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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.160 by root, Wed Nov 16 18:08:30 2016 UTC vs.
Revision 1.170 by root, Thu Nov 15 22:35:35 2018 UTC

…		…
35		35
36	This module converts Perl data structures to JSON and vice versa. Its	36	This module converts Perl data structures to JSON and vice versa. Its
37	primary goal is to be I<correct> and its secondary goal is to be	37	primary goal is to be I<correct> and its secondary goal is to be
38	I<fast>. To reach the latter goal it was written in C.	38	I<fast>. To reach the latter goal it was written in C.
39		39
40	Beginning with version 2.0 of the JSON module, when both JSON and
41	JSON::XS are installed, then JSON will fall back on JSON::XS (this can be
42	overridden) with no overhead due to emulation (by inheriting constructor
43	and methods). If JSON::XS is not available, it will fall back to the
44	compatible JSON::PP module as backend, so using JSON instead of JSON::XS
45	gives you a portable JSON API that can be fast when you need and doesn't
46	require a C compiler when that is a problem.
47
48	As this is the n-th-something JSON module on CPAN, what was the reason
49	to write yet another JSON module? While it seems there are many JSON
50	modules, none of them correctly handle all corner cases, and in most cases
51	their maintainers are unresponsive, gone missing, or not listening to bug
52	reports for other reasons.
53
54	See MAPPING, below, on how JSON::XS maps perl values to JSON values and	40	See MAPPING, below, on how JSON::XS maps perl values to JSON values and
55	vice versa.	41	vice versa.
56		42
57	=head2 FEATURES	43	=head2 FEATURES
58		44
59	=over 4	45	=over
60		46
61	=item * correct Unicode handling	47	=item * correct Unicode handling
62		48
63	This module knows how to handle Unicode, documents how and when it does	49	This module knows how to handle Unicode, documents how and when it does
64	so, and even documents what "correct" means.	50	so, and even documents what "correct" means.
…		…
101		87
102	package JSON::XS;	88	package JSON::XS;
103		89
104	use common::sense;	90	use common::sense;
105		91
106	our $VERSION = 3.02;	92	our $VERSION = '4.0';
107	our @ISA = qw(Exporter);	93	our @ISA = qw(Exporter);
108		94
109	our @EXPORT = qw(encode_json decode_json);	95	our @EXPORT = qw(encode_json decode_json);
110		96
111	use Exporter;	97	use Exporter;
…		…
116	=head1 FUNCTIONAL INTERFACE	102	=head1 FUNCTIONAL INTERFACE
117		103
118	The following convenience methods are provided by this module. They are	104	The following convenience methods are provided by this module. They are
119	exported by default:	105	exported by default:
120		106
121	=over 4	107	=over
122		108
123	=item $json_text = encode_json $perl_scalar	109	=item $json_text = encode_json $perl_scalar
124		110
125	Converts the given Perl data structure to a UTF-8 encoded, binary string	111	Converts the given Perl data structure to a UTF-8 encoded, binary string
126	(that is, the string contains octets only). Croaks on error.	112	(that is, the string contains octets only). Croaks on error.
…		…
131		117
132	Except being faster.	118	Except being faster.
133		119
134	=item $perl_scalar = decode_json $json_text	120	=item $perl_scalar = decode_json $json_text
135		121
136	The opposite of C<encode_json>: expects an UTF-8 (binary) string and tries	122	The opposite of C<encode_json>: expects a UTF-8 (binary) string and tries
137	to parse that as an UTF-8 encoded JSON text, returning the resulting	123	to parse that as a UTF-8 encoded JSON text, returning the resulting
138	reference. Croaks on error.	124	reference. Croaks on error.
