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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.128 by root, Tue Jan 19 00:31:13 2010 UTC vs.
Revision 1.150 by root, Tue Oct 29 00:48:07 2013 UTC

…		…
64	so, and even documents what "correct" means.	64	so, and even documents what "correct" means.
65		65
66	=item * round-trip integrity	66	=item * round-trip integrity
67		67
68	When you serialise a perl data structure using only data types supported	68	When you serialise a perl data structure using only data types supported
69	by JSON, the deserialised data structure is identical on the Perl level.	69	by JSON and Perl, the deserialised data structure is identical on the Perl
70	(e.g. the string "2.0" doesn't suddenly become "2" just because it looks	70	level. (e.g. the string "2.0" doesn't suddenly become "2" just because
71	like a number). There minor I<are> exceptions to this, read the MAPPING	71	it looks like a number). There I<are> minor exceptions to this, read the
72	section below to learn about those.	72	MAPPING section below to learn about those.
73		73
74	=item * strict checking of JSON correctness	74	=item * strict checking of JSON correctness
75		75
76	There is no guessing, no generating of illegal JSON texts by default,	76	There is no guessing, no generating of illegal JSON texts by default,
77	and only JSON is accepted as input by default (the latter is a security	77	and only JSON is accepted as input by default (the latter is a security
…		…
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 = '2.28';	106	our $VERSION = '3.0';
107	our @ISA = qw(Exporter);	107	our @ISA = qw(Exporter);
108		108
109	our @EXPORT = qw(encode_json decode_json to_json from_json);	109	our @EXPORT = qw(encode_json decode_json);
110
111	sub to_json($) {
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 $scalar
155
156	Returns true if the passed scalar represents either JSON::XS::true or
157	JSON::XS::false, two constants that act like C<1> and C<0>, respectively
158	and are used to represent JSON C<true> and C<false> values in Perl.
159
160	See MAPPING, below, for more information on how JSON values are mapped to
161	Perl.
162		145
163	=back	146	=back
164		147
165		148
166	=head1 A FEW NOTES ON UNICODE AND PERL	149	=head1 A FEW NOTES ON UNICODE AND PERL
…		…
432	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects	415	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
433	by sorting their keys. This is adding a comparatively high overhead.	416	by sorting their keys. This is adding a comparatively high overhead.
434		417
435	If C<$enable> is false, then the C<encode> method will output key-value	418	If C<$enable> is false, then the C<encode> method will output key-value
436	pairs in the order Perl stores them (which will likely change between runs	419	pairs in the order Perl stores them (which will likely change between runs
437	of the same script).	420	of the same script, and can change even within the same run from 5.18
		421	onwards).
438		422
439	This option is useful if you want the same data structure to be encoded as	423	This option is useful if you want the same data structure to be encoded as
440	the same JSON text (given the same overall settings). If it is disabled,	424	the same JSON text (given the same overall settings). If it is disabled,
441	the same hash might be encoded differently even if contains the same data,	425	the same hash might be encoded differently even if contains the same data,
442	as key-value pairs have no inherent ordering in Perl.	426	as key-value pairs have no inherent ordering in Perl.
…		…
483		467
484	=item $json = $json->allow_blessed ([$enable])	468	=item $json = $json->allow_blessed ([$enable])
485		469
486	=item $enabled = $json->get_allow_blessed	470	=item $enabled = $json->get_allow_blessed
487		471
		472	See L<OBJECT SERIALISATION> for details.
		473
488	If C<$enable> is true (or missing), then the C<encode> method will not	474	If C<$enable> is true (or missing), then the C<encode> method will not
489	barf when it encounters a blessed reference. Instead, the value of the	475	barf when it encounters a blessed reference that it cannot convert
490	B<convert_blessed> option will decide whether C<null> (C<convert_blessed>	476	otherwise. Instead, a JSON C<null> value is encoded instead of the object.
491	disabled or no C<TO_JSON> method found) or a representation of the
492	object (C<convert_blessed> enabled and C<TO_JSON> method found) is being
493	encoded. Has no effect on C<decode>.
494		477
495	If C<$enable> is false (the default), then C<encode> will throw an	478	If C<$enable> is false (the default), then C<encode> will throw an
496	exception when it encounters a blessed object.	479	exception when it encounters a blessed object that it cannot convert
		480	otherwise.
		481
		482	This setting has no effect on C<decode>.
497		483
498	=item $json = $json->convert_blessed ([$enable])	484	=item $json = $json->convert_blessed ([$enable])
499		485
500	=item $enabled = $json->get_convert_blessed	486	=item $enabled = $json->get_convert_blessed
		487
		488	See L<OBJECT SERIALISATION> for details.
501		489
502	If C<$enable> is true (or missing), then C<encode>, upon encountering a	490	If C<$enable> is true (or missing), then C<encode>, upon encountering a
503	blessed object, will check for the availability of the C<TO_JSON> method	491	blessed object, will check for the availability of the C<TO_JSON> method
504	on the object's class. If found, it will be called in scalar context	492	on the object's class. If found, it will be called in scalar context and
505	and the resulting scalar will be encoded instead of the object. If no	493	the resulting scalar will be encoded instead of the object.
506	C<TO_JSON> method is found, the value of C<allow_blessed> will decide what
507	to do.
