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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.8 by root, Fri Mar 23 15:57:18 2007 UTC vs.
Revision 1.28 by root, Tue Apr 3 23:59:04 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 = '1.1';
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<$enable> is true (or missing), then the C<encode> method will	155	If C<$enable> is true (or missing), then the C<encode> method will not
122	not generate characters outside the code range C<0..127>. Any unicode	156	generate characters outside the code range C<0..127> (which is ASCII). Any
123	characters outside that range will be escaped using either a single	157	unicode characters outside that range will be escaped using either a
124	\uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, as per	158	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
125	RFC4627.	159	as per RFC4627.
126		160
127	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
128	characters unless necessary.	162	characters unless required by the JSON syntax. This results in a faster
		163	and more compact format.
129		164
130	JSON::XS->new->ascii (1)->encode (chr 0x10401)	165	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
131	=> \ud801\udc01	166	=> ["\ud801\udc01"]
132		167
133	=item $json = $json->utf8 ([$enable])	168	=item $json = $json->utf8 ([$enable])
134		169
135	If C<$enable> is true (or missing), then the C<encode> method will encode	170	If C<$enable> is true (or missing), then the C<encode> method will encode
136	the JSON string into UTF-8, as required by many protocols, while the	171	the JSON result into UTF-8, as required by many protocols, while the
137	C<decode> method expects to be handled an UTF-8-encoded string. Please	172	C<decode> method expects to be handled an UTF-8-encoded string. Please
138	note that UTF-8-encoded strings do not contain any characters outside the	173	note that UTF-8-encoded strings do not contain any characters outside the
139	range 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.
140		177
141	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
142	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
143	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
144	to be done yourself, e.g. using the Encode module.	181	to be done yourself, e.g. using the Encode module.
145		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
146	=item $json = $json->pretty ([$enable])	193	=item $json = $json->pretty ([$enable])
147		194
148	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
149	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
150	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:
151		200
152	my $json = JSON::XS->new->pretty(1)->encode ({a => [1,2]})	201	my $json = JSON::XS->new->pretty(1)->encode ({a => [1,2]})
153	=>	202	=>
154	{	203	{
155	"a" : [	204	"a" : [
…		…
163	If C<$enable> is true (or missing), then the C<encode> method will use a multiline	212	If C<$enable> is true (or missing), then the C<encode> method will use a multiline
164	format as output, putting every array member or object/hash key-value pair	213	format as output, putting every array member or object/hash key-value pair
165	into its own line, identing them properly.	214	into its own line, identing them properly.
166		215
167	If C<$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
168	resulting JSON strings is guarenteed not to contain any C<newlines>.	217	resulting JSON text is guarenteed not to contain any C<newlines>.
169		218
170	This setting has no effect when decoding JSON strings.	219	This setting has no effect when decoding JSON texts.
171		220
172	=item $json = $json->space_before ([$enable])	221	=item $json = $json->space_before ([$enable])
173		222
174	If C<$enable> is true (or missing), then the C<encode> method will add an extra	223	If C<$enable> is true (or missing), then the C<encode> method will add an extra
175	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.
176		225
177	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
178	space at those places.	227	space at those places.
179		228
180	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
181	likely combine this setting with C<space_after>.	230	most likely combine this setting with C<space_after>.
		231
		232	Example, space_before enabled, space_after and indent disabled:
		233
		234	{"key" :"value"}
182		235
183	=item $json = $json->space_after ([$enable])	236	=item $json = $json->space_after ([$enable])
184		237
185	If C<$enable> is true (or missing), then the C<encode> method will add an extra	238	If C<$enable> is true (or missing), then the C<encode> method will add an extra
186	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
…		…
188	members.	241	members.
189		242
190	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
191	space at those places.	244	space at those places.
192		245
193	This setting has no effect when decoding JSON strings.	246	This setting has no effect when decoding JSON texts.
		247
		248	Example, space_before and indent disabled, space_after enabled:
		249
		250	{"key": "value"}
194		251
195	=item $json = $json->canonical ([$enable])	252	=item $json = $json->canonical ([$enable])
196		253
197	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects	254	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
198	by sorting their keys. This is adding a comparatively high overhead.	255	by sorting their keys. This is adding a comparatively high overhead.
