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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.12 by root, Fri Mar 23 18:33:50 2007 UTC vs.
Revision 1.51 by root, Mon Jul 2 01:12:27 2007 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use JSON::XS;	7	use JSON::XS;
8		8
9	# exported functions, croak on error	9	# exported functions, they croak on error
		10	# and expect/generate UTF-8
10		11
11	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;	12	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;
12	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;	13	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;
13		14
14	# oo-interface	15	# OO-interface
15		16
16	$coder = JSON::XS->new->ascii->pretty->allow_nonref;	17	$coder = JSON::XS->new->ascii->pretty->allow_nonref;
17	$pretty_printed_unencoded = $coder->encode ($perl_scalar);	18	$pretty_printed_unencoded = $coder->encode ($perl_scalar);
18	$perl_scalar = $coder->decode ($unicode_json_text);	19	$perl_scalar = $coder->decode ($unicode_json_text);
19		20
…		…
36		37
37	=head2 FEATURES	38	=head2 FEATURES
38		39
39	=over 4	40	=over 4
40		41
41	=item * correct handling of unicode issues	42	=item * correct unicode handling
42		43
43	This module knows how to handle Unicode, and even documents how and when	44	This module knows how to handle Unicode, and even documents how and when
44	it does so.	45	it does so.
45		46
46	=item * round-trip integrity	47	=item * round-trip integrity
47		48
48	When you serialise a perl data structure using only datatypes supported	49	When you serialise a perl data structure using only datatypes supported
49	by JSON, the deserialised data structure is identical on the Perl level.	50	by JSON, the deserialised data structure is identical on the Perl level.
50	(e.g. the string "2.0" doesn't suddenly become "2").	51	(e.g. the string "2.0" doesn't suddenly become "2" just because it looks
		52	like a number).
51		53
52	=item * strict checking of JSON correctness	54	=item * strict checking of JSON correctness
53		55
54	There is no guessing, no generating of illegal JSON strings by default,	56	There is no guessing, no generating of illegal JSON texts by default,
55	and only JSON is accepted as input by default (the latter is a security	57	and only JSON is accepted as input by default (the latter is a security
56	feature).	58	feature).
57		59
58	=item * fast	60	=item * fast
59		61
…		…
66	interface.	68	interface.
67		69
68	=item * reasonably versatile output formats	70	=item * reasonably versatile output formats
69		71
70	You can choose between the most compact guarenteed single-line format	72	You can choose between the most compact guarenteed single-line format
71	possible (nice for simple line-based protocols), a pure-ascii format (for	73	possible (nice for simple line-based protocols), a pure-ascii format
72	when your transport is not 8-bit clean), or a pretty-printed format (for	74	(for when your transport is not 8-bit clean, still supports the whole
73	when you want to read that stuff). Or you can combine those features in	75	unicode range), or a pretty-printed format (for when you want to read that
74	whatever way you like.	76	stuff). Or you can combine those features in whatever way you like.
75		77
76	=back	78	=back
77		79
78	=cut	80	=cut
79		81
80	package JSON::XS;	82	package JSON::XS;
81		83
82	BEGIN {	84	use strict;
		85
83	$VERSION = '0.3';	86	our $VERSION = '1.4';
84	@ISA = qw(Exporter);	87	our @ISA = qw(Exporter);
85		88
86	@EXPORT = qw(to_json from_json);	89	our @EXPORT = qw(to_json from_json);
87	require Exporter;
88		90
89	require XSLoader;	91	use Exporter;
90	XSLoader::load JSON::XS::, $VERSION;	92	use XSLoader;
91	}
92		93
93	=head1 FUNCTIONAL INTERFACE	94	=head1 FUNCTIONAL INTERFACE
94		95
95	The following convinience methods are provided by this module. They are	96	The following convinience methods are provided by this module. They are
96	exported by default:	97	exported by default:
97		98
98	=over 4	99	=over 4
99		100
100	=item $json_string = to_json $perl_scalar	101	=item $json_text = to_json $perl_scalar
101		102
102	Converts the given Perl data structure (a simple scalar or a reference to	103	Converts the given Perl data structure (a simple scalar or a reference to
103	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains	104	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains
104	octets only). Croaks on error.	105	octets only). Croaks on error.
105		106
106	This function call is functionally identical to C<< JSON::XS->new->utf8->encode ($perl_scalar) >>.	107	This function call is functionally identical to:
107		108
		109	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)
		110
		111	except being faster.
		112
108	=item $perl_scalar = from_json $json_string	113	=item $perl_scalar = from_json $json_text
109		114
110	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to	115	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to
111	parse that as an UTF-8 encoded JSON string, returning the resulting simple	116	parse that as an UTF-8 encoded JSON text, returning the resulting simple
112	scalar or reference. Croaks on error.	117	scalar or reference. Croaks on error.
113		118
114	This function call is functionally identical to C<< JSON::XS->new->utf8->decode ($json_string) >>.	119	This function call is functionally identical to:
		120
		121	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
		122
		123	except being faster.
		124
		125	=item $is_boolean = JSON::XS::is_bool $scalar
		126
		127	Returns true if the passed scalar represents either JSON::XS::true or
		128	JSON::XS::false, two constants that act like C<1> and C<0>, respectively
		129	and are used to represent JSON C<true> and C<false> values in Perl.
