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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.15 by root, Sat Mar 24 01:15:22 2007 UTC vs.
Revision 1.43 by root, Sat Jun 23 23:49:29 2007 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use JSON::XS;	7	use JSON::XS;
8		8
9	# exported functions, croak on error	9	# exported functions, they croak on error
		10	# and expect/generate UTF-8
10		11
11	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;	12	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;
12	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;	13	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;
13		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
14	# oo-interface	19	# OO-interface
15		20
16	$coder = JSON::XS->new->ascii->pretty->allow_nonref;	21	$coder = JSON::XS->new->ascii->pretty->allow_nonref;
17	$pretty_printed_unencoded = $coder->encode ($perl_scalar);	22	$pretty_printed_unencoded = $coder->encode ($perl_scalar);
18	$perl_scalar = $coder->decode ($unicode_json_text);	23	$perl_scalar = $coder->decode ($unicode_json_text);
19		24
…		…
36		41
37	=head2 FEATURES	42	=head2 FEATURES
38		43
39	=over 4	44	=over 4
40		45
41	=item * correct handling of unicode issues	46	=item * correct unicode handling
42		47
43	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
44	it does so.	49	it does so.
45		50
46	=item * round-trip integrity	51	=item * round-trip integrity
47		52
48	When you serialise a perl data structure using only datatypes supported	53	When you serialise a perl data structure using only datatypes supported
49	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.
50	(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).
51		57
52	=item * strict checking of JSON correctness	58	=item * strict checking of JSON correctness
53		59
54	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,
55	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
56	feature).	62	feature).
57		63
58	=item * fast	64	=item * fast
59		65
…		…
66	interface.	72	interface.
67		73
68	=item * reasonably versatile output formats	74	=item * reasonably versatile output formats
69		75
70	You can choose between the most compact guarenteed single-line format	76	You can choose between the most compact guarenteed single-line format
71	possible (nice for simple line-based protocols), a pure-ascii format (for	77	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	78	(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	79	unicode range), or a pretty-printed format (for when you want to read that
74	whatever way you like.	80	stuff). Or you can combine those features in whatever way you like.
75		81
76	=back	82	=back
77		83
78	=cut	84	=cut
79		85
80	package JSON::XS;	86	package JSON::XS;
81		87
82	BEGIN {	88	use strict;
		89
83	$VERSION = '0.31';	90	our $VERSION = '1.3';
84	@ISA = qw(Exporter);	91	our @ISA = qw(Exporter);
85		92
86	@EXPORT = qw(to_json from_json);	93	our @EXPORT = qw(to_json from_json objToJson jsonToObj);
87	require Exporter;
88		94
89	require XSLoader;	95	use Exporter;
90	XSLoader::load JSON::XS::, $VERSION;	96	use XSLoader;
91	}
92		97
93	=head1 FUNCTIONAL INTERFACE	98	=head1 FUNCTIONAL INTERFACE
94		99
95	The following convinience methods are provided by this module. They are	100	The following convinience methods are provided by this module. They are
96	exported by default:	101	exported by default:
97		102
98	=over 4	103	=over 4
99		104
100	=item $json_string = to_json $perl_scalar	105	=item $json_text = to_json $perl_scalar
101		106
102	Converts the given Perl data structure (a simple scalar or a reference to	107	Converts the given Perl data structure (a simple scalar or a reference to
103	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains	108	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains
104	octets only). Croaks on error.	109	octets only). Croaks on error.
105		110
106	This function call is functionally identical to C<< JSON::XS->new->utf8->encode ($perl_scalar) >>.	111	This function call is functionally identical to:
107		112
		113	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)
		114
		115	except being faster.
		116
108	=item $perl_scalar = from_json $json_string	117	=item $perl_scalar = from_json $json_text
109		118
110	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to	119	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to
111	parse that as an UTF-8 encoded JSON string, returning the resulting simple	120	parse that as an UTF-8 encoded JSON text, returning the resulting simple
112	scalar or reference. Croaks on error.	121	scalar or reference. Croaks on error.
113		122
114	This function call is functionally identical to C<< JSON::XS->new->utf8->decode ($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.
115		137
116	=back	138	=back
		139
117		140
118	=head1 OBJECT-ORIENTED INTERFACE	141	=head1 OBJECT-ORIENTED INTERFACE
119		142
120	The object oriented interface lets you configure your own encoding or	143	The object oriented interface lets you configure your own encoding or
121	decoding style, within the limits of supported formats.	144	decoding style, within the limits of supported formats.
