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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.13 by root, Fri Mar 23 18:37:30 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;
8		13
9	# exported functions, croak on error	14	# exported functions, they croak on error
		15	# and expect/generate UTF-8
10		16
11	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;	17	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;
12	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;	18	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;
13		19
14	# oo-interface	20	# OO-interface
15		21
16	$coder = JSON::XS->new->ascii->pretty->allow_nonref;	22	$coder = JSON::XS->new->ascii->pretty->allow_nonref;
17	$pretty_printed_unencoded = $coder->encode ($perl_scalar);	23	$pretty_printed_unencoded = $coder->encode ($perl_scalar);
18	$perl_scalar = $coder->decode ($unicode_json_text);	24	$perl_scalar = $coder->decode ($unicode_json_text);
19		25
36		42
37	=head2 FEATURES	43	=head2 FEATURES
38		44
39	=over 4	45	=over 4
40		46
41	=item * correct handling of unicode issues	47	=item * correct unicode handling
42		48
43	This module knows how to handle Unicode, and even documents how and when	49	This module knows how to handle Unicode, and even documents how and when
44	it does so.	50	it does so.
45		51
46	=item * round-trip integrity	52	=item * round-trip integrity
47		53
48	When you serialise a perl data structure using only datatypes supported	54	When you serialise a perl data structure using only datatypes supported
49	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.
50	(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).
51		58
52	=item * strict checking of JSON correctness	59	=item * strict checking of JSON correctness
53		60
54	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,
55	and only JSON is accepted as input by default (the latter is a security	62	and only JSON is accepted as input by default (the latter is a security
56	feature).	63	feature).
57		64
58	=item * fast	65	=item * fast
59		66
…		…
66	interface.	73	interface.
67		74
68	=item * reasonably versatile output formats	75	=item * reasonably versatile output formats
69		76
70	You can choose between the most compact guarenteed single-line format	77	You can choose between the most compact guarenteed single-line format
71	possible (nice for simple line-based protocols), a pure-ascii format (for	78	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	79	(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	80	unicode range), or a pretty-printed format (for when you want to read that
74	whatever way you like.	81	stuff). Or you can combine those features in whatever way you like.
75		82
76	=back	83	=back
77		84
78	=cut	85	=cut
79		86
80	package JSON::XS;	87	package JSON::XS;
81		88
82	BEGIN {	89	use strict;
		90
83	$VERSION = '0.3';	91	our $VERSION = '1.5';
84	@ISA = qw(Exporter);	92	our @ISA = qw(Exporter);
85		93
86	@EXPORT = qw(to_json from_json);	94	our @EXPORT = qw(to_json from_json);
87	require Exporter;
88		95
89	require XSLoader;	96	use Exporter;
90	XSLoader::load JSON::XS::, $VERSION;	97	use XSLoader;
91	}
92		98
93	=head1 FUNCTIONAL INTERFACE	99	=head1 FUNCTIONAL INTERFACE
94		100
95	The following convinience methods are provided by this module. They are	101	The following convinience methods are provided by this module. They are
96	exported by default:	102	exported by default:
97		103
98	=over 4	104	=over 4
99		105
100	=item $json_string = to_json $perl_scalar	106	=item $json_text = to_json $perl_scalar
101		107
102	Converts the given Perl data structure (a simple scalar or a reference to	108	Converts the given Perl data structure (a simple scalar or a reference to
103	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains	109	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains
104	octets only). Croaks on error.	110	octets only). Croaks on error.
105		111
106	This function call is functionally identical to C<< JSON::XS->new->utf8->encode ($perl_scalar) >>.	112	This function call is functionally identical to:
107		113
		114	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)
		115
		116	except being faster.
		117
108	=item $perl_scalar = from_json $json_string	118	=item $perl_scalar = from_json $json_text
109		119
110	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to	120	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to
111	parse that as an UTF-8 encoded JSON string, returning the resulting simple	121	parse that as an UTF-8 encoded JSON text, returning the resulting simple
112	scalar or reference. Croaks on error.	122	scalar or reference. Croaks on error.
