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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.143 by root, Fri Oct 25 20:02:54 2013 UTC vs.
Revision 1.169 by root, Thu Nov 15 20:49:12 2018 UTC

…		…
40	Beginning with version 2.0 of the JSON module, when both JSON and	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	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	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	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	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	45	gives you a portable JSON API that can be fast when you need it and
46	require a C compiler when that is a problem.	46	doesn't require a C compiler when that is a problem.
47		47
48	As this is the n-th-something JSON module on CPAN, what was the reason	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	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	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	51	their maintainers are unresponsive, gone missing, or not listening to bug
…		…
101		101
102	package JSON::XS;	102	package JSON::XS;
103		103
104	use common::sense;	104	use common::sense;
105		105
106	our $VERSION = 2.34;	106	our $VERSION = 3.04;
107	our @ISA = qw(Exporter);	107	our @ISA = qw(Exporter);
108		108
109	our @EXPORT = qw(encode_json decode_json);	109	our @EXPORT = qw(encode_json decode_json);
110		110
111	use Exporter;	111	use Exporter;
112	use XSLoader;	112	use XSLoader;
113		113
		114	use Types::Serialiser ();
		115
114	=head1 FUNCTIONAL INTERFACE	116	=head1 FUNCTIONAL INTERFACE
115		117
116	The following convenience methods are provided by this module. They are	118	The following convenience methods are provided by this module. They are
117	exported by default:	119	exported by default:
118		120
…		…
129		131
130	Except being faster.	132	Except being faster.
131		133
132	=item $perl_scalar = decode_json $json_text	134	=item $perl_scalar = decode_json $json_text
133		135
134	The opposite of C<encode_json>: expects an UTF-8 (binary) string and tries	136	The opposite of C<encode_json>: expects a UTF-8 (binary) string and tries
135	to parse that as an UTF-8 encoded JSON text, returning the resulting	137	to parse that as a UTF-8 encoded JSON text, returning the resulting
136	reference. Croaks on error.	138	reference. Croaks on error.
137		139
138	This function call is functionally identical to:	140	This function call is functionally identical to:
139		141
140	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)	142	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
141		143
142	Except being faster.	144	Except being faster.
143
144	=item $is_boolean = JSON::XS::is_bool $scalar
145
146	Returns true if the passed scalar represents either JSON::XS::true or
147	JSON::XS::false, two constants that act like C<1> and C<0>, respectively
148	and are used to represent JSON C<true> and C<false> values in Perl.
149
150	See MAPPING, below, for more information on how JSON values are mapped to
151	Perl.
152		145
153	=back	146	=back
154		147
155		148
156	=head1 A FEW NOTES ON UNICODE AND PERL	149	=head1 A FEW NOTES ON UNICODE AND PERL
…		…
209	=over 4	202	=over 4
210		203
211	=item $json = new JSON::XS	204	=item $json = new JSON::XS
212		205
213	Creates a new JSON::XS object that can be used to de/encode JSON	206	Creates a new JSON::XS object that can be used to de/encode JSON
214	strings. All boolean flags described below are by default I<disabled>.	207	strings. All boolean flags described below are by default I<disabled>
		208	(with the exception of C<allow_nonref>, which defaults to I<enabled> since
		209	version C<4.0>).
215		210
216	The mutators for flags all return the JSON object again and thus calls can	211	The mutators for flags all return the JSON object again and thus calls can
217	be chained:	212	be chained:
218		213
219	my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})	214	my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})
…		…
277		272
278	=item $enabled = $json->get_utf8	273	=item $enabled = $json->get_utf8
279		274
280	If C<$enable> is true (or missing), then the C<encode> method will encode	275	If C<$enable> is true (or missing), then the C<encode> method will encode
281	the JSON result into UTF-8, as required by many protocols, while the	276	the JSON result into UTF-8, as required by many protocols, while the
282	C<decode> method expects to be handled an UTF-8-encoded string. Please	277	C<decode> method expects to be handed a UTF-8-encoded string. Please
283	note that UTF-8-encoded strings do not contain any characters outside the	278	note that UTF-8-encoded strings do not contain any characters outside the
284	range C<0..255>, they are thus useful for bytewise/binary I/O. In future	279	range C<0..255>, they are thus useful for bytewise/binary I/O. In future
285	versions, enabling this option might enable autodetection of the UTF-16	280	versions, enabling this option might enable autodetection of the UTF-16
286	and UTF-32 encoding families, as described in RFC4627.	281	and UTF-32 encoding families, as described in RFC4627.
