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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.6 by root, Thu Mar 22 23:24:18 2007 UTC vs.
Revision 1.26 by root, Sat Mar 31 14:20:06 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
…		…
18	their maintainers are unresponsive, gone missing, or not listening to bug	34	their maintainers are unresponsive, gone missing, or not listening to bug
19	reports for other reasons.	35	reports for other reasons.
20		36
21	See COMPARISON, below, for a comparison to some other JSON modules.	37	See COMPARISON, below, for a comparison to some other JSON modules.
22		38
		39	See MAPPING, below, on how JSON::XS maps perl values to JSON values and
		40	vice versa.
		41
23	=head2 FEATURES	42	=head2 FEATURES
24		43
25	=over 4	44	=over 4
26		45
27	=item * correct handling of unicode issues	46	=item * correct unicode handling
28		47
29	This module knows how to handle Unicode, and even documents how it does so.	48	This module knows how to handle Unicode, and even documents how and when
		49	it does so.
30		50
31	=item * round-trip integrity	51	=item * round-trip integrity
32		52
33	When you serialise a perl data structure using only datatypes supported	53	When you serialise a perl data structure using only datatypes supported
34	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.
35	(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).
36		57
37	=item * strict checking of JSON correctness	58	=item * strict checking of JSON correctness
38		59
39	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,
40	and only JSON is accepted as input (the latter is a security feature).	61	and only JSON is accepted as input by default (the latter is a security
		62	feature).
41		63
42	=item * fast	64	=item * fast
43		65
44	compared to other JSON modules, this module compares favourably.	66	Compared to other JSON modules, this module compares favourably in terms
		67	of speed, too.
45		68
46	=item * simple to use	69	=item * simple to use
47		70
48	This module has both a simple functional interface as well as an OO	71	This module has both a simple functional interface as well as an OO
49	interface.	72	interface.
50		73
51	=item * reasonably versatile output formats	74	=item * reasonably versatile output formats
52		75
53	You can choose between the most compact format possible, a pure-ascii	76	You can choose between the most compact guarenteed single-line format
54	format, or a pretty-printed format. Or you can combine those features in	77	possible (nice for simple line-based protocols), a pure-ascii format
55	whatever way you like.	78	(for when your transport is not 8-bit clean, still supports the whole
		79	unicode range), or a pretty-printed format (for when you want to read that
		80	stuff). Or you can combine those features in whatever way you like.
56		81
57	=back	82	=back
58		83
59	=cut	84	=cut
60		85
61	package JSON::XS;	86	package JSON::XS;
62		87
		88	use strict;
		89
63	BEGIN {	90	BEGIN {
64	$VERSION = '0.2';	91	our $VERSION = '1.01';
65	@ISA = qw(Exporter);	92	our @ISA = qw(Exporter);
66		93
67	@EXPORT = qw(to_json from_json);	94	our @EXPORT = qw(to_json from_json objToJson jsonToObj);
68	require Exporter;	95	require Exporter;
69		96
70	require XSLoader;	97	require XSLoader;
71	XSLoader::load JSON::XS::, $VERSION;	98	XSLoader::load JSON::XS::, $VERSION;
72	}	99	}
…		…
76	The following convinience methods are provided by this module. They are	103	The following convinience methods are provided by this module. They are
77	exported by default:	104	exported by default:
78		105
79	=over 4	106	=over 4
80		107
81	=item $json_string = to_json $perl_scalar	108	=item $json_text = to_json $perl_scalar
82		109
83	Converts the given Perl data structure (a simple scalar or a reference to	110	Converts the given Perl data structure (a simple scalar or a reference to
84	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains	111	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains
85	octets only). Croaks on error.	112	octets only). Croaks on error.
86		113
87	This function call is functionally identical to C<< JSON::XS->new->utf8	114	This function call is functionally identical to:
88	(1)->encode ($perl_scalar) >>.
89		115
		116	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)
		117
		118	except being faster.
		119
90	=item $perl_scalar = from_json $json_string	120	=item $perl_scalar = from_json $json_text
91		121
92	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to	122	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to
93	parse that as an UTF-8 encoded JSON string, returning the resulting simple	123	parse that as an UTF-8 encoded JSON text, returning the resulting simple
94	scalar or reference. Croaks on error.	124	scalar or reference. Croaks on error.