113		123
114	This function call is functionally identical to C<< JSON::XS->new->utf8->decode ($json_string) >>.	124	This function call is functionally identical to:
		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.
115		138
116	=back	139	=back
		140
117		141
118	=head1 OBJECT-ORIENTED INTERFACE	142	=head1 OBJECT-ORIENTED INTERFACE
119		143
120	The object oriented interface lets you configure your own encoding or	144	The object oriented interface lets you configure your own encoding or
121	decoding style, within the limits of supported formats.	145	decoding style, within the limits of supported formats.
…		…
128	strings. All boolean flags described below are by default I<disabled>.	152	strings. All boolean flags described below are by default I<disabled>.
129		153
130	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
131	be chained:	155	be chained:
132		156
133	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]})
134	=> {"a": [1, 2]}	158	=> {"a": [1, 2]}
135		159
136	=item $json = $json->ascii ([$enable])	160	=item $json = $json->ascii ([$enable])
137		161
138	If C<$enable> is true (or missing), then the C<encode> method will	162	If C<$enable> is true (or missing), then the C<encode> method will not
139	not generate characters outside the code range C<0..127>. Any unicode	163	generate characters outside the code range C<0..127> (which is ASCII). Any
140	characters outside that range will be escaped using either a single	164	unicode characters outside that range will be escaped using either a
141	\uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, as per	165	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
142	RFC4627.	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.
143		169
144	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
145	characters unless necessary.	171	characters unless required by the JSON syntax or other flags. This results
		172	in a faster and more compact format.
146		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
147	JSON::XS->new->ascii (1)->encode (chr 0x10401)	178	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
148	=> \ud801\udc01	179	=> ["\ud801\udc01"]
		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)
149		203
150	=item $json = $json->utf8 ([$enable])	204	=item $json = $json->utf8 ([$enable])
151		205
152	If C<$enable> is true (or missing), then the C<encode> method will encode	206	If C<$enable> is true (or missing), then the C<encode> method will encode
153	the JSON string into UTF-8, as required by many protocols, while the	207	the JSON result into UTF-8, as required by many protocols, while the
154	C<decode> method expects to be handled an UTF-8-encoded string. Please	208	C<decode> method expects to be handled an UTF-8-encoded string. Please
155	note that UTF-8-encoded strings do not contain any characters outside the	209	note that UTF-8-encoded strings do not contain any characters outside the
156	range 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.
157		213
158	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
159	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
160	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
161	to be done yourself, e.g. using the Encode module.	217	to be done yourself, e.g. using the Encode module.
162		218
163	Example, output UTF-16-encoded JSON:	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);
164		228
165	=item $json = $json->pretty ([$enable])	229	=item $json = $json->pretty ([$enable])
166		230
167	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
168	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
…		…
184	If C<$enable> is true (or missing), then the C<encode> method will use a multiline	248	If C<$enable> is true (or missing), then the C<encode> method will use a multiline
185	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
186	into its own line, identing them properly.	250	into its own line, identing them properly.
187		251
188	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
189	resulting JSON strings is guarenteed not to contain any C<newlines>.	253	resulting JSON text is guarenteed not to contain any C<newlines>.
190		254
191	This setting has no effect when decoding JSON strings.	255	This setting has no effect when decoding JSON texts.
192		256
193	=item $json = $json->space_before ([$enable])	257	=item $json = $json->space_before ([$enable])
194		258
195	If C<$enable> is true (or missing), then the C<encode> method will add an extra	259	If C<$enable> is true (or missing), then the C<encode> method will add an extra
196	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.
197		261
198	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
199	space at those places.	263	space at those places.
200		264
201	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
202	likely combine this setting with C<space_after>.	266	most likely combine this setting with C<space_after>.