		130
		131	See MAPPING, below, for more information on how JSON values are mapped to
		132	Perl.
115		133
116	=back	134	=back
		135
117		136
118	=head1 OBJECT-ORIENTED INTERFACE	137	=head1 OBJECT-ORIENTED INTERFACE
119		138
120	The object oriented interface lets you configure your own encoding or	139	The object oriented interface lets you configure your own encoding or
121	decoding style, within the limits of supported formats.	140	decoding style, within the limits of supported formats.
…		…
128	strings. All boolean flags described below are by default I<disabled>.	147	strings. All boolean flags described below are by default I<disabled>.
129		148
130	The mutators for flags all return the JSON object again and thus calls can	149	The mutators for flags all return the JSON object again and thus calls can
131	be chained:	150	be chained:
132		151
133	my $json = JSON::XS->new->utf8(1)->space_after(1)->encode ({a => [1,2]})	152	my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})
134	=> {"a": [1, 2]}	153	=> {"a": [1, 2]}
135		154
136	=item $json = $json->ascii ([$enable])	155	=item $json = $json->ascii ([$enable])
137		156
138	If C<$enable> is true (or missing), then the C<encode> method will	157	If C<$enable> is true (or missing), then the C<encode> method will not
139	not generate characters outside the code range C<0..127>. Any unicode	158	generate characters outside the code range C<0..127> (which is ASCII). Any
140	characters outside that range will be escaped using either a single	159	unicode characters outside that range will be escaped using either a
141	\uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, as per	160	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
142	RFC4627.	161	as per RFC4627. The resulting encoded JSON text can be treated as a native
		162	unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
		163	or any other superset of ASCII.
143		164
144	If C<$enable> is false, then the C<encode> method will not escape Unicode	165	If C<$enable> is false, then the C<encode> method will not escape Unicode
145	characters unless necessary.	166	characters unless required by the JSON syntax or other flags. This results
		167	in a faster and more compact format.
146		168
		169	The main use for this flag is to produce JSON texts that can be
		170	transmitted over a 7-bit channel, as the encoded JSON texts will not
		171	contain any 8 bit characters.
		172
147	JSON::XS->new->ascii (1)->encode (chr 0x10401)	173	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
148	=> \ud801\udc01	174	=> ["\ud801\udc01"]
		175
		176	=item $json = $json->latin1 ([$enable])
		177
		178	If C<$enable> is true (or missing), then the C<encode> method will encode
		179	the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
		180	outside the code range C<0..255>. The resulting string can be treated as a
		181	latin1-encoded JSON text or a native unicode string. The C<decode> method
		182	will not be affected in any way by this flag, as C<decode> by default
		183	expects unicode, which is a strict superset of latin1.
		184
		185	If C<$enable> is false, then the C<encode> method will not escape Unicode
		186	characters unless required by the JSON syntax or other flags.
		187
		188	The main use for this flag is efficiently encoding binary data as JSON
		189	text, as most octets will not be escaped, resulting in a smaller encoded
		190	size. The disadvantage is that the resulting JSON text is encoded
		191	in latin1 (and must correctly be treated as such when storing and
		192	transfering), a rare encoding for JSON. It is therefore most useful when
		193	you want to store data structures known to contain binary data efficiently
		194	in files or databases, not when talking to other JSON encoders/decoders.
		195
		196	JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
		197	=> ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
149		198
150	=item $json = $json->utf8 ([$enable])	199	=item $json = $json->utf8 ([$enable])
151		200
152	If C<$enable> is true (or missing), then the C<encode> method will encode	201	If C<$enable> is true (or missing), then the C<encode> method will encode
153	the JSON string into UTF-8, as required by many protocols, while the	202	the JSON result into UTF-8, as required by many protocols, while the
154	C<decode> method expects to be handled an UTF-8-encoded string. Please	203	C<decode> method expects to be handled an UTF-8-encoded string. Please
155	note that UTF-8-encoded strings do not contain any characters outside the	204	note that UTF-8-encoded strings do not contain any characters outside the
156	range C<0..255>, they are thus useful for bytewise/binary I/O.	205	range C<0..255>, they are thus useful for bytewise/binary I/O. In future
		206	versions, enabling this option might enable autodetection of the UTF-16
		207	and UTF-32 encoding families, as described in RFC4627.
157		208
158	If C<$enable> is false, then the C<encode> method will return the JSON	209	If C<$enable> is false, then the C<encode> method will return the JSON
159	string as a (non-encoded) unicode string, while C<decode> expects thus a	210	string as a (non-encoded) unicode string, while C<decode> expects thus a
160	unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs	211	unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs
161	to be done yourself, e.g. using the Encode module.	212	to be done yourself, e.g. using the Encode module.
