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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.139 by root, Thu May 23 09:31:32 2013 UTC vs.
Revision 1.164 by root, Thu Aug 17 03:47:54 2017 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
…		…
83	this module usually compares favourably in terms of speed, too.	83	this module usually compares favourably in terms of speed, too.
84		84
85	=item * simple to use	85	=item * simple to use
86		86
87	This module has both a simple functional interface as well as an object	87	This module has both a simple functional interface as well as an object
88	oriented interface interface.	88	oriented interface.
89		89
90	=item * reasonably versatile output formats	90	=item * reasonably versatile output formats
91		91
92	You can choose between the most compact guaranteed-single-line format	92	You can choose between the most compact guaranteed-single-line format
93	possible (nice for simple line-based protocols), a pure-ASCII format	93	possible (nice for simple line-based protocols), a pure-ASCII format
…		…
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 $VERSION = 3.04;
107	our @ISA = qw(Exporter);	107	our @ISA = qw(Exporter);
108		108
109	our @EXPORT = qw(encode_json decode_json to_json from_json);	109	our @EXPORT = qw(encode_json decode_json);
110
111	sub to_json($) {
112	require Carp;
113	Carp::croak ("JSON::XS::to_json has been renamed to encode_json, either downgrade to pre-2.0 versions of JSON::XS or rename the call");
114	}
115
116	sub from_json($) {
117	require Carp;
118	Carp::croak ("JSON::XS::from_json has been renamed to decode_json, either downgrade to pre-2.0 versions of JSON::XS or rename the call");
119	}
120		110
121	use Exporter;	111	use Exporter;
122	use XSLoader;	112	use XSLoader;
		113
		114	use Types::Serialiser ();
123		115
124	=head1 FUNCTIONAL INTERFACE	116	=head1 FUNCTIONAL INTERFACE
125		117
126	The following convenience methods are provided by this module. They are	118	The following convenience methods are provided by this module. They are
127	exported by default:	119	exported by default:
…		…
148	This function call is functionally identical to:	140	This function call is functionally identical to:
149		141
150	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)	142	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
151		143
152	Except being faster.	144	Except being faster.
153
154	=item $is_boolean = JSON::XS::is_bool $scalar
155
156	Returns true if the passed scalar represents either JSON::XS::true or
157	JSON::XS::false, two constants that act like C<1> and C<0>, respectively
158	and are used to represent JSON C<true> and C<false> values in Perl.
159
160	See MAPPING, below, for more information on how JSON values are mapped to
161	Perl.
162		145
163	=back	146	=back
164		147
165		148
166	=head1 A FEW NOTES ON UNICODE AND PERL	149	=head1 A FEW NOTES ON UNICODE AND PERL
…		…
421	[	404	[
422	1, # this comment not allowed in JSON	405	1, # this comment not allowed in JSON
423	# neither this one...	406	# neither this one...
424	]	407	]
425		408
		409	=item * literal ASCII TAB characters in strings
		410
		411	Literal ASCII TAB characters are now allowed in strings (and treated as
		412	C<\t>).
		413
		414	[
		415	"Hello\tWorld",
		416	"Hello<TAB>World", # literal <TAB> would not normally be allowed
		417	]
		418
426	=back	419	=back
427		420
428	=item $json = $json->canonical ([$enable])	421	=item $json = $json->canonical ([$enable])
429		422
430	=item $enabled = $json->get_canonical	423	=item $enabled = $json->get_canonical
…		…
484		477
485	=item $json = $json->allow_blessed ([$enable])	478	=item $json = $json->allow_blessed ([$enable])
486		479
487	=item $enabled = $json->get_allow_blessed	480	=item $enabled = $json->get_allow_blessed
488		481
		482	See L<OBJECT SERIALISATION> for details.
		483
489	If C<$enable> is true (or missing), then the C<encode> method will not	484	If C<$enable> is true (or missing), then the C<encode> method will not
490	barf when it encounters a blessed reference. Instead, the value of the	485	barf when it encounters a blessed reference that it cannot convert
491	B<convert_blessed> option will decide whether C<null> (C<convert_blessed>	486	otherwise. Instead, a JSON C<null> value is encoded instead of the object.
492	disabled or no C<TO_JSON> method found) or a representation of the
493	object (C<convert_blessed> enabled and C<TO_JSON> method found) is being
494	encoded. Has no effect on C<decode>.
495		487
496	If C<$enable> is false (the default), then C<encode> will throw an	488	If C<$enable> is false (the default), then C<encode> will throw an
497	exception when it encounters a blessed object.	489	exception when it encounters a blessed object that it cannot convert
		490	otherwise.