203		267
204	Example, space_before enabled, space_after and indent disabled:	268	Example, space_before enabled, space_after and indent disabled:
205		269
206	{"key" :"value"}	270	{"key" :"value"}
207		271
…		…
213	members.	277	members.
214		278
215	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
216	space at those places.	280	space at those places.
217		281
218	This setting has no effect when decoding JSON strings.	282	This setting has no effect when decoding JSON texts.
219		283
220	Example, space_before and indent disabled, space_after enabled:	284	Example, space_before and indent disabled, space_after enabled:
221		285
222	{"key": "value"}	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
223		332
224	=item $json = $json->canonical ([$enable])	333	=item $json = $json->canonical ([$enable])
225		334
226	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects	335	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
227	by sorting their keys. This is adding a comparatively high overhead.	336	by sorting their keys. This is adding a comparatively high overhead.
…		…
229	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
230	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
231	of the same script).	340	of the same script).
232		341
233	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
234	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,
235	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,
236	as key-value pairs have no inherent ordering in Perl.	345	as key-value pairs have no inherent ordering in Perl.
237		346
238	This setting has no effect when decoding JSON strings.	347	This setting has no effect when decoding JSON texts.
239		348
240	=item $json = $json->allow_nonref ([$enable])	349	=item $json = $json->allow_nonref ([$enable])
241		350
242	If C<$enable> is true (or missing), then the C<encode> method can convert a	351	If C<$enable> is true (or missing), then the C<encode> method can convert a
243	non-reference into its corresponding string, number or null JSON value,	352	non-reference into its corresponding string, number or null JSON value,
244	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
245	values instead of croaking.	354	values instead of croaking.
246		355
247	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
248	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
249	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
250	JSON object or array.	359	JSON object or array.
251		360
252	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,	361	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,
253	resulting in an invalid JSON text:	362	resulting in an invalid JSON text:
254		363
255	JSON::XS->new->allow_nonref->encode ("Hello, World!")	364	JSON::XS->new->allow_nonref->encode ("Hello, World!")
256	=> "Hello, World!"	365	=> "Hello, World!"
257		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
258	=item $json = $json->shrink ([$enable])	479	=item $json = $json->shrink ([$enable])
259		480
260	Perl usually over-allocates memory a bit when allocating space for	481	Perl usually over-allocates memory a bit when allocating space for
261	strings. This flag optionally resizes strings generated by either	482	strings. This flag optionally resizes strings generated by either
262	C<encode> or C<decode> to their minimum size possible. This can save	483	C<encode> or C<decode> to their minimum size possible. This can save
263	memory when your JSON strings are either very very long or you have many	484	memory when your JSON texts are either very very long or you have many
264	short strings. It will also try to downgrade any strings to octet-form	485	short strings. It will also try to downgrade any strings to octet-form
265	if possible: perl stores strings internally either in an encoding called	486	if possible: perl stores strings internally either in an encoding called
266	UTF-X or in octet-form. The latter cannot store everything but uses less	487	UTF-X or in octet-form. The latter cannot store everything but uses less
267	space in general.	488	space in general (and some buggy Perl or C code might even rely on that
		489	internal representation being used).
268		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
269	If C<$enable> is true (or missing), the string returned by C<encode> will be shrunk-to-fit,	494	If C<$enable> is true (or missing), the string returned by C<encode> will
270	while all strings generated by C<decode> will also be shrunk-to-fit.	495	be shrunk-to-fit, while all strings generated by C<decode> will also be
		496	shrunk-to-fit.
271		497
272	If C<$enable> is false, then the normal perl allocation algorithms are used.	498	If C<$enable> is false, then the normal perl allocation algorithms are used.
273	If you work with your data, then this is likely to be faster.	499	If you work with your data, then this is likely to be faster.
274		500
275	In the future, this setting might control other things, such as converting	501	In the future, this setting might control other things, such as converting
276	strings that look like integers or floats into integers or floats	502	strings that look like integers or floats into integers or floats
277	internally (there is no difference on the Perl level), saving space.	503	internally (there is no difference on the Perl level), saving space.
