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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.1 by root, Thu Mar 22 16:40:16 2007 UTC vs.
Revision 1.38 by root, Wed Jun 6 18:16:52 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, 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);
		24
9	=head1 DESCRIPTION	25	=head1 DESCRIPTION
10		26
		27	This module converts Perl data structures to JSON and vice versa. Its
		28	primary goal is to be I<correct> and its secondary goal is to be
		29	I<fast>. To reach the latter goal it was written in C.
		30
		31	As this is the n-th-something JSON module on CPAN, what was the reason
		32	to write yet another JSON module? While it seems there are many JSON
		33	modules, none of them correctly handle all corner cases, and in most cases
		34	their maintainers are unresponsive, gone missing, or not listening to bug
		35	reports for other reasons.
		36
		37	See COMPARISON, below, for a comparison to some other JSON modules.
		38
		39	See MAPPING, below, on how JSON::XS maps perl values to JSON values and
		40	vice versa.
		41
		42	=head2 FEATURES
		43
11	=over 4	44	=over 4
12		45
		46	=item * correct unicode handling
		47
		48	This module knows how to handle Unicode, and even documents how and when
		49	it does so.
		50
		51	=item * round-trip integrity
		52
		53	When you serialise a perl data structure using only datatypes supported
		54	by JSON, the deserialised data structure is identical on the Perl level.
		55	(e.g. the string "2.0" doesn't suddenly become "2" just because it looks
		56	like a number).
		57
		58	=item * strict checking of JSON correctness
		59
		60	There is no guessing, no generating of illegal JSON texts by default,
		61	and only JSON is accepted as input by default (the latter is a security
		62	feature).
		63
		64	=item * fast
		65
		66	Compared to other JSON modules, this module compares favourably in terms
		67	of speed, too.
		68
		69	=item * simple to use
		70
		71	This module has both a simple functional interface as well as an OO
		72	interface.
		73
		74	=item * reasonably versatile output formats
		75
		76	You can choose between the most compact guarenteed single-line format
		77	possible (nice for simple line-based protocols), a pure-ascii format
		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.
		81
		82	=back
		83
13	=cut	84	=cut
14		85
15	package JSON::XS;	86	package JSON::XS;
16		87
		88	use strict;
		89
17	BEGIN {	90	BEGIN {
18	$VERSION = '0.1';	91	our $VERSION = '1.23';
19	@ISA = qw(Exporter);	92	our @ISA = qw(Exporter);
20		93
		94	our @EXPORT = qw(to_json from_json objToJson jsonToObj);
21	require Exporter;	95	require Exporter;
22		96
23	require XSLoader;	97	require XSLoader;
24	XSLoader::load JSON::XS::, $VERSION;	98	XSLoader::load JSON::XS::, $VERSION;
25	}	99	}
26		100
27	=item	101	=head1 FUNCTIONAL INTERFACE
		102
		103	The following convinience methods are provided by this module. They are
		104	exported by default:
		105
		106	=over 4
		107
		108	=item $json_text = to_json $perl_scalar
		109
		110	Converts the given Perl data structure (a simple scalar or a reference to
		111	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains
		112	octets only). Croaks on error.
		113
		114	This function call is functionally identical to:
		115
		116	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)
		117
		118	except being faster.
		119
		120	=item $perl_scalar = from_json $json_text
		121
		122	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to
		123	parse that as an UTF-8 encoded JSON text, returning the resulting simple
		124	scalar or reference. Croaks on error.
		125
		126	This function call is functionally identical to:
		127
		128	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
		129
		130	except being faster.
		131
		132	=back
		133
		134
		135	=head1 OBJECT-ORIENTED INTERFACE
		136
		137	The object oriented interface lets you configure your own encoding or
		138	decoding style, within the limits of supported formats.
		139
		140	=over 4
		141
		142	=item $json = new JSON::XS
		143
		144	Creates a new JSON::XS object that can be used to de/encode JSON
		145	strings. All boolean flags described below are by default I<disabled>.