508		494
509	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>	495	The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
510	returns other blessed objects, those will be handled in the same	496	returns other blessed objects, those will be handled in the same
511	way. C<TO_JSON> must take care of not causing an endless recursion cycle	497	way. C<TO_JSON> must take care of not causing an endless recursion cycle
512	(== crash) in this case. The name of C<TO_JSON> was chosen because other	498	(== crash) in this case. The name of C<TO_JSON> was chosen because other
513	methods called by the Perl core (== not by the user of the object) are	499	methods called by the Perl core (== not by the user of the object) are
514	usually in upper case letters and to avoid collisions with any C<to_json>	500	usually in upper case letters and to avoid collisions with any C<to_json>
515	function or method.	501	function or method.
516		502
517	This setting does not yet influence C<decode> in any way, but in the	503	If C<$enable> is false (the default), then C<encode> will not consider
518	future, global hooks might get installed that influence C<decode> and are	504	this type of conversion.
519	enabled by this setting.
520		505
521	If C<$enable> is false, then the C<allow_blessed> setting will decide what	506	This setting has no effect on C<decode>.
522	to do when a blessed object is found.	507
		508	=item $json = $json->allow_tags ([$enable])
		509
		510	=item $enabled = $json->allow_tags
		511
		512	See L<OBJECT SERIALISATION> for details.
		513
		514	If C<$enable> is true (or missing), then C<encode>, upon encountering a
		515	blessed object, will check for the availability of the C<FREEZE> method on
		516	the object's class. If found, it will be used to serialise the object into
		517	a nonstandard tagged JSON value (that JSON decoders cannot decode).
		518
		519	It also causes C<decode> to parse such tagged JSON values and deserialise
		520	them via a call to the C<THAW> method.
		521
		522	If C<$enable> is false (the default), then C<encode> will not consider
		523	this type of conversion, and tagged JSON values will cause a parse error
		524	in C<decode>, as if tags were not part of the grammar.
523		525
524	=item $json = $json->filter_json_object ([$coderef->($hashref)])	526	=item $json = $json->filter_json_object ([$coderef->($hashref)])
525		527
526	When C<$coderef> is specified, it will be called from C<decode> each	528	When C<$coderef> is specified, it will be called from C<decode> each
527	time it decodes a JSON object. The only argument is a reference to the	529	time it decodes a JSON object. The only argument is a reference to the
…		…
666		668
667	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	669	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
668		670
669	=item $json_text = $json->encode ($perl_scalar)	671	=item $json_text = $json->encode ($perl_scalar)
670		672
671	Converts the given Perl data structure (a simple scalar or a reference	673	Converts the given Perl value or data structure to its JSON
672	to a hash or array) to its JSON representation. Simple scalars will be	674	representation. Croaks on error.
673	converted into JSON string or number sequences, while references to arrays
674	become JSON arrays and references to hashes become JSON objects. Undefined
675	Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>
676	nor C<false> values will be generated.
677		675
678	=item $perl_scalar = $json->decode ($json_text)	676	=item $perl_scalar = $json->decode ($json_text)
679		677
680	The opposite of C<encode>: expects a JSON text and tries to parse it,	678	The opposite of C<encode>: expects a JSON text and tries to parse it,
681	returning the resulting simple scalar or reference. Croaks on error.	679	returning the resulting simple scalar or reference. Croaks on error.
682
683	JSON numbers and strings become simple Perl scalars. JSON arrays become
684	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
685	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
686		680
687	=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)	681	=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
688		682
689	This works like the C<decode> method, but instead of raising an exception	683	This works like the C<decode> method, but instead of raising an exception
690	when there is trailing garbage after the first JSON object, it will	684	when there is trailing garbage after the first JSON object, it will
691	silently stop parsing there and return the number of characters consumed	685	silently stop parsing there and return the number of characters consumed
692	so far.	686	so far.
693		687
694	This is useful if your JSON texts are not delimited by an outer protocol	688	This is useful if your JSON texts are not delimited by an outer protocol
695	(which is not the brightest thing to do in the first place) and you need
696	to know where the JSON text ends.	689	and you need to know where the JSON text ends.
697		690
698	JSON::XS->new->decode_prefix ("[1] the tail")	691	JSON::XS->new->decode_prefix ("[1] the tail")
699	=> ([], 3)	692	=> ([], 3)
700		693
701	=back	694	=back
…		…
713	calls).	706	calls).
714		707
715	JSON::XS will only attempt to parse the JSON text once it is sure it	708	JSON::XS will only attempt to parse the JSON text once it is sure it
716	has enough text to get a decisive result, using a very simple but	709	has enough text to get a decisive result, using a very simple but
717	truly incremental parser. This means that it sometimes won't stop as	710	truly incremental parser. This means that it sometimes won't stop as
718	early as the full parser, for example, it doesn't detect parenthese	711	early as the full parser, for example, it doesn't detect mismatched
719	mismatches. The only thing it guarantees is that it starts decoding as	712	parentheses. The only thing it guarantees is that it starts decoding as
720	soon as a syntactically valid JSON text has been seen. This means you need	713	soon as a syntactically valid JSON text has been seen. This means you need
721	to set resource limits (e.g. C<max_size>) to ensure the parser will stop	714	to set resource limits (e.g. C<max_size>) to ensure the parser will stop
722	parsing in the presence if syntax errors.	715	parsing in the presence if syntax errors.