139		125
140	This function call is functionally identical to:	126	This function call is functionally identical to:
141		127
142	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)	128	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
…		…
149	=head1 A FEW NOTES ON UNICODE AND PERL	135	=head1 A FEW NOTES ON UNICODE AND PERL
150		136
151	Since this often leads to confusion, here are a few very clear words on	137	Since this often leads to confusion, here are a few very clear words on
152	how Unicode works in Perl, modulo bugs.	138	how Unicode works in Perl, modulo bugs.
153		139
154	=over 4	140	=over
155		141
156	=item 1. Perl strings can store characters with ordinal values > 255.	142	=item 1. Perl strings can store characters with ordinal values > 255.
157		143
158	This enables you to store Unicode characters as single characters in a	144	This enables you to store Unicode characters as single characters in a
159	Perl string - very natural.	145	Perl string - very natural.
…		…
197	=head1 OBJECT-ORIENTED INTERFACE	183	=head1 OBJECT-ORIENTED INTERFACE
198		184
199	The object oriented interface lets you configure your own encoding or	185	The object oriented interface lets you configure your own encoding or
200	decoding style, within the limits of supported formats.	186	decoding style, within the limits of supported formats.
201		187
202	=over 4	188	=over
203		189
204	=item $json = new JSON::XS	190	=item $json = new JSON::XS
205		191
206	Creates a new JSON::XS object that can be used to de/encode JSON	192	Creates a new JSON::XS object that can be used to de/encode JSON
207	strings. All boolean flags described below are by default I<disabled>.	193	strings. All boolean flags described below are by default I<disabled>
		194	(with the exception of C<allow_nonref>, which defaults to I<enabled> since
		195	version C<4.0>).
208		196
209	The mutators for flags all return the JSON object again and thus calls can	197	The mutators for flags all return the JSON object again and thus calls can
210	be chained:	198	be chained:
211		199
212	my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})	200	my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})
…		…
270		258
271	=item $enabled = $json->get_utf8	259	=item $enabled = $json->get_utf8
272		260
273	If C<$enable> is true (or missing), then the C<encode> method will encode	261	If C<$enable> is true (or missing), then the C<encode> method will encode
274	the JSON result into UTF-8, as required by many protocols, while the	262	the JSON result into UTF-8, as required by many protocols, while the
275	C<decode> method expects to be handled an UTF-8-encoded string. Please	263	C<decode> method expects to be handed a UTF-8-encoded string. Please
276	note that UTF-8-encoded strings do not contain any characters outside the	264	note that UTF-8-encoded strings do not contain any characters outside the
277	range C<0..255>, they are thus useful for bytewise/binary I/O. In future	265	range C<0..255>, they are thus useful for bytewise/binary I/O. In future
278	versions, enabling this option might enable autodetection of the UTF-16	266	versions, enabling this option might enable autodetection of the UTF-16
279	and UTF-32 encoding families, as described in RFC4627.	267	and UTF-32 encoding families, as described in RFC4627.
280		268
…		…
365		353
366	=item $enabled = $json->get_relaxed	354	=item $enabled = $json->get_relaxed
367		355
368	If C<$enable> is true (or missing), then C<decode> will accept some	356	If C<$enable> is true (or missing), then C<decode> will accept some
369	extensions to normal JSON syntax (see below). C<encode> will not be	357	extensions to normal JSON syntax (see below). C<encode> will not be
370	affected in anyway. I<Be aware that this option makes you accept invalid	358	affected in any way. I<Be aware that this option makes you accept invalid
371	JSON texts as if they were valid!>. I suggest only to use this option to	359	JSON texts as if they were valid!>. I suggest only to use this option to
372	parse application-specific files written by humans (configuration files,	360	parse application-specific files written by humans (configuration files,
373	resource files etc.)	361	resource files etc.)
374		362
375	If C<$enable> is false (the default), then C<decode> will only accept	363	If C<$enable> is false (the default), then C<decode> will only accept
376	valid JSON texts.	364	valid JSON texts.
