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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.2 by root, Thu Mar 22 17:28:50 2007 UTC vs.
Revision 1.20 by root, Sun Mar 25 00:47:42 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, croak on error
		10
		11	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;
		12	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;
		13
		14	# oo-interface
		15
		16	$coder = JSON::XS->new->ascii->pretty->allow_nonref;
		17	$pretty_printed_unencoded = $coder->encode ($perl_scalar);
		18	$perl_scalar = $coder->decode ($unicode_json_text);
8		19
9	=head1 DESCRIPTION	20	=head1 DESCRIPTION
10		21
11	This module converts Perl data structures to JSON and vice versa. Its	22	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	23	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	29	their maintainers are unresponsive, gone missing, or not listening to bug
19	reports for other reasons.	30	reports for other reasons.
20		31
21	See COMPARISON, below, for a comparison to some other JSON modules.	32	See COMPARISON, below, for a comparison to some other JSON modules.
22		33
		34	See MAPPING, below, on how JSON::XS maps perl values to JSON values and
		35	vice versa.
		36
23	=head2 FEATURES	37	=head2 FEATURES
24		38
25	=over 4	39	=over 4
26		40
27	=item * correct handling of unicode issues	41	=item * correct handling of unicode issues
28		42
29	This module knows how to handle Unicode, and even documents how it does so.	43	This module knows how to handle Unicode, and even documents how and when
		44	it does so.
30		45
31	=item * round-trip integrity	46	=item * round-trip integrity
32		47
33	When you serialise a perl data structure using only datatypes supported	48	When you serialise a perl data structure using only datatypes supported
34	by JSON, the deserialised data structure is identical on the Perl level.	49	by JSON, the deserialised data structure is identical on the Perl level.
35	(e.g. the string "2.0" doesn't suddenly become "2").	50	(e.g. the string "2.0" doesn't suddenly become "2").
36		51
37	=item * strict checking of JSON correctness	52	=item * strict checking of JSON correctness
38		53
39	There is no guessing, no generating of illegal JSON strings by default,	54	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).	55	and only JSON is accepted as input by default (the latter is a security
		56	feature).
41		57
42	=item * fast	58	=item * fast
43		59
44	compared to other JSON modules, this module compares favourably.	60	Compared to other JSON modules, this module compares favourably in terms
		61	of speed, too.
45		62
46	=item * simple to use	63	=item * simple to use
47		64
48	This module has both a simple functional interface as well as an OO	65	This module has both a simple functional interface as well as an OO
49	interface.	66	interface.
50		67
51	=item * reasonably versatile output formats	68	=item * reasonably versatile output formats
52		69
53	You can choose between the most compact format possible, a pure-ascii	70	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	71	possible (nice for simple line-based protocols), a pure-ascii format (for
		72	when your transport is not 8-bit clean), or a pretty-printed format (for
		73	when you want to read that stuff). Or you can combine those features in
55	whatever way you like.	74	whatever way you like.
56		75
57	=back	76	=back
58		77
59	=cut	78	=cut
60		79
61	package JSON::XS;	80	package JSON::XS;
62		81
		82	use strict;
		83
63	BEGIN {	84	BEGIN {
64	$VERSION = '0.1';	85	our $VERSION = '0.7';
65	@ISA = qw(Exporter);	86	our @ISA = qw(Exporter);
66		87
67	@EXPORT = qw(to_json from_json);	88	our @EXPORT = qw(to_json from_json);
68	require Exporter;	89	require Exporter;
69		90
70	require XSLoader;	91	require XSLoader;
71	XSLoader::load JSON::XS::, $VERSION;	92	XSLoader::load JSON::XS::, $VERSION;
72	}	93	}
…		…
76	The following convinience methods are provided by this module. They are	97	The following convinience methods are provided by this module. They are
77	exported by default:	98	exported by default:
78		99
79	=over 4	100	=over 4
80		101
81	=item $json_string = to_json $perl_scalar	102	=item $json_text = to_json $perl_scalar
82		103
83	Converts the given Perl data structure (a simple scalar or a reference to	104	Converts the given Perl data structure (a simple scalar or a reference to
84	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains	105	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains
85	octets only). Croaks on error.	106	octets only). Croaks on error.
86		107
87	This function call is functionally identical to C<< JSON::XS->new->utf8	108	This function call is functionally identical to:
88	(1)->encode ($perl_scalar) >>.
89		109
		110	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)
		111
		112	except being faster.