287		282
…		…
372		367
373	=item $enabled = $json->get_relaxed	368	=item $enabled = $json->get_relaxed
374		369
375	If C<$enable> is true (or missing), then C<decode> will accept some	370	If C<$enable> is true (or missing), then C<decode> will accept some
376	extensions to normal JSON syntax (see below). C<encode> will not be	371	extensions to normal JSON syntax (see below). C<encode> will not be
377	affected in anyway. I<Be aware that this option makes you accept invalid	372	affected in any way. I<Be aware that this option makes you accept invalid
378	JSON texts as if they were valid!>. I suggest only to use this option to	373	JSON texts as if they were valid!>. I suggest only to use this option to
379	parse application-specific files written by humans (configuration files,	374	parse application-specific files written by humans (configuration files,
380	resource files etc.)	375	resource files etc.)
381		376
382	If C<$enable> is false (the default), then C<decode> will only accept	377	If C<$enable> is false (the default), then C<decode> will only accept
…		…
411	[	406	[
412	1, # this comment not allowed in JSON	407	1, # this comment not allowed in JSON
413	# neither this one...	408	# neither this one...
414	]	409	]
415		410
		411	=item * literal ASCII TAB characters in strings
		412
		413	Literal ASCII TAB characters are now allowed in strings (and treated as
		414	C<\t>).
		415
		416	[
		417	"Hello\tWorld",
		418	"Hello<TAB>World", # literal <TAB> would not normally be allowed
		419	]
		420
416	=back	421	=back
417		422
418	=item $json = $json->canonical ([$enable])	423	=item $json = $json->canonical ([$enable])
419		424
420	=item $enabled = $json->get_canonical	425	=item $enabled = $json->get_canonical
…		…
438		443
439	=item $json = $json->allow_nonref ([$enable])	444	=item $json = $json->allow_nonref ([$enable])
440		445
441	=item $enabled = $json->get_allow_nonref	446	=item $enabled = $json->get_allow_nonref
442		447
		448	Unlike other boolean options, this opotion is enabled by default beginning
		449	with version C<4.0>. See L<SECURITY CONSIDERATIONS> for the gory details.
		450
443	If C<$enable> is true (or missing), then the C<encode> method can convert a	451	If C<$enable> is true (or missing), then the C<encode> method can convert a
444	non-reference into its corresponding string, number or null JSON value,	452	non-reference into its corresponding string, number or null JSON value,
445	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON	453	which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
446	values instead of croaking.	454	values instead of croaking.
447		455
448	If C<$enable> is false, then the C<encode> method will croak if it isn't	456	If C<$enable> is false, then the C<encode> method will croak if it isn't
449	passed an arrayref or hashref, as JSON texts must either be an object	457	passed an arrayref or hashref, as JSON texts must either be an object
450	or array. Likewise, C<decode> will croak if given something that is not a	458	or array. Likewise, C<decode> will croak if given something that is not a
451	JSON object or array.	459	JSON object or array.
452		460
453	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,	461	Example, encode a Perl scalar as JSON value without enabled C<allow_nonref>,
454	resulting in an invalid JSON text:	462	resulting in an error:
455		463
456	JSON::XS->new->allow_nonref->encode ("Hello, World!")	464	JSON::XS->new->allow_nonref (0)->encode ("Hello, World!")
457	=> "Hello, World!"	465	=> hash- or arrayref expected...
458		466
459	=item $json = $json->allow_unknown ([$enable])	467	=item $json = $json->allow_unknown ([$enable])
460		468
461	=item $enabled = $json->get_allow_unknown	469	=item $enabled = $json->get_allow_unknown
462		470
…		…
474		482
475	=item $json = $json->allow_blessed ([$enable])	483	=item $json = $json->allow_blessed ([$enable])
476		484
477	=item $enabled = $json->get_allow_blessed	485	=item $enabled = $json->get_allow_blessed
478		486
		487	See L<OBJECT SERIALISATION> for details.
		488
479	If C<$enable> is true (or missing), then the C<encode> method will not	489	If C<$enable> is true (or missing), then the C<encode> method will not
480	barf when it encounters a blessed reference. Instead, the value of the	490	barf when it encounters a blessed reference that it cannot convert
481	B<convert_blessed> option will decide whether C<null> (C<convert_blessed>	491	otherwise. Instead, a JSON C<null> value is encoded instead of the object.
482	disabled or no C<TO_JSON> method found) or a representation of the
483	object (C<convert_blessed> enabled and C<TO_JSON> method found) is being
484	encoded. Has no effect on C<decode>.
485		492
486	If C<$enable> is false (the default), then C<encode> will throw an	493	If C<$enable> is false (the default), then C<encode> will throw an
487	exception when it encounters a blessed object.	494	exception when it encounters a blessed object that it cannot convert
		495	otherwise.