95		125
96	This function call is functionally identical to C<< JSON::XS->new->utf8	126	This function call is functionally identical to:
97	(1)->decode ($json_string) >>.	127
		128	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
		129
		130	except being faster.
98		131
99	=back	132	=back
		133
100		134
101	=head1 OBJECT-ORIENTED INTERFACE	135	=head1 OBJECT-ORIENTED INTERFACE
102		136
103	The object oriented interface lets you configure your own encoding or	137	The object oriented interface lets you configure your own encoding or
104	decoding style, within the limits of supported formats.	138	decoding style, within the limits of supported formats.
…		…
111	strings. All boolean flags described below are by default I<disabled>.	145	strings. All boolean flags described below are by default I<disabled>.
112		146
113	The mutators for flags all return the JSON object again and thus calls can	147	The mutators for flags all return the JSON object again and thus calls can
114	be chained:	148	be chained:
115		149
116	my $json = JSON::XS->new->utf8(1)->space_after(1)->encode ({a => [1,2]})	150	my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})
117	=> {"a": [1, 2]}	151	=> {"a": [1, 2]}
118		152
119	=item $json = $json->ascii ($enable)	153	=item $json = $json->ascii ([$enable])
120		154
121	If C<$enable> is true, then the C<encode> method will not generate	155	If C<$enable> is true (or missing), then the C<encode> method will not
122	characters outside the code range C<0..127>. Any unicode characters	156	generate characters outside the code range C<0..127> (which is ASCII). Any
123	outside that range will be escaped using either a single \uXXXX (BMP	157	unicode characters outside that range will be escaped using either a
124	characters) or a double \uHHHH\uLLLLL escape sequence, as per RFC4627.	158	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
		159	as per RFC4627.
125		160
126	If C<$enable> is false, then the C<encode> method will not escape Unicode	161	If C<$enable> is false, then the C<encode> method will not escape Unicode
127	characters unless necessary.	162	characters unless required by the JSON syntax. This results in a faster
		163	and more compact format.
128		164
129	JSON::XS->new->ascii (1)->encode (chr 0x10401)	165	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
130	=> \ud801\udc01	166	=> ["\ud801\udc01"]
131		167
132	=item $json = $json->utf8 ($enable)	168	=item $json = $json->utf8 ([$enable])
133		169
134	If C<$enable> is true, then the C<encode> method will encode the JSON	170	If C<$enable> is true (or missing), then the C<encode> method will encode
135	string into UTF-8, as required by many protocols, while the C<decode>	171	the JSON result into UTF-8, as required by many protocols, while the
136	method expects to be handled an UTF-8-encoded string. Please note that	172	C<decode> method expects to be handled an UTF-8-encoded string. Please
137	UTF-8-encoded strings do not contain any characters outside the range	173	note that UTF-8-encoded strings do not contain any characters outside the
138	C<0..255>, they are thus useful for bytewise/binary I/O.	174	range C<0..255>, they are thus useful for bytewise/binary I/O. In future
		175	versions, enabling this option might enable autodetection of the UTF-16
		176	and UTF-32 encoding families, as described in RFC4627.
139		177
140	If C<$enable> is false, then the C<encode> method will return the JSON	178	If C<$enable> is false, then the C<encode> method will return the JSON
141	string as a (non-encoded) unicode string, while C<decode> expects thus a	179	string as a (non-encoded) unicode string, while C<decode> expects thus a
142	unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs	180	unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs
143	to be done yourself, e.g. using the Encode module.	181	to be done yourself, e.g. using the Encode module.
144		182
		183	Example, output UTF-16BE-encoded JSON:
		184
		185	use Encode;
		186	$jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);
		187
		188	Example, decode UTF-32LE-encoded JSON:
		189
		190	use Encode;
		191	$object = JSON::XS->new->decode (decode "UTF-32LE", $jsontext);
		192
145	=item $json = $json->pretty ($enable)	193	=item $json = $json->pretty ([$enable])
146		194
147	This enables (or disables) all of the C<indent>, C<space_before> and	195	This enables (or disables) all of the C<indent>, C<space_before> and
148	C<space_after> (and in the future possibly more) flags in one call to	196	C<space_after> (and in the future possibly more) flags in one call to
149	generate the most readable (or most compact) form possible.	197	generate the most readable (or most compact) form possible.