723		716
724	The following methods implement this incremental parser.	717	The following methods implement this incremental parser.
…		…
740		733
741	If the method is called in scalar context, then it will try to extract	734	If the method is called in scalar context, then it will try to extract
742	exactly I<one> JSON object. If that is successful, it will return this	735	exactly I<one> JSON object. If that is successful, it will return this
743	object, otherwise it will return C<undef>. If there is a parse error,	736	object, otherwise it will return C<undef>. If there is a parse error,
744	this method will croak just as C<decode> would do (one can then use	737	this method will croak just as C<decode> would do (one can then use
745	C<incr_skip> to skip the errornous part). This is the most common way of	738	C<incr_skip> to skip the erroneous part). This is the most common way of
746	using the method.	739	using the method.
747		740
748	And finally, in list context, it will try to extract as many objects	741	And finally, in list context, it will try to extract as many objects
749	from the stream as it can find and return them, or the empty list	742	from the stream as it can find and return them, or the empty list
750	otherwise. For this to work, there must be no separators between the JSON	743	otherwise. For this to work, there must be no separators between the JSON
751	objects or arrays, instead they must be concatenated back-to-back. If	744	objects or arrays, instead they must be concatenated back-to-back. If
752	an error occurs, an exception will be raised as in the scalar context	745	an error occurs, an exception will be raised as in the scalar context
753	case. Note that in this case, any previously-parsed JSON texts will be	746	case. Note that in this case, any previously-parsed JSON texts will be
754	lost.	747	lost.
755		748
		749	Example: Parse some JSON arrays/objects in a given string and return
		750	them.
		751
		752	my @objs = JSON::XS->new->incr_parse ("[5][7][1,2]");
		753
756	=item $lvalue_string = $json->incr_text	754	=item $lvalue_string = $json->incr_text
757		755
758	This method returns the currently stored JSON fragment as an lvalue, that	756	This method returns the currently stored JSON fragment as an lvalue, that
759	is, you can manipulate it. This I<only> works when a preceding call to	757	is, you can manipulate it. This I<only> works when a preceding call to
760	C<incr_parse> in I<scalar context> successfully returned an object. Under	758	C<incr_parse> in I<scalar context> successfully returned an object. Under
…		…
774	C<incr_parse> died, in which case the input buffer and incremental parser	772	C<incr_parse> died, in which case the input buffer and incremental parser
775	state is left unchanged, to skip the text parsed so far and to reset the	773	state is left unchanged, to skip the text parsed so far and to reset the
776	parse state.	774	parse state.
777		775
778	The difference to C<incr_reset> is that only text until the parse error	776	The difference to C<incr_reset> is that only text until the parse error
779	occured is removed.	777	occurred is removed.
780		778
781	=item $json->incr_reset	779	=item $json->incr_reset
782		780
783	This completely resets the incremental parser, that is, after this call,	781	This completely resets the incremental parser, that is, after this call,
784	it will be as if the parser had never parsed anything.	782	it will be as if the parser had never parsed anything.
…		…
790	=back	788	=back
791		789
792	=head2 LIMITATIONS	790	=head2 LIMITATIONS
793		791
794	All options that affect decoding are supported, except	792	All options that affect decoding are supported, except
795	C<allow_nonref>. The reason for this is that it cannot be made to	793	C<allow_nonref>. The reason for this is that it cannot be made to work
796	work sensibly: JSON objects and arrays are self-delimited, i.e. you can concatenate	794	sensibly: JSON objects and arrays are self-delimited, i.e. you can
797	them back to back and still decode them perfectly. This does not hold true	795	concatenate them back to back and still decode them perfectly. This does
798	for JSON numbers, however.	796	not hold true for JSON numbers, however.
799		797
800	For example, is the string C<1> a single JSON number, or is it simply the	798	For example, is the string C<1> a single JSON number, or is it simply the
801	start of C<12>? Or is C<12> a single JSON number, or the concatenation	799	start of C<12>? Or is C<12> a single JSON number, or the concatenation
802	of C<1> and C<2>? In neither case you can tell, and this is why JSON::XS	800	of C<1> and C<2>? In neither case you can tell, and this is why JSON::XS
803	takes the conservative route and disallows this case.	801	takes the conservative route and disallows this case.
…		…
982	If the number consists of digits only, JSON::XS will try to represent	980	If the number consists of digits only, JSON::XS will try to represent
983	it as an integer value. If that fails, it will try to represent it as	981	it as an integer value. If that fails, it will try to represent it as
984	a numeric (floating point) value if that is possible without loss of	982	a numeric (floating point) value if that is possible without loss of
985	precision. Otherwise it will preserve the number as a string value (in	983	precision. Otherwise it will preserve the number as a string value (in
986	which case you lose roundtripping ability, as the JSON number will be	984	which case you lose roundtripping ability, as the JSON number will be
987	re-encoded toa JSON string).	985	re-encoded to a JSON string).