		496
		497	This setting has no effect on C<decode>.
488		498
489	=item $json = $json->convert_blessed ([$enable])	499	=item $json = $json->convert_blessed ([$enable])
490		500
491	=item $enabled = $json->get_convert_blessed	501	=item $enabled = $json->get_convert_blessed
		502
		503	See L<OBJECT SERIALISATION> for details.
492		504
493	If C<$enable> is true (or missing), then C<encode>, upon encountering a	505	If C<$enable> is true (or missing), then C<encode>, upon encountering a
494	blessed object, will check for the availability of the C<TO_JSON> method	506	blessed object, will check for the availability of the C<TO_JSON> method
495	on the object's class. If found, it will be called in scalar context	507	on the object's class. If found, it will be called in scalar context and
496	and the resulting scalar will be encoded instead of the object. If no	508	the resulting scalar will be encoded instead of the object.
497	C<TO_JSON> method is found, the value of C<allow_blessed> will decide what
498	to do.
499		509
500	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>	510	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
501	returns other blessed objects, those will be handled in the same	511	returns other blessed objects, those will be handled in the same
502	way. C<TO_JSON> must take care of not causing an endless recursion cycle	512	way. C<TO_JSON> must take care of not causing an endless recursion cycle
503	(== crash) in this case. The name of C<TO_JSON> was chosen because other	513	(== crash) in this case. The name of C<TO_JSON> was chosen because other
504	methods called by the Perl core (== not by the user of the object) are	514	methods called by the Perl core (== not by the user of the object) are
505	usually in upper case letters and to avoid collisions with any C<to_json>	515	usually in upper case letters and to avoid collisions with any C<to_json>
506	function or method.	516	function or method.
507		517
508	This setting does not yet influence C<decode> in any way, but in the	518	If C<$enable> is false (the default), then C<encode> will not consider
509	future, global hooks might get installed that influence C<decode> and are	519	this type of conversion.
510	enabled by this setting.
511		520
512	If C<$enable> is false, then the C<allow_blessed> setting will decide what	521	This setting has no effect on C<decode>.
513	to do when a blessed object is found.	522
		523	=item $json = $json->allow_tags ([$enable])
		524
		525	=item $enabled = $json->get_allow_tags
		526
		527	See L<OBJECT SERIALISATION> for details.
		528
		529	If C<$enable> is true (or missing), then C<encode>, upon encountering a
		530	blessed object, will check for the availability of the C<FREEZE> method on
		531	the object's class. If found, it will be used to serialise the object into
		532	a nonstandard tagged JSON value (that JSON decoders cannot decode).
		533
		534	It also causes C<decode> to parse such tagged JSON values and deserialise
		535	them via a call to the C<THAW> method.
		536
		537	If C<$enable> is false (the default), then C<encode> will not consider
		538	this type of conversion, and tagged JSON values will cause a parse error
		539	in C<decode>, as if tags were not part of the grammar.
514		540
515	=item $json = $json->filter_json_object ([$coderef->($hashref)])	541	=item $json = $json->filter_json_object ([$coderef->($hashref)])
516		542
517	When C<$coderef> is specified, it will be called from C<decode> each	543	When C<$coderef> is specified, it will be called from C<decode> each
518	time it decodes a JSON object. The only argument is a reference to the	544	time it decodes a JSON object. The only argument is a reference to
519	newly-created hash. If the code references returns a single scalar (which	545	the newly-created hash. If the code reference returns a single scalar
520	need not be a reference), this value (i.e. a copy of that scalar to avoid	546	(which need not be a reference), this value (or rather a copy of it) is
521	aliasing) is inserted into the deserialised data structure. If it returns	547	inserted into the deserialised data structure. If it returns an empty
522	an empty list (NOTE: I<not> C<undef>, which is a valid scalar), the	548	list (NOTE: I<not> C<undef>, which is a valid scalar), the original
523	original deserialised hash will be inserted. This setting can slow down	549	deserialised hash will be inserted. This setting can slow down decoding
524	decoding considerably.	550	considerably.
525		551
526	When C<$coderef> is omitted or undefined, any existing callback will	552	When C<$coderef> is omitted or undefined, any existing callback will
527	be removed and C<decode> will not change the deserialised hash in any	553	be removed and C<decode> will not change the deserialised hash in any
528	way.	554	way.
529		555
…		…
676		702
677	This is useful if your JSON texts are not delimited by an outer protocol	703	This is useful if your JSON texts are not delimited by an outer protocol
678	and you need to know where the JSON text ends.	704	and you need to know where the JSON text ends.