278		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
279	=item $json_string = $json->encode ($perl_scalar)	540	=item $json_text = $json->encode ($perl_scalar)
280		541
281	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
282	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
283	converted into JSON string or number sequences, while references to arrays	544	converted into JSON string or number sequences, while references to arrays
284	become JSON arrays and references to hashes become JSON objects. Undefined	545	become JSON arrays and references to hashes become JSON objects. Undefined
285	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>
286	nor C<false> values will be generated.	547	nor C<false> values will be generated.
287		548
288	=item $perl_scalar = $json->decode ($json_string)	549	=item $perl_scalar = $json->decode ($json_text)
289		550
290	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,
291	returning the resulting simple scalar or reference. Croaks on error.	552	returning the resulting simple scalar or reference. Croaks on error.
292		553
293	JSON numbers and strings become simple Perl scalars. JSON arrays become	554	JSON numbers and strings become simple Perl scalars. JSON arrays become
294	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes	555	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
295	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>.
296		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
297	=back	572	=back
		573
298		574
299	=head1 MAPPING	575	=head1 MAPPING
300		576
301	This section describes how JSON::XS maps Perl values to JSON values and	577	This section describes how JSON::XS maps Perl values to JSON values and
302	vice versa. These mappings are designed to "do the right thing" in most	578	vice versa. These mappings are designed to "do the right thing" in most
…		…
305		581
306	For the more enlightened: note that in the following descriptions,	582	For the more enlightened: note that in the following descriptions,
307	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>	583	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
308	refers to the abstract Perl language itself.	584	refers to the abstract Perl language itself.
309		585
		586
310	=head2 JSON -> PERL	587	=head2 JSON -> PERL
311		588
312	=over 4	589	=over 4
313		590
314	=item object	591	=item object
315		592
316	A JSON object becomes a reference to a hash in Perl. No ordering of object	593	A JSON object becomes a reference to a hash in Perl. No ordering of object
317	keys is preserved.	594	keys is preserved (JSON does not preserver object key ordering itself).
318		595
319	=item array	596	=item array
320		597
321	A JSON array becomes a reference to an array in Perl.	598	A JSON array becomes a reference to an array in Perl.
322		599
…		…
326	are represented by the same codepoints in the Perl string, so no manual	603	are represented by the same codepoints in the Perl string, so no manual
327	decoding is necessary.	604	decoding is necessary.
328		605
329	=item number	606	=item number
330		607
331	A JSON number becomes either an integer or numeric (floating point)	608	A JSON number becomes either an integer, numeric (floating point) or
332	scalar in perl, depending on its range and any fractional parts. On the	609	string scalar in perl, depending on its range and any fractional parts. On
333	Perl level, there is no difference between those as Perl handles all the	610	the Perl level, there is no difference between those as Perl handles all
334	conversion details, but an integer may take slightly less memory and might	611	the conversion details, but an integer may take slightly less memory and
335	represent more values exactly than (floating point) numbers.	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.
336		625
337	=item true, false	626	=item true, false
338		627
339	These JSON atoms become C<0>, C<1>, respectively. Information is lost in	628	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
340	this process. Future versions might represent those values differently,	629	respectively. They are overloaded to act almost exactly like the numbers
341	but they will be guarenteed to act like these integers would normally in	630	C<1> and C<0>. You can check wether a scalar is a JSON boolean by using