988		986
989	Numbers containing a fractional or exponential part will always be	987	Numbers containing a fractional or exponential part will always be
990	represented as numeric (floating point) values, possibly at a loss of	988	represented as numeric (floating point) values, possibly at a loss of
991	precision (in which case you might lose perfect roundtripping ability, but	989	precision (in which case you might lose perfect roundtripping ability, but
992	the JSON number will still be re-encoded as a JSON number).	990	the JSON number will still be re-encoded as a JSON number).
993		991
		992	Note that precision is not accuracy - binary floating point values cannot
		993	represent most decimal fractions exactly, and when converting from and to
		994	floating point, JSON::XS only guarantees precision up to but not including
		995	the least significant bit.
		996
994	=item true, false	997	=item true, false
995		998
996	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,	999	These JSON atoms become C<Types::Serialiser::true> and
997	respectively. They are overloaded to act almost exactly like the numbers	1000	C<Types::Serialiser::false>, respectively. They are overloaded to act
998	C<1> and C<0>. You can check whether a scalar is a JSON boolean by using	1001	almost exactly like the numbers C<1> and C<0>. You can check whether
999	the C<JSON::XS::is_bool> function.	1002	a scalar is a JSON boolean by using the C<Types::Serialiser::is_bool>
		1003	function (after C<use Types::Serialier>, of course).
1000		1004
1001	=item null	1005	=item null
1002		1006
1003	A JSON null atom becomes C<undef> in Perl.	1007	A JSON null atom becomes C<undef> in Perl.
		1008
		1009	=item shell-style comments (C<< # I<text> >>)
		1010
		1011	As a nonstandard extension to the JSON syntax that is enabled by the
		1012	C<relaxed> setting, shell-style comments are allowed. They can start
		1013	anywhere outside strings and go till the end of the line.
		1014
		1015	=item tagged values (C<< (I<tag>)I<value> >>).
		1016
		1017	Another nonstandard extension to the JSON syntax, enabled with the
		1018	C<allow_tags> setting, are tagged values. In this implementation, the
		1019	I<tag> must be a perl package/class name encoded as a JSON string, and the
		1020	I<value> must be a JSON array encoding optional constructor arguments.
		1021
		1022	See L<OBJECT SERIALISATION>, below, for details.
1004		1023
1005	=back	1024	=back
1006		1025
1007		1026
1008	=head2 PERL -> JSON	1027	=head2 PERL -> JSON
…		…
1013		1032
1014	=over 4	1033	=over 4
1015		1034
1016	=item hash references	1035	=item hash references
1017		1036
1018	Perl hash references become JSON objects. As there is no inherent ordering	1037	Perl hash references become JSON objects. As there is no inherent
1019	in hash keys (or JSON objects), they will usually be encoded in a	1038	ordering in hash keys (or JSON objects), they will usually be encoded
1020	pseudo-random order that can change between runs of the same program but	1039	in a pseudo-random order. JSON::XS can optionally sort the hash keys
1021	stays generally the same within a single run of a program. JSON::XS can	1040	(determined by the I<canonical> flag), so the same datastructure will
1022	optionally sort the hash keys (determined by the I<canonical> flag), so	1041	serialise to the same JSON text (given same settings and version of
1023	the same datastructure will serialise to the same JSON text (given same	1042	JSON::XS), but this incurs a runtime overhead and is only rarely useful,
1024	settings and version of JSON::XS), but this incurs a runtime overhead	1043	e.g. when you want to compare some JSON text against another for equality.
1025	and is only rarely useful, e.g. when you want to compare some JSON text
1026	against another for equality.
1027		1044
1028	=item array references	1045	=item array references
1029		1046
1030	Perl array references become JSON arrays.	1047	Perl array references become JSON arrays.
1031		1048
1032	=item other references	1049	=item other references
1033		1050
1034	Other unblessed references are generally not allowed and will cause an	1051	Other unblessed references are generally not allowed and will cause an
1035	exception to be thrown, except for references to the integers C<0> and	1052	exception to be thrown, except for references to the integers C<0> and
1036	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can	1053	C<1>, which get turned into C<false> and C<true> atoms in JSON.
1037	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
1038		1054
		1055	Since C<JSON::XS> uses the boolean model from L<Types::Serialiser>, you
		1056	can also C<use Types::Serialiser> and then use C<Types::Serialiser::false>
		1057	and C<Types::Serialiser::true> to improve readability.
		1058
		1059	use Types::Serialiser;
1039	encode_json [\0, JSON::XS::true] # yields [false,true]	1060	encode_json [\0, Types::Serialiser::true] # yields [false,true]
1040		1061
1041	=item JSON::XS::true, JSON::XS::false	1062	=item Types::Serialiser::true, Types::Serialiser::false
1042		1063
1043	These special values become JSON true and JSON false values,	1064	These special values from the L<Types::Serialiser> module become JSON true
1044	respectively. You can also use C<\1> and C<\0> directly if you want.	1065	and JSON false values, respectively. You can also use C<\1> and C<\0>
		1066	directly if you want.
1045		1067
1046	=item blessed objects	1068	=item blessed objects
1047		1069
1048	Blessed objects are not directly representable in JSON. See the	1070	Blessed objects are not directly representable in JSON, but C<JSON::XS>
1049	C<allow_blessed> and C<convert_blessed> methods on various options on	1071	allows various ways of handling objects. See L<OBJECT SERIALISATION>,
1050	how to deal with this: basically, you can choose between throwing an	1072	below, for details.