679		705
680	JSON::XS->new->decode_prefix ("[1] the tail")	706	JSON::XS->new->decode_prefix ("[1] the tail")
681	=> ([], 3)	707	=> ([1], 3)
682		708
683	=back	709	=back
684		710
685		711
686	=head1 INCREMENTAL PARSING	712	=head1 INCREMENTAL PARSING
…		…
727	C<incr_skip> to skip the erroneous part). This is the most common way of	753	C<incr_skip> to skip the erroneous part). This is the most common way of
728	using the method.	754	using the method.
729		755
730	And finally, in list context, it will try to extract as many objects	756	And finally, in list context, it will try to extract as many objects
731	from the stream as it can find and return them, or the empty list	757	from the stream as it can find and return them, or the empty list
732	otherwise. For this to work, there must be no separators between the JSON	758	otherwise. For this to work, there must be no separators (other than
733	objects or arrays, instead they must be concatenated back-to-back. If	759	whitespace) between the JSON objects or arrays, instead they must be
734	an error occurs, an exception will be raised as in the scalar context	760	concatenated back-to-back. If an error occurs, an exception will be
735	case. Note that in this case, any previously-parsed JSON texts will be	761	raised as in the scalar context case. Note that in this case, any
736	lost.	762	previously-parsed JSON texts will be lost.
737		763
738	Example: Parse some JSON arrays/objects in a given string and return	764	Example: Parse some JSON arrays/objects in a given string and return
739	them.	765	them.
740		766
741	my @objs = JSON::XS->new->incr_parse ("[5][7][1,2]");	767	my @objs = JSON::XS->new->incr_parse ("[5][7][1,2]");
…		…
747	C<incr_parse> in I<scalar context> successfully returned an object. Under	773	C<incr_parse> in I<scalar context> successfully returned an object. Under
748	all other circumstances you must not call this function (I mean it.	774	all other circumstances you must not call this function (I mean it.
749	although in simple tests it might actually work, it I<will> fail under	775	although in simple tests it might actually work, it I<will> fail under
750	real world conditions). As a special exception, you can also call this	776	real world conditions). As a special exception, you can also call this
751	method before having parsed anything.	777	method before having parsed anything.
		778
		779	That means you can only use this function to look at or manipulate text
		780	before or after complete JSON objects, not while the parser is in the
		781	middle of parsing a JSON object.
752		782
753	This function is useful in two cases: a) finding the trailing text after a	783	This function is useful in two cases: a) finding the trailing text after a
754	JSON object or b) parsing multiple JSON objects separated by non-JSON text	784	JSON object or b) parsing multiple JSON objects separated by non-JSON text
755	(such as commas).	785	(such as commas).
756		786
…		…
983	floating point, JSON::XS only guarantees precision up to but not including	1013	floating point, JSON::XS only guarantees precision up to but not including
984	the least significant bit.	1014	the least significant bit.
985		1015
986	=item true, false	1016	=item true, false
987		1017
988	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,	1018	These JSON atoms become C<Types::Serialiser::true> and
989	respectively. They are overloaded to act almost exactly like the numbers	1019	C<Types::Serialiser::false>, respectively. They are overloaded to act
990	C<1> and C<0>. You can check whether a scalar is a JSON boolean by using	1020	almost exactly like the numbers C<1> and C<0>. You can check whether
991	the C<JSON::XS::is_bool> function.	1021	a scalar is a JSON boolean by using the C<Types::Serialiser::is_bool>
		1022	function (after C<use Types::Serialier>, of course).
992		1023
993	=item null	1024	=item null
994		1025
995	A JSON null atom becomes C<undef> in Perl.	1026	A JSON null atom becomes C<undef> in Perl.
		1027
		1028	=item shell-style comments (C<< # I<text> >>)
		1029
		1030	As a nonstandard extension to the JSON syntax that is enabled by the
		1031	C<relaxed> setting, shell-style comments are allowed. They can start
		1032	anywhere outside strings and go till the end of the line.
		1033
		1034	=item tagged values (C<< (I<tag>)I<value> >>).
		1035
		1036	Another nonstandard extension to the JSON syntax, enabled with the
		1037	C<allow_tags> setting, are tagged values. In this implementation, the
		1038	I<tag> must be a perl package/class name encoded as a JSON string, and the
		1039	I<value> must be a JSON array encoding optional constructor arguments.
		1040
		1041	See L<OBJECT SERIALISATION>, below, for details.
996		1042
997	=back	1043	=back
998		1044
999		1045
1000	=head2 PERL -> JSON	1046	=head2 PERL -> JSON
…		…
1021		1067
1022	=item other references	1068	=item other references
1023		1069
1024	Other unblessed references are generally not allowed and will cause an	1070	Other unblessed references are generally not allowed and will cause an
1025	exception to be thrown, except for references to the integers C<0> and	1071	exception to be thrown, except for references to the integers C<0> and
1026	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can	1072	C<1>, which get turned into C<false> and C<true> atoms in JSON.