377		365
378	Currently accepted extensions are:	366	Currently accepted extensions are:
379		367
380	=over 4	368	=over
381		369
382	=item * list items can have an end-comma	370	=item * list items can have an end-comma
383		371
384	JSON I<separates> array elements and key-value pairs with commas. This	372	JSON I<separates> array elements and key-value pairs with commas. This
385	can be annoying if you write JSON texts manually and want to be able to	373	can be annoying if you write JSON texts manually and want to be able to
…		…
441		429
442	=item $json = $json->allow_nonref ([$enable])	430	=item $json = $json->allow_nonref ([$enable])
443		431
444	=item $enabled = $json->get_allow_nonref	432	=item $enabled = $json->get_allow_nonref
445		433
		434	Unlike other boolean options, this opotion is enabled by default beginning
		435	with version C<4.0>. See L<SECURITY CONSIDERATIONS> for the gory details.
		436
446	If C<$enable> is true (or missing), then the C<encode> method can convert a	437	If C<$enable> is true (or missing), then the C<encode> method can convert a
447	non-reference into its corresponding string, number or null JSON value,	438	non-reference into its corresponding string, number or null JSON value,
448	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON	439	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
449	values instead of croaking.	440	values instead of croaking.
450		441
451	If C<$enable> is false, then the C<encode> method will croak if it isn't	442	If C<$enable> is false, then the C<encode> method will croak if it isn't
452	passed an arrayref or hashref, as JSON texts must either be an object	443	passed an arrayref or hashref, as JSON texts must either be an object
453	or array. Likewise, C<decode> will croak if given something that is not a	444	or array. Likewise, C<decode> will croak if given something that is not a
454	JSON object or array.	445	JSON object or array.
455		446
456	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,	447	Example, encode a Perl scalar as JSON value without enabled C<allow_nonref>,
457	resulting in an invalid JSON text:	448	resulting in an error:
458		449
459	JSON::XS->new->allow_nonref->encode ("Hello, World!")	450	JSON::XS->new->allow_nonref (0)->encode ("Hello, World!")
460	=> "Hello, World!"	451	=> hash- or arrayref expected...
461		452
462	=item $json = $json->allow_unknown ([$enable])	453	=item $json = $json->allow_unknown ([$enable])
463		454
464	=item $enabled = $json->get_allow_unknown	455	=item $enabled = $json->get_allow_unknown
465		456
…		…
515		506
516	This setting has no effect on C<decode>.	507	This setting has no effect on C<decode>.
517		508
518	=item $json = $json->allow_tags ([$enable])	509	=item $json = $json->allow_tags ([$enable])
519		510
520	=item $enabled = $json->allow_tags	511	=item $enabled = $json->get_allow_tags
521		512
522	See L<OBJECT SERIALISATION> for details.	513	See L<OBJECT SERIALISATION> for details.
523		514
524	If C<$enable> is true (or missing), then C<encode>, upon encountering a	515	If C<$enable> is true (or missing), then C<encode>, upon encountering a
525	blessed object, will check for the availability of the C<FREEZE> method on	516	blessed object, will check for the availability of the C<FREEZE> method on
…		…
534	in C<decode>, as if tags were not part of the grammar.	525	in C<decode>, as if tags were not part of the grammar.
535		526
536	=item $json = $json->filter_json_object ([$coderef->($hashref)])	527	=item $json = $json->filter_json_object ([$coderef->($hashref)])
537		528
538	When C<$coderef> is specified, it will be called from C<decode> each	529	When C<$coderef> is specified, it will be called from C<decode> each
539	time it decodes a JSON object. The only argument is a reference to the	530	time it decodes a JSON object. The only argument is a reference to
540	newly-created hash. If the code references returns a single scalar (which	531	the newly-created hash. If the code reference returns a single scalar
541	need not be a reference), this value (i.e. a copy of that scalar to avoid	532	(which need not be a reference), this value (or rather a copy of it) is
542	aliasing) is inserted into the deserialised data structure. If it returns	533	inserted into the deserialised data structure. If it returns an empty
543	an empty list (NOTE: I<not> C<undef>, which is a valid scalar), the	534	list (NOTE: I<not> C<undef>, which is a valid scalar), the original
544	original deserialised hash will be inserted. This setting can slow down	535	deserialised hash will be inserted. This setting can slow down decoding
545	decoding considerably.	536	considerably.