…		…
128	strings. All boolean flags described below are by default I<disabled>.	151	strings. All boolean flags described below are by default I<disabled>.
129		152
130	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
131	be chained:	154	be chained:
132		155
133	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]})
134	=> {"a": [1, 2]}	157	=> {"a": [1, 2]}
135		158
136	=item $json = $json->ascii ([$enable])	159	=item $json = $json->ascii ([$enable])
137		160
138	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
139	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
140	characters outside that range will be escaped using either a single	163	unicode characters outside that range will be escaped using either a
141	\uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, as per	164	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
142	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.
143		168
144	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
145	characters unless necessary.	170	characters unless required by the JSON syntax or other flags. This results
		171	in a faster and more compact format.
146		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
147	JSON::XS->new->ascii (1)->encode (chr 0x10401)	177	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
148	=> \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)
149		202
150	=item $json = $json->utf8 ([$enable])	203	=item $json = $json->utf8 ([$enable])
151		204
152	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
153	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
154	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
155	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
156	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.
157		212
158	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
159	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
160	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
161	to be done yourself, e.g. using the Encode module.	216	to be done yourself, e.g. using the Encode module.
162		217
163	Example, output UTF-16-encoded JSON:	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);
164		227
165	=item $json = $json->pretty ([$enable])	228	=item $json = $json->pretty ([$enable])
166		229
167	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
168	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
…		…
184	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
185	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
186	into its own line, identing them properly.	249	into its own line, identing them properly.
187		250
188	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
189	resulting JSON strings is guarenteed not to contain any C<newlines>.	252	resulting JSON text is guarenteed not to contain any C<newlines>.
190		253
191	This setting has no effect when decoding JSON strings.	254	This setting has no effect when decoding JSON texts.
192		255
193	=item $json = $json->space_before ([$enable])	256	=item $json = $json->space_before ([$enable])
194		257
195	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
196	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.
197		260
198	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
199	space at those places.	262	space at those places.
200		263
201	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
202	likely combine this setting with C<space_after>.	265	most likely combine this setting with C<space_after>.
203		266
204	Example, space_before enabled, space_after and indent disabled:	267	Example, space_before enabled, space_after and indent disabled:
205		268
206	{"key" :"value"}	269	{"key" :"value"}
207		270
…		…
213	members.	276	members.
214		277
215	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
216	space at those places.	279	space at those places.
217		280
218	This setting has no effect when decoding JSON strings.	281	This setting has no effect when decoding JSON texts.
219		282
220	Example, space_before and indent disabled, space_after enabled:	283	Example, space_before and indent disabled, space_after enabled:
221		284
222	{"key": "value"}	285	{"key": "value"}
223		286
…		…
229	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
230	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
231	of the same script).	294	of the same script).
232		295
233	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
234	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,
235	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,
236	as key-value pairs have no inherent ordering in Perl.	299	as key-value pairs have no inherent ordering in Perl.
237		300
238	This setting has no effect when decoding JSON strings.	301	This setting has no effect when decoding JSON texts.
239		302
240	=item $json = $json->allow_nonref ([$enable])	303	=item $json = $json->allow_nonref ([$enable])
241		304
242	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
243	non-reference into its corresponding string, number or null JSON value,	306	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	307	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
245	values instead of croaking.	308	values instead of croaking.
246		309
247	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
248	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
249	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
250	JSON object or array.	313	JSON object or array.
251		314
252	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,	315	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,
253	resulting in an invalid JSON text:	316	resulting in an invalid JSON text:
…		…
256	=> "Hello, World!"	319	=> "Hello, World!"
257		320
258	=item $json = $json->shrink ([$enable])	321	=item $json = $json->shrink ([$enable])
259		322
260	Perl usually over-allocates memory a bit when allocating space for	323	Perl usually over-allocates memory a bit when allocating space for
261	strings. This flag optionally resizes strings generated by either	324	strings. This flag optionally resizes strings generated by either
262	C<encode> or C<decode> to their minimum size possible. This can save	325	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	326	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	327	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	328	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	329	UTF-X or in octet-form. The latter cannot store everything but uses less
267	space in general.	330	space in general (and some buggy Perl or C code might even rely on that
		331	internal representation being used).
