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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.84 by root, Wed Mar 19 02:52:15 2008 UTC vs.
Revision 1.139 by root, Thu May 23 09:31:32 2013 UTC

…		…
		1	=head1 NAME
		2
		3	JSON::XS - JSON serialising/deserialising, done correctly and fast
		4
1	=encoding utf-8	5	=encoding utf-8
2
3	=head1 NAME
4
5	JSON::XS - JSON serialising/deserialising, done correctly and fast
6		6
7	JSON::XS - 正しくて高速な JSON シリアライザ/デシリアライザ	7	JSON::XS - 正しくて高速な JSON シリアライザ/デシリアライザ
8	(http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html)	8	(http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html)
9		9
10	=head1 SYNOPSIS	10	=head1 SYNOPSIS
37	primary goal is to be I<correct> and its secondary goal is to be	37	primary goal is to be I<correct> and its secondary goal is to be
38	I<fast>. To reach the latter goal it was written in C.	38	I<fast>. To reach the latter goal it was written in C.
39		39
40	Beginning with version 2.0 of the JSON module, when both JSON and	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	overriden) with no overhead due to emulation (by inheritign 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 and doesn't
46	require a C compiler when that is a problem.	46	require a C compiler when that is a problem.
47		47
…		…
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
52	reports for other reasons.	52	reports for other reasons.
53		53
54	See COMPARISON, below, for a comparison to some other JSON modules.
55
56	See MAPPING, below, on how JSON::XS maps perl values to JSON values and	54	See MAPPING, below, on how JSON::XS maps perl values to JSON values and
57	vice versa.	55	vice versa.
58		56
59	=head2 FEATURES	57	=head2 FEATURES
60		58
…		…
65	This module knows how to handle Unicode, documents how and when it does	63	This module knows how to handle Unicode, documents how and when it does
66	so, and even documents what "correct" means.	64	so, and even documents what "correct" means.
67		65
68	=item * round-trip integrity	66	=item * round-trip integrity
69		67
70	When you serialise a perl data structure using only datatypes supported	68	When you serialise a perl data structure using only data types supported
71	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
72	(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
73	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
74	section below to learn about those.	72	MAPPING section below to learn about those.
75		73
76	=item * strict checking of JSON correctness	74	=item * strict checking of JSON correctness
77		75
78	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,
79	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
…		…
84	Compared to other JSON modules and other serialisers such as Storable,	82	Compared to other JSON modules and other serialisers such as Storable,
85	this module usually compares favourably in terms of speed, too.	83	this module usually compares favourably in terms of speed, too.
86		84
87	=item * simple to use	85	=item * simple to use
88		86
89	This module has both a simple functional interface as well as an objetc	87	This module has both a simple functional interface as well as an object
90	oriented interface interface.	88	oriented interface interface.
91		89
92	=item * reasonably versatile output formats	90	=item * reasonably versatile output formats
93		91
94	You can choose between the most compact guaranteed-single-line format	92	You can choose between the most compact guaranteed-single-line format
95	possible (nice for simple line-based protocols), a pure-ascii format	93	possible (nice for simple line-based protocols), a pure-ASCII format
96	(for when your transport is not 8-bit clean, still supports the whole	94	(for when your transport is not 8-bit clean, still supports the whole
97	Unicode range), or a pretty-printed format (for when you want to read that	95	Unicode range), or a pretty-printed format (for when you want to read that
98	stuff). Or you can combine those features in whatever way you like.	96	stuff). Or you can combine those features in whatever way you like.
99		97
100	=back	98	=back
101		99
102	=cut	100	=cut
103		101
104	package JSON::XS;	102	package JSON::XS;
105		103
106	use strict;	104	use common::sense;
107		105
108	our $VERSION = '2.01';	106	our $VERSION = 2.34;
109	our @ISA = qw(Exporter);	107	our @ISA = qw(Exporter);
110		108
111	our @EXPORT = qw(encode_json decode_json to_json from_json);	109	our @EXPORT = qw(encode_json decode_json to_json from_json);
112		110
113	sub to_json($) {	111	sub to_json($) {
…		…
137		135
138	This function call is functionally identical to:	136	This function call is functionally identical to:
139		137
140	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)	138	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)
141		139
142	except being faster.	140	Except being faster.
143		141
144	=item $perl_scalar = decode_json $json_text	142	=item $perl_scalar = decode_json $json_text
145		143
146	The opposite of C<encode_json>: expects an UTF-8 (binary) string and tries	144	The opposite of C<encode_json>: expects an UTF-8 (binary) string and tries
147	to parse that as an UTF-8 encoded JSON text, returning the resulting	145	to parse that as an UTF-8 encoded JSON text, returning the resulting
…		…
149		147
150	This function call is functionally identical to:	148	This function call is functionally identical to:
151		149
152	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)	150	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
153		151
154	except being faster.	152	Except being faster.
155		153
156	=item $is_boolean = JSON::XS::is_bool $scalar	154	=item $is_boolean = JSON::XS::is_bool $scalar
157		155
158	Returns true if the passed scalar represents either JSON::XS::true or	156	Returns true if the passed scalar represents either JSON::XS::true or
159	JSON::XS::false, two constants that act like C<1> and C<0>, respectively	157	JSON::XS::false, two constants that act like C<1> and C<0>, respectively
…		…
197		195
198	If you didn't know about that flag, just the better, pretend it doesn't	196	If you didn't know about that flag, just the better, pretend it doesn't
199	exist.	197	exist.
