 129366 \|	856	JSON::PC \| 65948.176 \| 74631.744 \|
345	JSON::Syck \| 59898 \| 44232 \|	857	JSON::PP \| 8931.652 \| 3817.168 \|
346	JSON::XS \| 1171478 \| 342435 \|	858	JSON::Syck \| 24877.248 \| 27776.848 \|
347	JSON::XS/2 \| 730760 \| 328714 \|	859	JSON::XS \| 388361.481 \| 227951.304 \|
		860	JSON::XS/2 \| 227951.304 \| 218453.333 \|
		861	JSON::XS/3 \| 338250.323 \| 218453.333 \|
		862	Storable \| 16500.016 \| 135300.129 \|
348	-----------+------------+------------+	863	-----------+------------+------------+
349		864
350	That is, JSON::XS is 6 times faster than than JSON::DWIW and about 80	865	That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
		866	about three times faster on decoding, and over fourty times faster
351	times faster than JSON, even with pretty-printing and key sorting.	867	than JSON, even with pretty-printing and key sorting. It also compares
		868	favourably to Storable for small amounts of data.
352		869
353	Using a longer test string (roughly 8KB, generated from Yahoo! Locals	870	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
354	search API (http://nanoref.com/yahooapis/mgPdGg):	871	search API (http://nanoref.com/yahooapis/mgPdGg):
355		872
356	module \| encode \| decode \|	873	module \| encode \| decode \|
357	-----------\|------------\|------------\|	874	-----------\|------------\|------------\|
358	JSON \| 673 \| 38 \|	875	JSON \| 55.260 \| 34.971 \|
359	JSON::DWIW \| 5271 \| 770 \|	876	JSON::DWIW \| 825.228 \| 1082.513 \|
360	JSON::PC \| 9901 \| 2491 \|	877	JSON::PC \| 3571.444 \| 2394.829 \|
361	JSON::Syck \| 2360 \| 786 \|	878	JSON::PP \| 210.987 \| 32.574 \|
362	JSON::XS \| 37398 \| 3202 \|	879	JSON::Syck \| 552.551 \| 787.544 \|
363	JSON::XS/2 \| 13765 \| 3153 \|	880	JSON::XS \| 5780.463 \| 4854.519 \|
		881	JSON::XS/2 \| 3869.998 \| 4798.975 \|
		882	JSON::XS/3 \| 5862.880 \| 4798.975 \|
		883	Storable \| 4445.002 \| 5235.027 \|
364	-----------+------------+------------+	884	-----------+------------+------------+
365		885
366	Again, JSON::XS leads by far in the encoding case, while still beating	886	Again, JSON::XS leads by far (except for Storable which non-surprisingly
367	every other module in the decoding case.	887	decodes faster).
368		888
369	Last example is an almost 8MB large hash with many large binary values	889	On large strings containing lots of high unicode characters, some modules
370	(PNG files), resulting in a lot of escaping:	890	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
		891	will be broken due to missing (or wrong) unicode handling. Others refuse
		892	to decode or encode properly, so it was impossible to prepare a fair
		893	comparison table for that case.
		894
		895
		896	=head1 SECURITY CONSIDERATIONS
		897
		898	When you are using JSON in a protocol, talking to untrusted potentially
		899	hostile creatures requires relatively few measures.
		900
		901	First of all, your JSON decoder should be secure, that is, should not have
		902	any buffer overflows. Obviously, this module should ensure that and I am
		903	trying hard on making that true, but you never know.
		904
		905	Second, you need to avoid resource-starving attacks. That means you should
		906	limit the size of JSON texts you accept, or make sure then when your
		907	resources run out, thats just fine (e.g. by using a separate process that
		908	can crash safely). The size of a JSON text in octets or characters is
		909	usually a good indication of the size of the resources required to decode
		910	it into a Perl structure. While JSON::XS can check the size of the JSON
		911	text, it might be too late when you already have it in memory, so you
		912	might want to check the size before you accept the string.
		913
		914	Third, JSON::XS recurses using the C stack when decoding objects and
		915	arrays. The C stack is a limited resource: for instance, on my amd64
		916	machine with 8MB of stack size I can decode around 180k nested arrays but
		917	only 14k nested JSON objects (due to perl itself recursing deeply on croak
		918	to free the temporary). If that is exceeded, the program crashes. to be
		919	conservative, the default nesting limit is set to 512. If your process
		920	has a smaller stack, you should adjust this setting accordingly with the
		921	C<max_depth> method.
		922
		923	And last but least, something else could bomb you that I forgot to think
		924	of. In that case, you get to keep the pieces. I am always open for hints,
		925	though...
		926
		927	If you are using JSON::XS to return packets to consumption
		928	by javascript scripts in a browser you should have a look at
		929	L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether
		930	you are vulnerable to some common attack vectors (which really are browser
		931	design bugs, but it is still you who will have to deal with it, as major
		932	browser developers care only for features, not about doing security
		933	right).
		934
371		935
372	=head1 BUGS	936	=head1 BUGS
373		937
374	While the goal of this module is to be correct, that unfortunately does	938	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	939	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	940	still relatively early in its development. If you keep reporting bugs they
377	be fixed swiftly, though.	941	will be fixed swiftly, though.
378		942
379	=cut	943	=cut
		944
		945	our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
		946	our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };
		947
		948	sub true() { $true }
		949	sub false() { $false }
		950
		951	sub is_bool($) {
		952	UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
		953	# or UNIVERSAL::isa $_[0], "JSON::Literal"
		954	}
		955
		956	XSLoader::load "JSON::XS", $VERSION;
		957
		958	package JSON::XS::Boolean;
		959
		960	use overload
		961	"0+" => sub { ${$_[0]} },
		962	"++" => sub { $_[0] = ${$_[0]} + 1 },
		963	"--" => sub { $_[0] = ${$_[0]} - 1 },
		964	fallback => 1;
380		965
381	1;	966	1;
382		967
383	=head1 AUTHOR	968	=head1 AUTHOR
384		969

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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 1.62 by root, Thu Oct 11 22:52:52 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 1.62 by root, Thu Oct 11 22:52:52 2007 UTC