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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.11 by root, Fri Mar 23 17:48:59 2007 UTC vs.
Revision 1.45 by root, Mon Jun 25 04:16:46 2007 UTC

…		…
3	JSON::XS - JSON serialising/deserialising, done correctly and fast	3	JSON::XS - JSON serialising/deserialising, done correctly and fast
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use JSON::XS;	7	use JSON::XS;
		8
		9	# exported functions, they croak on error
		10	# and expect/generate UTF-8
		11
		12	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;
		13	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;
		14
		15	# objToJson and jsonToObj aliases to to_json and from_json
		16	# are exported for compatibility to the JSON module,
		17	# but should not be used in new code.
		18
		19	# OO-interface
		20
		21	$coder = JSON::XS->new->ascii->pretty->allow_nonref;
		22	$pretty_printed_unencoded = $coder->encode ($perl_scalar);
		23	$perl_scalar = $coder->decode ($unicode_json_text);
8		24
9	=head1 DESCRIPTION	25	=head1 DESCRIPTION
10		26
11	This module converts Perl data structures to JSON and vice versa. Its	27	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	28	primary goal is to be I<correct> and its secondary goal is to be
…		…
25		41
26	=head2 FEATURES	42	=head2 FEATURES
27		43
28	=over 4	44	=over 4
29		45
30	=item * correct handling of unicode issues	46	=item * correct unicode handling
31		47
32	This module knows how to handle Unicode, and even documents how and when	48	This module knows how to handle Unicode, and even documents how and when
33	it does so.	49	it does so.
34		50
35	=item * round-trip integrity	51	=item * round-trip integrity
36		52
37	When you serialise a perl data structure using only datatypes supported	53	When you serialise a perl data structure using only datatypes supported
38	by JSON, the deserialised data structure is identical on the Perl level.	54	by JSON, the deserialised data structure is identical on the Perl level.
39	(e.g. the string "2.0" doesn't suddenly become "2").	55	(e.g. the string "2.0" doesn't suddenly become "2" just because it looks
		56	like a number).
40		57
41	=item * strict checking of JSON correctness	58	=item * strict checking of JSON correctness
42		59
43	There is no guessing, no generating of illegal JSON strings by default,	60	There is no guessing, no generating of illegal JSON texts by default,
44	and only JSON is accepted as input by default (the latter is a security	61	and only JSON is accepted as input by default (the latter is a security
45	feature).	62	feature).
46		63
47	=item * fast	64	=item * fast
48		65
…		…
55	interface.	72	interface.
56		73
57	=item * reasonably versatile output formats	74	=item * reasonably versatile output formats
58		75
59	You can choose between the most compact guarenteed single-line format	76	You can choose between the most compact guarenteed single-line format
60	possible (nice for simple line-based protocols), a pure-ascii format (for	77	possible (nice for simple line-based protocols), a pure-ascii format
61	when your transport is not 8-bit clean), or a pretty-printed format (for	78	(for when your transport is not 8-bit clean, still supports the whole
62	when you want to read that stuff). Or you can combine those features in	79	unicode range), or a pretty-printed format (for when you want to read that
63	whatever way you like.	80	stuff). Or you can combine those features in whatever way you like.
64		81
65	=back	82	=back
66		83
67	=cut	84	=cut
68		85
69	package JSON::XS;	86	package JSON::XS;
70		87
71	BEGIN {	88	use strict;
		89
72	$VERSION = '0.3';	90	our $VERSION = '1.4';
73	@ISA = qw(Exporter);	91	our @ISA = qw(Exporter);
74		92
75	@EXPORT = qw(to_json from_json);	93	our @EXPORT = qw(to_json from_json objToJson jsonToObj);
76	require Exporter;
77		94
78	require XSLoader;	95	use Exporter;
79	XSLoader::load JSON::XS::, $VERSION;	96	use XSLoader;
80	}
81		97
82	=head1 FUNCTIONAL INTERFACE	98	=head1 FUNCTIONAL INTERFACE
83		99
84	The following convinience methods are provided by this module. They are	100	The following convinience methods are provided by this module. They are
85	exported by default:	101	exported by default:
86		102
87	=over 4	103	=over 4
88		104
89	=item $json_string = to_json $perl_scalar	105	=item $json_text = to_json $perl_scalar
90		106
91	Converts the given Perl data structure (a simple scalar or a reference to	107	Converts the given Perl data structure (a simple scalar or a reference to
92	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains	108	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains
93	octets only). Croaks on error.	109	octets only). Croaks on error.
94		110
95	This function call is functionally identical to C<< JSON::XS->new->utf8->encode ($perl_scalar) >>.	111	This function call is functionally identical to:
96		112
		113	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)
		114
		115	except being faster.