200		198
201	=item 4. A "Unicode String" is simply a string where each character can be	199	=item 4. A "Unicode String" is simply a string where each character can be
202	validly interpreted as a Unicode codepoint.	200	validly interpreted as a Unicode code point.
203		201
204	If you have UTF-8 encoded data, it is no longer a Unicode string, but a	202	If you have UTF-8 encoded data, it is no longer a Unicode string, but a
205	Unicode string encoded in UTF-8, giving you a binary string.	203	Unicode string encoded in UTF-8, giving you a binary string.
206		204
207	=item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string.	205	=item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string.
…		…
245		243
246	If C<$enable> is false, then the C<encode> method will not escape Unicode	244	If C<$enable> is false, then the C<encode> method will not escape Unicode
247	characters unless required by the JSON syntax or other flags. This results	245	characters unless required by the JSON syntax or other flags. This results
248	in a faster and more compact format.	246	in a faster and more compact format.
249		247
		248	See also the section I<ENCODING/CODESET FLAG NOTES> later in this
		249	document.
		250
250	The main use for this flag is to produce JSON texts that can be	251	The main use for this flag is to produce JSON texts that can be
251	transmitted over a 7-bit channel, as the encoded JSON texts will not	252	transmitted over a 7-bit channel, as the encoded JSON texts will not
252	contain any 8 bit characters.	253	contain any 8 bit characters.
253		254
254	JSON::XS->new->ascii (1)->encode ([chr 0x10401])	255	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
…		…
265	will not be affected in any way by this flag, as C<decode> by default	266	will not be affected in any way by this flag, as C<decode> by default
266	expects Unicode, which is a strict superset of latin1.	267	expects Unicode, which is a strict superset of latin1.
267		268
268	If C<$enable> is false, then the C<encode> method will not escape Unicode	269	If C<$enable> is false, then the C<encode> method will not escape Unicode
269	characters unless required by the JSON syntax or other flags.	270	characters unless required by the JSON syntax or other flags.
		271
		272	See also the section I<ENCODING/CODESET FLAG NOTES> later in this
		273	document.
270		274
271	The main use for this flag is efficiently encoding binary data as JSON	275	The main use for this flag is efficiently encoding binary data as JSON
272	text, as most octets will not be escaped, resulting in a smaller encoded	276	text, as most octets will not be escaped, resulting in a smaller encoded
273	size. The disadvantage is that the resulting JSON text is encoded	277	size. The disadvantage is that the resulting JSON text is encoded
274	in latin1 (and must correctly be treated as such when storing and	278	in latin1 (and must correctly be treated as such when storing and
…		…
293		297
294	If C<$enable> is false, then the C<encode> method will return the JSON	298	If C<$enable> is false, then the C<encode> method will return the JSON
295	string as a (non-encoded) Unicode string, while C<decode> expects thus a	299	string as a (non-encoded) Unicode string, while C<decode> expects thus a
296	Unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs	300	Unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs
297	to be done yourself, e.g. using the Encode module.	301	to be done yourself, e.g. using the Encode module.
		302
		303	See also the section I<ENCODING/CODESET FLAG NOTES> later in this
		304	document.
298		305
299	Example, output UTF-16BE-encoded JSON:	306	Example, output UTF-16BE-encoded JSON:
300		307
301	use Encode;	308	use Encode;
302	$jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);	309	$jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);
…		…
425	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects	432	If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
426	by sorting their keys. This is adding a comparatively high overhead.	433	by sorting their keys. This is adding a comparatively high overhead.
427		434
428	If C<$enable> is false, then the C<encode> method will output key-value	435	If C<$enable> is false, then the C<encode> method will output key-value
429	pairs in the order Perl stores them (which will likely change between runs	436	pairs in the order Perl stores them (which will likely change between runs
430	of the same script).	437	of the same script, and can change even within the same run from 5.18
		438	onwards).
431		439
432	This option is useful if you want the same data structure to be encoded as	440	This option is useful if you want the same data structure to be encoded as
433	the same JSON text (given the same overall settings). If it is disabled,	441	the same JSON text (given the same overall settings). If it is disabled,
434	the same hash might be encoded differently even if contains the same data,	442	the same hash might be encoded differently even if contains the same data,
435	as key-value pairs have no inherent ordering in Perl.	443	as key-value pairs have no inherent ordering in Perl.
436		444
437	This setting has no effect when decoding JSON texts.	445	This setting has no effect when decoding JSON texts.
438		446
		447	This setting has currently no effect on tied hashes.
		448
439	=item $json = $json->allow_nonref ([$enable])	449	=item $json = $json->allow_nonref ([$enable])
440		450
441	=item $enabled = $json->get_allow_nonref	451	=item $enabled = $json->get_allow_nonref
442		452
443	If C<$enable> is true (or missing), then the C<encode> method can convert a	453	If C<$enable> is true (or missing), then the C<encode> method can convert a
…		…
453	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,	463	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,
454	resulting in an invalid JSON text:	464	resulting in an invalid JSON text:
455		465
456	JSON::XS->new->allow_nonref->encode ("Hello, World!")	466	JSON::XS->new->allow_nonref->encode ("Hello, World!")
457	=> "Hello, World!"	467	=> "Hello, World!"