1027	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
1028		1073
		1074	Since C<JSON::XS> uses the boolean model from L<Types::Serialiser>, you
		1075	can also C<use Types::Serialiser> and then use C<Types::Serialiser::false>
		1076	and C<Types::Serialiser::true> to improve readability.
		1077
		1078	use Types::Serialiser;
1029	encode_json [\0, JSON::XS::true] # yields [false,true]	1079	encode_json [\0, Types::Serialiser::true] # yields [false,true]
1030		1080
1031	=item JSON::XS::true, JSON::XS::false	1081	=item Types::Serialiser::true, Types::Serialiser::false
1032		1082
1033	These special values become JSON true and JSON false values,	1083	These special values from the L<Types::Serialiser> module become JSON true
1034	respectively. You can also use C<\1> and C<\0> directly if you want.	1084	and JSON false values, respectively. You can also use C<\1> and C<\0>
		1085	directly if you want.
1035		1086
1036	=item blessed objects	1087	=item blessed objects
1037		1088
1038	Blessed objects are not directly representable in JSON. See the	1089	Blessed objects are not directly representable in JSON, but C<JSON::XS>
1039	C<allow_blessed> and C<convert_blessed> methods on various options on	1090	allows various ways of handling objects. See L<OBJECT SERIALISATION>,
1040	how to deal with this: basically, you can choose between throwing an	1091	below, for details.
1041	exception, encoding the reference as if it weren't blessed, or provide
1042	your own serialiser method.
1043		1092
1044	=item simple scalars	1093	=item simple scalars
1045		1094
1046	Simple Perl scalars (any scalar that is not a reference) are the most	1095	Simple Perl scalars (any scalar that is not a reference) are the most
1047	difficult objects to encode: JSON::XS will encode undefined scalars as	1096	difficult objects to encode: JSON::XS will encode undefined scalars as
…		…
1083	extensions to the floating point numbers of your platform, such as	1132	extensions to the floating point numbers of your platform, such as
1084	infinities or NaN's - these cannot be represented in JSON, and it is an	1133	infinities or NaN's - these cannot be represented in JSON, and it is an
1085	error to pass those in.	1134	error to pass those in.
1086		1135
1087	=back	1136	=back
		1137
		1138	=head2 OBJECT SERIALISATION
		1139
		1140	As JSON cannot directly represent Perl objects, you have to choose between
		1141	a pure JSON representation (without the ability to deserialise the object
		1142	automatically again), and a nonstandard extension to the JSON syntax,
		1143	tagged values.
		1144
		1145	=head3 SERIALISATION
		1146
		1147	What happens when C<JSON::XS> encounters a Perl object depends on the
		1148	C<allow_blessed>, C<convert_blessed> and C<allow_tags> settings, which are
		1149	used in this order:
		1150
		1151	=over 4
		1152
		1153	=item 1. C<allow_tags> is enabled and the object has a C<FREEZE> method.
		1154
		1155	In this case, C<JSON::XS> uses the L<Types::Serialiser> object
		1156	serialisation protocol to create a tagged JSON value, using a nonstandard
		1157	extension to the JSON syntax.
		1158
		1159	This works by invoking the C<FREEZE> method on the object, with the first
		1160	argument being the object to serialise, and the second argument being the
		1161	constant string C<JSON> to distinguish it from other serialisers.
		1162
		1163	The C<FREEZE> method can return any number of values (i.e. zero or
		1164	more). These values and the paclkage/classname of the object will then be
		1165	encoded as a tagged JSON value in the following format:
		1166
		1167	("classname")[FREEZE return values...]
		1168
		1169	e.g.:
		1170
		1171	("URI")["http://www.google.com/"]
		1172	("MyDate")[2013,10,29]
		1173	("ImageData::JPEG")["Z3...VlCg=="]
		1174
		1175	For example, the hypothetical C<My::Object> C<FREEZE> method might use the
		1176	objects C<type> and C<id> members to encode the object:
		1177
		1178	sub My::Object::FREEZE {
		1179	my ($self, $serialiser) = @_;
		1180
		1181	($self->{type}, $self->{id})
		1182	}
		1183
		1184	=item 2. C<convert_blessed> is enabled and the object has a C<TO_JSON> method.
		1185
		1186	In this case, the C<TO_JSON> method of the object is invoked in scalar
		1187	context. It must return a single scalar that can be directly encoded into
		1188	JSON. This scalar replaces the object in the JSON text.
		1189
		1190	For example, the following C<TO_JSON> method will convert all L<URI>
		1191	objects to JSON strings when serialised. The fatc that these values
		1192	originally were L<URI> objects is lost.