		116
97	=item $perl_scalar = from_json $json_string	117	=item $perl_scalar = from_json $json_text
98		118
99	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to	119	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to
100	parse that as an UTF-8 encoded JSON string, returning the resulting simple	120	parse that as an UTF-8 encoded JSON text, returning the resulting simple
101	scalar or reference. Croaks on error.	121	scalar or reference. Croaks on error.
102		122
103	This function call is functionally identical to C<< JSON::XS->new->utf8->decode ($json_string) >>.	123	This function call is functionally identical to:
		124
		125	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
		126
		127	except being faster.
		128
		129	=item $is_boolean = JSON::XS::is_bool $scalar
		130
		131	Returns true if the passed scalar represents either JSON::XS::true or
		132	JSON::XS::false, two constants that act like C<1> and C<0>, respectively
		133	and are used to represent JSON C<true> and C<false> values in Perl.
		134
		135	See MAPPING, below, for more information on how JSON values are mapped to
		136	Perl.
104		137
105	=back	138	=back
		139
106		140
107	=head1 OBJECT-ORIENTED INTERFACE	141	=head1 OBJECT-ORIENTED INTERFACE
108		142
109	The object oriented interface lets you configure your own encoding or	143	The object oriented interface lets you configure your own encoding or
110	decoding style, within the limits of supported formats.	144	decoding style, within the limits of supported formats.
…		…
117	strings. All boolean flags described below are by default I<disabled>.	151	strings. All boolean flags described below are by default I<disabled>.
118		152
119	The mutators for flags all return the JSON object again and thus calls can	153	The mutators for flags all return the JSON object again and thus calls can
120	be chained:	154	be chained:
121		155
122	my $json = JSON::XS->new->utf8(1)->space_after(1)->encode ({a => [1,2]})	156	my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})
123	=> {"a": [1, 2]}	157	=> {"a": [1, 2]}
124		158
125	=item $json = $json->ascii ([$enable])	159	=item $json = $json->ascii ([$enable])
126		160
127	If C<$enable> is true (or missing), then the C<encode> method will	161	If C<$enable> is true (or missing), then the C<encode> method will not
128	not generate characters outside the code range C<0..127>. Any unicode	162	generate characters outside the code range C<0..127> (which is ASCII). Any
129	characters outside that range will be escaped using either a single	163	unicode characters outside that range will be escaped using either a
130	\uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, as per	164	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
131	RFC4627.	165	as per RFC4627. The resulting encoded JSON text can be treated as a native
		166	unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
		167	or any other superset of ASCII.
132		168
133	If C<$enable> is false, then the C<encode> method will not escape Unicode	169	If C<$enable> is false, then the C<encode> method will not escape Unicode
134	characters unless necessary.	170	characters unless required by the JSON syntax or other flags. This results
		171	in a faster and more compact format.
135		172
		173	The main use for this flag is to produce JSON texts that can be
		174	transmitted over a 7-bit channel, as the encoded JSON texts will not
		175	contain any 8 bit characters.
		176
136	JSON::XS->new->ascii (1)->encode (chr 0x10401)	177	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
137	=> \ud801\udc01	178	=> ["\ud801\udc01"]
		179
		180	=item $json = $json->latin1 ([$enable])
		181
		182	If C<$enable> is true (or missing), then the C<encode> method will encode
		183	the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
		184	outside the code range C<0..255>. The resulting string can be treated as a
		185	latin1-encoded JSON text or a native unicode string. The C<decode> method
		186	will not be affected in any way by this flag, as C<decode> by default
		187	expects unicode, which is a strict superset of latin1.
		188
		189	If C<$enable> is false, then the C<encode> method will not escape Unicode
		190	characters unless required by the JSON syntax or other flags.
		191
		192	The main use for this flag is efficiently encoding binary data as JSON
		193	text, as most octets will not be escaped, resulting in a smaller encoded
		194	size. The disadvantage is that the resulting JSON text is encoded
		195	in latin1 (and must correctly be treated as such when storing and
		196	transfering), a rare encoding for JSON. It is therefore most useful when
		197	you want to store data structures known to contain binary data efficiently
		198	in files or databases, not when talking to other JSON encoders/decoders.
		199
		200	JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
		201	=> ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
138		202
139	=item $json = $json->utf8 ([$enable])	203	=item $json = $json->utf8 ([$enable])
140		204
141	If C<$enable> is true (or missing), then the C<encode> method will encode	205	If C<$enable> is true (or missing), then the C<encode> method will encode
142	the JSON string into UTF-8, as required by many protocols, while the	206	the JSON result into UTF-8, as required by many protocols, while the
143	C<decode> method expects to be handled an UTF-8-encoded string. Please	207	C<decode> method expects to be handled an UTF-8-encoded string. Please
144	note that UTF-8-encoded strings do not contain any characters outside the	208	note that UTF-8-encoded strings do not contain any characters outside the
145	range C<0..255>, they are thus useful for bytewise/binary I/O.	209	range C<0..255>, they are thus useful for bytewise/binary I/O. In future
		210	versions, enabling this option might enable autodetection of the UTF-16
		211	and UTF-32 encoding families, as described in RFC4627.