		468
		469	=item $json = $json->allow_unknown ([$enable])
		470
		471	=item $enabled = $json->get_allow_unknown
		472
		473	If C<$enable> is true (or missing), then C<encode> will I<not> throw an
		474	exception when it encounters values it cannot represent in JSON (for
		475	example, filehandles) but instead will encode a JSON C<null> value. Note
		476	that blessed objects are not included here and are handled separately by
		477	c<allow_nonref>.
		478
		479	If C<$enable> is false (the default), then C<encode> will throw an
		480	exception when it encounters anything it cannot encode as JSON.
		481
		482	This option does not affect C<decode> in any way, and it is recommended to
		483	leave it off unless you know your communications partner.
458		484
459	=item $json = $json->allow_blessed ([$enable])	485	=item $json = $json->allow_blessed ([$enable])
460		486
461	=item $enabled = $json->get_allow_blessed	487	=item $enabled = $json->get_allow_blessed
462		488
…		…
603	=item $json = $json->max_depth ([$maximum_nesting_depth])	629	=item $json = $json->max_depth ([$maximum_nesting_depth])
604		630
605	=item $max_depth = $json->get_max_depth	631	=item $max_depth = $json->get_max_depth
606		632
607	Sets the maximum nesting level (default C<512>) accepted while encoding	633	Sets the maximum nesting level (default C<512>) accepted while encoding
608	or decoding. If the JSON text or Perl data structure has an equal or	634	or decoding. If a higher nesting level is detected in JSON text or a Perl
609	higher nesting level then this limit, then the encoder and decoder will	635	data structure, then the encoder and decoder will stop and croak at that
610	stop and croak at that point.	636	point.
611		637
612	Nesting level is defined by number of hash- or arrayrefs that the encoder	638	Nesting level is defined by number of hash- or arrayrefs that the encoder
613	needs to traverse to reach a given point or the number of C<{> or C<[>	639	needs to traverse to reach a given point or the number of C<{> or C<[>
614	characters without their matching closing parenthesis crossed to reach a	640	characters without their matching closing parenthesis crossed to reach a
615	given character in a string.	641	given character in a string.
616		642
617	Setting the maximum depth to one disallows any nesting, so that ensures	643	Setting the maximum depth to one disallows any nesting, so that ensures
618	that the object is only a single hash/object or array.	644	that the object is only a single hash/object or array.
619		645
620	The argument to C<max_depth> will be rounded up to the next highest power
621	of two. If no argument is given, the highest possible setting will be	646	If no argument is given, the highest possible setting will be used, which
622	used, which is rarely useful.	647	is rarely useful.
		648
		649	Note that nesting is implemented by recursion in C. The default value has
		650	been chosen to be as large as typical operating systems allow without
		651	crashing.
623		652
624	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	653	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
625		654
626	=item $json = $json->max_size ([$maximum_string_size])	655	=item $json = $json->max_size ([$maximum_string_size])
627		656
628	=item $max_size = $json->get_max_size	657	=item $max_size = $json->get_max_size
629		658
630	Set the maximum length a JSON text may have (in bytes) where decoding is	659	Set the maximum length a JSON text may have (in bytes) where decoding is
631	being attempted. The default is C<0>, meaning no limit. When C<decode>	660	being attempted. The default is C<0>, meaning no limit. When C<decode>
632	is called on a string longer then this number of characters it will not	661	is called on a string that is longer then this many bytes, it will not
633	attempt to decode the string but throw an exception. This setting has no	662	attempt to decode the string but throw an exception. This setting has no
634	effect on C<encode> (yet).	663	effect on C<encode> (yet).
635		664
636	The argument to C<max_size> will be rounded up to the next B<highest>	665	If no argument is given, the limit check will be deactivated (same as when
637	power of two (so may be more than requested). If no argument is given, the	666	C<0> is specified).
638	limit check will be deactivated (same as when C<0> is specified).
639		667
640	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	668	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
641		669
642	=item $json_text = $json->encode ($perl_scalar)	670	=item $json_text = $json->encode ($perl_scalar)
643		671
…		…
672	=> ([], 3)	700	=> ([], 3)
673		701
674	=back	702	=back
675		703
676		704
		705	=head1 INCREMENTAL PARSING
		706
		707	In some cases, there is the need for incremental parsing of JSON
		708	texts. While this module always has to keep both JSON text and resulting
		709	Perl data structure in memory at one time, it does allow you to parse a
		710	JSON stream incrementally. It does so by accumulating text until it has
		711	a full JSON object, which it then can decode. This process is similar to
		712	using C<decode_prefix> to see if a full JSON object is available, but
		713	is much more efficient (and can be implemented with a minimum of method
		714	calls).
		715
		716	JSON::XS will only attempt to parse the JSON text once it is sure it
		717	has enough text to get a decisive result, using a very simple but
		718	truly incremental parser. This means that it sometimes won't stop as
		719	early as the full parser, for example, it doesn't detect mismatched
		720	parentheses. The only thing it guarantees is that it starts decoding as
		721	soon as a syntactically valid JSON text has been seen. This means you need
		722	to set resource limits (e.g. C<max_size>) to ensure the parser will stop
		723	parsing in the presence if syntax errors.
		724
		725	The following methods implement this incremental parser.
		726
		727	=over 4
		728
		729	=item [void, scalar or list context] = $json->incr_parse ([$string])
		730
		731	This is the central parsing function. It can both append new text and
		732	extract objects from the stream accumulated so far (both of these
		733	functions are optional).
		734
		735	If C<$string> is given, then this string is appended to the already
		736	existing JSON fragment stored in the C<$json> object.