546		537
547	When C<$coderef> is omitted or undefined, any existing callback will	538	When C<$coderef> is omitted or undefined, any existing callback will
548	be removed and C<decode> will not change the deserialised hash in any	539	be removed and C<decode> will not change the deserialised hash in any
549	way.	540	way.
550		541
…		…
724	to set resource limits (e.g. C<max_size>) to ensure the parser will stop	715	to set resource limits (e.g. C<max_size>) to ensure the parser will stop
725	parsing in the presence if syntax errors.	716	parsing in the presence if syntax errors.
726		717
727	The following methods implement this incremental parser.	718	The following methods implement this incremental parser.
728		719
729	=over 4	720	=over
730		721
731	=item [void, scalar or list context] = $json->incr_parse ([$string])	722	=item [void, scalar or list context] = $json->incr_parse ([$string])
732		723
733	This is the central parsing function. It can both append new text and	724	This is the central parsing function. It can both append new text and
734	extract objects from the stream accumulated so far (both of these	725	extract objects from the stream accumulated so far (both of these
…		…
801		792
802	=back	793	=back
803		794
804	=head2 LIMITATIONS	795	=head2 LIMITATIONS
805		796
806	All options that affect decoding are supported, except	797	The incremental parser is a non-exact parser: it works by gathering as
807	C<allow_nonref>. The reason for this is that it cannot be made to work	798	much text as possible that I<could> be a valid JSON text, followed by
808	sensibly: JSON objects and arrays are self-delimited, i.e. you can	799	trying to decode it.
809	concatenate them back to back and still decode them perfectly. This does
810	not hold true for JSON numbers, however.
811		800
812	For example, is the string C<1> a single JSON number, or is it simply the	801	That means it sometimes needs to read more data than strictly necessary to
813	start of C<12>? Or is C<12> a single JSON number, or the concatenation	802	diagnose an invalid JSON text. For example, after parsing the following
814	of C<1> and C<2>? In neither case you can tell, and this is why JSON::XS	803	fragment, the parser I<could> stop with an error, as this fragment
815	takes the conservative route and disallows this case.	804	I<cannot> be the beginning of a valid JSON text:
		805
		806	[,
		807
		808	In reality, hopwever, the parser might continue to read data until a
		809	length limit is exceeded or it finds a closing bracket.
816		810
817	=head2 EXAMPLES	811	=head2 EXAMPLES
818		812
819	Some examples will make all this clearer. First, a simple example that	813	Some examples will make all this clearer. First, a simple example that
820	works similarly to C<decode_prefix>: We want to decode the JSON object at	814	works similarly to C<decode_prefix>: We want to decode the JSON object at
…		…
964	refers to the abstract Perl language itself.	958	refers to the abstract Perl language itself.
965		959
966		960
967	=head2 JSON -> PERL	961	=head2 JSON -> PERL
968		962
969	=over 4	963	=over
970		964
971	=item object	965	=item object
972		966
973	A JSON object becomes a reference to a hash in Perl. No ordering of object	967	A JSON object becomes a reference to a hash in Perl. No ordering of object
974	keys is preserved (JSON does not preserve object key ordering itself).	968	keys is preserved (JSON does not preserve object key ordering itself).
…		…
1042		1036
1043	The mapping from Perl to JSON is slightly more difficult, as Perl is a	1037	The mapping from Perl to JSON is slightly more difficult, as Perl is a
1044	truly typeless language, so we can only guess which JSON type is meant by	1038	truly typeless language, so we can only guess which JSON type is meant by
1045	a Perl value.	1039	a Perl value.