146		212
147	If C<$enable> is false, then the C<encode> method will return the JSON	213	If C<$enable> is false, then the C<encode> method will return the JSON
148	string as a (non-encoded) unicode string, while C<decode> expects thus a	214	string as a (non-encoded) unicode string, while C<decode> expects thus a
149	unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs	215	unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs
150	to be done yourself, e.g. using the Encode module.	216	to be done yourself, e.g. using the Encode module.
151		217
		218	Example, output UTF-16BE-encoded JSON:
		219
		220	use Encode;
		221	$jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);
		222
		223	Example, decode UTF-32LE-encoded JSON:
		224
		225	use Encode;
		226	$object = JSON::XS->new->decode (decode "UTF-32LE", $jsontext);
		227
152	=item $json = $json->pretty ([$enable])	228	=item $json = $json->pretty ([$enable])
153		229
154	This enables (or disables) all of the C<indent>, C<space_before> and	230	This enables (or disables) all of the C<indent>, C<space_before> and
155	C<space_after> (and in the future possibly more) flags in one call to	231	C<space_after> (and in the future possibly more) flags in one call to
156	generate the most readable (or most compact) form possible.	232	generate the most readable (or most compact) form possible.
		233
		234	Example, pretty-print some simple structure:
157		235
158	my $json = JSON::XS->new->pretty(1)->encode ({a => [1,2]})	236	my $json = JSON::XS->new->pretty(1)->encode ({a => [1,2]})
159	=>	237	=>
160	{	238	{
161	"a" : [	239	"a" : [
…		…
169	If C<$enable> is true (or missing), then the C<encode> method will use a multiline	247	If C<$enable> is true (or missing), then the C<encode> method will use a multiline
170	format as output, putting every array member or object/hash key-value pair	248	format as output, putting every array member or object/hash key-value pair
171	into its own line, identing them properly.	249	into its own line, identing them properly.
172		250
173	If C<$enable> is false, no newlines or indenting will be produced, and the	251	If C<$enable> is false, no newlines or indenting will be produced, and the
174	resulting JSON strings is guarenteed not to contain any C<newlines>.	252	resulting JSON text is guarenteed not to contain any C<newlines>.
175		253
176	This setting has no effect when decoding JSON strings.	254	This setting has no effect when decoding JSON texts.
177		255
178	=item $json = $json->space_before ([$enable])	256	=item $json = $json->space_before ([$enable])
179		257
180	If C<$enable> is true (or missing), then the C<encode> method will add an extra	258	If C<$enable> is true (or missing), then the C<encode> method will add an extra
181	optional space before the C<:> separating keys from values in JSON objects.	259	optional space before the C<:> separating keys from values in JSON objects.
182		260
183	If C<$enable> is false, then the C<encode> method will not add any extra	261	If C<$enable> is false, then the C<encode> method will not add any extra
184	space at those places.	262	space at those places.
185		263
186	This setting has no effect when decoding JSON strings. You will also most	264	This setting has no effect when decoding JSON texts. You will also
187	likely combine this setting with C<space_after>.	265	most likely combine this setting with C<space_after>.
		266
		267	Example, space_before enabled, space_after and indent disabled:
		268
		269	{"key" :"value"}
188		270
189	=item $json = $json->space_after ([$enable])	271	=item $json = $json->space_after ([$enable])
190		272
191	If C<$enable> is true (or missing), then the C<encode> method will add an extra	273	If C<$enable> is true (or missing), then the C<encode> method will add an extra
192	optional space after the C<:> separating keys from values in JSON objects	274	optional space after the C<:> separating keys from values in JSON objects
…		…
194	members.	276	members.
195		277
196	If C<$enable> is false, then the C<encode> method will not add any extra	278	If C<$enable> is false, then the C<encode> method will not add any extra
197	space at those places.	279	space at those places.
198		280
199	This setting has no effect when decoding JSON strings.	281	This setting has no effect when decoding JSON texts.
		282
		283	Example, space_before and indent disabled, space_after enabled:
		284
		285	{"key": "value"}
200		286
201	=item $json = $json->canonical ([$enable])	287	=item $json = $json->canonical ([$enable])
202		288
203	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects	289	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
204	by sorting their keys. This is adding a comparatively high overhead.	290	by sorting their keys. This is adding a comparatively high overhead.
…		…
206	If C<$enable> is false, then the C<encode> method will output key-value	292	If C<$enable> is false, then the C<encode> method will output key-value
207	pairs in the order Perl stores them (which will likely change between runs	293	pairs in the order Perl stores them (which will likely change between runs
208	of the same script).	294	of the same script).