		146
		147	The mutators for flags all return the JSON object again and thus calls can
		148	be chained:
		149
		150	my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})
		151	=> {"a": [1, 2]}
		152
		153	=item $json = $json->ascii ([$enable])
		154
		155	If C<$enable> is true (or missing), then the C<encode> method will not
		156	generate characters outside the code range C<0..127> (which is ASCII). Any
		157	unicode characters outside that range will be escaped using either a
		158	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
		159	as per RFC4627. The resulting encoded JSON text can be treated as a native
		160	unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
		161	or any other superset of ASCII.
		162
		163	If C<$enable> is false, then the C<encode> method will not escape Unicode
		164	characters unless required by the JSON syntax or other flags. This results
		165	in a faster and more compact format.
		166
		167	The main use for this flag is to produce JSON texts that can be
		168	transmitted over a 7-bit channel, as the encoded JSON texts will not
		169	contain any 8 bit characters.
		170
		171	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
		172	=> ["\ud801\udc01"]
		173
		174	=item $json = $json->latin1 ([$enable])
		175
		176	If C<$enable> is true (or missing), then the C<encode> method will encode
		177	the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
		178	outside the code range C<0..255>. The resulting string can be treated as a
		179	latin1-encoded JSON text or a native unicode string. The C<decode> method
		180	will not be affected in any way by this flag, as C<decode> by default
		181	expects unicode, which is a strict superset of latin1.
		182
		183	If C<$enable> is false, then the C<encode> method will not escape Unicode
		184	characters unless required by the JSON syntax or other flags.
		185
		186	The main use for this flag is efficiently encoding binary data as JSON
		187	text, as most octets will not be escaped, resulting in a smaller encoded
		188	size. The disadvantage is that the resulting JSON text is encoded
		189	in latin1 (and must correctly be treated as such when storing and
		190	transfering), a rare encoding for JSON. It is therefore most useful when
		191	you want to store data structures known to contain binary data efficiently
		192	in files or databases, not when talking to other JSON encoders/decoders.
		193
		194	JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
		195	=> ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
		196
		197	=item $json = $json->utf8 ([$enable])
		198
		199	If C<$enable> is true (or missing), then the C<encode> method will encode
		200	the JSON result into UTF-8, as required by many protocols, while the
		201	C<decode> method expects to be handled an UTF-8-encoded string. Please
		202	note that UTF-8-encoded strings do not contain any characters outside the
		203	range C<0..255>, they are thus useful for bytewise/binary I/O. In future
		204	versions, enabling this option might enable autodetection of the UTF-16
		205	and UTF-32 encoding families, as described in RFC4627.
		206
		207	If C<$enable> is false, then the C<encode> method will return the JSON
		208	string as a (non-encoded) unicode string, while C<decode> expects thus a
		209	unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs
		210	to be done yourself, e.g. using the Encode module.
		211
		212	Example, output UTF-16BE-encoded JSON:
		213
		214	use Encode;
		215	$jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);
		216
		217	Example, decode UTF-32LE-encoded JSON:
		218
		219	use Encode;
		220	$object = JSON::XS->new->decode (decode "UTF-32LE", $jsontext);
		221
		222	=item $json = $json->pretty ([$enable])
		223
		224	This enables (or disables) all of the C<indent>, C<space_before> and
		225	C<space_after> (and in the future possibly more) flags in one call to
		226	generate the most readable (or most compact) form possible.
		227
		228	Example, pretty-print some simple structure:
		229
		230	my $json = JSON::XS->new->pretty(1)->encode ({a => [1,2]})
		231	=>
		232	{
		233	"a" : [
		234	1,
		235	2
		236	]
		237	}
		238
		239	=item $json = $json->indent ([$enable])
		240
		241	If C<$enable> is true (or missing), then the C<encode> method will use a multiline
		242	format as output, putting every array member or object/hash key-value pair
		243	into its own line, identing them properly.