162		213
163	Example, output UTF-16-encoded JSON:	214	Example, output UTF-16BE-encoded JSON:
		215
		216	use Encode;
		217	$jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);
		218
		219	Example, decode UTF-32LE-encoded JSON:
		220
		221	use Encode;
		222	$object = JSON::XS->new->decode (decode "UTF-32LE", $jsontext);
164		223
165	=item $json = $json->pretty ([$enable])	224	=item $json = $json->pretty ([$enable])
166		225
167	This enables (or disables) all of the C<indent>, C<space_before> and	226	This enables (or disables) all of the C<indent>, C<space_before> and
168	C<space_after> (and in the future possibly more) flags in one call to	227	C<space_after> (and in the future possibly more) flags in one call to
…		…
184	If C<$enable> is true (or missing), then the C<encode> method will use a multiline	243	If C<$enable> is true (or missing), then the C<encode> method will use a multiline
185	format as output, putting every array member or object/hash key-value pair	244	format as output, putting every array member or object/hash key-value pair
186	into its own line, identing them properly.	245	into its own line, identing them properly.
187		246
188	If C<$enable> is false, no newlines or indenting will be produced, and the	247	If C<$enable> is false, no newlines or indenting will be produced, and the
189	resulting JSON strings is guarenteed not to contain any C<newlines>.	248	resulting JSON text is guarenteed not to contain any C<newlines>.
190		249
191	This setting has no effect when decoding JSON strings.	250	This setting has no effect when decoding JSON texts.
192		251
193	=item $json = $json->space_before ([$enable])	252	=item $json = $json->space_before ([$enable])
194		253
195	If C<$enable> is true (or missing), then the C<encode> method will add an extra	254	If C<$enable> is true (or missing), then the C<encode> method will add an extra
196	optional space before the C<:> separating keys from values in JSON objects.	255	optional space before the C<:> separating keys from values in JSON objects.
197		256
198	If C<$enable> is false, then the C<encode> method will not add any extra	257	If C<$enable> is false, then the C<encode> method will not add any extra
199	space at those places.	258	space at those places.
200		259
201	This setting has no effect when decoding JSON strings. You will also most	260	This setting has no effect when decoding JSON texts. You will also
202	likely combine this setting with C<space_after>.	261	most likely combine this setting with C<space_after>.
203		262
204	Example, space_before enabled, space_after and indent disabled:	263	Example, space_before enabled, space_after and indent disabled:
205		264
206	{"key" :"value"}	265	{"key" :"value"}
207		266
…		…
213	members.	272	members.
214		273
215	If C<$enable> is false, then the C<encode> method will not add any extra	274	If C<$enable> is false, then the C<encode> method will not add any extra
216	space at those places.	275	space at those places.
217		276
218	This setting has no effect when decoding JSON strings.	277	This setting has no effect when decoding JSON texts.
219		278
220	Example, space_before and indent disabled, space_after enabled:	279	Example, space_before and indent disabled, space_after enabled:
221		280
222	{"key": "value"}	281	{"key": "value"}
223		282
…		…
229	If C<$enable> is false, then the C<encode> method will output key-value	288	If C<$enable> is false, then the C<encode> method will output key-value
230	pairs in the order Perl stores them (which will likely change between runs	289	pairs in the order Perl stores them (which will likely change between runs
231	of the same script).	290	of the same script).
232		291
233	This option is useful if you want the same data structure to be encoded as	292	This option is useful if you want the same data structure to be encoded as
234	the same JSON string (given the same overall settings). If it is disabled,	293	the same JSON text (given the same overall settings). If it is disabled,
235	the same hash migh be encoded differently even if contains the same data,	294	the same hash migh be encoded differently even if contains the same data,
236	as key-value pairs have no inherent ordering in Perl.	295	as key-value pairs have no inherent ordering in Perl.
237		296
238	This setting has no effect when decoding JSON strings.	297	This setting has no effect when decoding JSON texts.
239		298
240	=item $json = $json->allow_nonref ([$enable])	299	=item $json = $json->allow_nonref ([$enable])
241		300
242	If C<$enable> is true (or missing), then the C<encode> method can convert a	301	If C<$enable> is true (or missing), then the C<encode> method can convert a
243	non-reference into its corresponding string, number or null JSON value,	302	non-reference into its corresponding string, number or null JSON value,
244	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON	303	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
245	values instead of croaking.	304	values instead of croaking.
246		305
247	If C<$enable> is false, then the C<encode> method will croak if it isn't	306	If C<$enable> is false, then the C<encode> method will croak if it isn't
248	passed an arrayref or hashref, as JSON strings must either be an object	307	passed an arrayref or hashref, as JSON texts must either be an object
249	or array. Likewise, C<decode> will croak if given something that is not a	308	or array. Likewise, C<decode> will croak if given something that is not a
250	JSON object or array.	309	JSON object or array.
251		310
252	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,	311	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,
253	resulting in an invalid JSON text:	312	resulting in an invalid JSON text:
254		313
255	JSON::XS->new->allow_nonref->encode ("Hello, World!")	314	JSON::XS->new->allow_nonref->encode ("Hello, World!")
256	=> "Hello, World!"	315	=> "Hello, World!"
257		316
		317	=item $json = $json->allow_blessed ([$enable])
		318
		319	If C<$enable> is true (or missing), then the C<encode> method will not
		320	barf when it encounters a blessed reference. Instead, the value of the
		321	B<convert_blessed> option will decide wether C<null> (C<convert_blessed>
		322	disabled or no C<to_json> method found) or a representation of the
		323	object (C<convert_blessed> enabled and C<to_json> method found) is being
		324	encoded. Has no effect on C<decode>.
		325
		326	If C<$enable> is false (the default), then C<encode> will throw an
		327	exception when it encounters a blessed object.