209		295
210	This option is useful if you want the same data structure to be encoded as	296	This option is useful if you want the same data structure to be encoded as
211	the same JSON string (given the same overall settings). If it is disabled,	297	the same JSON text (given the same overall settings). If it is disabled,
212	the same hash migh be encoded differently even if contains the same data,	298	the same hash migh be encoded differently even if contains the same data,
213	as key-value pairs have no inherent ordering in Perl.	299	as key-value pairs have no inherent ordering in Perl.
214		300
215	This setting has no effect when decoding JSON strings.	301	This setting has no effect when decoding JSON texts.
216		302
217	=item $json = $json->allow_nonref ([$enable])	303	=item $json = $json->allow_nonref ([$enable])
218		304
219	If C<$enable> is true (or missing), then the C<encode> method can convert a	305	If C<$enable> is true (or missing), then the C<encode> method can convert a
220	non-reference into its corresponding string, number or null JSON value,	306	non-reference into its corresponding string, number or null JSON value,
221	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON	307	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
222	values instead of croaking.	308	values instead of croaking.
223		309
224	If C<$enable> is false, then the C<encode> method will croak if it isn't	310	If C<$enable> is false, then the C<encode> method will croak if it isn't
225	passed an arrayref or hashref, as JSON strings must either be an object	311	passed an arrayref or hashref, as JSON texts must either be an object
226	or array. Likewise, C<decode> will croak if given something that is not a	312	or array. Likewise, C<decode> will croak if given something that is not a
227	JSON object or array.	313	JSON object or array.
228		314
		315	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,
		316	resulting in an invalid JSON text:
		317
		318	JSON::XS->new->allow_nonref->encode ("Hello, World!")
		319	=> "Hello, World!"
		320
		321	=item $json = $json->allow_blessed ([$enable])
		322
		323	If C<$enable> is true (or missing), then the C<encode> method will not
		324	barf when it encounters a blessed reference. Instead, the value of the
		325	B<convert_blessed> option will decide wether C<null> (C<convert_blessed>
		326	disabled or no C<to_json> method found) or a representation of the
		327	object (C<convert_blessed> enabled and C<to_json> method found) is being
		328	encoded. Has no effect on C<decode>.
		329
		330	If C<$enable> is false (the default), then C<encode> will throw an
		331	exception when it encounters a blessed object.
		332
		333	=item $json = $json->convert_blessed ([$enable])
		334
		335	If C<$enable> is true (or missing), then C<encode>, upon encountering a
		336	blessed object, will check for the availability of the C<TO_JSON> method
		337	on the object's class. If found, it will be called in scalar context
		338	and the resulting scalar will be encoded instead of the object. If no
		339	C<TO_JSON> method is found, the value of C<allow_blessed> will decide what
		340	to do.
		341
		342	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
		343	returns other blessed objects, those will be handled in the same
		344	way. C<TO_JSON> must take care of not causing an endless recursion cycle
		345	(== crash) in this case. The name of C<TO_JSON> was chosen because other
		346	methods called by the Perl core (== not the user of the object) are
		347	usually in upper case letters and to avoid collisions with the C<to_json>
		348	function.
		349
		350	This setting does not yet influence C<decode> in any way, but in the
		351	future, global hooks might get installed that influence C<decode> and are
		352	enabled by this setting.
		353
		354	If C<$enable> is false, then the C<allow_blessed> setting will decide what
		355	to do when a blessed object is found.
		356
229	=item $json = $json->shrink ([$enable])	357	=item $json = $json->shrink ([$enable])
230		358
231	Perl usually over-allocates memory a bit when allocating space for	359	Perl usually over-allocates memory a bit when allocating space for
232	strings. This flag optionally resizes strings generated by either	360	strings. This flag optionally resizes strings generated by either
233	C<encode> or C<decode> to their minimum size possible. This can save	361	C<encode> or C<decode> to their minimum size possible. This can save
234	memory when your JSON strings are either very very long or you have many	362	memory when your JSON texts are either very very long or you have many
235	short strings. It will also try to downgrade any strings to octet-form	363	short strings. It will also try to downgrade any strings to octet-form
236	if possible: perl stores strings internally either in an encoding called	364	if possible: perl stores strings internally either in an encoding called
237	UTF-X or in octet-form. The latter cannot store everything but uses less	365	UTF-X or in octet-form. The latter cannot store everything but uses less
238	space in general.	366	space in general (and some buggy Perl or C code might even rely on that
		367	internal representation being used).
239		368
		369	The actual definition of what shrink does might change in future versions,
		370	but it will always try to save space at the expense of time.
		371
240	If C<$enable> is true (or missing), the string returned by C<encode> will be shrunk-to-fit,	372	If C<$enable> is true (or missing), the string returned by C<encode> will
241	while all strings generated by C<decode> will also be shrunk-to-fit.	373	be shrunk-to-fit, while all strings generated by C<decode> will also be
		374	shrunk-to-fit.
242		375
243	If C<$enable> is false, then the normal perl allocation algorithms are used.	376	If C<$enable> is false, then the normal perl allocation algorithms are used.