1046		1040
1047	=over 4	1041	=over
1048		1042
1049	=item hash references	1043	=item hash references
1050		1044
1051	Perl hash references become JSON objects. As there is no inherent	1045	Perl hash references become JSON objects. As there is no inherent
1052	ordering in hash keys (or JSON objects), they will usually be encoded	1046	ordering in hash keys (or JSON objects), they will usually be encoded
…		…
1141		1135
1142	What happens when C<JSON::XS> encounters a Perl object depends on the	1136	What happens when C<JSON::XS> encounters a Perl object depends on the
1143	C<allow_blessed>, C<convert_blessed> and C<allow_tags> settings, which are	1137	C<allow_blessed>, C<convert_blessed> and C<allow_tags> settings, which are
1144	used in this order:	1138	used in this order:
1145		1139
1146	=over 4	1140	=over
1147		1141
1148	=item 1. C<allow_tags> is enabled and the object has a C<FREEZE> method.	1142	=item 1. C<allow_tags> is enabled and the object has a C<FREEZE> method.
1149		1143
1150	In this case, C<JSON::XS> uses the L<Types::Serialiser> object	1144	In this case, C<JSON::XS> uses the L<Types::Serialiser> object
1151	serialisation protocol to create a tagged JSON value, using a nonstandard	1145	serialisation protocol to create a tagged JSON value, using a nonstandard
…		…
1262	takes those codepoint numbers and I<encodes> them, in our case into	1256	takes those codepoint numbers and I<encodes> them, in our case into
1263	octets. Unicode is (among other things) a codeset, UTF-8 is an encoding,	1257	octets. Unicode is (among other things) a codeset, UTF-8 is an encoding,
1264	and ISO-8859-1 (= latin 1) and ASCII are both codesets I<and> encodings at	1258	and ISO-8859-1 (= latin 1) and ASCII are both codesets I<and> encodings at
1265	the same time, which can be confusing.	1259	the same time, which can be confusing.
1266		1260
1267	=over 4	1261	=over
1268		1262
1269	=item C<utf8> flag disabled	1263	=item C<utf8> flag disabled
1270		1264
1271	When C<utf8> is disabled (the default), then C<encode>/C<decode> generate	1265	When C<utf8> is disabled (the default), then C<encode>/C<decode> generate
1272	and expect Unicode strings, that is, characters with high ordinal Unicode	1266	and expect Unicode strings, that is, characters with high ordinal Unicode
…		…
1289	expect your input strings to be encoded as UTF-8, that is, no "character"	1283	expect your input strings to be encoded as UTF-8, that is, no "character"
1290	of the input string must have any value > 255, as UTF-8 does not allow	1284	of the input string must have any value > 255, as UTF-8 does not allow
1291	that.	1285	that.
1292		1286
1293	The C<utf8> flag therefore switches between two modes: disabled means you	1287	The C<utf8> flag therefore switches between two modes: disabled means you
1294	will get a Unicode string in Perl, enabled means you get an UTF-8 encoded	1288	will get a Unicode string in Perl, enabled means you get a UTF-8 encoded
1295	octet/binary string in Perl.	1289	octet/binary string in Perl.
1296		1290
1297	=item C<latin1> or C<ascii> flags enabled	1291	=item C<latin1> or C<ascii> flags enabled
1298		1292
1299	With C<latin1> (or C<ascii>) enabled, C<encode> will escape characters	1293	With C<latin1> (or C<ascii>) enabled, C<encode> will escape characters
…		…
1431	general you should not try to generate YAML with a JSON generator or vice	1425	general you should not try to generate YAML with a JSON generator or vice
1432	versa, or try to parse JSON with a YAML parser or vice versa: chances are	1426	versa, or try to parse JSON with a YAML parser or vice versa: chances are
1433	high that you will run into severe interoperability problems when you	1427	high that you will run into severe interoperability problems when you
1434	least expect it.	1428	least expect it.