		491
		492	This setting has no effect on C<decode>.
498		493
499	=item $json = $json->convert_blessed ([$enable])	494	=item $json = $json->convert_blessed ([$enable])
500		495
501	=item $enabled = $json->get_convert_blessed	496	=item $enabled = $json->get_convert_blessed
		497
		498	See L<OBJECT SERIALISATION> for details.
502		499
503	If C<$enable> is true (or missing), then C<encode>, upon encountering a	500	If C<$enable> is true (or missing), then C<encode>, upon encountering a
504	blessed object, will check for the availability of the C<TO_JSON> method	501	blessed object, will check for the availability of the C<TO_JSON> method
505	on the object's class. If found, it will be called in scalar context	502	on the object's class. If found, it will be called in scalar context and
506	and the resulting scalar will be encoded instead of the object. If no	503	the resulting scalar will be encoded instead of the object.
507	C<TO_JSON> method is found, the value of C<allow_blessed> will decide what
508	to do.
509		504
510	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>	505	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
511	returns other blessed objects, those will be handled in the same	506	returns other blessed objects, those will be handled in the same
512	way. C<TO_JSON> must take care of not causing an endless recursion cycle	507	way. C<TO_JSON> must take care of not causing an endless recursion cycle
513	(== crash) in this case. The name of C<TO_JSON> was chosen because other	508	(== crash) in this case. The name of C<TO_JSON> was chosen because other
514	methods called by the Perl core (== not by the user of the object) are	509	methods called by the Perl core (== not by the user of the object) are
515	usually in upper case letters and to avoid collisions with any C<to_json>	510	usually in upper case letters and to avoid collisions with any C<to_json>
516	function or method.	511	function or method.
517		512
518	This setting does not yet influence C<decode> in any way, but in the	513	If C<$enable> is false (the default), then C<encode> will not consider
519	future, global hooks might get installed that influence C<decode> and are	514	this type of conversion.
520	enabled by this setting.
521		515
522	If C<$enable> is false, then the C<allow_blessed> setting will decide what	516	This setting has no effect on C<decode>.
523	to do when a blessed object is found.	517
		518	=item $json = $json->allow_tags ([$enable])
		519
		520	=item $enabled = $json->allow_tags
		521
		522	See L<OBJECT SERIALISATION> for details.
		523
		524	If C<$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
		526	the object's class. If found, it will be used to serialise the object into
		527	a nonstandard tagged JSON value (that JSON decoders cannot decode).
		528
		529	It also causes C<decode> to parse such tagged JSON values and deserialise
		530	them via a call to the C<THAW> method.
		531
		532	If C<$enable> is false (the default), then C<encode> will not consider
		533	this type of conversion, and tagged JSON values will cause a parse error
		534	in C<decode>, as if tags were not part of the grammar.
524		535
525	=item $json = $json->filter_json_object ([$coderef->($hashref)])	536	=item $json = $json->filter_json_object ([$coderef->($hashref)])
526		537
527	When C<$coderef> is specified, it will be called from C<decode> each	538	When C<$coderef> is specified, it will be called from C<decode> each
528	time it decodes a JSON object. The only argument is a reference to the	539	time it decodes a JSON object. The only argument is a reference to the
…		…
667		678
668	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	679	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
669		680
670	=item $json_text = $json->encode ($perl_scalar)	681	=item $json_text = $json->encode ($perl_scalar)
671		682
672	Converts the given Perl data structure (a simple scalar or a reference	683	Converts the given Perl value or data structure to its JSON
673	to a hash or array) to its JSON representation. Simple scalars will be	684	representation. Croaks on error.
674	converted into JSON string or number sequences, while references to arrays
675	become JSON arrays and references to hashes become JSON objects. Undefined
676	Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>
677	nor C<false> values will be generated.
678		685
679	=item $perl_scalar = $json->decode ($json_text)	686	=item $perl_scalar = $json->decode ($json_text)
680		687
681	The opposite of C<encode>: expects a JSON text and tries to parse it,	688	The opposite of C<encode>: expects a JSON text and tries to parse it,
682	returning the resulting simple scalar or reference. Croaks on error.	689	returning the resulting simple scalar or reference. Croaks on error.
683
684	JSON numbers and strings become simple Perl scalars. JSON arrays become
685	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
686	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
687		690
688	=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)	691	=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
689		692
690	This works like the C<decode> method, but instead of raising an exception	693	This works like the C<decode> method, but instead of raising an exception
691	when there is trailing garbage after the first JSON object, it will	694	when there is trailing garbage after the first JSON object, it will
692	silently stop parsing there and return the number of characters consumed	695	silently stop parsing there and return the number of characters consumed
693	so far.	696	so far.
694		697
695	This is useful if your JSON texts are not delimited by an outer protocol	698	This is useful if your JSON texts are not delimited by an outer protocol
696	(which is not the brightest thing to do in the first place) and you need
697	to know where the JSON text ends.	699	and you need to know where the JSON text ends.