		1193
		1194	sub URI::TO_JSON {
		1195	my ($uri) = @_;
		1196	$uri->as_string
		1197	}
		1198
		1199	=item 3. C<allow_blessed> is enabled.
		1200
		1201	The object will be serialised as a JSON null value.
		1202
		1203	=item 4. none of the above
		1204
		1205	If none of the settings are enabled or the respective methods are missing,
		1206	C<JSON::XS> throws an exception.
		1207
		1208	=back
		1209
		1210	=head3 DESERIALISATION
		1211
		1212	For deserialisation there are only two cases to consider: either
		1213	nonstandard tagging was used, in which case C<allow_tags> decides,
		1214	or objects cannot be automatically be deserialised, in which
		1215	case you can use postprocessing or the C<filter_json_object> or
		1216	C<filter_json_single_key_object> callbacks to get some real objects our of
		1217	your JSON.
		1218
		1219	This section only considers the tagged value case: I a tagged JSON object
		1220	is encountered during decoding and C<allow_tags> is disabled, a parse
		1221	error will result (as if tagged values were not part of the grammar).
		1222
		1223	If C<allow_tags> is enabled, C<JSON::XS> will look up the C<THAW> method
		1224	of the package/classname used during serialisation (it will not attempt
		1225	to load the package as a Perl module). If there is no such method, the
		1226	decoding will fail with an error.
		1227
		1228	Otherwise, the C<THAW> method is invoked with the classname as first
		1229	argument, the constant string C<JSON> as second argument, and all the
		1230	values from the JSON array (the values originally returned by the
		1231	C<FREEZE> method) as remaining arguments.
		1232
		1233	The method must then return the object. While technically you can return
		1234	any Perl scalar, you might have to enable the C<enable_nonref> setting to
		1235	make that work in all cases, so better return an actual blessed reference.
		1236
		1237	As an example, let's implement a C<THAW> function that regenerates the
		1238	C<My::Object> from the C<FREEZE> example earlier:
		1239
		1240	sub My::Object::THAW {
		1241	my ($class, $serialiser, $type, $id) = @_;
		1242
		1243	$class->new (type => $type, id => $id)
		1244	}
1088		1245
1089		1246
1090	=head1 ENCODING/CODESET FLAG NOTES	1247	=head1 ENCODING/CODESET FLAG NOTES
1091		1248
1092	The interested reader might have seen a number of flags that signify	1249	The interested reader might have seen a number of flags that signify
…		…
1137	expect your input strings to be encoded as UTF-8, that is, no "character"	1294	expect your input strings to be encoded as UTF-8, that is, no "character"
1138	of the input string must have any value > 255, as UTF-8 does not allow	1295	of the input string must have any value > 255, as UTF-8 does not allow
1139	that.	1296	that.
1140		1297
1141	The C<utf8> flag therefore switches between two modes: disabled means you	1298	The C<utf8> flag therefore switches between two modes: disabled means you
1142	will get a Unicode string in Perl, enabled means you get an UTF-8 encoded	1299	will get a Unicode string in Perl, enabled means you get a UTF-8 encoded
1143	octet/binary string in Perl.	1300	octet/binary string in Perl.
1144		1301
1145	=item C<latin1> or C<ascii> flags enabled	1302	=item C<latin1> or C<ascii> flags enabled
1146		1303
1147	With C<latin1> (or C<ascii>) enabled, C<encode> will escape characters	1304	With C<latin1> (or C<ascii>) enabled, C<encode> will escape characters
…		…
1415	are browser design bugs, but it is still you who will have to deal with	1572	are browser design bugs, but it is still you who will have to deal with
1416	it, as major browser developers care only for features, not about getting	1573	it, as major browser developers care only for features, not about getting
1417	security right).	1574	security right).
1418		1575
1419		1576
		1577	=head2 "OLD" VS. "NEW" JSON (RFC 4627 VS. RFC 7159)
		1578
		1579	JSON originally required JSON texts to represent an array or object -
		1580	scalar values were explicitly not allowed. This has changed, and versions
		1581	of JSON::XS beginning with C<4.0> reflect this by allowing scalar values
		1582	by default.
		1583
		1584	One reason why one might not want this is that this removes a fundamental
		1585	property of JSON texts, namely that they are self-delimited and
		1586	self-contained, or in other words, you could take any number of "old"
		1587	JSON texts and paste them together, and the result would be unambiguously
		1588	parseable:
		1589
		1590	[1,3]{"k":5}[][null] # four JSON texts, without doubt
		1591
		1592	By allowing scalars, this property is lost: in the following example, is
		1593	this one JSON text (the number 12) or two JSON texts (the numbers 1 and
		1594	2):
		1595
		1596	12 # could be 12, or 1 and 2
		1597
		1598	Another lost property of "old" JSON is that no lookahead is required to
		1599	know the end of a JSON text, i.e. the JSON text definitely ended at the
		1600	last C<]> or C<}> character, there was no need to read extra characters.