		737
		738	After that, if the function is called in void context, it will simply
		739	return without doing anything further. This can be used to add more text
		740	in as many chunks as you want.
		741
		742	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
		744	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
		746	C<incr_skip> to skip the errornous part). This is the most common way of
		747	using the method.
		748
		749	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
		751	otherwise. For this to work, there must be no separators between the JSON
		752	objects or arrays, instead they must be concatenated back-to-back. If
		753	an error occurs, an exception will be raised as in the scalar context
		754	case. Note that in this case, any previously-parsed JSON texts will be
		755	lost.
		756
		757	Example: Parse some JSON arrays/objects in a given string and return
		758	them.
		759
		760	my @objs = JSON::XS->new->incr_parse ("[5][7][1,2]");
		761
		762	=item $lvalue_string = $json->incr_text
		763
		764	This method returns the currently stored JSON fragment as an lvalue, that
		765	is, you can manipulate it. This I<only> works when a preceding call to
		766	C<incr_parse> in I<scalar context> successfully returned an object. Under
		767	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
		769	real world conditions). As a special exception, you can also call this
		770	method before having parsed anything.
		771
		772	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
		774	(such as commas).
		775
		776	=item $json->incr_skip
		777
		778	This will reset the state of the incremental parser and will remove
		779	the parsed text from the input buffer so far. This is useful after
		780	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
		782	parse state.
		783
		784	The difference to C<incr_reset> is that only text until the parse error
		785	occured is removed.
		786
		787	=item $json->incr_reset
		788
		789	This completely resets the incremental parser, that is, after this call,
		790	it will be as if the parser had never parsed anything.
		791
		792	This is useful if you want to repeatedly parse JSON objects and want to
		793	ignore any trailing data, which means you have to reset the parser after
		794	each successful decode.
		795
		796	=back
		797
		798	=head2 LIMITATIONS
		799
		800	All options that affect decoding are supported, except
		801	C<allow_nonref>. The reason for this is that it cannot be made to
		802	work sensibly: JSON objects and arrays are self-delimited, i.e. you can concatenate
		803	them back to back and still decode them perfectly. This does not hold true
		804	for JSON numbers, however.
		805
		806	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
		808	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.
		810
		811	=head2 EXAMPLES
		812
		813	Some examples will make all this clearer. First, a simple example that
		814	works similarly to C<decode_prefix>: We want to decode the JSON object at
		815	the start of a string and identify the portion after the JSON object:
		816
		817	my $text = "[1,2,3] hello";
		818
		819	my $json = new JSON::XS;
		820
		821	my $obj = $json->incr_parse ($text)
		822	or die "expected JSON object or array at beginning of string";
		823
		824	my $tail = $json->incr_text;
		825	# $tail now contains " hello"
		826
		827	Easy, isn't it?
		828
		829	Now for a more complicated example: Imagine a hypothetical protocol where
		830	you read some requests from a TCP stream, and each request is a JSON
		831	array, without any separation between them (in fact, it is often useful to
		832	use newlines as "separators", as these get interpreted as whitespace at
		833	the start of the JSON text, which makes it possible to test said protocol
		834	with C<telnet>...).
		835
		836	Here is how you'd do it (it is trivial to write this in an event-based
		837	manner):
		838
		839	my $json = new JSON::XS;
		840
		841	# read some data from the socket
		842	while (sysread $socket, my $buf, 4096) {
		843
		844	# split and decode as many requests as possible
		845	for my $request ($json->incr_parse ($buf)) {
		846	# act on the $request
		847	}
		848	}
		849
		850	Another complicated example: Assume you have a string with JSON objects
		851	or arrays, all separated by (optional) comma characters (e.g. C<[1],[2],
		852	[3]>). To parse them, we have to skip the commas between the JSON texts,
		853	and here is where the lvalue-ness of C<incr_text> comes in useful:
		854
		855	my $text = "[1],[2], [3]";
		856	my $json = new JSON::XS;
		857
		858	# void context, so no parsing done
		859	$json->incr_parse ($text);
		860
		861	# now extract as many objects as possible. note the
		862	# use of scalar context so incr_text can be called.
		863	while (my $obj = $json->incr_parse) {
		864	# do something with $obj
		865
		866	# now skip the optional comma
		867	$json->incr_text =~ s/^ \s* , //x;
		868	}
		869
		870	Now lets go for a very complex example: Assume that you have a gigantic
		871	JSON array-of-objects, many gigabytes in size, and you want to parse it,
		872	but you cannot load it into memory fully (this has actually happened in
		873	the real world :).
		874
		875	Well, you lost, you have to implement your own JSON parser. But JSON::XS
		876	can still help you: You implement a (very simple) array parser and let
		877	JSON decode the array elements, which are all full JSON objects on their
		878	own (this wouldn't work if the array elements could be JSON numbers, for
		879	example):
		880
		881	my $json = new JSON::XS;
		882
		883	# open the monster
		884	open my $fh, "<bigfile.json"
		885	or die "bigfile: $!";
		886
		887	# first parse the initial "["
		888	for (;;) {
		889	sysread $fh, my $buf, 65536
		890	or die "read error: $!";
		891	$json->incr_parse ($buf); # void context, so no parsing
		892
		893	# Exit the loop once we found and removed(!) the initial "[".
		894	# In essence, we are (ab-)using the $json object as a simple scalar
		895	# we append data to.
		896	last if $json->incr_text =~ s/^ \s* \[ //x;
		897	}
		898
		899	# now we have the skipped the initial "[", so continue
		900	# parsing all the elements.