698		700
699	JSON::XS->new->decode_prefix ("[1] the tail")	701	JSON::XS->new->decode_prefix ("[1] the tail")
700	=> ([], 3)	702	=> ([1], 3)
701		703
702	=back	704	=back
703		705
704		706
705	=head1 INCREMENTAL PARSING	707	=head1 INCREMENTAL PARSING
…		…
741		743
742	If the method is called in scalar context, then it will try to extract	744	If the method is called in scalar context, then it will try to extract
743	exactly I<one> JSON object. If that is successful, it will return this	745	exactly I<one> JSON object. If that is successful, it will return this
744	object, otherwise it will return C<undef>. If there is a parse error,	746	object, otherwise it will return C<undef>. If there is a parse error,
745	this method will croak just as C<decode> would do (one can then use	747	this method will croak just as C<decode> would do (one can then use
746	C<incr_skip> to skip the errornous part). This is the most common way of	748	C<incr_skip> to skip the erroneous part). This is the most common way of
747	using the method.	749	using the method.
748		750
749	And finally, in list context, it will try to extract as many objects	751	And finally, in list context, it will try to extract as many objects
750	from the stream as it can find and return them, or the empty list	752	from the stream as it can find and return them, or the empty list
751	otherwise. For this to work, there must be no separators between the JSON	753	otherwise. For this to work, there must be no separators (other than
752	objects or arrays, instead they must be concatenated back-to-back. If	754	whitespace) between the JSON objects or arrays, instead they must be
753	an error occurs, an exception will be raised as in the scalar context	755	concatenated back-to-back. If an error occurs, an exception will be
754	case. Note that in this case, any previously-parsed JSON texts will be	756	raised as in the scalar context case. Note that in this case, any
755	lost.	757	previously-parsed JSON texts will be lost.
756		758
757	Example: Parse some JSON arrays/objects in a given string and return	759	Example: Parse some JSON arrays/objects in a given string and return
758	them.	760	them.
759		761
760	my @objs = JSON::XS->new->incr_parse ("[5][7][1,2]");	762	my @objs = JSON::XS->new->incr_parse ("[5][7][1,2]");
…		…
767	all other circumstances you must not call this function (I mean it.	769	all other circumstances you must not call this function (I mean it.
768	although in simple tests it might actually work, it I<will> fail under	770	although in simple tests it might actually work, it I<will> fail under
769	real world conditions). As a special exception, you can also call this	771	real world conditions). As a special exception, you can also call this
770	method before having parsed anything.	772	method before having parsed anything.
771		773
		774	That means you can only use this function to look at or manipulate text
		775	before or after complete JSON objects, not while the parser is in the
		776	middle of parsing a JSON object.
		777
772	This function is useful in two cases: a) finding the trailing text after a	778	This function is useful in two cases: a) finding the trailing text after a
773	JSON object or b) parsing multiple JSON objects separated by non-JSON text	779	JSON object or b) parsing multiple JSON objects separated by non-JSON text
774	(such as commas).	780	(such as commas).
775		781
776	=item $json->incr_skip	782	=item $json->incr_skip
…		…
780	C<incr_parse> died, in which case the input buffer and incremental parser	786	C<incr_parse> died, in which case the input buffer and incremental parser
781	state is left unchanged, to skip the text parsed so far and to reset the	787	state is left unchanged, to skip the text parsed so far and to reset the
782	parse state.	788	parse state.
783		789
784	The difference to C<incr_reset> is that only text until the parse error	790	The difference to C<incr_reset> is that only text until the parse error
785	occured is removed.	791	occurred is removed.
786		792
787	=item $json->incr_reset	793	=item $json->incr_reset
788		794
789	This completely resets the incremental parser, that is, after this call,	795	This completely resets the incremental parser, that is, after this call,
790	it will be as if the parser had never parsed anything.	796	it will be as if the parser had never parsed anything.
…		…
796	=back	802	=back
797		803
798	=head2 LIMITATIONS	804	=head2 LIMITATIONS
799		805
800	All options that affect decoding are supported, except	806	All options that affect decoding are supported, except
801	C<allow_nonref>. The reason for this is that it cannot be made to	807	C<allow_nonref>. The reason for this is that it cannot be made to work
802	work sensibly: JSON objects and arrays are self-delimited, i.e. you can concatenate	808	sensibly: JSON objects and arrays are self-delimited, i.e. you can
803	them back to back and still decode them perfectly. This does not hold true	809	concatenate them back to back and still decode them perfectly. This does
804	for JSON numbers, however.	810	not hold true for JSON numbers, however.
805		811
806	For example, is the string C<1> a single JSON number, or is it simply the	812	For example, is the string C<1> a single JSON number, or is it simply the
807	start of C<12>? Or is C<12> a single JSON number, or the concatenation	813	start of C<12>? Or is C<12> a single JSON number, or the concatenation
808	of C<1> and C<2>? In neither case you can tell, and this is why JSON::XS	814	of C<1> and C<2>? In neither case you can tell, and this is why JSON::XS
809	takes the conservative route and disallows this case.	815	takes the conservative route and disallows this case.