342	Perl.	631	the C<JSON::XS::is_bool> function.
343		632
344	=item null	633	=item null
345		634
346	A JSON null atom becomes C<undef> in Perl.	635	A JSON null atom becomes C<undef> in Perl.
347		636
348	=back	637	=back
		638
349		639
350	=head2 PERL -> JSON	640	=head2 PERL -> JSON
351		641
352	The mapping from Perl to JSON is slightly more difficult, as Perl is a	642	The mapping from Perl to JSON is slightly more difficult, as Perl is a
353	truly typeless language, so we can only guess which JSON type is meant by	643	truly typeless language, so we can only guess which JSON type is meant by
…		…
356	=over 4	646	=over 4
357		647
358	=item hash references	648	=item hash references
359		649
360	Perl hash references become JSON objects. As there is no inherent ordering	650	Perl hash references become JSON objects. As there is no inherent ordering
361	in hash keys, they will usually be encoded in a pseudo-random order that	651	in hash keys (or JSON objects), they will usually be encoded in a
362	can change between runs of the same program but stays generally the same	652	pseudo-random order that can change between runs of the same program but
363	within the single run of a program. JSON::XS can optionally sort the hash	653	stays generally the same within a single run of a program. JSON::XS can
364	keys (determined by the I<canonical> flag), so the same datastructure	654	optionally sort the hash keys (determined by the I<canonical> flag), so
365	will serialise to the same JSON text (given same settings and version of	655	the same datastructure will serialise to the same JSON text (given same
366	JSON::XS), but this incurs a runtime overhead.	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.
367		659
368	=item array references	660	=item array references
369		661
370	Perl array references become JSON arrays.	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.
371		677
372	=item blessed objects	678	=item blessed objects
373		679
374	Blessed objects are not allowed. JSON::XS currently tries to encode their	680	Blessed objects are not allowed. JSON::XS currently tries to encode their
375	underlying representation (hash- or arrayref), but this behaviour might	681	underlying representation (hash- or arrayref), but this behaviour might
…		…
408	$x *= 1; # same thing, the choise is yours.	714	$x *= 1; # same thing, the choise is yours.
409		715
410	You can not currently output JSON booleans or force the type in other,	716	You can not currently output JSON booleans or force the type in other,
411	less obscure, ways. Tell me if you need this capability.	717	less obscure, ways. Tell me if you need this capability.
412		718
413	=item circular data structures
414
415	Those will be encoded until memory or stackspace runs out.
416
417	=back	719	=back
		720
418		721
419	=head1 COMPARISON	722	=head1 COMPARISON
420		723
421	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
422	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
…		…
448		751
449	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
450	values will make it croak).	753	values will make it croak).
451		754
452	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}>
453	which is not a valid JSON string.	756	which is not a valid JSON text.
454		757
455	Unmaintained (maintainer unresponsive for many months, bugs are not	758	Unmaintained (maintainer unresponsive for many months, bugs are not
456	getting fixed).	759	getting fixed).
457		760
458	=item JSON::Syck 0.21	761	=item JSON::Syck 0.21
…		…
460	Very buggy (often crashes).	763	Very buggy (often crashes).
461		764
462	Very inflexible (no human-readable format supported, format pretty much	765	Very inflexible (no human-readable format supported, format pretty much
463	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
464	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
465	generate ASCII-only JSON strings).	768	generate ASCII-only JSON texts).
466		769
467	Completely broken (and confusingly documented) Unicode handling (unicode	770	Completely broken (and confusingly documented) Unicode handling (unicode
468	escapes are not working properly, you need to set ImplicitUnicode to	771	escapes are not working properly, you need to set ImplicitUnicode to
469	I<different> values on en- and decoding to get symmetric behaviour).	772	I<different> values on en- and decoding to get symmetric behaviour).
470		773
…		…
493		796
494	Very inflexible.	797	Very inflexible.
495		798
496	No roundtripping.	799	No roundtripping.
497		800
498	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
499	result in nothing being output)	802	result in nothing being output)
500		803
501	Does not check input for validity.	804	Does not check input for validity.
502		805
503	=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
504		831
505	=head2 SPEED	832	=head2 SPEED
506		833
507	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
508	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
509	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
510	system.	837	system.