		901	for (;;) {
		902	# in this loop we read data until we got a single JSON object
		903	for (;;) {
		904	if (my $obj = $json->incr_parse) {
		905	# do something with $obj
		906	last;
		907	}
		908
		909	# add more data
		910	sysread $fh, my $buf, 65536
		911	or die "read error: $!";
		912	$json->incr_parse ($buf); # void context, so no parsing
		913	}
		914
		915	# in this loop we read data until we either found and parsed the
		916	# separating "," between elements, or the final "]"
		917	for (;;) {
		918	# first skip whitespace
		919	$json->incr_text =~ s/^\s*//;
		920
		921	# if we find "]", we are done
		922	if ($json->incr_text =~ s/^\]//) {
		923	print "finished.\n";
		924	exit;
		925	}
		926
		927	# if we find ",", we can continue with the next element
		928	if ($json->incr_text =~ s/^,//) {
		929	last;
		930	}
		931
		932	# if we find anything else, we have a parse error!
		933	if (length $json->incr_text) {
		934	die "parse error near ", $json->incr_text;
		935	}
		936
		937	# else add more data
		938	sysread $fh, my $buf, 65536
		939	or die "read error: $!";
		940	$json->incr_parse ($buf); # void context, so no parsing
		941	}
		942
		943	This is a complex example, but most of the complexity comes from the fact
		944	that we are trying to be correct (bear with me if I am wrong, I never ran
		945	the above example :).
		946
		947
		948
677	=head1 MAPPING	949	=head1 MAPPING
678		950
679	This section describes how JSON::XS maps Perl values to JSON values and	951	This section describes how JSON::XS maps Perl values to JSON values and
680	vice versa. These mappings are designed to "do the right thing" in most	952	vice versa. These mappings are designed to "do the right thing" in most
681	circumstances automatically, preserving round-tripping characteristics	953	circumstances automatically, preserving round-tripping characteristics
…		…
722		994
723	Numbers containing a fractional or exponential part will always be	995	Numbers containing a fractional or exponential part will always be
724	represented as numeric (floating point) values, possibly at a loss of	996	represented as numeric (floating point) values, possibly at a loss of
725	precision (in which case you might lose perfect roundtripping ability, but	997	precision (in which case you might lose perfect roundtripping ability, but
726	the JSON number will still be re-encoded as a JSON number).	998	the JSON number will still be re-encoded as a JSON number).
		999
		1000	Note that precision is not accuracy - binary floating point values cannot
		1001	represent most decimal fractions exactly, and when converting from and to
		1002	floating point, JSON::XS only guarantees precision up to but not including
		1003	the leats significant bit.
727		1004
728	=item true, false	1005	=item true, false
729		1006
730	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,	1007	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
731	respectively. They are overloaded to act almost exactly like the numbers	1008	respectively. They are overloaded to act almost exactly like the numbers
…		…
768	Other unblessed references are generally not allowed and will cause an	1045	Other unblessed references are generally not allowed and will cause an
769	exception to be thrown, except for references to the integers C<0> and	1046	exception to be thrown, except for references to the integers C<0> and
770	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can	1047	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
771	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.	1048	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
772		1049
773	encode_json [\0,JSON::XS::true] # yields [false,true]	1050	encode_json [\0, JSON::XS::true] # yields [false,true]
774		1051
775	=item JSON::XS::true, JSON::XS::false	1052	=item JSON::XS::true, JSON::XS::false
776		1053
777	These special values become JSON true and JSON false values,	1054	These special values become JSON true and JSON false values,
778	respectively. You can also use C<\1> and C<\0> directly if you want.	1055	respectively. You can also use C<\1> and C<\0> directly if you want.
…		…
816	my $x = "3"; # some variable containing a string	1093	my $x = "3"; # some variable containing a string
817	$x += 0; # numify it, ensuring it will be dumped as a number	1094	$x += 0; # numify it, ensuring it will be dumped as a number
818	$x *= 1; # same thing, the choice is yours.	1095	$x *= 1; # same thing, the choice is yours.
819		1096
820	You can not currently force the type in other, less obscure, ways. Tell me	1097	You can not currently force the type in other, less obscure, ways. Tell me
821	if you need this capability (but don't forget to explain why its needed	1098	if you need this capability (but don't forget to explain why it's needed
822	:).	1099	:).
		1100
		1101	Note that numerical precision has the same meaning as under Perl (so
		1102	binary to decimal conversion follows the same rules as in Perl, which
		1103	can differ to other languages). Also, your perl interpreter might expose
		1104	extensions to the floating point numbers of your platform, such as
		1105	infinities or NaN's - these cannot be represented in JSON, and it is an
		1106	error to pass those in.
823		1107
824	=back	1108	=back
825		1109
826		1110
827	=head1 ENCODING/CODESET FLAG NOTES	1111	=head1 ENCODING/CODESET FLAG NOTES
828		1112
829	The interested reader might have seen a number of flags that signify	1113	The interested reader might have seen a number of flags that signify
830	encodings or codesets - C<utf8>, C<latin1> and C<ascii>. There seems to be	1114	encodings or codesets - C<utf8>, C<latin1> and C<ascii>. There seems to be
831	some confusion on what these do, so here is a short comparison:	1115	some confusion on what these do, so here is a short comparison:
832		1116
833	C<utf8> controls wether the JSON text created by C<encode> (and expected	1117	C<utf8> controls whether the JSON text created by C<encode> (and expected
834	by C<decode>) is UTF-8 encoded or not, while C<latin1> and C<ascii> only	1118	by C<decode>) is UTF-8 encoded or not, while C<latin1> and C<ascii> only
835	control wether C<encode> escapes character values outside their respective	1119	control whether C<encode> escapes character values outside their respective
836	codeset range. Neither of these flags conflict with each other, although	1120	codeset range. Neither of these flags conflict with each other, although
837	some combinations make less sense than others.	1121	some combinations make less sense than others.