…		…
988	If the number consists of digits only, JSON::XS will try to represent	994	If the number consists of digits only, JSON::XS will try to represent
989	it as an integer value. If that fails, it will try to represent it as	995	it as an integer value. If that fails, it will try to represent it as
990	a numeric (floating point) value if that is possible without loss of	996	a numeric (floating point) value if that is possible without loss of
991	precision. Otherwise it will preserve the number as a string value (in	997	precision. Otherwise it will preserve the number as a string value (in
992	which case you lose roundtripping ability, as the JSON number will be	998	which case you lose roundtripping ability, as the JSON number will be
993	re-encoded toa JSON string).	999	re-encoded to a JSON string).
994		1000
995	Numbers containing a fractional or exponential part will always be	1001	Numbers containing a fractional or exponential part will always be
996	represented as numeric (floating point) values, possibly at a loss of	1002	represented as numeric (floating point) values, possibly at a loss of
997	precision (in which case you might lose perfect roundtripping ability, but	1003	precision (in which case you might lose perfect roundtripping ability, but
998	the JSON number will still be re-encoded as a JSON number).	1004	the JSON number will still be re-encoded as a JSON number).
999		1005
1000	Note that precision is not accuracy - binary floating point values cannot	1006	Note that precision is not accuracy - binary floating point values cannot
1001	represent most decimal fractions exactly, and when converting from and to	1007	represent most decimal fractions exactly, and when converting from and to
1002	floating point, JSON::XS only guarantees precision up to but not including	1008	floating point, JSON::XS only guarantees precision up to but not including
1003	the leats significant bit.	1009	the least significant bit.
1004		1010
1005	=item true, false	1011	=item true, false
1006		1012
1007	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,	1013	These JSON atoms become C<Types::Serialiser::true> and
1008	respectively. They are overloaded to act almost exactly like the numbers	1014	C<Types::Serialiser::false>, respectively. They are overloaded to act
1009	C<1> and C<0>. You can check whether a scalar is a JSON boolean by using	1015	almost exactly like the numbers C<1> and C<0>. You can check whether
1010	the C<JSON::XS::is_bool> function.	1016	a scalar is a JSON boolean by using the C<Types::Serialiser::is_bool>
		1017	function (after C<use Types::Serialier>, of course).
1011		1018
1012	=item null	1019	=item null
1013		1020
1014	A JSON null atom becomes C<undef> in Perl.	1021	A JSON null atom becomes C<undef> in Perl.
		1022
		1023	=item shell-style comments (C<< # I<text> >>)
		1024
		1025	As a nonstandard extension to the JSON syntax that is enabled by the
		1026	C<relaxed> setting, shell-style comments are allowed. They can start
		1027	anywhere outside strings and go till the end of the line.
		1028
		1029	=item tagged values (C<< (I<tag>)I<value> >>).
		1030
		1031	Another nonstandard extension to the JSON syntax, enabled with the
		1032	C<allow_tags> setting, are tagged values. In this implementation, the
		1033	I<tag> must be a perl package/class name encoded as a JSON string, and the
		1034	I<value> must be a JSON array encoding optional constructor arguments.
		1035
		1036	See L<OBJECT SERIALISATION>, below, for details.
1015		1037
1016	=back	1038	=back
1017		1039
1018		1040
1019	=head2 PERL -> JSON	1041	=head2 PERL -> JSON
…		…
1024		1046
1025	=over 4	1047	=over 4
1026		1048
1027	=item hash references	1049	=item hash references
1028		1050
1029	Perl hash references become JSON objects. As there is no inherent ordering	1051	Perl hash references become JSON objects. As there is no inherent
1030	in hash keys (or JSON objects), they will usually be encoded in a	1052	ordering in hash keys (or JSON objects), they will usually be encoded
1031	pseudo-random order that can change between runs of the same program but	1053	in a pseudo-random order. JSON::XS can optionally sort the hash keys
1032	stays generally the same within a single run of a program. JSON::XS can	1054	(determined by the I<canonical> flag), so the same datastructure will
1033	optionally sort the hash keys (determined by the I<canonical> flag), so	1055	serialise to the same JSON text (given same settings and version of
1034	the same datastructure will serialise to the same JSON text (given same	1056	JSON::XS), but this incurs a runtime overhead and is only rarely useful,
1035	settings and version of JSON::XS), but this incurs a runtime overhead	1057	e.g. when you want to compare some JSON text against another for equality.
1036	and is only rarely useful, e.g. when you want to compare some JSON text
1037	against another for equality.