		113
90	=item $perl_scalar = from_json $json_string	114	=item $perl_scalar = from_json $json_text
91		115
92	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to	116	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to
93	parse that as an UTF-8 encoded JSON string, returning the resulting simple	117	parse that as an UTF-8 encoded JSON text, returning the resulting simple
94	scalar or reference. Croaks on error.	118	scalar or reference. Croaks on error.
95		119
96	This function call is functionally identical to C<< JSON::XS->new->utf8	120	This function call is functionally identical to:
97	(1)->decode ($json_string) >>.	121
		122	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
		123
		124	except being faster.
98		125
99	=back	126	=back
100		127
101	=head1 OBJECT-ORIENTED INTERFACE	128	=head1 OBJECT-ORIENTED INTERFACE
102		129
…		…
111	strings. All boolean flags described below are by default I<disabled>.	138	strings. All boolean flags described below are by default I<disabled>.
112		139
113	The mutators for flags all return the JSON object again and thus calls can	140	The mutators for flags all return the JSON object again and thus calls can
114	be chained:	141	be chained:
115		142
116	my $json = JSON::XS->new->utf8(1)->pretty(1)->encode ({a => [1,2]})	143	my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})
117	=> {"a" : [1, 2]}	144	=> {"a": [1, 2]}
118		145
119	=item $json = $json->ascii ($enable)	146	=item $json = $json->ascii ([$enable])
120		147
121	If C<$enable> is true, then the C<encode> method will not generate	148	If C<$enable> is true (or missing), then the C<encode> method will not
122	characters outside the code range C<0..127>. Any unicode characters	149	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	150	unicode characters outside that range will be escaped using either a
124	characters) or a double \uHHHH\uLLLLL escape sequence, as per RFC4627.	151	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
		152	as per RFC4627.
125		153
126	If C<$enable> is false, then the C<encode> method will not escape Unicode	154	If C<$enable> is false, then the C<encode> method will not escape Unicode
127	characters unless necessary.	155	characters unless required by the JSON syntax. This results in a faster
		156	and more compact format.
128		157
		158	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
		159	=> ["\ud801\udc01"]
		160
129	=item $json = $json->utf8 ($enable)	161	=item $json = $json->utf8 ([$enable])
130		162
131	If C<$enable> is true, then the C<encode> method will encode the JSON	163	If C<$enable> is true (or missing), then the C<encode> method will encode
132	string into UTF-8, as required by many protocols, while the C<decode>	164	the JSON result into UTF-8, as required by many protocols, while the
133	method expects to be handled an UTF-8-encoded string. Please note that	165	C<decode> method expects to be handled an UTF-8-encoded string. Please
134	UTF-8-encoded strings do not contain any characters outside the range	166	note that UTF-8-encoded strings do not contain any characters outside the
135	C<0..255>, they are thus useful for bytewise/binary I/O.	167	range C<0..255>, they are thus useful for bytewise/binary I/O. In future
		168	versions, enabling this option might enable autodetection of the UTF-16
		169	and UTF-32 encoding families, as described in RFC4627.
136		170
137	If C<$enable> is false, then the C<encode> method will return the JSON	171	If C<$enable> is false, then the C<encode> method will return the JSON
138	string as a (non-encoded) unicode string, while C<decode> expects thus a	172	string as a (non-encoded) unicode string, while C<decode> expects thus a
139	unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs	173	unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs
140	to be done yourself, e.g. using the Encode module.	174	to be done yourself, e.g. using the Encode module.
141		175
		176	Example, output UTF-16BE-encoded JSON:
		177
		178	use Encode;
		179	$jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);
		180
		181	Example, decode UTF-32LE-encoded JSON:
		182
		183	use Encode;
		184	$object = JSON::XS->new->decode (decode "UTF-32LE", $jsontext);
		185
142	=item $json = $json->pretty ($enabla)	186	=item $json = $json->pretty ([$enable])
143		187
144	This enables (or disables) all of the C<indent>, C<space_before> and	188	This enables (or disables) all of the C<indent>, C<space_before> and
145	C<space_after> (and in the future possibly more) settings in one call to	189	C<space_after> (and in the future possibly more) flags in one call to
146	generate the most readable (or most compact) form possible.	190	generate the most readable (or most compact) form possible.