		244
		245	If C<$enable> is false, no newlines or indenting will be produced, and the
		246	resulting JSON text is guarenteed not to contain any C<newlines>.
		247
		248	This setting has no effect when decoding JSON texts.
		249
		250	=item $json = $json->space_before ([$enable])
		251
		252	If C<$enable> is true (or missing), then the C<encode> method will add an extra
		253	optional space before the C<:> separating keys from values in JSON objects.
		254
		255	If C<$enable> is false, then the C<encode> method will not add any extra
		256	space at those places.
		257
		258	This setting has no effect when decoding JSON texts. You will also
		259	most likely combine this setting with C<space_after>.
		260
		261	Example, space_before enabled, space_after and indent disabled:
		262
		263	{"key" :"value"}
		264
		265	=item $json = $json->space_after ([$enable])
		266
		267	If C<$enable> is true (or missing), then the C<encode> method will add an extra
		268	optional space after the C<:> separating keys from values in JSON objects
		269	and extra whitespace after the C<,> separating key-value pairs and array
		270	members.
		271
		272	If C<$enable> is false, then the C<encode> method will not add any extra
		273	space at those places.
		274
		275	This setting has no effect when decoding JSON texts.
		276
		277	Example, space_before and indent disabled, space_after enabled:
		278
		279	{"key": "value"}
		280
		281	=item $json = $json->canonical ([$enable])
		282
		283	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
		284	by sorting their keys. This is adding a comparatively high overhead.
		285
		286	If C<$enable> is false, then the C<encode> method will output key-value
		287	pairs in the order Perl stores them (which will likely change between runs
		288	of the same script).
		289
		290	This option is useful if you want the same data structure to be encoded as
		291	the same JSON text (given the same overall settings). If it is disabled,
		292	the same hash migh be encoded differently even if contains the same data,
		293	as key-value pairs have no inherent ordering in Perl.
		294
		295	This setting has no effect when decoding JSON texts.
		296
		297	=item $json = $json->allow_nonref ([$enable])
		298
		299	If C<$enable> is true (or missing), then the C<encode> method can convert a
		300	non-reference into its corresponding string, number or null JSON value,
		301	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
		302	values instead of croaking.
		303
		304	If C<$enable> is false, then the C<encode> method will croak if it isn't
		305	passed an arrayref or hashref, as JSON texts must either be an object
		306	or array. Likewise, C<decode> will croak if given something that is not a
		307	JSON object or array.
		308
		309	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,
		310	resulting in an invalid JSON text:
		311
		312	JSON::XS->new->allow_nonref->encode ("Hello, World!")
		313	=> "Hello, World!"
		314
		315	=item $json = $json->shrink ([$enable])
		316
		317	Perl usually over-allocates memory a bit when allocating space for
		318	strings. This flag optionally resizes strings generated by either
		319	C<encode> or C<decode> to their minimum size possible. This can save
		320	memory when your JSON texts are either very very long or you have many
		321	short strings. It will also try to downgrade any strings to octet-form
		322	if possible: perl stores strings internally either in an encoding called
		323	UTF-X or in octet-form. The latter cannot store everything but uses less
		324	space in general (and some buggy Perl or C code might even rely on that
		325	internal representation being used).
		326
		327	The actual definition of what shrink does might change in future versions,
		328	but it will always try to save space at the expense of time.
		329
		330	If C<$enable> is true (or missing), the string returned by C<encode> will
		331	be shrunk-to-fit, while all strings generated by C<decode> will also be
		332	shrunk-to-fit.
		333
		334	If C<$enable> is false, then the normal perl allocation algorithms are used.
		335	If you work with your data, then this is likely to be faster.
		336
		337	In the future, this setting might control other things, such as converting
		338	strings that look like integers or floats into integers or floats
		339	internally (there is no difference on the Perl level), saving space.