1038		1058
1039	=item array references	1059	=item array references
1040		1060
1041	Perl array references become JSON arrays.	1061	Perl array references become JSON arrays.
1042		1062
1043	=item other references	1063	=item other references
1044		1064
1045	Other unblessed references are generally not allowed and will cause an	1065	Other unblessed references are generally not allowed and will cause an
1046	exception to be thrown, except for references to the integers C<0> and	1066	exception to be thrown, except for references to the integers C<0> and
1047	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can	1067	C<1>, which get turned into C<false> and C<true> atoms in JSON.
1048	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
1049		1068
		1069	Since C<JSON::XS> uses the boolean model from L<Types::Serialiser>, you
		1070	can also C<use Types::Serialiser> and then use C<Types::Serialiser::false>
		1071	and C<Types::Serialiser::true> to improve readability.
		1072
		1073	use Types::Serialiser;
1050	encode_json [\0, JSON::XS::true] # yields [false,true]	1074	encode_json [\0, Types::Serialiser::true] # yields [false,true]
1051		1075
1052	=item JSON::XS::true, JSON::XS::false	1076	=item Types::Serialiser::true, Types::Serialiser::false
1053		1077
1054	These special values become JSON true and JSON false values,	1078	These special values from the L<Types::Serialiser> module become JSON true
1055	respectively. You can also use C<\1> and C<\0> directly if you want.	1079	and JSON false values, respectively. You can also use C<\1> and C<\0>
		1080	directly if you want.
1056		1081
1057	=item blessed objects	1082	=item blessed objects
1058		1083
1059	Blessed objects are not directly representable in JSON. See the	1084	Blessed objects are not directly representable in JSON, but C<JSON::XS>
1060	C<allow_blessed> and C<convert_blessed> methods on various options on	1085	allows various ways of handling objects. See L<OBJECT SERIALISATION>,
1061	how to deal with this: basically, you can choose between throwing an	1086	below, for details.
1062	exception, encoding the reference as if it weren't blessed, or provide
1063	your own serialiser method.
1064		1087
1065	=item simple scalars	1088	=item simple scalars
1066		1089
1067	Simple Perl scalars (any scalar that is not a reference) are the most	1090	Simple Perl scalars (any scalar that is not a reference) are the most
1068	difficult objects to encode: JSON::XS will encode undefined scalars as	1091	difficult objects to encode: JSON::XS will encode undefined scalars as
…		…
1105	infinities or NaN's - these cannot be represented in JSON, and it is an	1128	infinities or NaN's - these cannot be represented in JSON, and it is an
1106	error to pass those in.	1129	error to pass those in.
1107		1130
1108	=back	1131	=back
1109		1132
		1133	=head2 OBJECT SERIALISATION
		1134
		1135	As JSON cannot directly represent Perl objects, you have to choose between
		1136	a pure JSON representation (without the ability to deserialise the object
		1137	automatically again), and a nonstandard extension to the JSON syntax,
		1138	tagged values.
		1139
		1140	=head3 SERIALISATION
		1141
		1142	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
		1144	used in this order:
		1145
		1146	=over 4
		1147
		1148	=item 1. C<allow_tags> is enabled and the object has a C<FREEZE> method.
		1149
		1150	In this case, C<JSON::XS> uses the L<Types::Serialiser> object
		1151	serialisation protocol to create a tagged JSON value, using a nonstandard
		1152	extension to the JSON syntax.
		1153
		1154	This works by invoking the C<FREEZE> method on the object, with the first
		1155	argument being the object to serialise, and the second argument being the
		1156	constant string C<JSON> to distinguish it from other serialisers.
		1157
		1158	The C<FREEZE> method can return any number of values (i.e. zero or
		1159	more). These values and the paclkage/classname of the object will then be
		1160	encoded as a tagged JSON value in the following format:
		1161
		1162	("classname")[FREEZE return values...]
		1163
		1164	e.g.:
		1165
		1166	("URI")["http://www.google.com/"]
		1167	("MyDate")[2013,10,29]
		1168	("ImageData::JPEG")["Z3...VlCg=="]
		1169
		1170	For example, the hypothetical C<My::Object> C<FREEZE> method might use the
		1171	objects C<type> and C<id> members to encode the object:
		1172
		1173	sub My::Object::FREEZE {
		1174	my ($self, $serialiser) = @_;
		1175
		1176	($self->{type}, $self->{id})
		1177	}
		1178
		1179	=item 2. C<convert_blessed> is enabled and the object has a C<TO_JSON> method.
		1180
		1181	In this case, the C<TO_JSON> method of the object is invoked in scalar
		1182	context. It must return a single scalar that can be directly encoded into
		1183	JSON. This scalar replaces the object in the JSON text.
		1184
		1185	For example, the following C<TO_JSON> method will convert all L<URI>
		1186	objects to JSON strings when serialised. The fatc that these values
		1187	originally were L<URI> objects is lost.