147		191
		192	Example, pretty-print some simple structure:
		193
		194	my $json = JSON::XS->new->pretty(1)->encode ({a => [1,2]})
		195	=>
		196	{
		197	"a" : [
		198	1,
		199	2
		200	]
		201	}
		202
148	=item $json = $json->indent ($enable)	203	=item $json = $json->indent ([$enable])
149		204
150	If C<$enable> is true, then the C<encode> method will use a multiline	205	If C<$enable> is true (or missing), then the C<encode> method will use a multiline
151	format as output, putting every array member or object/hash key-value pair	206	format as output, putting every array member or object/hash key-value pair
152	into its own line, identing them properly.	207	into its own line, identing them properly.
153		208
154	If C<$enable> is false, no newlines or indenting will be produced, and the	209	If C<$enable> is false, no newlines or indenting will be produced, and the
155	resulting JSON strings is guarenteed not to contain any C<newlines>.	210	resulting JSON text is guarenteed not to contain any C<newlines>.
156		211
157	This setting has no effect when decoding JSON strings.	212	This setting has no effect when decoding JSON texts.
158		213
159	=item $json = $json->space_before ($enable)	214	=item $json = $json->space_before ([$enable])
160		215
161	If C<$enable> is true, then the C<encode> method will add an extra	216	If C<$enable> is true (or missing), then the C<encode> method will add an extra
162	optional space before the C<:> separating keys from values in JSON objects.	217	optional space before the C<:> separating keys from values in JSON objects.
163		218
164	If C<$enable> is false, then the C<encode> method will not add any extra	219	If C<$enable> is false, then the C<encode> method will not add any extra
165	space at those places.	220	space at those places.
166		221
167	This setting has no effect when decoding JSON strings. You will also most	222	This setting has no effect when decoding JSON texts. You will also
168	likely combine this setting with C<space_after>.	223	most likely combine this setting with C<space_after>.
169		224
		225	Example, space_before enabled, space_after and indent disabled:
		226
		227	{"key" :"value"}
		228
170	=item $json = $json->space_after ($enable)	229	=item $json = $json->space_after ([$enable])
171		230
172	If C<$enable> is true, then the C<encode> method will add an extra	231	If C<$enable> is true (or missing), then the C<encode> method will add an extra
173	optional space after the C<:> separating keys from values in JSON objects	232	optional space after the C<:> separating keys from values in JSON objects
174	and extra whitespace after the C<,> separating key-value pairs and array	233	and extra whitespace after the C<,> separating key-value pairs and array
175	members.	234	members.
176		235
177	If C<$enable> is false, then the C<encode> method will not add any extra	236	If C<$enable> is false, then the C<encode> method will not add any extra
178	space at those places.	237	space at those places.
179		238
180	This setting has no effect when decoding JSON strings.	239	This setting has no effect when decoding JSON texts.
181		240
		241	Example, space_before and indent disabled, space_after enabled:
		242
		243	{"key": "value"}
		244
182	=item $json = $json->canonical ($enable)	245	=item $json = $json->canonical ([$enable])
183		246
184	If C<$enable> is true, then the C<encode> method will output JSON objects	247	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
185	by sorting their keys. This is adding a comparatively high overhead.	248	by sorting their keys. This is adding a comparatively high overhead.
186		249
187	If C<$enable> is false, then the C<encode> method will output key-value	250	If C<$enable> is false, then the C<encode> method will output key-value
188	pairs in the order Perl stores them (which will likely change between runs	251	pairs in the order Perl stores them (which will likely change between runs
189	of the same script).	252	of the same script).
190		253
191	This option is useful if you want the same data structure to be encoded as	254	This option is useful if you want the same data structure to be encoded as
192	the same JSON string (given the same overall settings). If it is disabled,	255	the same JSON text (given the same overall settings). If it is disabled,
193	the same hash migh be encoded differently even if contains the same data,	256	the same hash migh be encoded differently even if contains the same data,
194	as key-value pairs have no inherent ordering in Perl.	257	as key-value pairs have no inherent ordering in Perl.
195		258
196	This setting has no effect when decoding JSON strings.	259	This setting has no effect when decoding JSON texts.
197		260
		261	=item $json = $json->allow_nonref ([$enable])
		262
		263	If C<$enable> is true (or missing), then the C<encode> method can convert a
		264	non-reference into its corresponding string, number or null JSON value,
		265	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
		266	values instead of croaking.