		1601
		1602	For example, a viable network protocol with "old" JSON was to simply
		1603	exchange JSON texts without delimiter. For "new" JSON, you have to use a
		1604	suitable delimiter (such as a newline) after every JSON text or ensure you
		1605	never encode/decode scalar values.
		1606
		1607	Most protocols do work by only transferring arrays or objects, and the
		1608	easiest way to avoid problems with the "new" JSON definition is to
		1609	explicitly disallow scalar values in your encoder and decoder:
		1610
		1611	$json_coder = JSON::XS->new->allow_nonref (0)
		1612
		1613	This is a somewhat unhappy situation, and the blame can fully be put on
		1614	JSON's inmventor, Douglas Crockford, who unilaterally changed the format
		1615	in 2006 without consulting the IETF, forcing the IETF to either fork the
		1616	format or go with it (as I was told, the IETF wasn't amused).
		1617
		1618
		1619	=head1 INTEROPERABILITY WITH OTHER MODULES
		1620
		1621	C<JSON::XS> uses the L<Types::Serialiser> module to provide boolean
		1622	constants. That means that the JSON true and false values will be
		1623	comaptible to true and false values of other modules that do the same,
		1624	such as L<JSON::PP> and L<CBOR::XS>.
		1625
		1626
		1627	=head1 INTEROPERABILITY WITH OTHER JSON DECODERS
		1628
		1629	As long as you only serialise data that can be directly expressed in JSON,
		1630	C<JSON::XS> is incapable of generating invalid JSON output (modulo bugs,
		1631	but C<JSON::XS> has found more bugs in the official JSON testsuite (1)
		1632	than the official JSON testsuite has found in C<JSON::XS> (0)).
		1633
		1634	When you have trouble decoding JSON generated by this module using other
		1635	decoders, then it is very likely that you have an encoding mismatch or the
		1636	other decoder is broken.
		1637
		1638	When decoding, C<JSON::XS> is strict by default and will likely catch all
		1639	errors. There are currently two settings that change this: C<relaxed>
		1640	makes C<JSON::XS> accept (but not generate) some non-standard extensions,
		1641	and C<allow_tags> will allow you to encode and decode Perl objects, at the
		1642	cost of not outputting valid JSON anymore.
		1643
		1644	=head2 TAGGED VALUE SYNTAX AND STANDARD JSON EN/DECODERS
		1645
		1646	When you use C<allow_tags> to use the extended (and also nonstandard and
		1647	invalid) JSON syntax for serialised objects, and you still want to decode
		1648	the generated When you want to serialise objects, you can run a regex
		1649	to replace the tagged syntax by standard JSON arrays (it only works for
		1650	"normal" package names without comma, newlines or single colons). First,
		1651	the readable Perl version:
		1652
		1653	# if your FREEZE methods return no values, you need this replace first:
		1654	$json =~ s/$ \s* (" (?: [^\\":,]+\|\\.\|::)* ") \s* $ \s* \[\s*\]/[$1]/gx;
		1655
		1656	# this works for non-empty constructor arg lists:
		1657	$json =~ s/$ \s* (" (?: [^\\":,]+\|\\.\|::)* ") \s* $ \s* \[/[$1,/gx;
		1658
		1659	And here is a less readable version that is easy to adapt to other
		1660	languages:
		1661
		1662	$json =~ s/$\s("([^\\":,]+\|\\.\|::)")\s$\s\[/[$1,/g;
		1663
		1664	Here is an ECMAScript version (same regex):
		1665
		1666	json = json.replace (/$\s("([^\\":,]+\|\\.\|::)")\s$\s\[/g, "[$1,");
		1667
		1668	Since this syntax converts to standard JSON arrays, it might be hard to
		1669	distinguish serialised objects from normal arrays. You can prepend a
		1670	"magic number" as first array element to reduce chances of a collision:
		1671
		1672	$json =~ s/$\s("([^\\":,]+\|\\.\|::)")\s$\s\[/["XU1peReLzT4ggEllLanBYq4G9VzliwKF",$1,/g;
		1673
		1674	And after decoding the JSON text, you could walk the data
		1675	structure looking for arrays with a first element of
		1676	C<XU1peReLzT4ggEllLanBYq4G9VzliwKF>.
		1677
		1678	The same approach can be used to create the tagged format with another
		1679	encoder. First, you create an array with the magic string as first member,
		1680	the classname as second, and constructor arguments last, encode it as part
		1681	of your JSON structure, and then:
		1682
		1683	$json =~ s/\[\s"XU1peReLzT4ggEllLanBYq4G9VzliwKF"\s,\s("([^\\":,]+\|\\.\|::)")\s*,/($1)[/g;
		1684
		1685	Again, this has some limitations - the magic string must not be encoded
		1686	with character escapes, and the constructor arguments must be non-empty.