268		332
		333	The actual definition of what shrink does might change in future versions,
		334	but it will always try to save space at the expense of time.
		335
269	If C<$enable> is true (or missing), the string returned by C<encode> will be shrunk-to-fit,	336	If C<$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.	337	be shrunk-to-fit, while all strings generated by C<decode> will also be
		338	shrunk-to-fit.
271		339
272	If C<$enable> is false, then the normal perl allocation algorithms are used.	340	If C<$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.	341	If you work with your data, then this is likely to be faster.
274		342
275	In the future, this setting might control other things, such as converting	343	In the future, this setting might control other things, such as converting
276	strings that look like integers or floats into integers or floats	344	strings that look like integers or floats into integers or floats
277	internally (there is no difference on the Perl level), saving space.	345	internally (there is no difference on the Perl level), saving space.
278		346
		347	=item $json = $json->max_depth ([$maximum_nesting_depth])
		348
		349	Sets the maximum nesting level (default C<512>) accepted while encoding
		350	or decoding. If the JSON text or Perl data structure has an equal or
		351	higher nesting level then this limit, then the encoder and decoder will
		352	stop and croak at that point.
		353
		354	Nesting level is defined by number of hash- or arrayrefs that the encoder
		355	needs to traverse to reach a given point or the number of C<{> or C<[>
		356	characters without their matching closing parenthesis crossed to reach a
		357	given character in a string.
		358
		359	Setting the maximum depth to one disallows any nesting, so that ensures
		360	that the object is only a single hash/object or array.
		361
		362	The argument to C<max_depth> will be rounded up to the next nearest power
		363	of two.
		364
		365	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
		366
279	=item $json_string = $json->encode ($perl_scalar)	367	=item $json_text = $json->encode ($perl_scalar)
280		368
281	Converts the given Perl data structure (a simple scalar or a reference	369	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	370	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	371	converted into JSON string or number sequences, while references to arrays
284	become JSON arrays and references to hashes become JSON objects. Undefined	372	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>	373	Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>
286	nor C<false> values will be generated.	374	nor C<false> values will be generated.
287		375
288	=item $perl_scalar = $json->decode ($json_string)	376	=item $perl_scalar = $json->decode ($json_text)
289		377
290	The opposite of C<encode>: expects a JSON string and tries to parse it,	378	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.	379	returning the resulting simple scalar or reference. Croaks on error.
292		380
293	JSON numbers and strings become simple Perl scalars. JSON arrays become	381	JSON numbers and strings become simple Perl scalars. JSON arrays become
294	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes	382	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>.	383	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
296		384
		385	=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
		386
		387	This works like the C<decode> method, but instead of raising an exception
		388	when there is trailing garbage after the first JSON object, it will
		389	silently stop parsing there and return the number of characters consumed
		390	so far.
		391
		392	This is useful if your JSON texts are not delimited by an outer protocol
		393	(which is not the brightest thing to do in the first place) and you need
		394	to know where the JSON text ends.
		395
		396	JSON::XS->new->decode_prefix ("[1] the tail")
		397	=> ([], 3)
		398
297	=back	399	=back
		400
298		401
299	=head1 MAPPING	402	=head1 MAPPING
300		403
301	This section describes how JSON::XS maps Perl values to JSON values and	404	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	405	vice versa. These mappings are designed to "do the right thing" in most
…		…
304	(what you put in comes out as something equivalent).	407	(what you put in comes out as something equivalent).
305		408
306	For the more enlightened: note that in the following descriptions,	409	For the more enlightened: note that in the following descriptions,
307	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>	410	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
308	refers to the abstract Perl language itself.	411	refers to the abstract Perl language itself.
		412
309		413
310	=head2 JSON -> PERL	414	=head2 JSON -> PERL
311		415
312	=over 4	416	=over 4
313		417
…		…
334	conversion details, but an integer may take slightly less memory and might	438	conversion details, but an integer may take slightly less memory and might
335	represent more values exactly than (floating point) numbers.	439	represent more values exactly than (floating point) numbers.