		340
		341	=item $json = $json->max_depth ([$maximum_nesting_depth])
		342
		343	Sets the maximum nesting level (default C<512>) accepted while encoding
		344	or decoding. If the JSON text or Perl data structure has an equal or
		345	higher nesting level then this limit, then the encoder and decoder will
		346	stop and croak at that point.
		347
		348	Nesting level is defined by number of hash- or arrayrefs that the encoder
		349	needs to traverse to reach a given point or the number of C<{> or C<[>
		350	characters without their matching closing parenthesis crossed to reach a
		351	given character in a string.
		352
		353	Setting the maximum depth to one disallows any nesting, so that ensures
		354	that the object is only a single hash/object or array.
		355
		356	The argument to C<max_depth> will be rounded up to the next nearest power
		357	of two.
		358
		359	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
		360
		361	=item $json_text = $json->encode ($perl_scalar)
		362
		363	Converts the given Perl data structure (a simple scalar or a reference
		364	to a hash or array) to its JSON representation. Simple scalars will be
		365	converted into JSON string or number sequences, while references to arrays
		366	become JSON arrays and references to hashes become JSON objects. Undefined
		367	Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>
		368	nor C<false> values will be generated.
		369
		370	=item $perl_scalar = $json->decode ($json_text)
		371
		372	The opposite of C<encode>: expects a JSON text and tries to parse it,
		373	returning the resulting simple scalar or reference. Croaks on error.
		374
		375	JSON numbers and strings become simple Perl scalars. JSON arrays become
		376	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
		377	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
		378
		379	=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
		380
		381	This works like the C<decode> method, but instead of raising an exception
		382	when there is trailing garbage after the first JSON object, it will
		383	silently stop parsing there and return the number of characters consumed
		384	so far.
		385
		386	This is useful if your JSON texts are not delimited by an outer protocol
		387	(which is not the brightest thing to do in the first place) and you need
		388	to know where the JSON text ends.
		389
		390	JSON::XS->new->decode_prefix ("[1] the tail")
		391	=> ([], 3)
		392
		393	=back
		394
		395
		396	=head1 MAPPING
		397
		398	This section describes how JSON::XS maps Perl values to JSON values and
		399	vice versa. These mappings are designed to "do the right thing" in most
		400	circumstances automatically, preserving round-tripping characteristics
		401	(what you put in comes out as something equivalent).
		402
		403	For the more enlightened: note that in the following descriptions,
		404	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
		405	refers to the abstract Perl language itself.
		406
		407	=head2 JSON -> PERL
		408
		409	=over 4
		410
		411	=item object
		412
		413	A JSON object becomes a reference to a hash in Perl. No ordering of object
		414	keys is preserved (JSON does not preserver object key ordering itself).
		415
		416	=item array
		417
		418	A JSON array becomes a reference to an array in Perl.
		419
		420	=item string
		421
		422	A JSON string becomes a string scalar in Perl - Unicode codepoints in JSON
		423	are represented by the same codepoints in the Perl string, so no manual
		424	decoding is necessary.
		425
		426	=item number
		427
		428	A JSON number becomes either an integer or numeric (floating point)
		429	scalar in perl, depending on its range and any fractional parts. On the
		430	Perl level, there is no difference between those as Perl handles all the
		431	conversion details, but an integer may take slightly less memory and might
		432	represent more values exactly than (floating point) numbers.
		433
		434	=item true, false
		435
		436	These JSON atoms become C<0>, C<1>, respectively. Information is lost in
		437	this process. Future versions might represent those values differently,
		438	but they will be guarenteed to act like these integers would normally in
		439	Perl.
		440
		441	=item null
		442
		443	A JSON null atom becomes C<undef> in Perl.
		444
		445	=back
		446
		447	=head2 PERL -> JSON
		448
		449	The mapping from Perl to JSON is slightly more difficult, as Perl is a
		450	truly typeless language, so we can only guess which JSON type is meant by
		451	a Perl value.