1051	exception, encoding the reference as if it weren't blessed, or provide
1052	your own serialiser method.
1053		1073
1054	=item simple scalars	1074	=item simple scalars
1055		1075
1056	Simple Perl scalars (any scalar that is not a reference) are the most	1076	Simple Perl scalars (any scalar that is not a reference) are the most
1057	difficult objects to encode: JSON::XS will encode undefined scalars as	1077	difficult objects to encode: JSON::XS will encode undefined scalars as
…		…
1085		1105
1086	You can not currently force the type in other, less obscure, ways. Tell me	1106	You can not currently force the type in other, less obscure, ways. Tell me
1087	if you need this capability (but don't forget to explain why it's needed	1107	if you need this capability (but don't forget to explain why it's needed
1088	:).	1108	:).
1089		1109
		1110	Note that numerical precision has the same meaning as under Perl (so
		1111	binary to decimal conversion follows the same rules as in Perl, which
		1112	can differ to other languages). Also, your perl interpreter might expose
		1113	extensions to the floating point numbers of your platform, such as
		1114	infinities or NaN's - these cannot be represented in JSON, and it is an
		1115	error to pass those in.
		1116
1090	=back	1117	=back
		1118
		1119	=head2 OBJECT SERIALISATION
		1120
		1121	As JSON cannot directly represent Perl objects, you have to choose between
		1122	a pure JSON representation (without the ability to deserialise the object
		1123	automatically again), and a nonstandard extension to the JSON syntax,
		1124	tagged values.
		1125
		1126	=head3 SERIALISATION
		1127
		1128	What happens when C<JSON::XS> encounters a Perl object depends on the
		1129	C<allow_blessed>, C<convert_blessed> and C<allow_tags> settings, which are
		1130	used in this order:
		1131
		1132	=over 4
		1133
		1134	=item 1. C<allow_tags> is enabled and the object has a C<FREEZE> method.
		1135
		1136	In this case, C<JSON::XS> uses the L<Types::Serialiser> object
		1137	serialisation protocol to create a tagged JSON value, using a nonstandard
		1138	extension to the JSON syntax.
		1139
		1140	This works by invoking the C<FREEZE> method on the object, with the first
		1141	argument being the object to serialise, and the second argument being the
		1142	constant string C<JSON> to distinguish it from other serialisers.
		1143
		1144	The C<FREEZE> method can return any number of values (i.e. zero or
		1145	more). These values and the paclkage/classname of the object will then be
		1146	encoded as a tagged JSON value in the following format:
		1147
		1148	("classname")[FREEZE return values...]
		1149
		1150	e.g.:
		1151
		1152	("URI")["http://www.google.com/"]
		1153	("MyDate")[2013,10,29]
		1154	("ImageData::JPEG")["Z3...VlCg=="]
		1155
		1156	For example, the hypothetical C<My::Object> C<FREEZE> method might use the
		1157	objects C<type> and C<id> members to encode the object:
		1158
		1159	sub My::Object::FREEZE {
		1160	my ($self, $serialiser) = @_;
		1161
		1162	($self->{type}, $self->{id})
		1163	}
		1164
		1165	=item 2. C<convert_blessed> is enabled and the object has a C<TO_JSON> method.
		1166
		1167	In this case, the C<TO_JSON> method of the object is invoked in scalar
		1168	context. It must return a single scalar that can be directly encoded into
		1169	JSON. This scalar replaces the object in the JSON text.
		1170
		1171	For example, the following C<TO_JSON> method will convert all L<URI>
		1172	objects to JSON strings when serialised. The fatc that these values
		1173	originally were L<URI> objects is lost.
		1174
		1175	sub URI::TO_JSON {
		1176	my ($uri) = @_;
		1177	$uri->as_string
		1178	}
		1179
		1180	=item 3. C<allow_blessed> is enabled.
		1181
		1182	The object will be serialised as a JSON null value.
		1183
		1184	=item 4. none of the above
		1185
		1186	If none of the settings are enabled or the respective methods are missing,
		1187	C<JSON::XS> throws an exception.
		1188
		1189	=back
		1190
		1191	=head3 DESERIALISATION
		1192
		1193	For deserialisation there are only two cases to consider: either
		1194	nonstandard tagging was used, in which case C<allow_tags> decides,
		1195	or objects cannot be automatically be deserialised, in which
		1196	case you can use postprocessing or the C<filter_json_object> or
		1197	C<filter_json_single_key_object> callbacks to get some real objects our of
		1198	your JSON.
		1199
		1200	This section only considers the tagged value case: I a tagged JSON object
		1201	is encountered during decoding and C<allow_tags> is disabled, a parse
		1202	error will result (as if tagged values were not part of the grammar).
		1203
		1204	If C<allow_tags> is enabled, C<JSON::XS> will look up the C<THAW> method
		1205	of the package/classname used during serialisation (it will not attempt
		1206	to load the package as a Perl module). If there is no such method, the
		1207	decoding will fail with an error.