336		440
337	=item true, false	441	=item true, false
338		442
339	These JSON atoms become C<0>, C<1>, respectively. Information is lost in	443	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
340	this process. Future versions might represent those values differently,	444	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	445	C<1> and C<0>. You can check wether a scalar is a JSON boolean by using
342	Perl.	446	the C<JSON::XS::is_bool> function.
343		447
344	=item null	448	=item null
345		449
346	A JSON null atom becomes C<undef> in Perl.	450	A JSON null atom becomes C<undef> in Perl.
347		451
348	=back	452	=back
		453
349		454
350	=head2 PERL -> JSON	455	=head2 PERL -> JSON
351		456
352	The mapping from Perl to JSON is slightly more difficult, as Perl is a	457	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	458	truly typeless language, so we can only guess which JSON type is meant by
…		…
356	=over 4	461	=over 4
357		462
358	=item hash references	463	=item hash references
359		464
360	Perl hash references become JSON objects. As there is no inherent ordering	465	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	466	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	467	pseudo-random order that can change between runs of the same program but
363	within a single run of a program. JSON::XS can optionally sort the hash	468	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	469	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	470	the same datastructure will serialise to the same JSON text (given same
366	JSON::XS), but this incurs a runtime overhead.	471	settings and version of JSON::XS), but this incurs a runtime overhead
		472	and is only rarely useful, e.g. when you want to compare some JSON text
		473	against another for equality.
367		474
368	=item array references	475	=item array references
369		476
370	Perl array references become JSON arrays.	477	Perl array references become JSON arrays.
		478
		479	=item other references
		480
		481	Other unblessed references are generally not allowed and will cause an
		482	exception to be thrown, except for references to the integers C<0> and
		483	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
		484	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
		485
		486	to_json [\0,JSON::XS::true] # yields [false,true]
		487
		488	=item JSON::XS::true, JSON::XS::false
		489
		490	These special values become JSON true and JSON false values,
		491	respectively. You cna alos use C<\1> and C<\0> directly if you want.
371		492
372	=item blessed objects	493	=item blessed objects
373		494
374	Blessed objects are not allowed. JSON::XS currently tries to encode their	495	Blessed objects are not allowed. JSON::XS currently tries to encode their
375	underlying representation (hash- or arrayref), but this behaviour might	496	underlying representation (hash- or arrayref), but this behaviour might
…		…
408	$x *= 1; # same thing, the choise is yours.	529	$x *= 1; # same thing, the choise is yours.
409		530
410	You can not currently output JSON booleans or force the type in other,	531	You can not currently output JSON booleans or force the type in other,
411	less obscure, ways. Tell me if you need this capability.	532	less obscure, ways. Tell me if you need this capability.
412		533
413	=item circular data structures
414
415	Those will be encoded until memory or stackspace runs out.
416
417	=back	534	=back
		535
418		536
419	=head1 COMPARISON	537	=head1 COMPARISON
420		538
421	As already mentioned, this module was created because none of the existing	539	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	540	JSON modules could be made to work correctly. First I will describe the
…		…
448		566
449	Has problems handling many Perl values (e.g. regex results and other magic	567	Has problems handling many Perl values (e.g. regex results and other magic
450	values will make it croak).	568	values will make it croak).
451		569
452	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>	570	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>
453	which is not a valid JSON string.	571	which is not a valid JSON text.
454		572
455	Unmaintained (maintainer unresponsive for many months, bugs are not	573	Unmaintained (maintainer unresponsive for many months, bugs are not
456	getting fixed).	574	getting fixed).
457		575
458	=item JSON::Syck 0.21	576	=item JSON::Syck 0.21
…		…
460	Very buggy (often crashes).	578	Very buggy (often crashes).
461		579
462	Very inflexible (no human-readable format supported, format pretty much	580	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	581	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	582	single-line compact format for use in a protocol, and preferably a way to
465	generate ASCII-only JSON strings).	583	generate ASCII-only JSON texts).
466		584
467	Completely broken (and confusingly documented) Unicode handling (unicode	585	Completely broken (and confusingly documented) Unicode handling (unicode
468	escapes are not working properly, you need to set ImplicitUnicode to	586	escapes are not working properly, you need to set ImplicitUnicode to
469	I<different> values on en- and decoding to get symmetric behaviour).	587	I<different> values on en- and decoding to get symmetric behaviour).
470		588
…		…
493		611
494	Very inflexible.	612	Very inflexible.
495		613
496	No roundtripping.	614	No roundtripping.
497		615
498	Does not generate valid JSON (key strings are often unquoted, empty keys	616	Does not generate valid JSON texts (key strings are often unquoted, empty keys
499	result in nothing being output)	617	result in nothing being output)
500		618
501	Does not check input for validity.	619	Does not check input for validity.
502		620
503	=back	621	=back
		622
		623
		624	=head2 JSON and YAML
		625
		626	You often hear that JSON is a subset (or a close subset) of YAML. This is,
		627	however, a mass hysteria and very far from the truth. In general, there is
		628	no way to configure JSON::XS to output a data structure as valid YAML.