		452
		453	=over 4
		454
		455	=item hash references
		456
		457	Perl hash references become JSON objects. As there is no inherent ordering
		458	in hash keys (or JSON objects), they will usually be encoded in a
		459	pseudo-random order that can change between runs of the same program but
		460	stays generally the same within a single run of a program. JSON::XS can
		461	optionally sort the hash keys (determined by the I<canonical> flag), so
		462	the same datastructure will serialise to the same JSON text (given same
		463	settings and version of JSON::XS), but this incurs a runtime overhead
		464	and is only rarely useful, e.g. when you want to compare some JSON text
		465	against another for equality.
		466
		467	=item array references
		468
		469	Perl array references become JSON arrays.
		470
		471	=item other references
		472
		473	Other unblessed references are generally not allowed and will cause an
		474	exception to be thrown, except for references to the integers C<0> and
		475	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
		476	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
		477
		478	to_json [\0,JSON::XS::true] # yields [false,true]
		479
		480	=item blessed objects
		481
		482	Blessed objects are not allowed. JSON::XS currently tries to encode their
		483	underlying representation (hash- or arrayref), but this behaviour might
		484	change in future versions.
		485
		486	=item simple scalars
		487
		488	Simple Perl scalars (any scalar that is not a reference) are the most
		489	difficult objects to encode: JSON::XS will encode undefined scalars as
		490	JSON null value, scalars that have last been used in a string context
		491	before encoding as JSON strings and anything else as number value:
		492
		493	# dump as number
		494	to_json [2] # yields [2]
		495	to_json [-3.0e17] # yields [-3e+17]
		496	my $value = 5; to_json [$value] # yields [5]
		497
		498	# used as string, so dump as string
		499	print $value;
		500	to_json [$value] # yields ["5"]
		501
		502	# undef becomes null
		503	to_json [undef] # yields [null]
		504
		505	You can force the type to be a string by stringifying it:
		506
		507	my $x = 3.1; # some variable containing a number
		508	"$x"; # stringified
		509	$x .= ""; # another, more awkward way to stringify
		510	print $x; # perl does it for you, too, quite often
		511
		512	You can force the type to be a number by numifying it:
		513
		514	my $x = "3"; # some variable containing a string
		515	$x += 0; # numify it, ensuring it will be dumped as a number
		516	$x *= 1; # same thing, the choise is yours.
		517
		518	You can not currently output JSON booleans or force the type in other,
		519	less obscure, ways. Tell me if you need this capability.
		520
		521	=back
		522
		523
		524	=head1 COMPARISON
		525
		526	As already mentioned, this module was created because none of the existing
		527	JSON modules could be made to work correctly. First I will describe the
		528	problems (or pleasures) I encountered with various existing JSON modules,
		529	followed by some benchmark values. JSON::XS was designed not to suffer
		530	from any of these problems or limitations.
		531
		532	=over 4
		533
		534	=item JSON 1.07
		535
		536	Slow (but very portable, as it is written in pure Perl).
		537
		538	Undocumented/buggy Unicode handling (how JSON handles unicode values is
		539	undocumented. One can get far by feeding it unicode strings and doing
		540	en-/decoding oneself, but unicode escapes are not working properly).
		541
		542	No roundtripping (strings get clobbered if they look like numbers, e.g.
		543	the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will
		544	decode into the number 2.
		545
		546	=item JSON::PC 0.01
		547
		548	Very fast.
		549
		550	Undocumented/buggy Unicode handling.
		551
		552	No roundtripping.
		553
		554	Has problems handling many Perl values (e.g. regex results and other magic
		555	values will make it croak).
		556
		557	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>
		558	which is not a valid JSON text.
		559
		560	Unmaintained (maintainer unresponsive for many months, bugs are not
		561	getting fixed).