1435		1429
1436	=over 4	1430	=over
1437		1431
1438	=item (*)	1432	=item (*)
1439		1433
1440	I have been pressured multiple times by Brian Ingerson (one of the	1434	I have been pressured multiple times by Brian Ingerson (one of the
1441	authors of the YAML specification) to remove this paragraph, despite him	1435	authors of the YAML specification) to remove this paragraph, despite him
…		…
1567	are browser design bugs, but it is still you who will have to deal with	1561	are browser design bugs, but it is still you who will have to deal with
1568	it, as major browser developers care only for features, not about getting	1562	it, as major browser developers care only for features, not about getting
1569	security right).	1563	security right).
1570		1564
1571		1565
1572	=head1 "OLD" VS. "NEW" JSON (RFC 4627 VS. RFC 7159)	1566	=head2 "OLD" VS. "NEW" JSON (RFC4627 VS. RFC7159)
1573		1567
1574	TL;DR: Due to security concerns, JSON::XS will not allow scalar data in	1568	JSON originally required JSON texts to represent an array or object -
1575	JSON texts by default - you need to create your own JSON::XS object and	1569	scalar values were explicitly not allowed. This has changed, and versions
1576	enable C<allow_nonref>:	1570	of JSON::XS beginning with C<4.0> reflect this by allowing scalar values
		1571	by default.
1577		1572
		1573	One reason why one might not want this is that this removes a fundamental
		1574	property of JSON texts, namely that they are self-delimited and
		1575	self-contained, or in other words, you could take any number of "old"
		1576	JSON texts and paste them together, and the result would be unambiguously
		1577	parseable:
1578		1578
		1579	[1,3]{"k":5}[][null] # four JSON texts, without doubt
		1580
		1581	By allowing scalars, this property is lost: in the following example, is
		1582	this one JSON text (the number 12) or two JSON texts (the numbers 1 and
		1583	2):
		1584
		1585	12 # could be 12, or 1 and 2
		1586
		1587	Another lost property of "old" JSON is that no lookahead is required to
		1588	know the end of a JSON text, i.e. the JSON text definitely ended at the
		1589	last C<]> or C<}> character, there was no need to read extra characters.
		1590
		1591	For example, a viable network protocol with "old" JSON was to simply
		1592	exchange JSON texts without delimiter. For "new" JSON, you have to use a
		1593	suitable delimiter (such as a newline) after every JSON text or ensure you
		1594	never encode/decode scalar values.
		1595
		1596	Most protocols do work by only transferring arrays or objects, and the
		1597	easiest way to avoid problems with the "new" JSON definition is to
		1598	explicitly disallow scalar values in your encoder and decoder:
		1599
1579	my $json = JSON::XS->new->allow_nonref;	1600	$json_coder = JSON::XS->new->allow_nonref (0)
1580		1601
1581	$text = $json->encode ($data);	1602	This is a somewhat unhappy situation, and the blame can fully be put on
1582	$data = $json->decode ($text);	1603	JSON's inmventor, Douglas Crockford, who unilaterally changed the format
		1604	in 2006 without consulting the IETF, forcing the IETF to either fork the
		1605	format or go with it (as I was told, the IETF wasn't amused).
1583		1606
1584	The long version: JSON being an important and supposedly stable format,
1585	the IETF standardised it as RFC 4627 in 2006. Unfortunately, the inventor
1586	of JSON, Dougles Crockford, unilaterally changed the definition of JSON in
1587	javascript. Rather than create a fork, the IETF decided to standardise the
1588	new syntax (apparently, so Iw as told, without finding it very amusing).