		328
		329	=item $json = $json->convert_blessed ([$enable])
		330
		331	If C<$enable> is true (or missing), then C<encode>, upon encountering a
		332	blessed object, will check for the availability of the C<TO_JSON> method
		333	on the object's class. If found, it will be called in scalar context
		334	and the resulting scalar will be encoded instead of the object. If no
		335	C<TO_JSON> method is found, the value of C<allow_blessed> will decide what
		336	to do.
		337
		338	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
		339	returns other blessed objects, those will be handled in the same
		340	way. C<TO_JSON> must take care of not causing an endless recursion cycle
		341	(== crash) in this case. The name of C<TO_JSON> was chosen because other
		342	methods called by the Perl core (== not by the user of the object) are
		343	usually in upper case letters and to avoid collisions with the C<to_json>
		344	function.
		345
		346	This setting does not yet influence C<decode> in any way, but in the
		347	future, global hooks might get installed that influence C<decode> and are
		348	enabled by this setting.
		349
		350	If C<$enable> is false, then the C<allow_blessed> setting will decide what
		351	to do when a blessed object is found.
		352
		353	=item $json = $json->filter_json_object ([$coderef])
		354
		355	When C<$coderef> is specified, it will be called from C<decode> each
		356	time it decodes a JSON object. The only argument is a reference to the
		357	newly-created hash. If the code references returns a single scalar (which
		358	need not be a reference), this value (i.e. a copy of that scalar to avoid
		359	aliasing) is inserted into the deserialised data structure. If it returns
		360	an empty list (NOTE: I<not> C<undef>, which is a valid scalar), the
		361	original deserialised hash will be inserted. This setting can slow down
		362	decoding considerably.
		363
		364	When C<$coderef> is omitted or undefined, C<decode> will not change the
		365	deserialised hash in any way. This is maximally fast.
		366
		367	Example, convert all JSON objects into the integer 5:
		368
		369	my $js = JSON::XS->new->filter_json_object (sub { 5 });
		370	# returns [5]
		371	$js->decode ('[{}]')
		372	# throw an exception because allow_nonref is not enabled:
		373	$js->decode ('{"a":1, "b":2}');
		374
		375	=item $json = $json->filter_json_single_key_object ([$coderef])
		376
		377	Works like C<filter_json_object>, but is only called for JSON objects
		378	having only a single key.
		379
		380	This C<$coderef> is called before the one specified via
		381	C<filter_json_object>, if any. If it returns something, that will be
		382	inserted into the data structure. If it returns nothing, the callback
		383	from C<filter_json_object> will be called next. If you want to force
		384	insertion of single-key objects even in the presence of a mutating
		385	C<filter_json_object> callback, simply return the passed hash.
		386
		387	As this callback gets called less often then the C<filter_json_object>
		388	one, decoding speed will not usually suffer as much. Therefore, single-key
		389	objects make excellent targets to serialise Perl objects into, especially
		390	as single-key JSON objects are as close to the type-tagged value concept
		391	as JSON gets (its basically an ID/VALUE tuple). Of course, JSON does not
		392	support this in any way, so you need to make sure your data never looks
		393	like a serialised Perl hash.
		394
		395	Typical names for the single object key are C<__class_whatever__>, or
		396	C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even
		397	things like C<__class_md5sum(classname)__>, to reduce the risk of clashing
		398	with real hashes.
		399
		400	Example, decode JSON objects of the form C<< { "__widget__" => <id> } >>
		401	into the corresponding C<< $WIDGET{<id>} >> object:
		402
		403	# return whatever is in $WIDGET{5}:
		404	JSON::XS
		405	->new
		406	->filter_json_single_key_object (sub {
		407	exists $_[0]{__widget__}
		408	? $WIDGET{ $_[0]{__widget__} }
		409	: ()
		410	})
		411	->decode ('{"__widget__": 5')
		412
		413	# this can be used with a TO_JSON method in some "widget" class
		414	# for serialisation to json:
		415	sub WidgetBase::TO_JSON {
		416	my ($self) = @_;
		417
		418	unless ($self->{id}) {
		419	$self->{id} = ..get..some..id..;
		420	$WIDGET{$self->{id}} = $self;
		421	}
		422
		423	{ __widget__ => $self->{id} }
		424	}
		425
258	=item $json = $json->shrink ([$enable])	426	=item $json = $json->shrink ([$enable])
259		427
260	Perl usually over-allocates memory a bit when allocating space for	428	Perl usually over-allocates memory a bit when allocating space for
261	strings. This flag optionally resizes strings generated by either	429	strings. This flag optionally resizes strings generated by either
262	C<encode> or C<decode> to their minimum size possible. This can save	430	C<encode> or C<decode> to their minimum size possible. This can save
263	memory when your JSON strings are either very very long or you have many	431	memory when your JSON texts are either very very long or you have many
264	short strings. It will also try to downgrade any strings to octet-form	432	short strings. It will also try to downgrade any strings to octet-form
265	if possible: perl stores strings internally either in an encoding called	433	if possible: perl stores strings internally either in an encoding called
266	UTF-X or in octet-form. The latter cannot store everything but uses less	434	UTF-X or in octet-form. The latter cannot store everything but uses less
267	space in general.	435	space in general (and some buggy Perl or C code might even rely on that
		436	internal representation being used).