		562
		563	=item JSON::Syck 0.21
		564
		565	Very buggy (often crashes).
		566
		567	Very inflexible (no human-readable format supported, format pretty much
		568	undocumented. I need at least a format for easy reading by humans and a
		569	single-line compact format for use in a protocol, and preferably a way to
		570	generate ASCII-only JSON texts).
		571
		572	Completely broken (and confusingly documented) Unicode handling (unicode
		573	escapes are not working properly, you need to set ImplicitUnicode to
		574	I<different> values on en- and decoding to get symmetric behaviour).
		575
		576	No roundtripping (simple cases work, but this depends on wether the scalar
		577	value was used in a numeric context or not).
		578
		579	Dumping hashes may skip hash values depending on iterator state.
		580
		581	Unmaintained (maintainer unresponsive for many months, bugs are not
		582	getting fixed).
		583
		584	Does not check input for validity (i.e. will accept non-JSON input and
		585	return "something" instead of raising an exception. This is a security
		586	issue: imagine two banks transfering money between each other using
		587	JSON. One bank might parse a given non-JSON request and deduct money,
		588	while the other might reject the transaction with a syntax error. While a
		589	good protocol will at least recover, that is extra unnecessary work and
		590	the transaction will still not succeed).
		591
		592	=item JSON::DWIW 0.04
		593
		594	Very fast. Very natural. Very nice.
		595
		596	Undocumented unicode handling (but the best of the pack. Unicode escapes
		597	still don't get parsed properly).
		598
		599	Very inflexible.
		600
		601	No roundtripping.
		602
		603	Does not generate valid JSON texts (key strings are often unquoted, empty keys
		604	result in nothing being output)
		605
		606	Does not check input for validity.
		607
		608	=back
		609
		610	=head2 SPEED
		611
		612	It seems that JSON::XS is surprisingly fast, as shown in the following
		613	tables. They have been generated with the help of the C<eg/bench> program
		614	in the JSON::XS distribution, to make it easy to compare on your own
		615	system.
		616
		617	First comes a comparison between various modules using a very short
		618	single-line JSON string:
		619
		620	{"method": "handleMessage", "params": ["user1", "we were just talking"], \
		621	"id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
		622
		623	It shows the number of encodes/decodes per second (JSON::XS uses the
		624	functional interface, while JSON::XS/2 uses the OO interface with
		625	pretty-printing and hashkey sorting enabled). Higher is better:
		626
		627	module \| encode \| decode \|
		628	-----------\|------------\|------------\|
		629	JSON \| 7645.468 \| 4208.613 \|
		630	JSON::DWIW \| 68534.379 \| 79437.576 \|
		631	JSON::PC \| 65948.176 \| 78251.940 \|
		632	JSON::Syck \| 23379.621 \| 28416.694 \|
		633	JSON::XS \| 388361.481 \| 199728.762 \|
		634	JSON::XS/2 \| 218453.333 \| 192399.266 \|
		635	JSON::XS/3 \| 338250.323 \| 192399.266 \|
		636	Storable \| 15732.573 \| 28571.553 \|
		637	-----------+------------+------------+
		638
		639	That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
		640	about three times faster on decoding, and over fourty times faster
		641	than JSON, even with pretty-printing and key sorting. It also compares
		642	favourably to Storable for small amounts of data.
		643
		644	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
		645	search API (http://nanoref.com/yahooapis/mgPdGg):
		646
		647	module \| encode \| decode \|
		648	-----------\|------------\|------------\|
		649	JSON \| 254.685 \| 37.665 \|
		650	JSON::DWIW \| 1014.244 \| 1087.678 \|
		651	JSON::PC \| 3602.116 \| 2307.352 \|
		652	JSON::Syck \| 558.035 \| 776.263 \|
		653	JSON::XS \| 5747.196 \| 3543.684 \|
		654	JSON::XS/2 \| 3968.121 \| 3589.170 \|
		655	JSON::XS/3 \| 6105.246 \| 3561.134 \|
		656	Storable \| 4456.337 \| 5320.020 \|
		657	-----------+------------+------------+
		658
		659	Again, JSON::XS leads by far.
		660
		661	On large strings containing lots of high unicode characters, some modules
		662	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
		663	will be broken due to missing (or wrong) unicode handling. Others refuse
		664	to decode or encode properly, so it was impossible to prepare a fair
		665	comparison table for that case.