		629
		630	If you really must use JSON::XS to generate YAML, you should use this
		631	algorithm (subject to change in future versions):
		632
		633	my $to_yaml = JSON::XS->new->utf8->space_after (1);
		634	my $yaml = $to_yaml->encode ($ref) . "\n";
		635
		636	This will usually generate JSON texts that also parse as valid
		637	YAML. Please note that YAML has hardcoded limits on (simple) object key
		638	lengths that JSON doesn't have, so you should make sure that your hash
		639	keys are noticably shorter than the 1024 characters YAML allows.
		640
		641	There might be other incompatibilities that I am not aware of. In general
		642	you should not try to generate YAML with a JSON generator or vice versa,
		643	or try to parse JSON with a YAML parser or vice versa: chances are high
		644	that you will run into severe interoperability problems.
		645
504		646
505	=head2 SPEED	647	=head2 SPEED
506		648
507	It seems that JSON::XS is surprisingly fast, as shown in the following	649	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	650	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	651	in the JSON::XS distribution, to make it easy to compare on your own
510	system.	652	system.
511		653
512	First comes a comparison between various modules using a very short JSON	654	First comes a comparison between various modules using a very short
513	string (83 bytes), showing the number of encodes/decodes per second	655	single-line JSON string:
		656
		657	{"method": "handleMessage", "params": ["user1", "we were just talking"], \
		658	"id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
		659
		660	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	661	the functional interface, while JSON::XS/2 uses the OO interface
515	interface with pretty-printing and hashkey sorting enabled). Higher is	662	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
516	better:	663	shrink). Higher is better:
517		664
518	module \| encode \| decode \|	665	module \| encode \| decode \|
519	-----------\|------------\|------------\|	666	-----------\|------------\|------------\|
520	JSON \| 14006 \| 6820 \|	667	JSON \| 7645.468 \| 4208.613 \|
521	JSON::DWIW \| 200937 \| 120386 \|	668	JSON::DWIW \| 40721.398 \| 77101.176 \|
522	JSON::PC \| 85065 \| 129366 \|	669	JSON::PC \| 65948.176 \| 78251.940 \|
523	JSON::Syck \| 59898 \| 44232 \|	670	JSON::Syck \| 22844.793 \| 26479.192 \|
524	JSON::XS \| 1171478 \| 342435 \|	671	JSON::XS \| 388361.481 \| 199728.762 \|
525	JSON::XS/2 \| 730760 \| 328714 \|	672	JSON::XS/2 \| 218453.333 \| 192399.266 \|
		673	JSON::XS/3 \| 338250.323 \| 192399.266 \|
		674	Storable \| 15779.925 \| 14169.946 \|
526	-----------+------------+------------+	675	-----------+------------+------------+
527		676
528	That is, JSON::XS is 6 times faster than than JSON::DWIW and about 80	677	That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
		678	about three times faster on decoding, and over fourty times faster
529	times faster than JSON, even with pretty-printing and key sorting.	679	than JSON, even with pretty-printing and key sorting. It also compares
		680	favourably to Storable for small amounts of data.
530		681
531	Using a longer test string (roughly 18KB, generated from Yahoo! Locals	682	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
532	search API (http://nanoref.com/yahooapis/mgPdGg):	683	search API (http://nanoref.com/yahooapis/mgPdGg):
533		684
534	module \| encode \| decode \|	685	module \| encode \| decode \|
535	-----------\|------------\|------------\|	686	-----------\|------------\|------------\|
536	JSON \| 673 \| 38 \|	687	JSON \| 254.685 \| 37.665 \|
537	JSON::DWIW \| 5271 \| 770 \|	688	JSON::DWIW \| 843.343 \| 1049.731 \|
538	JSON::PC \| 9901 \| 2491 \|	689	JSON::PC \| 3602.116 \| 2307.352 \|
539	JSON::Syck \| 2360 \| 786 \|	690	JSON::Syck \| 505.107 \| 787.899 \|
540	JSON::XS \| 37398 \| 3202 \|	691	JSON::XS \| 5747.196 \| 3690.220 \|
541	JSON::XS/2 \| 13765 \| 3153 \|	692	JSON::XS/2 \| 3968.121 \| 3676.634 \|
		693	JSON::XS/3 \| 6105.246 \| 3662.508 \|
		694	Storable \| 4417.337 \| 5285.161 \|
542	-----------+------------+------------+	695	-----------+------------+------------+
543		696
544	Again, JSON::XS leads by far in the encoding case, while still beating	697	Again, JSON::XS leads by far (except for Storable which non-surprisingly
545	every other module in the decoding case.	698	decodes faster).