268		437
		438	The actual definition of what shrink does might change in future versions,
		439	but it will always try to save space at the expense of time.
		440
269	If C<$enable> is true (or missing), the string returned by C<encode> will be shrunk-to-fit,	441	If C<$enable> is true (or missing), the string returned by C<encode> will
270	while all strings generated by C<decode> will also be shrunk-to-fit.	442	be shrunk-to-fit, while all strings generated by C<decode> will also be
		443	shrunk-to-fit.
271		444
272	If C<$enable> is false, then the normal perl allocation algorithms are used.	445	If C<$enable> is false, then the normal perl allocation algorithms are used.
273	If you work with your data, then this is likely to be faster.	446	If you work with your data, then this is likely to be faster.
274		447
275	In the future, this setting might control other things, such as converting	448	In the future, this setting might control other things, such as converting
276	strings that look like integers or floats into integers or floats	449	strings that look like integers or floats into integers or floats
277	internally (there is no difference on the Perl level), saving space.	450	internally (there is no difference on the Perl level), saving space.
278		451
		452	=item $json = $json->max_depth ([$maximum_nesting_depth])
		453
		454	Sets the maximum nesting level (default C<512>) accepted while encoding
		455	or decoding. If the JSON text or Perl data structure has an equal or
		456	higher nesting level then this limit, then the encoder and decoder will
		457	stop and croak at that point.
		458
		459	Nesting level is defined by number of hash- or arrayrefs that the encoder
		460	needs to traverse to reach a given point or the number of C<{> or C<[>
		461	characters without their matching closing parenthesis crossed to reach a
		462	given character in a string.
		463
		464	Setting the maximum depth to one disallows any nesting, so that ensures
		465	that the object is only a single hash/object or array.
		466
		467	The argument to C<max_depth> will be rounded up to the next highest power
		468	of two. If no argument is given, the highest possible setting will be
		469	used, which is rarely useful.
		470
		471	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
		472
		473	=item $json = $json->max_size ([$maximum_string_size])
		474
		475	Set the maximum length a JSON text may have (in bytes) where decoding is
		476	being attempted. The default is C<0>, meaning no limit. When C<decode>
		477	is called on a string longer then this number of characters it will not
		478	attempt to decode the string but throw an exception. This setting has no
		479	effect on C<encode> (yet).
		480
		481	The argument to C<max_size> will be rounded up to the next B<highest>
		482	power of two (so may be more than requested). If no argument is given, the
		483	limit check will be deactivated (same as when C<0> is specified).
		484
		485	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
		486
279	=item $json_string = $json->encode ($perl_scalar)	487	=item $json_text = $json->encode ($perl_scalar)
280		488
281	Converts the given Perl data structure (a simple scalar or a reference	489	Converts the given Perl data structure (a simple scalar or a reference
282	to a hash or array) to its JSON representation. Simple scalars will be	490	to a hash or array) to its JSON representation. Simple scalars will be
283	converted into JSON string or number sequences, while references to arrays	491	converted into JSON string or number sequences, while references to arrays
284	become JSON arrays and references to hashes become JSON objects. Undefined	492	become JSON arrays and references to hashes become JSON objects. Undefined
285	Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>	493	Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>
286	nor C<false> values will be generated.	494	nor C<false> values will be generated.
287		495
288	=item $perl_scalar = $json->decode ($json_string)	496	=item $perl_scalar = $json->decode ($json_text)
289		497
290	The opposite of C<encode>: expects a JSON string and tries to parse it,	498	The opposite of C<encode>: expects a JSON text and tries to parse it,
291	returning the resulting simple scalar or reference. Croaks on error.	499	returning the resulting simple scalar or reference. Croaks on error.
292		500
293	JSON numbers and strings become simple Perl scalars. JSON arrays become	501	JSON numbers and strings become simple Perl scalars. JSON arrays become
294	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes	502	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
295	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.	503	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
296		504
		505	=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
		506
		507	This works like the C<decode> method, but instead of raising an exception
		508	when there is trailing garbage after the first JSON object, it will
		509	silently stop parsing there and return the number of characters consumed
		510	so far.
		511
		512	This is useful if your JSON texts are not delimited by an outer protocol
		513	(which is not the brightest thing to do in the first place) and you need
		514	to know where the JSON text ends.
		515
		516	JSON::XS->new->decode_prefix ("[1] the tail")
		517	=> ([], 3)
		518
297	=back	519	=back
		520
298		521
299	=head1 MAPPING	522	=head1 MAPPING
300		523
301	This section describes how JSON::XS maps Perl values to JSON values and	524	This section describes how JSON::XS maps Perl values to JSON values and
302	vice versa. These mappings are designed to "do the right thing" in most	525	vice versa. These mappings are designed to "do the right thing" in most
…		…
305		528
306	For the more enlightened: note that in the following descriptions,	529	For the more enlightened: note that in the following descriptions,
307	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>	530	lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
308	refers to the abstract Perl language itself.	531	refers to the abstract Perl language itself.
309		532
		533
310	=head2 JSON -> PERL	534	=head2 JSON -> PERL
311		535
312	=over 4	536	=over 4
313		537
314	=item object	538	=item object
315		539
316	A JSON object becomes a reference to a hash in Perl. No ordering of object	540	A JSON object becomes a reference to a hash in Perl. No ordering of object
317	keys is preserved.	541	keys is preserved (JSON does not preserver object key ordering itself).