		1188
		1189	sub URI::TO_JSON {
		1190	my ($uri) = @_;
		1191	$uri->as_string
		1192	}
		1193
		1194	=item 3. C<allow_blessed> is enabled.
		1195
		1196	The object will be serialised as a JSON null value.
		1197
		1198	=item 4. none of the above
		1199
		1200	If none of the settings are enabled or the respective methods are missing,
		1201	C<JSON::XS> throws an exception.
		1202
		1203	=back
		1204
		1205	=head3 DESERIALISATION
		1206
		1207	For deserialisation there are only two cases to consider: either
		1208	nonstandard tagging was used, in which case C<allow_tags> decides,
		1209	or objects cannot be automatically be deserialised, in which
		1210	case you can use postprocessing or the C<filter_json_object> or
		1211	C<filter_json_single_key_object> callbacks to get some real objects our of
		1212	your JSON.
		1213
		1214	This section only considers the tagged value case: I a tagged JSON object
		1215	is encountered during decoding and C<allow_tags> is disabled, a parse
		1216	error will result (as if tagged values were not part of the grammar).
		1217
		1218	If C<allow_tags> is enabled, C<JSON::XS> will look up the C<THAW> method
		1219	of the package/classname used during serialisation (it will not attempt
		1220	to load the package as a Perl module). If there is no such method, the
		1221	decoding will fail with an error.
		1222
		1223	Otherwise, the C<THAW> method is invoked with the classname as first
		1224	argument, the constant string C<JSON> as second argument, and all the
		1225	values from the JSON array (the values originally returned by the
		1226	C<FREEZE> method) as remaining arguments.
		1227
		1228	The method must then return the object. While technically you can return
		1229	any Perl scalar, you might have to enable the C<enable_nonref> setting to
		1230	make that work in all cases, so better return an actual blessed reference.
		1231
		1232	As an example, let's implement a C<THAW> function that regenerates the
		1233	C<My::Object> from the C<FREEZE> example earlier:
		1234
		1235	sub My::Object::THAW {
		1236	my ($class, $serialiser, $type, $id) = @_;
		1237
		1238	$class->new (type => $type, id => $id)
		1239	}
		1240
1110		1241
1111	=head1 ENCODING/CODESET FLAG NOTES	1242	=head1 ENCODING/CODESET FLAG NOTES
1112		1243
1113	The interested reader might have seen a number of flags that signify	1244	The interested reader might have seen a number of flags that signify
1114	encodings or codesets - C<utf8>, C<latin1> and C<ascii>. There seems to be	1245	encodings or codesets - C<utf8>, C<latin1> and C<ascii>. There seems to be
…		…
1138	=item C<utf8> flag disabled	1269	=item C<utf8> flag disabled
1139		1270
1140	When C<utf8> is disabled (the default), then C<encode>/C<decode> generate	1271	When C<utf8> is disabled (the default), then C<encode>/C<decode> generate
1141	and expect Unicode strings, that is, characters with high ordinal Unicode	1272	and expect Unicode strings, that is, characters with high ordinal Unicode
1142	values (> 255) will be encoded as such characters, and likewise such	1273	values (> 255) will be encoded as such characters, and likewise such
1143	characters are decoded as-is, no canges to them will be done, except	1274	characters are decoded as-is, no changes to them will be done, except
1144	"(re-)interpreting" them as Unicode codepoints or Unicode characters,	1275	"(re-)interpreting" them as Unicode codepoints or Unicode characters,
1145	respectively (to Perl, these are the same thing in strings unless you do	1276	respectively (to Perl, these are the same thing in strings unless you do
1146	funny/weird/dumb stuff).	1277	funny/weird/dumb stuff).
1147		1278
1148	This is useful when you want to do the encoding yourself (e.g. when you	1279	This is useful when you want to do the encoding yourself (e.g. when you
…		…
1264	output for these property strings, e.g.:	1395	output for these property strings, e.g.:
1265		1396
1266	$json =~ s/"__proto__"\s*:/"__proto__renamed":/g;	1397	$json =~ s/"__proto__"\s*:/"__proto__renamed":/g;
1267		1398
1268	This works because C<__proto__> is not valid outside of strings, so every	1399	This works because C<__proto__> is not valid outside of strings, so every
1269	occurence of C<"__proto__"\s*:> must be a string used as property name.	1400	occurrence of C<"__proto__"\s*:> must be a string used as property name.
1270		1401
1271	If you know of other incompatibilities, please let me know.	1402	If you know of other incompatibilities, please let me know.
1272		1403
1273		1404
1274	=head2 JSON and YAML	1405	=head2 JSON and YAML
…		…
1436	are browser design bugs, but it is still you who will have to deal with	1567	are browser design bugs, but it is still you who will have to deal with
1437	it, as major browser developers care only for features, not about getting	1568	it, as major browser developers care only for features, not about getting
1438	security right).	1569	security right).