244	If you work with your data, then this is likely to be faster.	377	If you work with your data, then this is likely to be faster.
245		378
246	In the future, this setting might control other things, such as converting	379	In the future, this setting might control other things, such as converting
247	strings that look like integers or floats into integers or floats	380	strings that look like integers or floats into integers or floats
248	internally (there is no difference on the Perl level), saving space.	381	internally (there is no difference on the Perl level), saving space.
249		382
		383	=item $json = $json->max_depth ([$maximum_nesting_depth])
		384
		385	Sets the maximum nesting level (default C<512>) accepted while encoding
		386	or decoding. If the JSON text or Perl data structure has an equal or
		387	higher nesting level then this limit, then the encoder and decoder will
		388	stop and croak at that point.
		389
		390	Nesting level is defined by number of hash- or arrayrefs that the encoder
		391	needs to traverse to reach a given point or the number of C<{> or C<[>
		392	characters without their matching closing parenthesis crossed to reach a
		393	given character in a string.
		394
		395	Setting the maximum depth to one disallows any nesting, so that ensures
		396	that the object is only a single hash/object or array.
		397
		398	The argument to C<max_depth> will be rounded up to the next nearest power
		399	of two.
		400
		401	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
		402
250	=item $json_string = $json->encode ($perl_scalar)	403	=item $json_text = $json->encode ($perl_scalar)
251		404
252	Converts the given Perl data structure (a simple scalar or a reference	405	Converts the given Perl data structure (a simple scalar or a reference
253	to a hash or array) to its JSON representation. Simple scalars will be	406	to a hash or array) to its JSON representation. Simple scalars will be
254	converted into JSON string or number sequences, while references to arrays	407	converted into JSON string or number sequences, while references to arrays
255	become JSON arrays and references to hashes become JSON objects. Undefined	408	become JSON arrays and references to hashes become JSON objects. Undefined
256	Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>	409	Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>
257	nor C<false> values will be generated.	410	nor C<false> values will be generated.
258		411
259	=item $perl_scalar = $json->decode ($json_string)	412	=item $perl_scalar = $json->decode ($json_text)
260		413
261	The opposite of C<encode>: expects a JSON string and tries to parse it,	414	The opposite of C<encode>: expects a JSON text and tries to parse it,
262	returning the resulting simple scalar or reference. Croaks on error.	415	returning the resulting simple scalar or reference. Croaks on error.
263		416
264	JSON numbers and strings become simple Perl scalars. JSON arrays become	417	JSON numbers and strings become simple Perl scalars. JSON arrays become
265	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes	418	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
266	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.	419	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
267		420
		421	=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
		422
		423	This works like the C<decode> method, but instead of raising an exception
		424	when there is trailing garbage after the first JSON object, it will
		425	silently stop parsing there and return the number of characters consumed
		426	so far.
		427
		428	This is useful if your JSON texts are not delimited by an outer protocol
		429	(which is not the brightest thing to do in the first place) and you need
		430	to know where the JSON text ends.
		431
		432	JSON::XS->new->decode_prefix ("[1] the tail")
		433	=> ([], 3)
		434
268	=back	435	=back
		436
269		437
270	=head1 MAPPING	438	=head1 MAPPING
271		439
272	This section describes how JSON::XS maps Perl values to JSON values and	440	This section describes how JSON::XS maps Perl values to JSON values and
273	vice versa. These mappings are designed to "do the right thing" in most	441	vice versa. These mappings are designed to "do the right thing" in most
…		…
276		444
277	For the more enlightened: note that in the following descriptions,	445	For the more enlightened: note that in the following descriptions,
278	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>	446	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
279	refers to the abstract Perl language itself.	447	refers to the abstract Perl language itself.
280		448
		449
281	=head2 JSON -> PERL	450	=head2 JSON -> PERL
282		451
283	=over 4	452	=over 4
284		453
285	=item object	454	=item object
286		455
287	A JSON object becomes a reference to a hash in Perl. No ordering of object	456	A JSON object becomes a reference to a hash in Perl. No ordering of object
288	keys is preserved.	457	keys is preserved (JSON does not preserver object key ordering itself).
289		458
290	=item array	459	=item array
291		460
292	A JSON array becomes a reference to an array in Perl.	461	A JSON array becomes a reference to an array in Perl.
293		462
…		…
305	conversion details, but an integer may take slightly less memory and might	474	conversion details, but an integer may take slightly less memory and might
306	represent more values exactly than (floating point) numbers.	475	represent more values exactly than (floating point) numbers.