		267
		268	If C<$enable> is false, then the C<encode> method will croak if it isn't
		269	passed an arrayref or hashref, as JSON texts must either be an object
		270	or array. Likewise, C<decode> will croak if given something that is not a
		271	JSON object or array.
		272
		273	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,
		274	resulting in an invalid JSON text:
		275
		276	JSON::XS->new->allow_nonref->encode ("Hello, World!")
		277	=> "Hello, World!"
		278
		279	=item $json = $json->shrink ([$enable])
		280
		281	Perl usually over-allocates memory a bit when allocating space for
		282	strings. This flag optionally resizes strings generated by either
		283	C<encode> or C<decode> to their minimum size possible. This can save
		284	memory when your JSON texts are either very very long or you have many
		285	short strings. It will also try to downgrade any strings to octet-form
		286	if possible: perl stores strings internally either in an encoding called
		287	UTF-X or in octet-form. The latter cannot store everything but uses less
		288	space in general.
		289
		290	If C<$enable> is true (or missing), the string returned by C<encode> will be shrunk-to-fit,
		291	while all strings generated by C<decode> will also be shrunk-to-fit.
		292
		293	If C<$enable> is false, then the normal perl allocation algorithms are used.
		294	If you work with your data, then this is likely to be faster.
		295
		296	In the future, this setting might control other things, such as converting
		297	strings that look like integers or floats into integers or floats
		298	internally (there is no difference on the Perl level), saving space.
		299
198	=item $json_string = $json->encode ($perl_scalar)	300	=item $json_text = $json->encode ($perl_scalar)
199		301
200	Converts the given Perl data structure (a simple scalar or a reference	302	Converts the given Perl data structure (a simple scalar or a reference
201	to a hash or array) to its JSON representation. Simple scalars will be	303	to a hash or array) to its JSON representation. Simple scalars will be
202	converted into JSON string or number sequences, while references to arrays	304	converted into JSON string or number sequences, while references to arrays
203	become JSON arrays and references to hashes become JSON objects. Undefined	305	become JSON arrays and references to hashes become JSON objects. Undefined
204	Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>	306	Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>
205	nor C<false> values will be generated.	307	nor C<false> values will be generated.
206		308
207	=item $perl_scalar = $json->decode ($json_string)	309	=item $perl_scalar = $json->decode ($json_text)
208		310
209	The opposite of C<encode>: expects a JSON string and tries to parse it,	311	The opposite of C<encode>: expects a JSON text and tries to parse it,
210	returning the resulting simple scalar or reference. Croaks on error.	312	returning the resulting simple scalar or reference. Croaks on error.
211		313
212	JSON numbers and strings become simple Perl scalars. JSON arrays become	314	JSON numbers and strings become simple Perl scalars. JSON arrays become
213	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes	315	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
214	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.	316	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
215		317
216	=back	318	=back
217		319
		320	=head1 MAPPING
		321
		322	This section describes how JSON::XS maps Perl values to JSON values and
		323	vice versa. These mappings are designed to "do the right thing" in most
		324	circumstances automatically, preserving round-tripping characteristics
		325	(what you put in comes out as something equivalent).
		326
		327	For the more enlightened: note that in the following descriptions,
		328	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
		329	refers to the abstract Perl language itself.
		330
		331	=head2 JSON -> PERL
		332
		333	=over 4
		334
		335	=item object
		336
		337	A JSON object becomes a reference to a hash in Perl. No ordering of object
		338	keys is preserved (JSON does not preserver object key ordering itself).
		339
		340	=item array
		341
		342	A JSON array becomes a reference to an array in Perl.
		343
		344	=item string
		345
		346	A JSON string becomes a string scalar in Perl - Unicode codepoints in JSON
		347	are represented by the same codepoints in the Perl string, so no manual
		348	decoding is necessary.
		349
		350	=item number
		351
		352	A JSON number becomes either an integer or numeric (floating point)
		353	scalar in perl, depending on its range and any fractional parts. On the
		354	Perl level, there is no difference between those as Perl handles all the
		355	conversion details, but an integer may take slightly less memory and might
		356	represent more values exactly than (floating point) numbers.
		357
		358	=item true, false
		359
		360	These JSON atoms become C<0>, C<1>, respectively. Information is lost in
		361	this process. Future versions might represent those values differently,
		362	but they will be guarenteed to act like these integers would normally in
		363	Perl.
		364
		365	=item null
		366
		367	A JSON null atom becomes C<undef> in Perl.
		368
		369	=back
		370
		371	=head2 PERL -> JSON
		372
		373	The mapping from Perl to JSON is slightly more difficult, as Perl is a
		374	truly typeless language, so we can only guess which JSON type is meant by
		375	a Perl value.