546		699
547	On large strings containing lots of unicode characters, some modules	700	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	701	(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	702	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	703	to decode or encode properly, so it was impossible to prepare a fair
551	case.	704	comparison table for that case.
552		705
553	=head1 RESOURCE LIMITS
554		706
555	JSON::XS does not impose any limits on the size of JSON texts or Perl	707	=head1 SECURITY CONSIDERATIONS
556	values they represent - if your machine can handle it, JSON::XS will	708
557	encode or decode it. Future versions might optionally impose structure	709	When you are using JSON in a protocol, talking to untrusted potentially
558	depth and memory use resource limits.	710	hostile creatures requires relatively few measures.
		711
		712	First of all, your JSON decoder should be secure, that is, should not have
		713	any buffer overflows. Obviously, this module should ensure that and I am
		714	trying hard on making that true, but you never know.
		715
		716	Second, you need to avoid resource-starving attacks. That means you should
		717	limit the size of JSON texts you accept, or make sure then when your
		718	resources run out, thats just fine (e.g. by using a separate process that
		719	can crash safely). The size of a JSON text in octets or characters is
		720	usually a good indication of the size of the resources required to decode
		721	it into a Perl structure.
		722
		723	Third, JSON::XS recurses using the C stack when decoding objects and
		724	arrays. The C stack is a limited resource: for instance, on my amd64
		725	machine with 8MB of stack size I can decode around 180k nested arrays but
		726	only 14k nested JSON objects (due to perl itself recursing deeply on croak
		727	to free the temporary). If that is exceeded, the program crashes. to be
		728	conservative, the default nesting limit is set to 512. If your process
		729	has a smaller stack, you should adjust this setting accordingly with the
		730	C<max_depth> method.
		731
		732	And last but least, something else could bomb you that I forgot to think
		733	of. In that case, you get to keep the pieces. I am always open for hints,
		734	though...
		735
		736	If you are using JSON::XS to return packets to consumption
		737	by javascript scripts in a browser you should have a look at
		738	L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether
		739	you are vulnerable to some common attack vectors (which really are browser
		740	design bugs, but it is still you who will have to deal with it, as major
		741	browser developers care only for features, not about doing security
		742	right).
		743
559		744
560	=head1 BUGS	745	=head1 BUGS
561		746
562	While the goal of this module is to be correct, that unfortunately does	747	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	748	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	749	still relatively early in its development. If you keep reporting bugs they
565	be fixed swiftly, though.	750	will be fixed swiftly, though.
566		751
567	=cut	752	=cut
		753
		754	our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
		755	our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };
		756
		757	sub true() { $true }
		758	sub false() { $false }
		759
		760	sub is_bool($) {
		761	UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
		762	or UNIVERSAL::isa $_[0], "JSON::Literal"
		763	}
		764
		765	XSLoader::load "JSON::XS", $VERSION;
		766
		767	package JSON::XS::Boolean;
		768
		769	use overload
		770	"0+" => sub { ${$_[0]} },
		771	"++" => sub { $_[0] = ${$_[0]} + 1 },
		772	"--" => sub { $_[0] = ${$_[0]} - 1 },
		773	fallback => 1;
568		774
569	1;	775	1;
570		776
571	=head1 AUTHOR	777	=head1 AUTHOR
572		778

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Comparing JSON-XS/XS.pm (file contents): Revision 1.15 by root, Sat Mar 24 01:15:22 2007 UTC vs. Revision 1.43 by root, Sat Jun 23 23:49:29 2007 UTC

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Comparing JSON-XS/XS.pm (file contents):
Revision 1.15 by root, Sat Mar 24 01:15:22 2007 UTC vs.
Revision 1.43 by root, Sat Jun 23 23:49:29 2007 UTC