		666
		667
		668	=head1 SECURITY CONSIDERATIONS
		669
		670	When you are using JSON in a protocol, talking to untrusted potentially
		671	hostile creatures requires relatively few measures.
		672
		673	First of all, your JSON decoder should be secure, that is, should not have
		674	any buffer overflows. Obviously, this module should ensure that and I am
		675	trying hard on making that true, but you never know.
		676
		677	Second, you need to avoid resource-starving attacks. That means you should
		678	limit the size of JSON texts you accept, or make sure then when your
		679	resources run out, thats just fine (e.g. by using a separate process that
		680	can crash safely). The size of a JSON text in octets or characters is
		681	usually a good indication of the size of the resources required to decode
		682	it into a Perl structure.
		683
		684	Third, JSON::XS recurses using the C stack when decoding objects and
		685	arrays. The C stack is a limited resource: for instance, on my amd64
		686	machine with 8MB of stack size I can decode around 180k nested arrays but
		687	only 14k nested JSON objects (due to perl itself recursing deeply on croak
		688	to free the temporary). If that is exceeded, the program crashes. to be
		689	conservative, the default nesting limit is set to 512. If your process
		690	has a smaller stack, you should adjust this setting accordingly with the
		691	C<max_depth> method.
		692
		693	And last but least, something else could bomb you that I forgot to think
		694	of. In that case, you get to keep the pieces. I am always open for hints,
		695	though...
		696
		697
		698	=head1 BUGS
		699
		700	While the goal of this module is to be correct, that unfortunately does
		701	not mean its bug-free, only that I think its design is bug-free. It is
		702	still relatively early in its development. If you keep reporting bugs they
		703	will be fixed swiftly, though.
28		704
29	=cut	705	=cut
30		706
31	use JSON::DWIW;	707	sub true() { \1 }
32	use Benchmark;	708	sub false() { \0 }
33
34	use utf8;
35	#my $json = '{"ü":1,"a":[1,{"3":4},2],"b":5,"üü":2}';
36	my $json = '{"test":9555555555555555555,"hu" : -1e+5, "arr" : [ 1,2,3,4,5]}';
37
38	my $js = JSON::XS->new;
39	warn $js->indent (0);
40	warn $js->canonical (0);
41	warn $js->ascii (0);
42	warn $js->space_after (0);
43	use Data::Dumper;
44	warn Dumper $js->decode ($json);
45	warn Dumper $js->encode ($js->decode ($json));
46	#my $x = {"üü" => 2, "ü" => 1, "a" => [1,{3,4},2], b => 5};
47
48	#my $js2 = JSON::DWIW->new;
49	#
50	#timethese 200000, {
51	# a => sub { $js->encode ($x) },
52	# b => sub { $js2->to_json ($x) },
53	#};
54		709
55	1;	710	1;
56
57	=back
58		711
59	=head1 AUTHOR	712	=head1 AUTHOR
60		713
61	Marc Lehmann <schmorp@schmorp.de>	714	Marc Lehmann <schmorp@schmorp.de>
62	http://home.schmorp.de/	715	http://home.schmorp.de/

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Comparing JSON-XS/XS.pm (file contents): Revision 1.1 by root, Thu Mar 22 16:40:16 2007 UTC vs. Revision 1.38 by root, Wed Jun 6 18:16:52 2007 UTC

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Revision 1.38 by root, Wed Jun 6 18:16:52 2007 UTC