307		476
308	=item true, false	477	=item true, false
309		478
310	These JSON atoms become C<0>, C<1>, respectively. Information is lost in	479	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
311	this process. Future versions might represent those values differently,	480	respectively. They are overloaded to act almost exactly like the numbers
312	but they will be guarenteed to act like these integers would normally in	481	C<1> and C<0>. You can check wether a scalar is a JSON boolean by using
313	Perl.	482	the C<JSON::XS::is_bool> function.
314		483
315	=item null	484	=item null
316		485
317	A JSON null atom becomes C<undef> in Perl.	486	A JSON null atom becomes C<undef> in Perl.
318		487
319	=back	488	=back
		489
320		490
321	=head2 PERL -> JSON	491	=head2 PERL -> JSON
322		492
323	The mapping from Perl to JSON is slightly more difficult, as Perl is a	493	The mapping from Perl to JSON is slightly more difficult, as Perl is a
324	truly typeless language, so we can only guess which JSON type is meant by	494	truly typeless language, so we can only guess which JSON type is meant by
…		…
327	=over 4	497	=over 4
328		498
329	=item hash references	499	=item hash references
330		500
331	Perl hash references become JSON objects. As there is no inherent ordering	501	Perl hash references become JSON objects. As there is no inherent ordering
332	in hash keys, they will usually be encoded in a pseudo-random order that	502	in hash keys (or JSON objects), they will usually be encoded in a
333	can change between runs of the same program but stays generally the same	503	pseudo-random order that can change between runs of the same program but
334	within the single run of a program. JSON::XS can optionally sort the hash	504	stays generally the same within a single run of a program. JSON::XS can
335	keys (determined by the I<canonical> flag), so the same datastructure	505	optionally sort the hash keys (determined by the I<canonical> flag), so
336	will serialise to the same JSON text (given same settings and version of	506	the same datastructure will serialise to the same JSON text (given same
337	JSON::XS), but this incurs a runtime overhead.	507	settings and version of JSON::XS), but this incurs a runtime overhead
		508	and is only rarely useful, e.g. when you want to compare some JSON text
		509	against another for equality.
338		510
339	=item array references	511	=item array references
340		512
341	Perl array references become JSON arrays.	513	Perl array references become JSON arrays.
		514
		515	=item other references
		516
		517	Other unblessed references are generally not allowed and will cause an
		518	exception to be thrown, except for references to the integers C<0> and
		519	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
		520	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
		521
		522	to_json [\0,JSON::XS::true] # yields [false,true]
		523
		524	=item JSON::XS::true, JSON::XS::false
		525
		526	These special values become JSON true and JSON false values,
		527	respectively. You cna alos use C<\1> and C<\0> directly if you want.
342		528
343	=item blessed objects	529	=item blessed objects
344		530
345	Blessed objects are not allowed. JSON::XS currently tries to encode their	531	Blessed objects are not allowed. JSON::XS currently tries to encode their
346	underlying representation (hash- or arrayref), but this behaviour might	532	underlying representation (hash- or arrayref), but this behaviour might
…		…
379	$x *= 1; # same thing, the choise is yours.	565	$x *= 1; # same thing, the choise is yours.
380		566
381	You can not currently output JSON booleans or force the type in other,	567	You can not currently output JSON booleans or force the type in other,
382	less obscure, ways. Tell me if you need this capability.	568	less obscure, ways. Tell me if you need this capability.
383		569
384	=item circular data structures
385
386	Those will be encoded until memory or stackspace runs out.
387
388	=back	570	=back
		571
389		572
390	=head1 COMPARISON	573	=head1 COMPARISON
391		574
392	As already mentioned, this module was created because none of the existing	575	As already mentioned, this module was created because none of the existing
393	JSON modules could be made to work correctly. First I will describe the	576	JSON modules could be made to work correctly. First I will describe the
…		…
419		602
420	Has problems handling many Perl values (e.g. regex results and other magic	603	Has problems handling many Perl values (e.g. regex results and other magic
421	values will make it croak).	604	values will make it croak).
422		605
423	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>	606	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>
424	which is not a valid JSON string.	607	which is not a valid JSON text.
425		608
426	Unmaintained (maintainer unresponsive for many months, bugs are not	609	Unmaintained (maintainer unresponsive for many months, bugs are not
427	getting fixed).	610	getting fixed).
428		611
429	=item JSON::Syck 0.21	612	=item JSON::Syck 0.21
…		…
431	Very buggy (often crashes).	614	Very buggy (often crashes).
432		615
433	Very inflexible (no human-readable format supported, format pretty much	616	Very inflexible (no human-readable format supported, format pretty much
434	undocumented. I need at least a format for easy reading by humans and a	617	undocumented. I need at least a format for easy reading by humans and a
435	single-line compact format for use in a protocol, and preferably a way to	618	single-line compact format for use in a protocol, and preferably a way to
436	generate ASCII-only JSON strings).	619	generate ASCII-only JSON texts).
437		620
438	Completely broken (and confusingly documented) Unicode handling (unicode	621	Completely broken (and confusingly documented) Unicode handling (unicode
439	escapes are not working properly, you need to set ImplicitUnicode to	622	escapes are not working properly, you need to set ImplicitUnicode to
440	I<different> values on en- and decoding to get symmetric behaviour).	623	I<different> values on en- and decoding to get symmetric behaviour).