…		…
200	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
201	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
202	of the same script).	259	of the same script).
203		260
204	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
205	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,
206	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,
207	as key-value pairs have no inherent ordering in Perl.	264	as key-value pairs have no inherent ordering in Perl.
208		265
209	This setting has no effect when decoding JSON strings.	266	This setting has no effect when decoding JSON texts.
210		267
211	=item $json = $json->allow_nonref ([$enable])	268	=item $json = $json->allow_nonref ([$enable])
212		269
213	If C<$enable> is true (or missing), then the C<encode> method can convert a	270	If C<$enable> is true (or missing), then the C<encode> method can convert a
214	non-reference into its corresponding string, number or null JSON value,	271	non-reference into its corresponding string, number or null JSON value,
215	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
216	values instead of croaking.	273	values instead of croaking.
217		274
218	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
219	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
220	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
221	JSON object or array.	278	JSON object or array.
222		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
223	=item $json = $json->shrink ([$enable])	286	=item $json = $json->shrink ([$enable])
224		287
225	Perl usually over-allocates memory a bit when allocating space for	288	Perl usually over-allocates memory a bit when allocating space for
226	strings. This flag optionally resizes strings generated by either	289	strings. This flag optionally resizes strings generated by either
227	C<encode> or C<decode> to their minimum size possible. This can save	290	C<encode> or C<decode> to their minimum size possible. This can save
228	memory when your JSON strings are either very very long or you have many	291	memory when your JSON texts are either very very long or you have many
229	short strings. It will also try to downgrade any strings to octet-form	292	short strings. It will also try to downgrade any strings to octet-form
230	if possible: perl stores strings internally either in an encoding called	293	if possible: perl stores strings internally either in an encoding called
231	UTF-X or in octet-form. The latter cannot store everything but uses less	294	UTF-X or in octet-form. The latter cannot store everything but uses less
232	space in general.	295	space in general (and some buggy Perl or C code might even rely on that
		296	internal representation being used).
233		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
234	If C<$enable> is true (or missing), the string returned by C<encode> will be shrunk-to-fit,	301	If C<$enable> is true (or missing), the string returned by C<encode> will
235	while all strings generated by C<decode> will also be shrunk-to-fit.	302	be shrunk-to-fit, while all strings generated by C<decode> will also be
		303	shrunk-to-fit.
236		304
237	If C<$enable> is false, then the normal perl allocation algorithms are used.	305	If C<$enable> is false, then the normal perl allocation algorithms are used.
238	If you work with your data, then this is likely to be faster.	306	If you work with your data, then this is likely to be faster.
239		307
240	In the future, this setting might control other things, such as converting	308	In the future, this setting might control other things, such as converting
241	strings that look like integers or floats into integers or floats	309	strings that look like integers or floats into integers or floats
242	internally (there is no difference on the Perl level), saving space.	310	internally (there is no difference on the Perl level), saving space.
243		311
		312	=item $json = $json->max_depth ([$maximum_nesting_depth])
		313
		314	Sets the maximum nesting level (default C<512>) 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
244	=item $json_string = $json->encode ($perl_scalar)	332	=item $json_text = $json->encode ($perl_scalar)
245		333
246	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
247	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
248	converted into JSON string or number sequences, while references to arrays	336	converted into JSON string or number sequences, while references to arrays
249	become JSON arrays and references to hashes become JSON objects. Undefined	337	become JSON arrays and references to hashes become JSON objects. Undefined
250	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>
251	nor C<false> values will be generated.	339	nor C<false> values will be generated.
252		340
253	=item $perl_scalar = $json->decode ($json_string)	341	=item $perl_scalar = $json->decode ($json_text)
254		342
255	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,
256	returning the resulting simple scalar or reference. Croaks on error.	344	returning the resulting simple scalar or reference. Croaks on error.
257		345
258	JSON numbers and strings become simple Perl scalars. JSON arrays become	346	JSON numbers and strings become simple Perl scalars. JSON arrays become
259	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes	347	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
260	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>.