		376
		377	=over 4
		378
		379	=item hash references
		380
		381	Perl hash references become JSON objects. As there is no inherent ordering
		382	in hash keys, they will usually be encoded in a pseudo-random order that
		383	can change between runs of the same program but stays generally the same
		384	within a single run of a program. JSON::XS can optionally sort the hash
		385	keys (determined by the I<canonical> flag), so the same datastructure
		386	will serialise to the same JSON text (given same settings and version of
		387	JSON::XS), but this incurs a runtime overhead.
		388
		389	=item array references
		390
		391	Perl array references become JSON arrays.
		392
		393	=item blessed objects
		394
		395	Blessed objects are not allowed. JSON::XS currently tries to encode their
		396	underlying representation (hash- or arrayref), but this behaviour might
		397	change in future versions.
		398
		399	=item simple scalars
		400
		401	Simple Perl scalars (any scalar that is not a reference) are the most
		402	difficult objects to encode: JSON::XS will encode undefined scalars as
		403	JSON null value, scalars that have last been used in a string context
		404	before encoding as JSON strings and anything else as number value:
		405
		406	# dump as number
		407	to_json [2] # yields [2]
		408	to_json [-3.0e17] # yields [-3e+17]
		409	my $value = 5; to_json [$value] # yields [5]
		410
		411	# used as string, so dump as string
		412	print $value;
		413	to_json [$value] # yields ["5"]
		414
		415	# undef becomes null
		416	to_json [undef] # yields [null]
		417
		418	You can force the type to be a string by stringifying it:
		419
		420	my $x = 3.1; # some variable containing a number
		421	"$x"; # stringified
		422	$x .= ""; # another, more awkward way to stringify
		423	print $x; # perl does it for you, too, quite often
		424
		425	You can force the type to be a number by numifying it:
		426
		427	my $x = "3"; # some variable containing a string
		428	$x += 0; # numify it, ensuring it will be dumped as a number
		429	$x *= 1; # same thing, the choise is yours.
		430
		431	You can not currently output JSON booleans or force the type in other,
		432	less obscure, ways. Tell me if you need this capability.
		433
		434	=item circular data structures
		435
		436	Those will be encoded until memory or stackspace runs out.
		437
		438	=back
		439
		440	=head1 COMPARISON
		441
		442	As already mentioned, this module was created because none of the existing
		443	JSON modules could be made to work correctly. First I will describe the
		444	problems (or pleasures) I encountered with various existing JSON modules,
		445	followed by some benchmark values. JSON::XS was designed not to suffer
		446	from any of these problems or limitations.
		447
		448	=over 4
		449
		450	=item JSON 1.07
		451
		452	Slow (but very portable, as it is written in pure Perl).
		453
		454	Undocumented/buggy Unicode handling (how JSON handles unicode values is
		455	undocumented. One can get far by feeding it unicode strings and doing
		456	en-/decoding oneself, but unicode escapes are not working properly).
		457
		458	No roundtripping (strings get clobbered if they look like numbers, e.g.
		459	the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will
		460	decode into the number 2.
		461
		462	=item JSON::PC 0.01
		463
		464	Very fast.
		465
		466	Undocumented/buggy Unicode handling.
		467
		468	No roundtripping.
		469
		470	Has problems handling many Perl values (e.g. regex results and other magic
		471	values will make it croak).
		472
		473	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>
		474	which is not a valid JSON text.
		475
		476	Unmaintained (maintainer unresponsive for many months, bugs are not
		477	getting fixed).
		478
		479	=item JSON::Syck 0.21
		480
		481	Very buggy (often crashes).
		482
		483	Very inflexible (no human-readable format supported, format pretty much
		484	undocumented. I need at least a format for easy reading by humans and a
		485	single-line compact format for use in a protocol, and preferably a way to
		486	generate ASCII-only JSON texts).
		487
		488	Completely broken (and confusingly documented) Unicode handling (unicode
		489	escapes are not working properly, you need to set ImplicitUnicode to
		490	I<different> values on en- and decoding to get symmetric behaviour).
		491
		492	No roundtripping (simple cases work, but this depends on wether the scalar
		493	value was used in a numeric context or not).
		494
		495	Dumping hashes may skip hash values depending on iterator state.
		496
		497	Unmaintained (maintainer unresponsive for many months, bugs are not
		498	getting fixed).