		198
		199	Example, pretty-print some simple structure:
150		200
151	my $json = JSON::XS->new->pretty(1)->encode ({a => [1,2]})	201	my $json = JSON::XS->new->pretty(1)->encode ({a => [1,2]})
152	=>	202	=>
153	{	203	{
154	"a" : [	204	"a" : [
155	1,	205	1,
156	2	206	2
157	]	207	]
158	}	208	}
159		209
160	=item $json = $json->indent ($enable)	210	=item $json = $json->indent ([$enable])
161		211
162	If C<$enable> is true, then the C<encode> method will use a multiline	212	If C<$enable> is true (or missing), then the C<encode> method will use a multiline
163	format as output, putting every array member or object/hash key-value pair	213	format as output, putting every array member or object/hash key-value pair
164	into its own line, identing them properly.	214	into its own line, identing them properly.
165		215
166	If C<$enable> is false, no newlines or indenting will be produced, and the	216	If C<$enable> is false, no newlines or indenting will be produced, and the
167	resulting JSON strings is guarenteed not to contain any C<newlines>.	217	resulting JSON text is guarenteed not to contain any C<newlines>.
168		218
169	This setting has no effect when decoding JSON strings.	219	This setting has no effect when decoding JSON texts.
170		220
171	=item $json = $json->space_before ($enable)	221	=item $json = $json->space_before ([$enable])
172		222
173	If C<$enable> is true, then the C<encode> method will add an extra	223	If C<$enable> is true (or missing), then the C<encode> method will add an extra
174	optional space before the C<:> separating keys from values in JSON objects.	224	optional space before the C<:> separating keys from values in JSON objects.
175		225
176	If C<$enable> is false, then the C<encode> method will not add any extra	226	If C<$enable> is false, then the C<encode> method will not add any extra
177	space at those places.	227	space at those places.
178		228
179	This setting has no effect when decoding JSON strings. You will also most	229	This setting has no effect when decoding JSON texts. You will also
180	likely combine this setting with C<space_after>.	230	most likely combine this setting with C<space_after>.
181		231
		232	Example, space_before enabled, space_after and indent disabled:
		233
		234	{"key" :"value"}
		235
182	=item $json = $json->space_after ($enable)	236	=item $json = $json->space_after ([$enable])
183		237
184	If C<$enable> is true, then the C<encode> method will add an extra	238	If C<$enable> is true (or missing), then the C<encode> method will add an extra
185	optional space after the C<:> separating keys from values in JSON objects	239	optional space after the C<:> separating keys from values in JSON objects
186	and extra whitespace after the C<,> separating key-value pairs and array	240	and extra whitespace after the C<,> separating key-value pairs and array
187	members.	241	members.
188		242
189	If C<$enable> is false, then the C<encode> method will not add any extra	243	If C<$enable> is false, then the C<encode> method will not add any extra
190	space at those places.	244	space at those places.
191		245
192	This setting has no effect when decoding JSON strings.	246	This setting has no effect when decoding JSON texts.
193		247
		248	Example, space_before and indent disabled, space_after enabled:
		249
		250	{"key": "value"}
		251
194	=item $json = $json->canonical ($enable)	252	=item $json = $json->canonical ([$enable])
195		253
196	If C<$enable> is true, then the C<encode> method will output JSON objects	254	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
197	by sorting their keys. This is adding a comparatively high overhead.	255	by sorting their keys. This is adding a comparatively high overhead.
198		256
199	If C<$enable> is false, then the C<encode> method will output key-value	257	If C<$enable> is false, then the C<encode> method will output key-value
200	pairs in the order Perl stores them (which will likely change between runs	258	pairs in the order Perl stores them (which will likely change between runs
201	of the same script).	259	of the same script).
202		260
203	This option is useful if you want the same data structure to be encoded as	261	This option is useful if you want the same data structure to be encoded as
204	the same JSON string (given the same overall settings). If it is disabled,	262	the same JSON text (given the same overall settings). If it is disabled,
205	the same hash migh be encoded differently even if contains the same data,	263	the same hash migh be encoded differently even if contains the same data,
206	as key-value pairs have no inherent ordering in Perl.	264	as key-value pairs have no inherent ordering in Perl.
207		265
208	This setting has no effect when decoding JSON strings.	266	This setting has no effect when decoding JSON texts.
209		267
210	=item $json = $json->allow_nonref ($enable)	268	=item $json = $json->allow_nonref ([$enable])
211		269
212	If C<$enable> is true, then the C<encode> method can convert a	270	If C<$enable> is true (or missing), then the C<encode> method can convert a
213	non-reference into its corresponding string, number or null JSON value,	271	non-reference into its corresponding string, number or null JSON value,
214	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON	272	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
215	values instead of croaking.	273	values instead of croaking.