1439		1570
1440		1571
		1572	=head1 "OLD" VS. "NEW" JSON (RFC 4627 VS. RFC 7159)
		1573
		1574	TL;DR: Due to security concerns, JSON::XS will not allow scalar data in
		1575	JSON texts by default - you need to create your own JSON::XS object and
		1576	enable C<allow_nonref>:
		1577
		1578
		1579	my $json = JSON::XS->new->allow_nonref;
		1580
		1581	$text = $json->encode ($data);
		1582	$data = $json->decode ($text);
		1583
		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
		1590	The biggest difference between thed original JSON and the new JSON is that
		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
		1596	For example, imagine you have two banks communicating, and on one side,
		1597	trhe JSON coder gets upgraded. Two messages, such as C<10> and C<1000>
		1598	might then be confused to mean C<101000>, something that couldn't happen
		1599	in the original JSON, because niether of these messages would be valid
		1600	JSON.
		1601
		1602	If one side accepts these messages, then an upgrade in the coder on either
		1603	side could result in this becoming exploitable.
		1604
		1605	This module has always allowed these messages as an optional extension, by
		1606	default disabled. The security concerns are the reason why the default is
		1607	still disabled, but future versions might/will likely upgrade to the newer
		1608	RFC as default format, so you are advised to check your implementation
		1609	and/or override the default with C<< ->allow_nonref (0) >> to ensure that
		1610	future versions are safe.
		1611
		1612
		1613	=head1 INTEROPERABILITY WITH OTHER MODULES
		1614
		1615	C<JSON::XS> uses the L<Types::Serialiser> module to provide boolean
		1616	constants. That means that the JSON true and false values will be
		1617	comaptible to true and false values of other modules that do the same,
		1618	such as L<JSON::PP> and L<CBOR::XS>.
		1619
		1620
		1621	=head1 INTEROPERABILITY WITH OTHER JSON DECODERS
		1622
		1623	As long as you only serialise data that can be directly expressed in JSON,
		1624	C<JSON::XS> is incapable of generating invalid JSON output (modulo bugs,
		1625	but C<JSON::XS> has found more bugs in the official JSON testsuite (1)
		1626	than the official JSON testsuite has found in C<JSON::XS> (0)).
		1627
		1628	When you have trouble decoding JSON generated by this module using other
		1629	decoders, then it is very likely that you have an encoding mismatch or the
		1630	other decoder is broken.
		1631
		1632	When decoding, C<JSON::XS> is strict by default and will likely catch all
		1633	errors. There are currently two settings that change this: C<relaxed>
		1634	makes C<JSON::XS> accept (but not generate) some non-standard extensions,
		1635	and C<allow_tags> will allow you to encode and decode Perl objects, at the
		1636	cost of not outputting valid JSON anymore.
		1637
		1638	=head2 TAGGED VALUE SYNTAX AND STANDARD JSON EN/DECODERS
		1639
		1640	When you use C<allow_tags> to use the extended (and also nonstandard and
		1641	invalid) JSON syntax for serialised objects, and you still want to decode
		1642	the generated When you want to serialise objects, you can run a regex
		1643	to replace the tagged syntax by standard JSON arrays (it only works for
		1644	"normal" package names without comma, newlines or single colons). First,
		1645	the readable Perl version:
		1646
		1647	# if your FREEZE methods return no values, you need this replace first:
		1648	$json =~ s/$ \s* (" (?: [^\\":,]+\|\\.\|::)* ") \s* $ \s* \[\s*\]/[$1]/gx;
		1649
		1650	# this works for non-empty constructor arg lists:
		1651	$json =~ s/$ \s* (" (?: [^\\":,]+\|\\.\|::)* ") \s* $ \s* \[/[$1,/gx;
		1652
		1653	And here is a less readable version that is easy to adapt to other
		1654	languages:
		1655
		1656	$json =~ s/$\s("([^\\":,]+\|\\.\|::)")\s$\s\[/[$1,/g;
		1657
		1658	Here is an ECMAScript version (same regex):
		1659
		1660	json = json.replace (/$\s("([^\\":,]+\|\\.\|::)")\s$\s\[/g, "[$1,");
		1661
		1662	Since this syntax converts to standard JSON arrays, it might be hard to
		1663	distinguish serialised objects from normal arrays. You can prepend a
		1664	"magic number" as first array element to reduce chances of a collision:
		1665
		1666	$json =~ s/$\s("([^\\":,]+\|\\.\|::)")\s$\s\[/["XU1peReLzT4ggEllLanBYq4G9VzliwKF",$1,/g;
		1667
		1668	And after decoding the JSON text, you could walk the data
		1669	structure looking for arrays with a first element of
		1670	C<XU1peReLzT4ggEllLanBYq4G9VzliwKF>.
		1671
		1672	The same approach can be used to create the tagged format with another
		1673	encoder. First, you create an array with the magic string as first member,
		1674	the classname as second, and constructor arguments last, encode it as part
		1675	of your JSON structure, and then:
		1676
		1677	$json =~ s/\[\s"XU1peReLzT4ggEllLanBYq4G9VzliwKF"\s,\s("([^\\":,]+\|\\.\|::)")\s*,/($1)[/g;
		1678
		1679	Again, this has some limitations - the magic string must not be encoded
		1680	with character escapes, and the constructor arguments must be non-empty.