		499
		500	Does not check input for validity (i.e. will accept non-JSON input and
		501	return "something" instead of raising an exception. This is a security
		502	issue: imagine two banks transfering money between each other using
		503	JSON. One bank might parse a given non-JSON request and deduct money,
		504	while the other might reject the transaction with a syntax error. While a
		505	good protocol will at least recover, that is extra unnecessary work and
		506	the transaction will still not succeed).
		507
		508	=item JSON::DWIW 0.04
		509
		510	Very fast. Very natural. Very nice.
		511
		512	Undocumented unicode handling (but the best of the pack. Unicode escapes
		513	still don't get parsed properly).
		514
		515	Very inflexible.
		516
		517	No roundtripping.
		518
		519	Does not generate valid JSON texts (key strings are often unquoted, empty keys
		520	result in nothing being output)
		521
		522	Does not check input for validity.
		523
		524	=back
		525
		526	=head2 SPEED
		527
		528	It seems that JSON::XS is surprisingly fast, as shown in the following
		529	tables. They have been generated with the help of the C<eg/bench> program
		530	in the JSON::XS distribution, to make it easy to compare on your own
		531	system.
		532
		533	First comes a comparison between various modules using a very short JSON
		534	string:
		535
		536	{"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null}
		537
		538	It shows the number of encodes/decodes per second (JSON::XS uses the
		539	functional interface, while JSON::XS/2 uses the OO interface with
		540	pretty-printing and hashkey sorting enabled). Higher is better:
		541
		542	module \| encode \| decode \|
		543	-----------\|------------\|------------\|
		544	JSON \| 11488.516 \| 7823.035 \|
		545	JSON::DWIW \| 94708.054 \| 129094.260 \|
		546	JSON::PC \| 63884.157 \| 128528.212 \|
		547	JSON::Syck \| 34898.677 \| 42096.911 \|
		548	JSON::XS \| 654027.064 \| 396423.669 \|
		549	JSON::XS/2 \| 371564.190 \| 371725.613 \|
		550	-----------+------------+------------+
		551
		552	That is, JSON::XS is more than six times faster than JSON::DWIW on
		553	encoding, more than three times faster on decoding, and about thirty times
		554	faster than JSON, even with pretty-printing and key sorting.
		555
		556	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
		557	search API (http://nanoref.com/yahooapis/mgPdGg):
		558
		559	module \| encode \| decode \|
		560	-----------\|------------\|------------\|
		561	JSON \| 273.023 \| 44.674 \|
		562	JSON::DWIW \| 1089.383 \| 1145.704 \|
		563	JSON::PC \| 3097.419 \| 2393.921 \|
		564	JSON::Syck \| 514.060 \| 843.053 \|
		565	JSON::XS \| 6479.668 \| 3636.364 \|
		566	JSON::XS/2 \| 3774.221 \| 3599.124 \|
		567	-----------+------------+------------+
		568
		569	Again, JSON::XS leads by far.
		570
		571	On large strings containing lots of high unicode characters, some modules
		572	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
		573	will be broken due to missing (or wrong) unicode handling. Others refuse
		574	to decode or encode properly, so it was impossible to prepare a fair
		575	comparison table for that case.
		576
		577	=head1 RESOURCE LIMITS
		578
		579	JSON::XS does not impose any limits on the size of JSON texts or Perl
		580	values they represent - if your machine can handle it, JSON::XS will
		581	encode or decode it. Future versions might optionally impose structure
		582	depth and memory use resource limits.
		583
		584	=head1 BUGS
		585
		586	While the goal of this module is to be correct, that unfortunately does
		587	not mean its bug-free, only that I think its design is bug-free. It is
		588	still very young and not well-tested. If you keep reporting bugs they will
		589	be fixed swiftly, though.
		590
218	=cut	591	=cut
219		592
220	1;	593	1;
221		594
222	=head1 AUTHOR	595	=head1 AUTHOR

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Comparing JSON-XS/XS.pm (file contents): Revision 1.2 by root, Thu Mar 22 17:28:50 2007 UTC vs. Revision 1.20 by root, Sun Mar 25 00:47:42 2007 UTC

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Comparing JSON-XS/XS.pm (file contents):
Revision 1.2 by root, Thu Mar 22 17:28:50 2007 UTC vs.
Revision 1.20 by root, Sun Mar 25 00:47:42 2007 UTC