511		838
512	First comes a comparison between various modules using a very short JSON	839	First comes a comparison between various modules using a very short
513	string (83 bytes), showing the number of encodes/decodes per second	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
		845	It shows the number of encodes/decodes per second (JSON::XS uses
514	(JSON::XS is the functional interface, while JSON::XS/2 is the OO	846	the functional interface, while JSON::XS/2 uses the OO interface
515	interface with pretty-printing and hashkey sorting enabled). Higher is	847	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
516	better:	848	shrink). Higher is better:
517		849
		850	Storable \| 15779.925 \| 14169.946 \|
		851	-----------+------------+------------+
518	module \| encode \| decode \|	852	module \| encode \| decode \|
519	-----------\|------------\|------------\|	853	-----------\|------------\|------------\|
520	JSON \| 14006 \| 6820 \|	854	JSON \| 4990.842 \| 4088.813 \|
521	JSON::DWIW \| 200937 \| 120386 \|	855	JSON::DWIW \| 51653.990 \| 71575.154 \|
522	JSON::PC \| 85065 \| 129366 \|	856	JSON::PC \| 65948.176 \| 74631.744 \|
523	JSON::Syck \| 59898 \| 44232 \|	857	JSON::PP \| 8931.652 \| 3817.168 \|
524	JSON::XS \| 1171478 \| 342435 \|	858	JSON::Syck \| 24877.248 \| 27776.848 \|
525	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 \|
526	-----------+------------+------------+	863	-----------+------------+------------+
527		864
528	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
529	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.
530		869
531	Using a longer test string (roughly 18KB, generated from Yahoo! Locals	870	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
532	search API (http://nanoref.com/yahooapis/mgPdGg):	871	search API (http://nanoref.com/yahooapis/mgPdGg):
533		872
534	module \| encode \| decode \|	873	module \| encode \| decode \|
535	-----------\|------------\|------------\|	874	-----------\|------------\|------------\|
536	JSON \| 673 \| 38 \|	875	JSON \| 55.260 \| 34.971 \|
537	JSON::DWIW \| 5271 \| 770 \|	876	JSON::DWIW \| 825.228 \| 1082.513 \|
538	JSON::PC \| 9901 \| 2491 \|	877	JSON::PC \| 3571.444 \| 2394.829 \|
539	JSON::Syck \| 2360 \| 786 \|	878	JSON::PP \| 210.987 \| 32.574 \|
540	JSON::XS \| 37398 \| 3202 \|	879	JSON::Syck \| 552.551 \| 787.544 \|
541	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 \|
542	-----------+------------+------------+	884	-----------+------------+------------+
543		885
544	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
545	every other module in the decoding case.	887	decodes faster).
546		888
547	On large strings containing lots of unicode characters, some modules	889	On large strings containing lots of high unicode characters, some modules
548	(such as JSON::PC) decode faster than JSON::XS, but the result will be	890	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
549	broken due to missing unicode handling. Others refuse to decode or encode	891	will be broken due to missing (or wrong) unicode handling. Others refuse
550	properly, so it was impossible to prepare a fair comparison table for that	892	to decode or encode properly, so it was impossible to prepare a fair
551	case.	893	comparison table for that case.
552		894
553	=head1 RESOURCE LIMITS
554		895
555	JSON::XS does not impose any limits on the size of JSON texts or Perl	896	=head1 SECURITY CONSIDERATIONS
556	values they represent - if your machine can handle it, JSON::XS will	897
557	encode or decode it. Future versions might optionally impose structure	898	When you are using JSON in a protocol, talking to untrusted potentially
558	depth and memory use resource limits.	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
559		935
560	=head1 BUGS	936	=head1 BUGS
561		937
562	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
563	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
564	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
565	be fixed swiftly, though.	941	will be fixed swiftly, though.
566		942
567	=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;
568		965
569	1;	966	1;
570		967
571	=head1 AUTHOR	968	=head1 AUTHOR
572		969

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Comparing JSON-XS/XS.pm (file contents): Revision 1.13 by root, Fri Mar 23 18:37:30 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 1.13 by root, Fri Mar 23 18:37:30 2007 UTC vs.
Revision 1.62 by root, Thu Oct 11 22:52:52 2007 UTC