		1208
		1209	Otherwise, the C<THAW> method is invoked with the classname as first
		1210	argument, the constant string C<JSON> as second argument, and all the
		1211	values from the JSON array (the values originally returned by the
		1212	C<FREEZE> method) as remaining arguments.
		1213
		1214	The method must then return the object. While technically you can return
		1215	any Perl scalar, you might have to enable the C<enable_nonref> setting to
		1216	make that work in all cases, so better return an actual blessed reference.
		1217
		1218	As an example, let's implement a C<THAW> function that regenerates the
		1219	C<My::Object> from the C<FREEZE> example earlier:
		1220
		1221	sub My::Object::THAW {
		1222	my ($class, $serialiser, $type, $id) = @_;
		1223
		1224	$class->new (type => $type, id => $id)
		1225	}
1091		1226
1092		1227
1093	=head1 ENCODING/CODESET FLAG NOTES	1228	=head1 ENCODING/CODESET FLAG NOTES
1094		1229
1095	The interested reader might have seen a number of flags that signify	1230	The interested reader might have seen a number of flags that signify
…		…
1120	=item C<utf8> flag disabled	1255	=item C<utf8> flag disabled
1121		1256
1122	When C<utf8> is disabled (the default), then C<encode>/C<decode> generate	1257	When C<utf8> is disabled (the default), then C<encode>/C<decode> generate
1123	and expect Unicode strings, that is, characters with high ordinal Unicode	1258	and expect Unicode strings, that is, characters with high ordinal Unicode
1124	values (> 255) will be encoded as such characters, and likewise such	1259	values (> 255) will be encoded as such characters, and likewise such
1125	characters are decoded as-is, no canges to them will be done, except	1260	characters are decoded as-is, no changes to them will be done, except
1126	"(re-)interpreting" them as Unicode codepoints or Unicode characters,	1261	"(re-)interpreting" them as Unicode codepoints or Unicode characters,
1127	respectively (to Perl, these are the same thing in strings unless you do	1262	respectively (to Perl, these are the same thing in strings unless you do
1128	funny/weird/dumb stuff).	1263	funny/weird/dumb stuff).
1129		1264
1130	This is useful when you want to do the encoding yourself (e.g. when you	1265	This is useful when you want to do the encoding yourself (e.g. when you
…		…
1238	well - using C<eval> naively simply I<will> cause problems.	1373	well - using C<eval> naively simply I<will> cause problems.
1239		1374
1240	Another problem is that some javascript implementations reserve	1375	Another problem is that some javascript implementations reserve
1241	some property names for their own purposes (which probably makes	1376	some property names for their own purposes (which probably makes
1242	them non-ECMAscript-compliant). For example, Iceweasel reserves the	1377	them non-ECMAscript-compliant). For example, Iceweasel reserves the
1243	C<__proto__> property name for it's own purposes.	1378	C<__proto__> property name for its own purposes.
1244		1379
1245	If that is a problem, you could parse try to filter the resulting JSON	1380	If that is a problem, you could parse try to filter the resulting JSON
1246	output for these property strings, e.g.:	1381	output for these property strings, e.g.:
1247		1382
1248	$json =~ s/"__proto__"\s*:/"__proto__renamed":/g;	1383	$json =~ s/"__proto__"\s*:/"__proto__renamed":/g;
1249		1384
1250	This works because C<__proto__> is not valid outside of strings, so every	1385	This works because C<__proto__> is not valid outside of strings, so every
1251	occurence of C<"__proto__"\s*:> must be a string used as property name.	1386	occurrence of C<"__proto__"\s*:> must be a string used as property name.
1252		1387
1253	If you know of other incompatibilities, please let me know.	1388	If you know of other incompatibilities, please let me know.
1254		1389
1255		1390
1256	=head2 JSON and YAML	1391	=head2 JSON and YAML
…		…
1302	that difficult or long) and finally make YAML compatible to it, and	1437	that difficult or long) and finally make YAML compatible to it, and
1303	educating users about the changes, instead of spreading lies about the	1438	educating users about the changes, instead of spreading lies about the
1304	real compatibility for many I<years> and trying to silence people who	1439	real compatibility for many I<years> and trying to silence people who
1305	point out that it isn't true.	1440	point out that it isn't true.
1306		1441
1307	Addendum/2009: the YAML 1.2 spec is still incomaptible with JSON, even	1442	Addendum/2009: the YAML 1.2 spec is still incompatible with JSON, even
1308	though the incompatibilities have been documented (and are known to	1443	though the incompatibilities have been documented (and are known to Brian)
1309	Brian) for many years and the spec makes explicit claims that YAML is a	1444	for many years and the spec makes explicit claims that YAML is a superset
1310	superset of JSON. It would be so easy to fix, but apparently, bullying and	1445	of JSON. It would be so easy to fix, but apparently, bullying people and
1311	corrupting userdata is so much easier.	1446	corrupting userdata is so much easier.