441		624
…		…
464		647
465	Very inflexible.	648	Very inflexible.
466		649
467	No roundtripping.	650	No roundtripping.
468		651
469	Does not generate valid JSON (key strings are often unquoted, empty keys	652	Does not generate valid JSON texts (key strings are often unquoted, empty keys
470	result in nothing being output)	653	result in nothing being output)
471		654
472	Does not check input for validity.	655	Does not check input for validity.
473		656
474	=back	657	=back
		658
		659
		660	=head2 JSON and YAML
		661
		662	You often hear that JSON is a subset (or a close subset) of YAML. This is,
		663	however, a mass hysteria and very far from the truth. In general, there is
		664	no way to configure JSON::XS to output a data structure as valid YAML.
		665
		666	If you really must use JSON::XS to generate YAML, you should use this
		667	algorithm (subject to change in future versions):
		668
		669	my $to_yaml = JSON::XS->new->utf8->space_after (1);
		670	my $yaml = $to_yaml->encode ($ref) . "\n";
		671
		672	This will usually generate JSON texts that also parse as valid
		673	YAML. Please note that YAML has hardcoded limits on (simple) object key
		674	lengths that JSON doesn't have, so you should make sure that your hash
		675	keys are noticably shorter than the 1024 characters YAML allows.
		676
		677	There might be other incompatibilities that I am not aware of. In general
		678	you should not try to generate YAML with a JSON generator or vice versa,
		679	or try to parse JSON with a YAML parser or vice versa: chances are high
		680	that you will run into severe interoperability problems.
		681
475		682
476	=head2 SPEED	683	=head2 SPEED
477		684
478	It seems that JSON::XS is surprisingly fast, as shown in the following	685	It seems that JSON::XS is surprisingly fast, as shown in the following
479	tables. They have been generated with the help of the C<eg/bench> program	686	tables. They have been generated with the help of the C<eg/bench> program
480	in the JSON::XS distribution, to make it easy to compare on your own	687	in the JSON::XS distribution, to make it easy to compare on your own
481	system.	688	system.
482		689
483	First is a comparison between various modules using a very simple JSON	690	First comes a comparison between various modules using a very short
		691	single-line JSON string:
		692
		693	{"method": "handleMessage", "params": ["user1", "we were just talking"], \
		694	"id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
		695
484	string, showing the number of encodes/decodes per second (JSON::XS is	696	It shows the number of encodes/decodes per second (JSON::XS uses
485	the functional interface, while JSON::XS/2 is the OO interface with	697	the functional interface, while JSON::XS/2 uses the OO interface
486	pretty-printing and hashkey sorting enabled).	698	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
		699	shrink). Higher is better:
487		700
488	module \| encode \| decode \|	701	module \| encode \| decode \|
489	-----------\|------------\|------------\|	702	-----------\|------------\|------------\|
490	JSON \| 14006 \| 6820 \|	703	JSON \| 7645.468 \| 4208.613 \|
491	JSON::DWIW \| 200937 \| 120386 \|	704	JSON::DWIW \| 40721.398 \| 77101.176 \|
492	JSON::PC \| 85065 \| 129366 \|	705	JSON::PC \| 65948.176 \| 78251.940 \|
493	JSON::Syck \| 59898 \| 44232 \|	706	JSON::Syck \| 22844.793 \| 26479.192 \|
494	JSON::XS \| 1171478 \| 342435 \|	707	JSON::XS \| 388361.481 \| 199728.762 \|
495	JSON::XS/2 \| 730760 \| 328714 \|	708	JSON::XS/2 \| 218453.333 \| 192399.266 \|
		709	JSON::XS/3 \| 338250.323 \| 192399.266 \|
		710	Storable \| 15779.925 \| 14169.946 \|
496	-----------+------------+------------+	711	-----------+------------+------------+
497		712
498	That is, JSON::XS is 6 times faster than than JSON::DWIW and about 80	713	That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
		714	about three times faster on decoding, and over fourty times faster
499	times faster than JSON, even with pretty-printing and key sorting.	715	than JSON, even with pretty-printing and key sorting. It also compares
		716	favourably to Storable for small amounts of data.