838		1122
839	Care has been taken to make all flags symmetrical with respect to	1123	Care has been taken to make all flags symmetrical with respect to
840	C<encode> and C<decode>, that is, texts encoded with any combination of	1124	C<encode> and C<decode>, that is, texts encoded with any combination of
…		…
920	proper subset of most 8-bit and multibyte encodings in use in the world.	1204	proper subset of most 8-bit and multibyte encodings in use in the world.
921		1205
922	=back	1206	=back
923		1207
924		1208
925	=head1 COMPARISON	1209	=head2 JSON and ECMAscript
926		1210
927	As already mentioned, this module was created because none of the existing	1211	JSON syntax is based on how literals are represented in javascript (the
928	JSON modules could be made to work correctly. First I will describe the	1212	not-standardised predecessor of ECMAscript) which is presumably why it is
929	problems (or pleasures) I encountered with various existing JSON modules,	1213	called "JavaScript Object Notation".
930	followed by some benchmark values. JSON::XS was designed not to suffer
931	from any of these problems or limitations.
932		1214
933	=over 4	1215	However, JSON is not a subset (and also not a superset of course) of
		1216	ECMAscript (the standard) or javascript (whatever browsers actually
		1217	implement).
934		1218
935	=item JSON 2.xx	1219	If you want to use javascript's C<eval> function to "parse" JSON, you
		1220	might run into parse errors for valid JSON texts, or the resulting data
		1221	structure might not be queryable:
936		1222
937	A marvellous piece of engineering, this module either uses JSON::XS	1223	One of the problems is that U+2028 and U+2029 are valid characters inside
938	directly when available (so will be 100% compatible with it, including	1224	JSON strings, but are not allowed in ECMAscript string literals, so the
939	speed), or it uses JSON::PP, which is basically JSON::XS translated to	1225	following Perl fragment will not output something that can be guaranteed
940	Pure Perl, which should be 100% compatible with JSON::XS, just a bit	1226	to be parsable by javascript's C<eval>:
941	slower.
942		1227
943	You cannot really lose by using this module.	1228	use JSON::XS;
944		1229
945	=item JSON 1.07	1230	print encode_json [chr 0x2028];
946		1231
947	Slow (but very portable, as it is written in pure Perl).	1232	The right fix for this is to use a proper JSON parser in your javascript
		1233	programs, and not rely on C<eval> (see for example Douglas Crockford's
		1234	F<json2.js> parser).
948		1235
949	Undocumented/buggy Unicode handling (how JSON handles Unicode values is	1236	If this is not an option, you can, as a stop-gap measure, simply encode to
950	undocumented. One can get far by feeding it Unicode strings and doing	1237	ASCII-only JSON:
951	en-/decoding oneself, but Unicode escapes are not working properly).
952		1238
953	No round-tripping (strings get clobbered if they look like numbers, e.g.	1239	use JSON::XS;
954	the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will
955	decode into the number 2.
956		1240
957	=item JSON::PC 0.01	1241	print JSON::XS->new->ascii->encode ([chr 0x2028]);
958		1242
959	Very fast.	1243	Note that this will enlarge the resulting JSON text quite a bit if you
		1244	have many non-ASCII characters. You might be tempted to run some regexes
		1245	to only escape U+2028 and U+2029, e.g.:
960		1246
961	Undocumented/buggy Unicode handling.	1247	# DO NOT USE THIS!
		1248	my $json = JSON::XS->new->utf8->encode ([chr 0x2028]);
		1249	$json =~ s/\xe2\x80\xa8/\\u2028/g; # escape U+2028
		1250	$json =~ s/\xe2\x80\xa9/\\u2029/g; # escape U+2029
		1251	print $json;
962		1252
963	No round-tripping.	1253	Note that I<this is a bad idea>: the above only works for U+2028 and
		1254	U+2029 and thus only for fully ECMAscript-compliant parsers. Many existing
		1255	javascript implementations, however, have issues with other characters as
		1256	well - using C<eval> naively simply I<will> cause problems.
964		1257
965	Has problems handling many Perl values (e.g. regex results and other magic	1258	Another problem is that some javascript implementations reserve
966	values will make it croak).	1259	some property names for their own purposes (which probably makes
		1260	them non-ECMAscript-compliant). For example, Iceweasel reserves the
		1261	C<__proto__> property name for its own purposes.
967		1262
968	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>	1263	If that is a problem, you could parse try to filter the resulting JSON
969	which is not a valid JSON text.	1264	output for these property strings, e.g.:
970		1265
971	Unmaintained (maintainer unresponsive for many months, bugs are not	1266	$json =~ s/"__proto__"\s*:/"__proto__renamed":/g;
972	getting fixed).
973		1267
974	=item JSON::Syck 0.21	1268	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.
975		1270
976	Very buggy (often crashes).	1271	If you know of other incompatibilities, please let me know.
977
978	Very inflexible (no human-readable format supported, format pretty much
979	undocumented. I need at least a format for easy reading by humans and a
980	single-line compact format for use in a protocol, and preferably a way to
981	generate ASCII-only JSON texts).