216		274
217	If C<$enable> is false, then the C<encode> method will croak if it isn't	275	If C<$enable> is false, then the C<encode> method will croak if it isn't
218	passed an arrayref or hashref, as JSON strings must either be an object	276	passed an arrayref or hashref, as JSON texts must either be an object
219	or array. Likewise, C<decode> will croak if given something that is not a	277	or array. Likewise, C<decode> will croak if given something that is not a
220	JSON object or array.	278	JSON object or array.
221		279
		280	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,
		281	resulting in an invalid JSON text:
		282
		283	JSON::XS->new->allow_nonref->encode ("Hello, World!")
		284	=> "Hello, World!"
		285
		286	=item $json = $json->shrink ([$enable])
		287
		288	Perl usually over-allocates memory a bit when allocating space for
		289	strings. This flag optionally resizes strings generated by either
		290	C<encode> or C<decode> to their minimum size possible. This can save
		291	memory when your JSON texts are either very very long or you have many
		292	short strings. It will also try to downgrade any strings to octet-form
		293	if possible: perl stores strings internally either in an encoding called
		294	UTF-X or in octet-form. The latter cannot store everything but uses less
		295	space in general (and some buggy Perl or C code might even rely on that
		296	internal representation being used).
		297
		298	The actual definition of what shrink does might change in future versions,
		299	but it will always try to save space at the expense of time.
		300
		301	If C<$enable> is true (or missing), the string returned by C<encode> will
		302	be shrunk-to-fit, while all strings generated by C<decode> will also be
		303	shrunk-to-fit.
		304
		305	If C<$enable> is false, then the normal perl allocation algorithms are used.
		306	If you work with your data, then this is likely to be faster.
		307
		308	In the future, this setting might control other things, such as converting
		309	strings that look like integers or floats into integers or floats
		310	internally (there is no difference on the Perl level), saving space.
		311
		312	=item $json = $json->max_depth ([$maximum_nesting_depth])
		313
		314	Sets the maximum nesting level (default C<4096>) accepted while encoding
		315	or decoding. If the JSON text or Perl data structure has an equal or
		316	higher nesting level then this limit, then the encoder and decoder will
		317	stop and croak at that point.
		318
		319	Nesting level is defined by number of hash- or arrayrefs that the encoder
		320	needs to traverse to reach a given point or the number of C<{> or C<[>
		321	characters without their matching closing parenthesis crossed to reach a
		322	given character in a string.
		323
		324	Setting the maximum depth to one disallows any nesting, so that ensures
		325	that the object is only a single hash/object or array.
		326
		327	The argument to C<max_depth> will be rounded up to the next nearest power
		328	of two.
		329
		330	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
		331
222	=item $json_string = $json->encode ($perl_scalar)	332	=item $json_text = $json->encode ($perl_scalar)
223		333
224	Converts the given Perl data structure (a simple scalar or a reference	334	Converts the given Perl data structure (a simple scalar or a reference
225	to a hash or array) to its JSON representation. Simple scalars will be	335	to a hash or array) to its JSON representation. Simple scalars will be
226	converted into JSON string or number sequences, while references to arrays	336	converted into JSON string or number sequences, while references to arrays
227	become JSON arrays and references to hashes become JSON objects. Undefined	337	become JSON arrays and references to hashes become JSON objects. Undefined
228	Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>	338	Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>
229	nor C<false> values will be generated.	339	nor C<false> values will be generated.
230		340
231	=item $perl_scalar = $json->decode ($json_string)	341	=item $perl_scalar = $json->decode ($json_text)
232		342
233	The opposite of C<encode>: expects a JSON string and tries to parse it,	343	The opposite of C<encode>: expects a JSON text and tries to parse it,
234	returning the resulting simple scalar or reference. Croaks on error.	344	returning the resulting simple scalar or reference. Croaks on error.
235		345
236	JSON numbers and strings become simple Perl scalars. JSON arrays become	346	JSON numbers and strings become simple Perl scalars. JSON arrays become
237	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes	347	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
238	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.	348	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
239		349
240	=back	350	=back
		351
		352
		353	=head1 MAPPING
		354
		355	This section describes how JSON::XS maps Perl values to JSON values and
		356	vice versa. These mappings are designed to "do the right thing" in most
		357	circumstances automatically, preserving round-tripping characteristics
		358	(what you put in comes out as something equivalent).