318		542
319	=item array	543	=item array
320		544
321	A JSON array becomes a reference to an array in Perl.	545	A JSON array becomes a reference to an array in Perl.
322		546
…		…
334	conversion details, but an integer may take slightly less memory and might	558	conversion details, but an integer may take slightly less memory and might
335	represent more values exactly than (floating point) numbers.	559	represent more values exactly than (floating point) numbers.
336		560
337	=item true, false	561	=item true, false
338		562
339	These JSON atoms become C<0>, C<1>, respectively. Information is lost in	563	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
340	this process. Future versions might represent those values differently,	564	respectively. They are overloaded to act almost exactly like the numbers
341	but they will be guarenteed to act like these integers would normally in	565	C<1> and C<0>. You can check wether a scalar is a JSON boolean by using
342	Perl.	566	the C<JSON::XS::is_bool> function.
343		567
344	=item null	568	=item null
345		569
346	A JSON null atom becomes C<undef> in Perl.	570	A JSON null atom becomes C<undef> in Perl.
347		571
348	=back	572	=back
		573
349		574
350	=head2 PERL -> JSON	575	=head2 PERL -> JSON
351		576
352	The mapping from Perl to JSON is slightly more difficult, as Perl is a	577	The mapping from Perl to JSON is slightly more difficult, as Perl is a
353	truly typeless language, so we can only guess which JSON type is meant by	578	truly typeless language, so we can only guess which JSON type is meant by
…		…
356	=over 4	581	=over 4
357		582
358	=item hash references	583	=item hash references
359		584
360	Perl hash references become JSON objects. As there is no inherent ordering	585	Perl hash references become JSON objects. As there is no inherent ordering
361	in hash keys, they will usually be encoded in a pseudo-random order that	586	in hash keys (or JSON objects), they will usually be encoded in a
362	can change between runs of the same program but stays generally the same	587	pseudo-random order that can change between runs of the same program but
363	within the single run of a program. JSON::XS can optionally sort the hash	588	stays generally the same within a single run of a program. JSON::XS can
364	keys (determined by the I<canonical> flag), so the same datastructure	589	optionally sort the hash keys (determined by the I<canonical> flag), so
365	will serialise to the same JSON text (given same settings and version of	590	the same datastructure will serialise to the same JSON text (given same
366	JSON::XS), but this incurs a runtime overhead.	591	settings and version of JSON::XS), but this incurs a runtime overhead
		592	and is only rarely useful, e.g. when you want to compare some JSON text
		593	against another for equality.
367		594
368	=item array references	595	=item array references
369		596
370	Perl array references become JSON arrays.	597	Perl array references become JSON arrays.
		598
		599	=item other references
		600
		601	Other unblessed references are generally not allowed and will cause an
		602	exception to be thrown, except for references to the integers C<0> and
		603	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
		604	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
		605
		606	to_json [\0,JSON::XS::true] # yields [false,true]
		607
		608	=item JSON::XS::true, JSON::XS::false
		609
		610	These special values become JSON true and JSON false values,
		611	respectively. You cna alos use C<\1> and C<\0> directly if you want.
371		612
372	=item blessed objects	613	=item blessed objects
373		614
374	Blessed objects are not allowed. JSON::XS currently tries to encode their	615	Blessed objects are not allowed. JSON::XS currently tries to encode their
375	underlying representation (hash- or arrayref), but this behaviour might	616	underlying representation (hash- or arrayref), but this behaviour might
…		…
408	$x *= 1; # same thing, the choise is yours.	649	$x *= 1; # same thing, the choise is yours.
409		650
410	You can not currently output JSON booleans or force the type in other,	651	You can not currently output JSON booleans or force the type in other,
411	less obscure, ways. Tell me if you need this capability.	652	less obscure, ways. Tell me if you need this capability.
412		653
413	=item circular data structures
414
415	Those will be encoded until memory or stackspace runs out.
416
417	=back	654	=back
		655
418		656
419	=head1 COMPARISON	657	=head1 COMPARISON
420		658
421	As already mentioned, this module was created because none of the existing	659	As already mentioned, this module was created because none of the existing
422	JSON modules could be made to work correctly. First I will describe the	660	JSON modules could be made to work correctly. First I will describe the
…		…
448		686
449	Has problems handling many Perl values (e.g. regex results and other magic	687	Has problems handling many Perl values (e.g. regex results and other magic
450	values will make it croak).	688	values will make it croak).
451		689
452	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>	690	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>
453	which is not a valid JSON string.	691	which is not a valid JSON text.
454		692
455	Unmaintained (maintainer unresponsive for many months, bugs are not	693	Unmaintained (maintainer unresponsive for many months, bugs are not
456	getting fixed).	694	getting fixed).
457		695
458	=item JSON::Syck 0.21	696	=item JSON::Syck 0.21
…		…
460	Very buggy (often crashes).	698	Very buggy (often crashes).
461		699
462	Very inflexible (no human-readable format supported, format pretty much	700	Very inflexible (no human-readable format supported, format pretty much
463	undocumented. I need at least a format for easy reading by humans and a	701	undocumented. I need at least a format for easy reading by humans and a
464	single-line compact format for use in a protocol, and preferably a way to	702	single-line compact format for use in a protocol, and preferably a way to
465	generate ASCII-only JSON strings).	703	generate ASCII-only JSON texts).