1312		1447
1313	=back	1448	=back
1314		1449
1315		1450
…		…
1324	a very short single-line JSON string (also available at	1459	a very short single-line JSON string (also available at
1325	L<http://dist.schmorp.de/misc/json/short.json>).	1460	L<http://dist.schmorp.de/misc/json/short.json>).
1326		1461
1327	{"method": "handleMessage", "params": ["user1",	1462	{"method": "handleMessage", "params": ["user1",
1328	"we were just talking"], "id": null, "array":[1,11,234,-5,1e5,1e7,	1463	"we were just talking"], "id": null, "array":[1,11,234,-5,1e5,1e7,
1329	true, false]}	1464	1, 0]}
1330		1465
1331	It shows the number of encodes/decodes per second (JSON::XS uses	1466	It shows the number of encodes/decodes per second (JSON::XS uses
1332	the functional interface, while JSON::XS/2 uses the OO interface	1467	the functional interface, while JSON::XS/2 uses the OO interface
1333	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables	1468	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
1334	shrink). Higher is better:	1469	shrink. JSON::DWIW/DS uses the deserialise function, while JSON::DWIW::FJ
		1470	uses the from_json method). Higher is better:
1335		1471
1336	module \| encode \| decode \|	1472	module \| encode \| decode \|
1337	-----------\|------------\|------------\|	1473	--------------\|------------\|------------\|
1338	JSON 1.x \| 4990.842 \| 4088.813 \|	1474	JSON::DWIW/DS \| 86302.551 \| 102300.098 \|
1339	JSON::DWIW \| 51653.990 \| 71575.154 \|	1475	JSON::DWIW/FJ \| 86302.551 \| 75983.768 \|
1340	JSON::PC \| 65948.176 \| 74631.744 \|	1476	JSON::PP \| 15827.562 \| 6638.658 \|
1341	JSON::PP \| 8931.652 \| 3817.168 \|	1477	JSON::Syck \| 63358.066 \| 47662.545 \|
1342	JSON::Syck \| 24877.248 \| 27776.848 \|	1478	JSON::XS \| 511500.488 \| 511500.488 \|
1343	JSON::XS \| 388361.481 \| 227951.304 \|	1479	JSON::XS/2 \| 291271.111 \| 388361.481 \|
1344	JSON::XS/2 \| 227951.304 \| 218453.333 \|	1480	JSON::XS/3 \| 361577.931 \| 361577.931 \|
1345	JSON::XS/3 \| 338250.323 \| 218453.333 \|	1481	Storable \| 66788.280 \| 265462.278 \|
1346	Storable \| 16500.016 \| 135300.129 \|
1347	-----------+------------+------------+	1482	--------------+------------+------------+
1348		1483
1349	That is, JSON::XS is about five times faster than JSON::DWIW on encoding,	1484	That is, JSON::XS is almost six times faster than JSON::DWIW on encoding,
1350	about three times faster on decoding, and over forty times faster	1485	about five times faster on decoding, and over thirty to seventy times
1351	than JSON, even with pretty-printing and key sorting. It also compares	1486	faster than JSON's pure perl implementation. It also compares favourably
1352	favourably to Storable for small amounts of data.	1487	to Storable for small amounts of data.
1353		1488
1354	Using a longer test string (roughly 18KB, generated from Yahoo! Locals	1489	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
1355	search API (L<http://dist.schmorp.de/misc/json/long.json>).	1490	search API (L<http://dist.schmorp.de/misc/json/long.json>).
1356		1491
1357	module \| encode \| decode \|	1492	module \| encode \| decode \|
1358	-----------\|------------\|------------\|	1493	--------------\|------------\|------------\|
1359	JSON 1.x \| 55.260 \| 34.971 \|	1494	JSON::DWIW/DS \| 1647.927 \| 2673.916 \|
1360	JSON::DWIW \| 825.228 \| 1082.513 \|	1495	JSON::DWIW/FJ \| 1630.249 \| 2596.128 \|
1361	JSON::PC \| 3571.444 \| 2394.829 \|
1362	JSON::PP \| 210.987 \| 32.574 \|	1496	JSON::PP \| 400.640 \| 62.311 \|
1363	JSON::Syck \| 552.551 \| 787.544 \|	1497	JSON::Syck \| 1481.040 \| 1524.869 \|
1364	JSON::XS \| 5780.463 \| 4854.519 \|	1498	JSON::XS \| 20661.596 \| 9541.183 \|
1365	JSON::XS/2 \| 3869.998 \| 4798.975 \|	1499	JSON::XS/2 \| 10683.403 \| 9416.938 \|
1366	JSON::XS/3 \| 5862.880 \| 4798.975 \|	1500	JSON::XS/3 \| 20661.596 \| 9400.054 \|
1367	Storable \| 4445.002 \| 5235.027 \|	1501	Storable \| 19765.806 \| 10000.725 \|
1368	-----------+------------+------------+	1502	--------------+------------+------------+
1369		1503
1370	Again, JSON::XS leads by far (except for Storable which non-surprisingly	1504	Again, JSON::XS leads by far (except for Storable which non-surprisingly
1371	decodes faster).	1505	decodes a bit faster).
1372		1506
1373	On large strings containing lots of high Unicode characters, some modules	1507	On large strings containing lots of high Unicode characters, some modules
1374	(such as JSON::PC) seem to decode faster than JSON::XS, but the result	1508	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
1375	will be broken due to missing (or wrong) Unicode handling. Others refuse	1509	will be broken due to missing (or wrong) Unicode handling. Others refuse
1376	to decode or encode properly, so it was impossible to prepare a fair	1510	to decode or encode properly, so it was impossible to prepare a fair
…		…
1419	are browser design bugs, but it is still you who will have to deal with	1553	are browser design bugs, but it is still you who will have to deal with
1420	it, as major browser developers care only for features, not about getting	1554	it, as major browser developers care only for features, not about getting
1421	security right).	1555	security right).