		359
		360	For the more enlightened: note that in the following descriptions,
		361	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
		362	refers to the abstract Perl language itself.
		363
		364	=head2 JSON -> PERL
		365
		366	=over 4
		367
		368	=item object
		369
		370	A JSON object becomes a reference to a hash in Perl. No ordering of object
		371	keys is preserved (JSON does not preserver object key ordering itself).
		372
		373	=item array
		374
		375	A JSON array becomes a reference to an array in Perl.
		376
		377	=item string
		378
		379	A JSON string becomes a string scalar in Perl - Unicode codepoints in JSON
		380	are represented by the same codepoints in the Perl string, so no manual
		381	decoding is necessary.
		382
		383	=item number
		384
		385	A JSON number becomes either an integer or numeric (floating point)
		386	scalar in perl, depending on its range and any fractional parts. On the
		387	Perl level, there is no difference between those as Perl handles all the
		388	conversion details, but an integer may take slightly less memory and might
		389	represent more values exactly than (floating point) numbers.
		390
		391	=item true, false
		392
		393	These JSON atoms become C<0>, C<1>, respectively. Information is lost in
		394	this process. Future versions might represent those values differently,
		395	but they will be guarenteed to act like these integers would normally in
		396	Perl.
		397
		398	=item null
		399
		400	A JSON null atom becomes C<undef> in Perl.
		401
		402	=back
		403
		404	=head2 PERL -> JSON
		405
		406	The mapping from Perl to JSON is slightly more difficult, as Perl is a
		407	truly typeless language, so we can only guess which JSON type is meant by
		408	a Perl value.
		409
		410	=over 4
		411
		412	=item hash references
		413
		414	Perl hash references become JSON objects. As there is no inherent ordering
		415	in hash keys (or JSON objects), they will usually be encoded in a
		416	pseudo-random order that can change between runs of the same program but
		417	stays generally the same within a single run of a program. JSON::XS can
		418	optionally sort the hash keys (determined by the I<canonical> flag), so
		419	the same datastructure will serialise to the same JSON text (given same
		420	settings and version of JSON::XS), but this incurs a runtime overhead
		421	and is only rarely useful, e.g. when you want to compare some JSON text
		422	against another for equality.
		423
		424	=item array references
		425
		426	Perl array references become JSON arrays.
		427
		428	=item other references
		429
		430	Other unblessed references are generally not allowed and will cause an
		431	exception to be thrown, except for references to the integers C<0> and
		432	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
		433	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
		434
		435	to_json [\0,JSON::XS::true] # yields [false,true]
		436
		437	=item blessed objects
		438
		439	Blessed objects are not allowed. JSON::XS currently tries to encode their
		440	underlying representation (hash- or arrayref), but this behaviour might
		441	change in future versions.
		442
		443	=item simple scalars
		444
		445	Simple Perl scalars (any scalar that is not a reference) are the most
		446	difficult objects to encode: JSON::XS will encode undefined scalars as
		447	JSON null value, scalars that have last been used in a string context
		448	before encoding as JSON strings and anything else as number value:
		449
		450	# dump as number
		451	to_json [2] # yields [2]
		452	to_json [-3.0e17] # yields [-3e+17]
		453	my $value = 5; to_json [$value] # yields [5]
		454
		455	# used as string, so dump as string
		456	print $value;
		457	to_json [$value] # yields ["5"]
		458
		459	# undef becomes null
		460	to_json [undef] # yields [null]
		461
		462	You can force the type to be a string by stringifying it:
		463
		464	my $x = 3.1; # some variable containing a number
		465	"$x"; # stringified
		466	$x .= ""; # another, more awkward way to stringify
		467	print $x; # perl does it for you, too, quite often
		468
		469	You can force the type to be a number by numifying it:
		470
		471	my $x = "3"; # some variable containing a string
		472	$x += 0; # numify it, ensuring it will be dumped as a number
		473	$x *= 1; # same thing, the choise is yours.
		474
		475	You can not currently output JSON booleans or force the type in other,
		476	less obscure, ways. Tell me if you need this capability.