466		704
467	Completely broken (and confusingly documented) Unicode handling (unicode	705	Completely broken (and confusingly documented) Unicode handling (unicode
468	escapes are not working properly, you need to set ImplicitUnicode to	706	escapes are not working properly, you need to set ImplicitUnicode to
469	I<different> values on en- and decoding to get symmetric behaviour).	707	I<different> values on en- and decoding to get symmetric behaviour).
470		708
…		…
493		731
494	Very inflexible.	732	Very inflexible.
495		733
496	No roundtripping.	734	No roundtripping.
497		735
498	Does not generate valid JSON (key strings are often unquoted, empty keys	736	Does not generate valid JSON texts (key strings are often unquoted, empty keys
499	result in nothing being output)	737	result in nothing being output)
500		738
501	Does not check input for validity.	739	Does not check input for validity.
502		740
503	=back	741	=back
		742
		743
		744	=head2 JSON and YAML
		745
		746	You often hear that JSON is a subset (or a close subset) of YAML. This is,
		747	however, a mass hysteria and very far from the truth. In general, there is
		748	no way to configure JSON::XS to output a data structure as valid YAML.
		749
		750	If you really must use JSON::XS to generate YAML, you should use this
		751	algorithm (subject to change in future versions):
		752
		753	my $to_yaml = JSON::XS->new->utf8->space_after (1);
		754	my $yaml = $to_yaml->encode ($ref) . "\n";
		755
		756	This will usually generate JSON texts that also parse as valid
		757	YAML. Please note that YAML has hardcoded limits on (simple) object key
		758	lengths that JSON doesn't have, so you should make sure that your hash
		759	keys are noticably shorter than the 1024 characters YAML allows.
		760
		761	There might be other incompatibilities that I am not aware of. In general
		762	you should not try to generate YAML with a JSON generator or vice versa,
		763	or try to parse JSON with a YAML parser or vice versa: chances are high
		764	that you will run into severe interoperability problems.
		765
504		766
505	=head2 SPEED	767	=head2 SPEED
506		768
507	It seems that JSON::XS is surprisingly fast, as shown in the following	769	It seems that JSON::XS is surprisingly fast, as shown in the following
508	tables. They have been generated with the help of the C<eg/bench> program	770	tables. They have been generated with the help of the C<eg/bench> program
509	in the JSON::XS distribution, to make it easy to compare on your own	771	in the JSON::XS distribution, to make it easy to compare on your own
510	system.	772	system.
511		773
512	First is a comparison between various modules using a very simple JSON	774	First comes a comparison between various modules using a very short
		775	single-line JSON string:
		776
		777	{"method": "handleMessage", "params": ["user1", "we were just talking"], \
		778	"id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
		779
513	string, showing the number of encodes/decodes per second (JSON::XS is	780	It shows the number of encodes/decodes per second (JSON::XS uses
514	the functional interface, while JSON::XS/2 is the OO interface with	781	the functional interface, while JSON::XS/2 uses the OO interface
515	pretty-printing and hashkey sorting enabled).	782	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
		783	shrink). Higher is better:
516		784
		785	Storable \| 15779.925 \| 14169.946 \|
		786	-----------+------------+------------+
517	module \| encode \| decode \|	787	module \| encode \| decode \|
518	-----------\|------------\|------------\|	788	-----------\|------------\|------------\|
519	JSON \| 14006 \| 6820 \|	789	JSON \| 4990.842 \| 4088.813 \|
520	JSON::DWIW \| 200937 \| 120386 \|	790	JSON::DWIW \| 51653.990 \| 71575.154 \|
521	JSON::PC \| 85065 \| 129366 \|	791	JSON::PC \| 65948.176 \| 74631.744 \|
522	JSON::Syck \| 59898 \| 44232 \|	792	JSON::PP \| 8931.652 \| 3817.168 \|
523	JSON::XS \| 1171478 \| 342435 \|	793	JSON::Syck \| 24877.248 \| 27776.848 \|
524	JSON::XS/2 \| 730760 \| 328714 \|	794	JSON::XS \| 388361.481 \| 227951.304 \|
		795	JSON::XS/2 \| 227951.304 \| 218453.333 \|
		796	JSON::XS/3 \| 338250.323 \| 218453.333 \|
		797	Storable \| 16500.016 \| 135300.129 \|
525	-----------+------------+------------+	798	-----------+------------+------------+
526		799
527	That is, JSON::XS is 6 times faster than than JSON::DWIW and about 80	800	That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
		801	about three times faster on decoding, and over fourty times faster
528	times faster than JSON, even with pretty-printing and key sorting.	802	than JSON, even with pretty-printing and key sorting. It also compares
		803	favourably to Storable for small amounts of data.