261		349
262	=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	=back
		479
263		480
264	=head1 COMPARISON	481	=head1 COMPARISON
265		482
266	As already mentioned, this module was created because none of the existing	483	As already mentioned, this module was created because none of the existing
267	JSON modules could be made to work correctly. First I will describe the	484	JSON modules could be made to work correctly. First I will describe the
…		…
293		510
294	Has problems handling many Perl values (e.g. regex results and other magic	511	Has problems handling many Perl values (e.g. regex results and other magic
295	values will make it croak).	512	values will make it croak).
296		513
297	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>	514	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>
298	which is not a valid JSON string.	515	which is not a valid JSON text.
299		516
300	Unmaintained (maintainer unresponsive for many months, bugs are not	517	Unmaintained (maintainer unresponsive for many months, bugs are not
301	getting fixed).	518	getting fixed).
302		519
303	=item JSON::Syck 0.21	520	=item JSON::Syck 0.21
…		…
305	Very buggy (often crashes).	522	Very buggy (often crashes).
306		523
307	Very inflexible (no human-readable format supported, format pretty much	524	Very inflexible (no human-readable format supported, format pretty much
308	undocumented. I need at least a format for easy reading by humans and a	525	undocumented. I need at least a format for easy reading by humans and a
309	single-line compact format for use in a protocol, and preferably a way to	526	single-line compact format for use in a protocol, and preferably a way to
310	generate ASCII-only JSON strings).	527	generate ASCII-only JSON texts).
311		528
312	Completely broken (and confusingly documented) Unicode handling (unicode	529	Completely broken (and confusingly documented) Unicode handling (unicode
313	escapes are not working properly, you need to set ImplicitUnicode to	530	escapes are not working properly, you need to set ImplicitUnicode to
314	I<different> values on en- and decoding to get symmetric behaviour).	531	I<different> values on en- and decoding to get symmetric behaviour).
315		532
…		…
338		555
339	Very inflexible.	556	Very inflexible.
340		557
341	No roundtripping.	558	No roundtripping.
342		559
343	Does not generate valid JSON (key strings are often unquoted, empty keys	560	Does not generate valid JSON texts (key strings are often unquoted, empty keys
344	result in nothing being output)	561	result in nothing being output)
345		562
346	Does not check input for validity.	563	Does not check input for validity.
347		564
348	=back	565	=back
…		…
352	It seems that JSON::XS is surprisingly fast, as shown in the following	569	It seems that JSON::XS is surprisingly fast, as shown in the following
353	tables. They have been generated with the help of the C<eg/bench> program	570	tables. They have been generated with the help of the C<eg/bench> program
354	in the JSON::XS distribution, to make it easy to compare on your own	571	in the JSON::XS distribution, to make it easy to compare on your own
355	system.	572	system.
356		573
357	First is a comparison between various modules using a very simple JSON	574	First comes a comparison between various modules using a very short JSON
		575	string:
		576
		577	{"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null}
		578
358	string, showing the number of encodes/decodes per second (JSON::XS is	579	It shows the number of encodes/decodes per second (JSON::XS uses the
359	the functional interface, while JSON::XS/2 is the OO interface with	580	functional interface, while JSON::XS/2 uses the OO interface with
360	pretty-printing and hashkey sorting enabled).	581	pretty-printing and hashkey sorting enabled). Higher is better:
361		582
362	module \| encode \| decode \|	583	module \| encode \| decode \|
363	-----------\|------------\|------------\|	584	-----------\|------------\|------------\|
364	JSON \| 14006 \| 6820 \|	585	JSON \| 11488.516 \| 7823.035 \|
365	JSON::DWIW \| 200937 \| 120386 \|	586	JSON::DWIW \| 94708.054 \| 129094.260 \|
366	JSON::PC \| 85065 \| 129366 \|	587	JSON::PC \| 63884.157 \| 128528.212 \|
367	JSON::Syck \| 59898 \| 44232 \|	588	JSON::Syck \| 34898.677 \| 42096.911 \|
368	JSON::XS \| 1171478 \| 342435 \|	589	JSON::XS \| 654027.064 \| 396423.669 \|
369	JSON::XS/2 \| 730760 \| 328714 \|	590	JSON::XS/2 \| 371564.190 \| 371725.613 \|
370	-----------+------------+------------+	591	-----------+------------+------------+
371		592
372	That is, JSON::XS is 6 times faster than than JSON::DWIW and about 80	593	That is, JSON::XS is more than six times faster than JSON::DWIW on
		594	encoding, more than three times faster on decoding, and about thirty times
373	times faster than JSON, even with pretty-printing and key sorting.	595	faster than JSON, even with pretty-printing and key sorting.