		477
		478	=item circular data structures
		479
		480	Those will be encoded until memory or stackspace runs out.
		481
		482	=back
		483
241		484
242	=head1 COMPARISON	485	=head1 COMPARISON
243		486
244	As already mentioned, this module was created because none of the existing	487	As already mentioned, this module was created because none of the existing
245	JSON modules could be made to work correctly. First I will describe the	488	JSON modules could be made to work correctly. First I will describe the
…		…
271		514
272	Has problems handling many Perl values (e.g. regex results and other magic	515	Has problems handling many Perl values (e.g. regex results and other magic
273	values will make it croak).	516	values will make it croak).
274		517
275	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>	518	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>
276	which is not a valid JSON string.	519	which is not a valid JSON text.
277		520
278	Unmaintained (maintainer unresponsive for many months, bugs are not	521	Unmaintained (maintainer unresponsive for many months, bugs are not
279	getting fixed).	522	getting fixed).
280		523
281	=item JSON::Syck 0.21	524	=item JSON::Syck 0.21
…		…
283	Very buggy (often crashes).	526	Very buggy (often crashes).
284		527
285	Very inflexible (no human-readable format supported, format pretty much	528	Very inflexible (no human-readable format supported, format pretty much
286	undocumented. I need at least a format for easy reading by humans and a	529	undocumented. I need at least a format for easy reading by humans and a
287	single-line compact format for use in a protocol, and preferably a way to	530	single-line compact format for use in a protocol, and preferably a way to
288	generate ASCII-only JSON strings).	531	generate ASCII-only JSON texts).
289		532
290	Completely broken (and confusingly documented) Unicode handling (unicode	533	Completely broken (and confusingly documented) Unicode handling (unicode
291	escapes are not working properly, you need to set ImplicitUnicode to	534	escapes are not working properly, you need to set ImplicitUnicode to
292	I<different> values on en- and decoding to get symmetric behaviour).	535	I<different> values on en- and decoding to get symmetric behaviour).
293		536
…		…
316		559
317	Very inflexible.	560	Very inflexible.
318		561
319	No roundtripping.	562	No roundtripping.
320		563
321	Does not generate valid JSON (key strings are often unquoted, empty keys	564	Does not generate valid JSON texts (key strings are often unquoted, empty keys
322	result in nothing being output)	565	result in nothing being output)
323		566
324	Does not check input for validity.	567	Does not check input for validity.
325		568
326	=back	569	=back
…		…
330	It seems that JSON::XS is surprisingly fast, as shown in the following	573	It seems that JSON::XS is surprisingly fast, as shown in the following
331	tables. They have been generated with the help of the C<eg/bench> program	574	tables. They have been generated with the help of the C<eg/bench> program
332	in the JSON::XS distribution, to make it easy to compare on your own	575	in the JSON::XS distribution, to make it easy to compare on your own
333	system.	576	system.
334		577
335	First is a comparison between various modules using a very simple JSON	578	First comes a comparison between various modules using a very short JSON
		579	string:
		580
		581	{"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null}
		582
336	string, showing the number of encodes/decodes per second (JSON::XS is	583	It shows the number of encodes/decodes per second (JSON::XS uses the
337	the functional interface, while JSON::XS/2 is the OO interface with	584	functional interface, while JSON::XS/2 uses the OO interface with
338	pretty-printing and hashkey sorting enabled).	585	pretty-printing and hashkey sorting enabled). Higher is better:
339		586
340	module \| encode \| decode \|	587	module \| encode \| decode \|
341	-----------\|------------\|------------\|	588	-----------\|------------\|------------\|
342	JSON \| 14006 \| 6820 \|	589	JSON \| 11488.516 \| 7823.035 \|
343	JSON::DWIW \| 200937 \| 120386 \|	590	JSON::DWIW \| 94708.054 \| 129094.260 \|
344	JSON::PC \| 85065 \| 129366 \|	591	JSON::PC \| 63884.157 \| 128528.212 \|
345	JSON::Syck \| 59898 \| 44232 \|	592	JSON::Syck \| 34898.677 \| 42096.911 \|
346	JSON::XS \| 1171478 \| 342435 \|	593	JSON::XS \| 654027.064 \| 396423.669 \|
347	JSON::XS/2 \| 730760 \| 328714 \|	594	JSON::XS/2 \| 371564.190 \| 371725.613 \|
348	-----------+------------+------------+	595	-----------+------------+------------+
349		596
350	That is, JSON::XS is 6 times faster than than JSON::DWIW and about 80	597	That is, JSON::XS is more than six times faster than JSON::DWIW on
		598	encoding, more than three times faster on decoding, and about thirty times
351	times faster than JSON, even with pretty-printing and key sorting.	599	faster than JSON, even with pretty-printing and key sorting.