529		804
530	Using a longer test string (roughly 8KB, generated from Yahoo! Locals	805	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
531	search API (http://nanoref.com/yahooapis/mgPdGg):	806	search API (http://nanoref.com/yahooapis/mgPdGg):
532		807
533	module \| encode \| decode \|	808	module \| encode \| decode \|
534	-----------\|------------\|------------\|	809	-----------\|------------\|------------\|
535	JSON \| 673 \| 38 \|	810	JSON \| 55.260 \| 34.971 \|
536	JSON::DWIW \| 5271 \| 770 \|	811	JSON::DWIW \| 825.228 \| 1082.513 \|
537	JSON::PC \| 9901 \| 2491 \|	812	JSON::PC \| 3571.444 \| 2394.829 \|
538	JSON::Syck \| 2360 \| 786 \|	813	JSON::PP \| 210.987 \| 32.574 \|
539	JSON::XS \| 37398 \| 3202 \|	814	JSON::Syck \| 552.551 \| 787.544 \|
540	JSON::XS/2 \| 13765 \| 3153 \|	815	JSON::XS \| 5780.463 \| 4854.519 \|
		816	JSON::XS/2 \| 3869.998 \| 4798.975 \|
		817	JSON::XS/3 \| 5862.880 \| 4798.975 \|
		818	Storable \| 4445.002 \| 5235.027 \|
541	-----------+------------+------------+	819	-----------+------------+------------+
542		820
543	Again, JSON::XS leads by far in the encoding case, while still beating	821	Again, JSON::XS leads by far (except for Storable which non-surprisingly
544	every other module in the decoding case.	822	decodes faster).
545		823
546	=head1 RESOURCE LIMITS	824	On large strings containing lots of high unicode characters, some modules
		825	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
		826	will be broken due to missing (or wrong) unicode handling. Others refuse
		827	to decode or encode properly, so it was impossible to prepare a fair
		828	comparison table for that case.
547		829
548	JSON::XS does not impose any limits on the size of JSON texts or Perl	830
549	values they represent - if your machine can handle it, JSON::XS will	831	=head1 SECURITY CONSIDERATIONS
550	encode or decode it. Future versions might optionally impose structure	832
551	depth and memory use resource limits.	833	When you are using JSON in a protocol, talking to untrusted potentially
		834	hostile creatures requires relatively few measures.
		835
		836	First of all, your JSON decoder should be secure, that is, should not have
		837	any buffer overflows. Obviously, this module should ensure that and I am
		838	trying hard on making that true, but you never know.
		839
		840	Second, you need to avoid resource-starving attacks. That means you should
		841	limit the size of JSON texts you accept, or make sure then when your
		842	resources run out, thats just fine (e.g. by using a separate process that
		843	can crash safely). The size of a JSON text in octets or characters is
		844	usually a good indication of the size of the resources required to decode
		845	it into a Perl structure. While JSON::XS can check the size of the JSON
		846	text, it might be too late when you already have it in memory, so you
		847	might want to check the size before you accept the string.
		848
		849	Third, JSON::XS recurses using the C stack when decoding objects and
		850	arrays. The C stack is a limited resource: for instance, on my amd64
		851	machine with 8MB of stack size I can decode around 180k nested arrays but
		852	only 14k nested JSON objects (due to perl itself recursing deeply on croak
		853	to free the temporary). If that is exceeded, the program crashes. to be
		854	conservative, the default nesting limit is set to 512. If your process
		855	has a smaller stack, you should adjust this setting accordingly with the
		856	C<max_depth> method.
		857
		858	And last but least, something else could bomb you that I forgot to think
		859	of. In that case, you get to keep the pieces. I am always open for hints,
		860	though...
		861
		862	If you are using JSON::XS to return packets to consumption
		863	by javascript scripts in a browser you should have a look at
		864	L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether
		865	you are vulnerable to some common attack vectors (which really are browser
		866	design bugs, but it is still you who will have to deal with it, as major
		867	browser developers care only for features, not about doing security
		868	right).
		869
552		870
553	=head1 BUGS	871	=head1 BUGS
554		872
555	While the goal of this module is to be correct, that unfortunately does	873	While the goal of this module is to be correct, that unfortunately does
556	not mean its bug-free, only that I think its design is bug-free. It is	874	not mean its bug-free, only that I think its design is bug-free. It is
557	still very young and not well-tested. If you keep reporting bugs they will	875	still relatively early in its development. If you keep reporting bugs they
558	be fixed swiftly, though.	876	will be fixed swiftly, though.
559		877
560	=cut	878	=cut
		879
		880	our $true = do { bless \(my $dummy = "1"), "JSON::XS::Boolean" };
		881	our $false = do { bless \(my $dummy = "0"), "JSON::XS::Boolean" };
		882
		883	sub true() { $true }
		884	sub false() { $false }
		885
		886	sub is_bool($) {
		887	UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
		888	# or UNIVERSAL::isa $_[0], "JSON::Literal"
		889	}
		890
		891	XSLoader::load "JSON::XS", $VERSION;
		892
		893	package JSON::XS::Boolean;
		894
		895	use overload
		896	"0+" => sub { ${$_[0]} },
		897	"++" => sub { $_[0] = ${$_[0]} + 1 },
		898	"--" => sub { $_[0] = ${$_[0]} - 1 },
		899	fallback => 1;
561		900
562	1;	901	1;
563		902
564	=head1 AUTHOR	903	=head1 AUTHOR
565		904

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Revision 1.12 by root, Fri Mar 23 18:33:50 2007 UTC vs.
Revision 1.51 by root, Mon Jul 2 01:12:27 2007 UTC