1422		1556
1423		1557
		1558	=head1 INTEROPERABILITY WITH OTHER MODULES
		1559
		1560	C<JSON::XS> uses the L<Types::Serialiser> module to provide boolean
		1561	constants. That means that the JSON true and false values will be
		1562	comaptible to true and false values of iother modules that do the same,
		1563	such as L<JSON::PP> and L<CBOR::XS>.
		1564
		1565
1424	=head1 THREADS	1566	=head1 THREADS
1425		1567
1426	This module is I<not> guaranteed to be thread safe and there are no	1568	This module is I<not> guaranteed to be thread safe and there are no
1427	plans to change this until Perl gets thread support (as opposed to the	1569	plans to change this until Perl gets thread support (as opposed to the
1428	horribly slow so-called "threads" which are simply slow and bloated	1570	horribly slow so-called "threads" which are simply slow and bloated
1429	process simulations - use fork, it's I<much> faster, cheaper, better).	1571	process simulations - use fork, it's I<much> faster, cheaper, better).
1430		1572
1431	(It might actually work, but you have been warned).	1573	(It might actually work, but you have been warned).
1432		1574
1433		1575
		1576	=head1 THE PERILS OF SETLOCALE
		1577
		1578	Sometimes people avoid the Perl locale support and directly call the
		1579	system's setlocale function with C<LC_ALL>.
		1580
		1581	This breaks both perl and modules such as JSON::XS, as stringification of
		1582	numbers no longer works correctly (e.g. C<$x = 0.1; print "$x"+1> might
		1583	print C<1>, and JSON::XS might output illegal JSON as JSON::XS relies on
		1584	perl to stringify numbers).
		1585
		1586	The solution is simple: don't call C<setlocale>, or use it for only those
		1587	categories you need, such as C<LC_MESSAGES> or C<LC_CTYPE>.
		1588
		1589	If you need C<LC_NUMERIC>, you should enable it only around the code that
		1590	actually needs it (avoiding stringification of numbers), and restore it
		1591	afterwards.
		1592
		1593
1434	=head1 BUGS	1594	=head1 BUGS
1435		1595
1436	While the goal of this module is to be correct, that unfortunately does	1596	While the goal of this module is to be correct, that unfortunately does
1437	not mean it's bug-free, only that I think its design is bug-free. If you	1597	not mean it's bug-free, only that I think its design is bug-free. If you
1438	keep reporting bugs they will be fixed swiftly, though.	1598	keep reporting bugs they will be fixed swiftly, though.
…		…
1440	Please refrain from using rt.cpan.org or any other bug reporting	1600	Please refrain from using rt.cpan.org or any other bug reporting
1441	service. I put the contact address into my modules for a reason.	1601	service. I put the contact address into my modules for a reason.
1442		1602
1443	=cut	1603	=cut
1444		1604
1445	our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };	1605	BEGIN {
1446	our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };	1606	*true = \$Types::Serialiser::true;
		1607	*true = \&Types::Serialiser::true;
		1608	*false = \$Types::Serialiser::false;
		1609	*false = \&Types::Serialiser::false;
		1610	*is_bool = \&Types::Serialiser::is_bool;
1447		1611
1448	sub true() { $true }	1612	JSON::XS::Boolean:: = Types::Serialiser::Boolean::;
1449	sub false() { $false }
1450
1451	sub is_bool($) {
1452	UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
1453	# or UNIVERSAL::isa $_[0], "JSON::Literal"
1454	}	1613	}
1455		1614
1456	XSLoader::load "JSON::XS", $VERSION;	1615	XSLoader::load "JSON::XS", $VERSION;
1457
1458	package JSON::XS::Boolean;
1459
1460	use overload
1461	"0+" => sub { ${$_[0]} },
1462	"++" => sub { $_[0] = ${$_[0]} + 1 },
1463	"--" => sub { $_[0] = ${$_[0]} - 1 },
1464	fallback => 1;
1465
1466	1;
1467		1616
1468	=head1 SEE ALSO	1617	=head1 SEE ALSO
1469		1618
1470	The F<json_xs> command line utility for quick experiments.	1619	The F<json_xs> command line utility for quick experiments.
1471		1620
…		…
1474	Marc Lehmann <schmorp@schmorp.de>	1623	Marc Lehmann <schmorp@schmorp.de>
1475	http://home.schmorp.de/	1624	http://home.schmorp.de/
1476		1625
1477	=cut	1626	=cut
1478		1627
		1628	1
		1629

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Comparing JSON-XS/XS.pm (file contents): Revision 1.128 by root, Tue Jan 19 00:31:13 2010 UTC vs. Revision 1.150 by root, Tue Oct 29 00:48:07 2013 UTC

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Comparing JSON-XS/XS.pm (file contents):
Revision 1.128 by root, Tue Jan 19 00:31:13 2010 UTC vs.
Revision 1.150 by root, Tue Oct 29 00:48:07 2013 UTC