374		596
375	Using a longer test string (roughly 8KB, generated from Yahoo! Locals	597	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
376	search API (http://nanoref.com/yahooapis/mgPdGg):	598	search API (http://nanoref.com/yahooapis/mgPdGg):
377		599
378	module \| encode \| decode \|	600	module \| encode \| decode \|
379	-----------\|------------\|------------\|	601	-----------\|------------\|------------\|
380	JSON \| 673 \| 38 \|	602	JSON \| 273.023 \| 44.674 \|
381	JSON::DWIW \| 5271 \| 770 \|	603	JSON::DWIW \| 1089.383 \| 1145.704 \|
382	JSON::PC \| 9901 \| 2491 \|	604	JSON::PC \| 3097.419 \| 2393.921 \|
383	JSON::Syck \| 2360 \| 786 \|	605	JSON::Syck \| 514.060 \| 843.053 \|
384	JSON::XS \| 37398 \| 3202 \|	606	JSON::XS \| 6479.668 \| 3636.364 \|
385	JSON::XS/2 \| 13765 \| 3153 \|	607	JSON::XS/2 \| 3774.221 \| 3599.124 \|
386	-----------+------------+------------+	608	-----------+------------+------------+
387		609
388	Again, JSON::XS leads by far in the encoding case, while still beating	610	Again, JSON::XS leads by far.
389	every other module in the decoding case.
390		611
391	Last example is an almost 8MB large hash with many large binary values	612	On large strings containing lots of high unicode characters, some modules
392	(PNG files), resulting in a lot of escaping:	613	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
		614	will be broken due to missing (or wrong) unicode handling. Others refuse
		615	to decode or encode properly, so it was impossible to prepare a fair
		616	comparison table for that case.
		617
		618
		619	=head1 SECURITY CONSIDERATIONS
		620
		621	When you are using JSON in a protocol, talking to untrusted potentially
		622	hostile creatures requires relatively few measures.
		623
		624	First of all, your JSON decoder should be secure, that is, should not have
		625	any buffer overflows. Obviously, this module should ensure that and I am
		626	trying hard on making that true, but you never know.
		627
		628	Second, you need to avoid resource-starving attacks. That means you should
		629	limit the size of JSON texts you accept, or make sure then when your
		630	resources run out, thats just fine (e.g. by using a separate process that
		631	can crash safely). The size of a JSON text in octets or characters is
		632	usually a good indication of the size of the resources required to decode
		633	it into a Perl structure.
		634
		635	Third, JSON::XS recurses using the C stack when decoding objects and
		636	arrays. The C stack is a limited resource: for instance, on my amd64
		637	machine with 8MB of stack size I can decode around 180k nested arrays but
		638	only 14k nested JSON objects (due to perl itself recursing deeply on croak
		639	to free the temporary). If that is exceeded, the program crashes. to be
		640	conservative, the default nesting limit is set to 512. If your process
		641	has a smaller stack, you should adjust this setting accordingly with the
		642	C<max_depth> method.
		643
		644	And last but least, something else could bomb you that I forgot to think
		645	of. In that case, you get to keep the pieces. I am alway sopen for hints,
		646	though...
		647
393		648
394	=head1 BUGS	649	=head1 BUGS
395		650
396	While the goal of this module is to be correct, that unfortunately does	651	While the goal of this module is to be correct, that unfortunately does
397	not mean its bug-free, only that I think its design is bug-free. It is	652	not mean its bug-free, only that I think its design is bug-free. It is
398	still very young and not well-tested. If you keep reporting bugs they will	653	still relatively early in its development. If you keep reporting bugs they
399	be fixed swiftly, though.	654	will be fixed swiftly, though.
400		655
401	=cut	656	=cut
		657
		658	sub true() { \1 }
		659	sub false() { \0 }
402		660
403	1;	661	1;
404		662
405	=head1 AUTHOR	663	=head1 AUTHOR
406		664

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Revision 1.28 by root, Tue Apr 3 23:59:04 2007 UTC