		1687
		1688
		1689	=head1 RFC7159
		1690
		1691	Since this module was written, Google has written a new JSON RFC, RFC 7159
		1692	(and RFC7158). Unfortunately, this RFC breaks compatibility with both the
		1693	original JSON specification on www.json.org and RFC4627.
		1694
		1695	As far as I can see, you can get partial compatibility when parsing by
		1696	using C<< ->allow_nonref >>. However, consider the security implications
		1697	of doing so.
		1698
		1699	I haven't decided yet when to break compatibility with RFC4627 by default
		1700	(and potentially leave applications insecure) and change the default to
		1701	follow RFC7159, but application authors are well advised to call C<<
		1702	->allow_nonref(0) >> even if this is the current default, if they cannot
		1703	handle non-reference values, in preparation for the day when the default
		1704	will change.
		1705
		1706
1420	=head1 THREADS	1707	=head1 (I-)THREADS
1421		1708
1422	This module is I<not> guaranteed to be thread safe and there are no	1709	This module is I<not> guaranteed to be ithread (or MULTIPLICITY-) safe
1423	plans to change this until Perl gets thread support (as opposed to the	1710	and there are no plans to change this. Note that perl's builtin so-called
1424	horribly slow so-called "threads" which are simply slow and bloated	1711	threads/ithreads are officially deprecated and should not be used.
1425	process simulations - use fork, it's I<much> faster, cheaper, better).
1426
1427	(It might actually work, but you have been warned).
1428		1712
1429		1713
1430	=head1 THE PERILS OF SETLOCALE	1714	=head1 THE PERILS OF SETLOCALE
1431		1715
1432	Sometimes people avoid the Perl locale support and directly call the	1716	Sometimes people avoid the Perl locale support and directly call the
…		…
1454	Please refrain from using rt.cpan.org or any other bug reporting	1738	Please refrain from using rt.cpan.org or any other bug reporting
1455	service. I put the contact address into my modules for a reason.	1739	service. I put the contact address into my modules for a reason.
1456		1740
1457	=cut	1741	=cut
1458		1742
1459	our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };	1743	BEGIN {
1460	our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };	1744	*true = \$Types::Serialiser::true;
		1745	*true = \&Types::Serialiser::true;
		1746	*false = \$Types::Serialiser::false;
		1747	*false = \&Types::Serialiser::false;
		1748	*is_bool = \&Types::Serialiser::is_bool;
1461		1749
1462	sub true() { $true }	1750	JSON::XS::Boolean:: = Types::Serialiser::Boolean::;
1463	sub false() { $false }
1464
1465	sub is_bool($) {
1466	UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
1467	# or UNIVERSAL::isa $_[0], "JSON::Literal"
1468	}	1751	}
1469		1752
1470	XSLoader::load "JSON::XS", $VERSION;	1753	XSLoader::load "JSON::XS", $VERSION;
1471
1472	package JSON::XS::Boolean;
1473
1474	use overload
1475	"0+" => sub { ${$_[0]} },
1476	"++" => sub { $_[0] = ${$_[0]} + 1 },
1477	"--" => sub { $_[0] = ${$_[0]} - 1 },
1478	fallback => 1;
1479
1480	1;
1481		1754
1482	=head1 SEE ALSO	1755	=head1 SEE ALSO
1483		1756
1484	The F<json_xs> command line utility for quick experiments.	1757	The F<json_xs> command line utility for quick experiments.
1485		1758
…		…
1488	Marc Lehmann <schmorp@schmorp.de>	1761	Marc Lehmann <schmorp@schmorp.de>
1489	http://home.schmorp.de/	1762	http://home.schmorp.de/
1490		1763
1491	=cut	1764	=cut
1492		1765
		1766	1
		1767

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Comparing JSON-XS/XS.pm (file contents): Revision 1.143 by root, Fri Oct 25 20:02:54 2013 UTC vs. Revision 1.169 by root, Thu Nov 15 20:49:12 2018 UTC

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Comparing JSON-XS/XS.pm (file contents):
Revision 1.143 by root, Fri Oct 25 20:02:54 2013 UTC vs.
Revision 1.169 by root, Thu Nov 15 20:49:12 2018 UTC