500		717
501	Using a longer test string (roughly 8KB, generated from Yahoo! Locals	718	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
502	search API (http://nanoref.com/yahooapis/mgPdGg):	719	search API (http://nanoref.com/yahooapis/mgPdGg):
503		720
504	module \| encode \| decode \|	721	module \| encode \| decode \|
505	-----------\|------------\|------------\|	722	-----------\|------------\|------------\|
506	JSON \| 673 \| 38 \|	723	JSON \| 254.685 \| 37.665 \|
507	JSON::DWIW \| 5271 \| 770 \|	724	JSON::DWIW \| 843.343 \| 1049.731 \|
508	JSON::PC \| 9901 \| 2491 \|	725	JSON::PC \| 3602.116 \| 2307.352 \|
509	JSON::Syck \| 2360 \| 786 \|	726	JSON::Syck \| 505.107 \| 787.899 \|
510	JSON::XS \| 37398 \| 3202 \|	727	JSON::XS \| 5747.196 \| 3690.220 \|
511	JSON::XS/2 \| 13765 \| 3153 \|	728	JSON::XS/2 \| 3968.121 \| 3676.634 \|
		729	JSON::XS/3 \| 6105.246 \| 3662.508 \|
		730	Storable \| 4417.337 \| 5285.161 \|
512	-----------+------------+------------+	731	-----------+------------+------------+
513		732
514	Again, JSON::XS leads by far in the encoding case, while still beating	733	Again, JSON::XS leads by far (except for Storable which non-surprisingly
515	every other module in the decoding case.	734	decodes faster).
516		735
517	Last example is an almost 8MB large hash with many large binary values	736	On large strings containing lots of high unicode characters, some modules
518	(PNG files), resulting in a lot of escaping:	737	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
		738	will be broken due to missing (or wrong) unicode handling. Others refuse
		739	to decode or encode properly, so it was impossible to prepare a fair
		740	comparison table for that case.
519		741
520	=head1 RESOURCE LIMITS
521		742
522	JSON::XS does not impose any limits on the size of JSON texts or Perl	743	=head1 SECURITY CONSIDERATIONS
523	values they represent - if your machine cna handle it, JSON::XS will	744
524	encode or decode it. Future versions might optionally impose structure	745	When you are using JSON in a protocol, talking to untrusted potentially
525	depth and memory use resource limits.	746	hostile creatures requires relatively few measures.
		747
		748	First of all, your JSON decoder should be secure, that is, should not have
		749	any buffer overflows. Obviously, this module should ensure that and I am
		750	trying hard on making that true, but you never know.
		751
		752	Second, you need to avoid resource-starving attacks. That means you should
		753	limit the size of JSON texts you accept, or make sure then when your
		754	resources run out, thats just fine (e.g. by using a separate process that
		755	can crash safely). The size of a JSON text in octets or characters is
		756	usually a good indication of the size of the resources required to decode
		757	it into a Perl structure.
		758
		759	Third, JSON::XS recurses using the C stack when decoding objects and
		760	arrays. The C stack is a limited resource: for instance, on my amd64
		761	machine with 8MB of stack size I can decode around 180k nested arrays but
		762	only 14k nested JSON objects (due to perl itself recursing deeply on croak
		763	to free the temporary). If that is exceeded, the program crashes. to be
		764	conservative, the default nesting limit is set to 512. If your process
		765	has a smaller stack, you should adjust this setting accordingly with the
		766	C<max_depth> method.
		767
		768	And last but least, something else could bomb you that I forgot to think
		769	of. In that case, you get to keep the pieces. I am always open for hints,
		770	though...
		771
		772	If you are using JSON::XS to return packets to consumption
		773	by javascript scripts in a browser you should have a look at
		774	L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether
		775	you are vulnerable to some common attack vectors (which really are browser
		776	design bugs, but it is still you who will have to deal with it, as major
		777	browser developers care only for features, not about doing security
		778	right).
		779
526		780
527	=head1 BUGS	781	=head1 BUGS
528		782
529	While the goal of this module is to be correct, that unfortunately does	783	While the goal of this module is to be correct, that unfortunately does
530	not mean its bug-free, only that I think its design is bug-free. It is	784	not mean its bug-free, only that I think its design is bug-free. It is
531	still very young and not well-tested. If you keep reporting bugs they will	785	still relatively early in its development. If you keep reporting bugs they
532	be fixed swiftly, though.	786	will be fixed swiftly, though.
533		787
534	=cut	788	=cut
		789
		790	our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
		791	our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };
		792
		793	sub true() { $true }
		794	sub false() { $false }
		795
		796	sub is_bool($) {
		797	UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
		798	# or UNIVERSAL::isa $_[0], "JSON::Literal"
		799	}
		800
		801	XSLoader::load "JSON::XS", $VERSION;
		802
		803	package JSON::XS::Boolean;
		804
		805	use overload
		806	"0+" => sub { ${$_[0]} },
		807	"++" => sub { $_[0] = ${$_[0]} + 1 },
		808	"--" => sub { $_[0] = ${$_[0]} - 1 },
		809	fallback => 1;
535		810
536	1;	811	1;
537		812
538	=head1 AUTHOR	813	=head1 AUTHOR
539		814

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Comparing JSON-XS/XS.pm (file contents): Revision 1.11 by root, Fri Mar 23 17:48:59 2007 UTC vs. Revision 1.45 by root, Mon Jun 25 04:16:46 2007 UTC

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Revision 1.11 by root, Fri Mar 23 17:48:59 2007 UTC vs.
Revision 1.45 by root, Mon Jun 25 04:16:46 2007 UTC