982
983	Completely broken (and confusingly documented) Unicode handling (Unicode
984	escapes are not working properly, you need to set ImplicitUnicode to
985	I<different> values on en- and decoding to get symmetric behaviour).
986
987	No round-tripping (simple cases work, but this depends on whether the scalar
988	value was used in a numeric context or not).
989
990	Dumping hashes may skip hash values depending on iterator state.
991
992	Unmaintained (maintainer unresponsive for many months, bugs are not
993	getting fixed).
994
995	Does not check input for validity (i.e. will accept non-JSON input and
996	return "something" instead of raising an exception. This is a security
997	issue: imagine two banks transferring money between each other using
998	JSON. One bank might parse a given non-JSON request and deduct money,
999	while the other might reject the transaction with a syntax error. While a
1000	good protocol will at least recover, that is extra unnecessary work and
1001	the transaction will still not succeed).
1002
1003	=item JSON::DWIW 0.04
1004
1005	Very fast. Very natural. Very nice.
1006
1007	Undocumented Unicode handling (but the best of the pack. Unicode escapes
1008	still don't get parsed properly).
1009
1010	Very inflexible.
1011
1012	No round-tripping.
1013
1014	Does not generate valid JSON texts (key strings are often unquoted, empty keys
1015	result in nothing being output)
1016
1017	Does not check input for validity.
1018
1019	=back
1020		1272
1021		1273
1022	=head2 JSON and YAML	1274	=head2 JSON and YAML
1023		1275
1024	You often hear that JSON is a subset of YAML. This is, however, a mass	1276	You often hear that JSON is a subset of YAML. This is, however, a mass
1025	hysteria(*) and very far from the truth. In general, there is no way to	1277	hysteria(*) and very far from the truth (as of the time of this writing),
		1278	so let me state it clearly: I<in general, there is no way to configure
1026	configure JSON::XS to output a data structure as valid YAML that works for	1279	JSON::XS to output a data structure as valid YAML> that works in all
1027	all cases.	1280	cases.
1028		1281
1029	If you really must use JSON::XS to generate YAML, you should use this	1282	If you really must use JSON::XS to generate YAML, you should use this
1030	algorithm (subject to change in future versions):	1283	algorithm (subject to change in future versions):
1031		1284
1032	my $to_yaml = JSON::XS->new->utf8->space_after (1);	1285	my $to_yaml = JSON::XS->new->utf8->space_after (1);
1033	my $yaml = $to_yaml->encode ($ref) . "\n";	1286	my $yaml = $to_yaml->encode ($ref) . "\n";
1034		1287
1035	This will I<usually> generate JSON texts that also parse as valid	1288	This will I<usually> generate JSON texts that also parse as valid
1036	YAML. Please note that YAML has hardcoded limits on (simple) object key	1289	YAML. Please note that YAML has hardcoded limits on (simple) object key
1037	lengths that JSON doesn't have and also has different and incompatible	1290	lengths that JSON doesn't have and also has different and incompatible
1038	unicode handling, so you should make sure that your hash keys are	1291	unicode character escape syntax, so you should make sure that your hash
1039	noticeably shorter than the 1024 "stream characters" YAML allows and that	1292	keys are noticeably shorter than the 1024 "stream characters" YAML allows
1040	you do not have codepoints with values outside the Unicode BMP (basic	1293	and that you do not have characters with codepoint values outside the
1041	multilingual page). YAML also does not allow C<\/> sequences in strings	1294	Unicode BMP (basic multilingual page). YAML also does not allow C<\/>
1042	(which JSON::XS does not I<currently> generate).	1295	sequences in strings (which JSON::XS does not I<currently> generate, but
		1296	other JSON generators might).
1043		1297
1044	There might be other incompatibilities that I am not aware of (or the YAML	1298	There might be other incompatibilities that I am not aware of (or the YAML
1045	specification has been changed yet again - it does so quite often). In	1299	specification has been changed yet again - it does so quite often). In
1046	general you should not try to generate YAML with a JSON generator or vice	1300	general you should not try to generate YAML with a JSON generator or vice
1047	versa, or try to parse JSON with a YAML parser or vice versa: chances are	1301	versa, or try to parse JSON with a YAML parser or vice versa: chances are
…		…
1050		1304
1051	=over 4	1305	=over 4
1052		1306
1053	=item (*)	1307	=item (*)
1054		1308
1055	This is spread actively by the YAML team, however. For many years now they	1309	I have been pressured multiple times by Brian Ingerson (one of the
1056	claim YAML were a superset of JSON, even when proven otherwise.	1310	authors of the YAML specification) to remove this paragraph, despite him
		1311	acknowledging that the actual incompatibilities exist. As I was personally
		1312	bitten by this "JSON is YAML" lie, I refused and said I will continue to
		1313	educate people about these issues, so others do not run into the same
		1314	problem again and again. After this, Brian called me a (quote)I<complete
		1315	and worthless idiot>(unquote).