1589		1607
1590	The biggest difference between thed original JSON and the new JSON is that	1608	=head1 RELATIONSHIP WITH I-JSON
1591	the new JSON supports scalars (anything other than arrays and objects) at
1592	the toplevel of a JSON text. While this is strictly backwards compatible
1593	to older versions, it breaks a number of protocols that relied on sending
1594	JSON back-to-back, and is a minor security concern.
1595		1609
1596	For example, imagine you have two banks communicating, and on one side,	1610	JSON is a somewhat sloppily-defined format - it carries around obvious
1597	trhe JSON coder gets upgraded. Two messages, such as C<10> and C<1000>	1611	Javascript baggage, such as not really defining number range, probably
1598	might then be confused to mean C<101000>, something that couldn't happen	1612	because Javascript only has one type of numbers: IEEE 64 bit floats
1599	in the original JSON, because niether of these messages would be valid	1613	("binary64").
1600	JSON.
1601		1614
1602	If one side accepts these messages, then an upgrade in the coder on either	1615	For this reaosn, RFC7493 defines "Internet JSON", which is a restricted
1603	side could result in this becoming exploitable.	1616	subset of JSON that is supposedly more interoperable on the internet.
1604		1617
1605	This module has always allowed these messages as an optional extension, by	1618	While C<JSON::XS> does not offer specific support for I-JSON, it of course
1606	default disabled. The security concerns are the reason why the default is	1619	accepts valid I-JSON and by default implements some of the limitations
1607	still disabled, but future versions might/will likely upgrade to the newer	1620	of I-JSON, such as parsing numbers as perl numbers, which are usually a
1608	RFC as default format, so you are advised to check your implementation	1621	superset of binary64 numbers.
1609	and/or override the default with C<< ->allow_nonref (0) >> to ensure that	1622
1610	future versions are safe.	1623	To generate I-JSON, follow these rules:
		1624
		1625	=over
		1626
		1627	=item * always generate UTF-8
		1628
		1629	I-JSON must be encoded in UTF-8, the default for C<encode_json>.
		1630
		1631	=item * numbers should be within IEEE 754 binary64 range
		1632
		1633	Basically all existing perl installations use binary64 to represent
		1634	floating point numbers, so all you need to do is to avoid large integers.
		1635
		1636	=item * objects must not have duplicate keys
		1637
		1638	This is trivially done, as C<JSON::XS> does not allow duplicate keys.
		1639
		1640	=item * do not generate scalar JSON texts, use C<< ->allow_nonref (0) >>
		1641
		1642	I-JSON strongly requests you to only encode arrays and objects into JSON.
		1643
		1644	=item * times should be strings in ISO 8601 format
		1645
		1646	There are a myriad of modules on CPAN dealing with ISO 8601 - search for
		1647	C<ISO8601> on CPAN and use one.
		1648
		1649	=item * encode binary data as base64
		1650
		1651	While it's tempting to just dump binary data as a string (and let
		1652	C<JSON::XS> do the escaping), for I-JSON, it's I<recommended> to encode
		1653	binary data as base64.
		1654
		1655	=back
		1656
		1657	There are some other considerations - read RFC7493 for the details if
		1658	interested.
1611		1659
1612		1660
1613	=head1 INTEROPERABILITY WITH OTHER MODULES	1661	=head1 INTEROPERABILITY WITH OTHER MODULES
1614		1662
1615	C<JSON::XS> uses the L<Types::Serialiser> module to provide boolean	1663	C<JSON::XS> uses the L<Types::Serialiser> module to provide boolean
…		…
1678		1726
1679	Again, this has some limitations - the magic string must not be encoded	1727	Again, this has some limitations - the magic string must not be encoded
1680	with character escapes, and the constructor arguments must be non-empty.	1728	with character escapes, and the constructor arguments must be non-empty.
1681		1729
1682		1730
1683	=head1 RFC7159
1684
1685	Since this module was written, Google has written a new JSON RFC, RFC 7159
1686	(and RFC7158). Unfortunately, this RFC breaks compatibility with both the
1687	original JSON specification on www.json.org and RFC4627.
1688
1689	As far as I can see, you can get partial compatibility when parsing by
1690	using C<< ->allow_nonref >>. However, consider the security implications
1691	of doing so.