352		600
353	Using a longer test string (roughly 8KB, generated from Yahoo! Locals	601	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
354	search API (http://nanoref.com/yahooapis/mgPdGg):	602	search API (http://nanoref.com/yahooapis/mgPdGg):
355		603
356	module \| encode \| decode \|	604	module \| encode \| decode \|
357	-----------\|------------\|------------\|	605	-----------\|------------\|------------\|
358	JSON \| 673 \| 38 \|	606	JSON \| 273.023 \| 44.674 \|
359	JSON::DWIW \| 5271 \| 770 \|	607	JSON::DWIW \| 1089.383 \| 1145.704 \|
360	JSON::PC \| 9901 \| 2491 \|	608	JSON::PC \| 3097.419 \| 2393.921 \|
361	JSON::Syck \| 2360 \| 786 \|	609	JSON::Syck \| 514.060 \| 843.053 \|
362	JSON::XS \| 37398 \| 3202 \|	610	JSON::XS \| 6479.668 \| 3636.364 \|
363	JSON::XS/2 \| 13765 \| 3153 \|	611	JSON::XS/2 \| 3774.221 \| 3599.124 \|
364	-----------+------------+------------+	612	-----------+------------+------------+
365		613
366	Again, JSON::XS leads by far in the encoding case, while still beating	614	Again, JSON::XS leads by far.
367	every other module in the decoding case.
368		615
369	Last example is an almost 8MB large hash with many large binary values	616	On large strings containing lots of high unicode characters, some modules
370	(PNG files), resulting in a lot of escaping:	617	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
		618	will be broken due to missing (or wrong) unicode handling. Others refuse
		619	to decode or encode properly, so it was impossible to prepare a fair
		620	comparison table for that case.
		621
		622
		623	=head1 SECURITY CONSIDERATIONS
		624
		625	When you are using JSON in a protocol, talking to untrusted potentially
		626	hostile creatures requires relatively few measures.
		627
		628	First of all, your JSON decoder should be secure, that is, should not have
		629	any buffer overflows. Obviously, this module should ensure that and I am
		630	trying hard on making that true, but you never know.
		631
		632	Second, you need to avoid resource-starving attacks. That means you should
		633	limit the size of JSON texts you accept, or make sure then when your
		634	resources run out, thats just fine (e.g. by using a separate process that
		635	can crash safely). The size of a JSON text in octets or characters is
		636	usually a good indication of the size of the resources required to decode
		637	it into a Perl structure.
		638
		639	Third, JSON::XS recurses using the C stack when decoding objects and
		640	arrays. The C stack is a limited resource: for instance, on my amd64
		641	machine with 8MB of stack size I can decode around 180k nested arrays
		642	but only 14k nested JSON objects. If that is exceeded, the program
		643	crashes. Thats why the default nesting limit is set to 4096. If your
		644	process has a smaller stack, you should adjust this setting accordingly
		645	with the C<max_depth> method.
		646
		647	And last but least, something else could bomb you that I forgot to think
		648	of. In that case, you get to keep the pieces. I am alway sopen for hints,
		649	though...
		650
371		651
372	=head1 BUGS	652	=head1 BUGS
373		653
374	While the goal of this module is to be correct, that unfortunately does	654	While the goal of this module is to be correct, that unfortunately does
375	not mean its bug-free, only that I think its design is bug-free. It is	655	not mean its bug-free, only that I think its design is bug-free. It is
376	still very young and not well-tested. If you keep reporting bugs they will	656	still relatively early in its development. If you keep reporting bugs they
377	be fixed swiftly, though.	657	will be fixed swiftly, though.
378		658
379	=cut	659	=cut
		660
		661	sub true() { \1 }
		662	sub false() { \0 }
380		663
381	1;	664	1;
382		665
383	=head1 AUTHOR	666	=head1 AUTHOR
384		667

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Comparing JSON-XS/XS.pm (file contents): Revision 1.6 by root, Thu Mar 22 23:24:18 2007 UTC vs. Revision 1.26 by root, Sat Mar 31 14:20:06 2007 UTC

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Revision 1.26 by root, Sat Mar 31 14:20:06 2007 UTC