		1681
		1682
		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
1441	=head1 THREADS	1701	=head1 (I-)THREADS
1442		1702
1443	This module is I<not> guaranteed to be thread safe and there are no	1703	This module is I<not> guaranteed to be ithread (or MULTIPLICITY-) safe
1444	plans to change this until Perl gets thread support (as opposed to the	1704	and there are no plans to change this. Note that perl's builtin so-called
1445	horribly slow so-called "threads" which are simply slow and bloated	1705	theeads/ithreads are officially deprecated and should not be used.
1446	process simulations - use fork, it's I<much> faster, cheaper, better).
1447
1448	(It might actually work, but you have been warned).
1449		1706
1450		1707
1451	=head1 THE PERILS OF SETLOCALE	1708	=head1 THE PERILS OF SETLOCALE
1452		1709
1453	Sometimes people avoid the Perl locale support and directly call the	1710	Sometimes people avoid the Perl locale support and directly call the
1454	system's setlocale function with C<LC_ALL>.	1711	system's setlocale function with C<LC_ALL>.
1455		1712
1456	This breaks both perl and modules such as JSON::XS, as stringification of	1713	This breaks both perl and modules such as JSON::XS, as stringification of
1457	numbers no longer works correcly (e.g. C<$x = 0.1; print "$x"+1> might	1714	numbers no longer works correctly (e.g. C<$x = 0.1; print "$x"+1> might
1458	print C<1>, and JSON::XS might output illegal JSON as JSON::XS relies on	1715	print C<1>, and JSON::XS might output illegal JSON as JSON::XS relies on
1459	perl to stringify numbers).	1716	perl to stringify numbers).
1460		1717
1461	The solution is simple: don't call C<setlocale>, or use it for only those	1718	The solution is simple: don't call C<setlocale>, or use it for only those
1462	categories you need, such as C<LC_MESSAGES> or C<LC_CTYPE>.	1719	categories you need, such as C<LC_MESSAGES> or C<LC_CTYPE>.
…		…
1475	Please refrain from using rt.cpan.org or any other bug reporting	1732	Please refrain from using rt.cpan.org or any other bug reporting
1476	service. I put the contact address into my modules for a reason.	1733	service. I put the contact address into my modules for a reason.
1477		1734
1478	=cut	1735	=cut
1479		1736
1480	our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };	1737	BEGIN {
1481	our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };	1738	*true = \$Types::Serialiser::true;
		1739	*true = \&Types::Serialiser::true;
		1740	*false = \$Types::Serialiser::false;
		1741	*false = \&Types::Serialiser::false;
		1742	*is_bool = \&Types::Serialiser::is_bool;
1482		1743
1483	sub true() { $true }	1744	JSON::XS::Boolean:: = Types::Serialiser::Boolean::;
1484	sub false() { $false }
1485
1486	sub is_bool($) {
1487	UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
1488	# or UNIVERSAL::isa $_[0], "JSON::Literal"
1489	}	1745	}
1490		1746
1491	XSLoader::load "JSON::XS", $VERSION;	1747	XSLoader::load "JSON::XS", $VERSION;
1492
1493	package JSON::XS::Boolean;
1494
1495	use overload
1496	"0+" => sub { ${$_[0]} },
1497	"++" => sub { $_[0] = ${$_[0]} + 1 },
1498	"--" => sub { $_[0] = ${$_[0]} - 1 },
1499	fallback => 1;
1500
1501	1;
1502		1748
1503	=head1 SEE ALSO	1749	=head1 SEE ALSO
1504		1750
1505	The F<json_xs> command line utility for quick experiments.	1751	The F<json_xs> command line utility for quick experiments.
1506		1752
…		…
1509	Marc Lehmann <schmorp@schmorp.de>	1755	Marc Lehmann <schmorp@schmorp.de>
1510	http://home.schmorp.de/	1756	http://home.schmorp.de/
1511		1757
1512	=cut	1758	=cut
1513		1759
		1760	1
		1761

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Comparing JSON-XS/XS.pm (file contents): Revision 1.139 by root, Thu May 23 09:31:32 2013 UTC vs. Revision 1.164 by root, Thu Aug 17 03:47:54 2017 UTC

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Comparing JSON-XS/XS.pm (file contents):
Revision 1.139 by root, Thu May 23 09:31:32 2013 UTC vs.
Revision 1.164 by root, Thu Aug 17 03:47:54 2017 UTC