1692
1693	I haven't decided yet when to break compatibility with RFC4627 by default
1694	(and potentially leave applications insecure) and change the default to
1695	follow RFC7159, but application authors are well advised to call C<<
1696	->allow_nonref(0) >> even if this is the current default, if they cannot
1697	handle non-reference values, in preparation for the day when the default
1698	will change.
1699
1700
1701	=head1 THREADS	1731	=head1 (I-)THREADS
1702		1732
1703	This module is I<not> guaranteed to be thread safe and there are no	1733	This module is I<not> guaranteed to be ithread (or MULTIPLICITY-) safe
1704	plans to change this until Perl gets thread support (as opposed to the	1734	and there are no plans to change this. Note that perl's builtin so-called
1705	horribly slow so-called "threads" which are simply slow and bloated	1735	threads/ithreads are officially deprecated and should not be used.
1706	process simulations - use fork, it's I<much> faster, cheaper, better).
1707
1708	(It might actually work, but you have been warned).
1709		1736
1710		1737
1711	=head1 THE PERILS OF SETLOCALE	1738	=head1 THE PERILS OF SETLOCALE
1712		1739
1713	Sometimes people avoid the Perl locale support and directly call the	1740	Sometimes people avoid the Perl locale support and directly call the
…		…
1722	categories you need, such as C<LC_MESSAGES> or C<LC_CTYPE>.	1749	categories you need, such as C<LC_MESSAGES> or C<LC_CTYPE>.
1723		1750
1724	If you need C<LC_NUMERIC>, you should enable it only around the code that	1751	If you need C<LC_NUMERIC>, you should enable it only around the code that
1725	actually needs it (avoiding stringification of numbers), and restore it	1752	actually needs it (avoiding stringification of numbers), and restore it
1726	afterwards.	1753	afterwards.
		1754
		1755
		1756	=head1 SOME HISTORY
		1757
		1758	At the time this module was created there already were a number of JSON
		1759	modules available on CPAN, so what was the reason to write yet another
		1760	JSON module? While it seems there are many JSON modules, none of them
		1761	correctly handled all corner cases, and in most cases their maintainers
		1762	are unresponsive, gone missing, or not listening to bug reports for other
		1763	reasons.
		1764
		1765	Beginning with version 2.0 of the JSON module, when both JSON and
		1766	JSON::XS are installed, then JSON will fall back on JSON::XS (this can be
		1767	overridden) with no overhead due to emulation (by inheriting constructor
		1768	and methods). If JSON::XS is not available, it will fall back to the
		1769	compatible JSON::PP module as backend, so using JSON instead of JSON::XS
		1770	gives you a portable JSON API that can be fast when you need it and
		1771	doesn't require a C compiler when that is a problem.
		1772
		1773	Somewhere around version 3, this module was forked into
		1774	C<Cpanel::JSON::XS>, because its maintainer had serious trouble
		1775	understanding JSON and insisted on a fork with many bugs "fixed" that
		1776	weren't actually bugs, while spreading FUD about this module without
		1777	actually giving any details on his accusations. You be the judge, but
		1778	in my personal opinion, if you want quality, you will stay away from
		1779	dangerous forks like that.
1727		1780
1728		1781
1729	=head1 BUGS	1782	=head1 BUGS
1730		1783
1731	While the goal of this module is to be correct, that unfortunately does	1784	While the goal of this module is to be correct, that unfortunately does

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Comparing JSON-XS/XS.pm (file contents): Revision 1.160 by root, Wed Nov 16 18:08:30 2016 UTC vs. Revision 1.170 by root, Thu Nov 15 22:35:35 2018 UTC

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Comparing JSON-XS/XS.pm (file contents):
Revision 1.160 by root, Wed Nov 16 18:08:30 2016 UTC vs.
Revision 1.170 by root, Thu Nov 15 22:35:35 2018 UTC