1057		1316
1058	Even the author of this manpage was at some point accused of providing	1317	In my opinion, instead of pressuring and insulting people who actually
1059	"incorrect" information, despite the evidence presented (claims ranged	1318	clarify issues with YAML and the wrong statements of some of its
1060	from "your documentation contains inaccurate and negative statements about	1319	proponents, I would kindly suggest reading the JSON spec (which is not
1061	YAML" (the only negative comment is this footnote, and it didn't exist	1320	that difficult or long) and finally make YAML compatible to it, and
1062	back then; the question on which claims were inaccurate was never answered	1321	educating users about the changes, instead of spreading lies about the
1063	etc.) to "the YAML spec is not up-to-date" (the real and supposedly	1322	real compatibility for many I<years> and trying to silence people who
1064	JSON-compatible spec is apparently not currently publicly available)	1323	point out that it isn't true.
1065	to actual requests to replace this section by incorrect information,
1066	suppressing information about the real problem).
1067		1324
1068	So whenever you are told that YAML was a superset of JSON, first check	1325	Addendum/2009: the YAML 1.2 spec is still incompatible with JSON, even
1069	wether it is really true (it might be when you check it, but it certainly	1326	though the incompatibilities have been documented (and are known to Brian)
1070	was not true when this was written). I would much prefer if the YAML team	1327	for many years and the spec makes explicit claims that YAML is a superset
1071	would spent their time on actually making JSON compatibility a truth	1328	of JSON. It would be so easy to fix, but apparently, bullying people and
1072	(JSON, after all, has a very small and simple specification) instead of	1329	corrupting userdata is so much easier.
1073	trying to lobby/force people into reporting untruths.
1074		1330
1075	=back	1331	=back
1076		1332
1077		1333
1078	=head2 SPEED	1334	=head2 SPEED
…		…
1080	It seems that JSON::XS is surprisingly fast, as shown in the following	1336	It seems that JSON::XS is surprisingly fast, as shown in the following
1081	tables. They have been generated with the help of the C<eg/bench> program	1337	tables. They have been generated with the help of the C<eg/bench> program
1082	in the JSON::XS distribution, to make it easy to compare on your own	1338	in the JSON::XS distribution, to make it easy to compare on your own
1083	system.	1339	system.
1084		1340
1085	First comes a comparison between various modules using a very short	1341	First comes a comparison between various modules using
1086	single-line JSON string:	1342	a very short single-line JSON string (also available at
		1343	L<http://dist.schmorp.de/misc/json/short.json>).
1087		1344
1088	{"method": "handleMessage", "params": ["user1", "we were just talking"], \	1345	{"method": "handleMessage", "params": ["user1",
1089	"id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}	1346	"we were just talking"], "id": null, "array":[1,11,234,-5,1e5,1e7,
		1347	1, 0]}
1090		1348
1091	It shows the number of encodes/decodes per second (JSON::XS uses	1349	It shows the number of encodes/decodes per second (JSON::XS uses
1092	the functional interface, while JSON::XS/2 uses the OO interface	1350	the functional interface, while JSON::XS/2 uses the OO interface
1093	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables	1351	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
1094	shrink). Higher is better:	1352	shrink. JSON::DWIW/DS uses the deserialise function, while JSON::DWIW::FJ
		1353	uses the from_json method). Higher is better:
1095		1354
1096	module \| encode \| decode \|	1355	module \| encode \| decode \|
1097	-----------\|------------\|------------\|	1356	--------------\|------------\|------------\|
1098	JSON 1.x \| 4990.842 \| 4088.813 \|	1357	JSON::DWIW/DS \| 86302.551 \| 102300.098 \|
1099	JSON::DWIW \| 51653.990 \| 71575.154 \|	1358	JSON::DWIW/FJ \| 86302.551 \| 75983.768 \|
1100	JSON::PC \| 65948.176 \| 74631.744 \|	1359	JSON::PP \| 15827.562 \| 6638.658 \|
1101	JSON::PP \| 8931.652 \| 3817.168 \|	1360	JSON::Syck \| 63358.066 \| 47662.545 \|
1102	JSON::Syck \| 24877.248 \| 27776.848 \|	1361	JSON::XS \| 511500.488 \| 511500.488 \|
1103	JSON::XS \| 388361.481 \| 227951.304 \|	1362	JSON::XS/2 \| 291271.111 \| 388361.481 \|
1104	JSON::XS/2 \| 227951.304 \| 218453.333 \|	1363	JSON::XS/3 \| 361577.931 \| 361577.931 \|
1105	JSON::XS/3 \| 338250.323 \| 218453.333 \|	1364	Storable \| 66788.280 \| 265462.278 \|
1106	Storable \| 16500.016 \| 135300.129 \|
1107	-----------+------------+------------+	1365	--------------+------------+------------+
1108		1366
1109	That is, JSON::XS is about five times faster than JSON::DWIW on encoding,	1367	That is, JSON::XS is almost six times faster than JSON::DWIW on encoding,
1110	about three times faster on decoding, and over forty times faster	1368	about five times faster on decoding, and over thirty to seventy times
1111	than JSON, even with pretty-printing and key sorting. It also compares	1369	faster than JSON's pure perl implementation. It also compares favourably
1112	favourably to Storable for small amounts of data.	1370	to Storable for small amounts of data.
1113		1371
1114	Using a longer test string (roughly 18KB, generated from Yahoo! Locals	1372	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
1115	search API (http://nanoref.com/yahooapis/mgPdGg):	1373	search API (L<http://dist.schmorp.de/misc/json/long.json>).
1116		1374
1117	module \| encode \| decode \|	1375	module \| encode \| decode \|
1118	-----------\|------------\|------------\|	1376	--------------\|------------\|------------\|
1119	JSON 1.x \| 55.260 \| 34.971 \|	1377	JSON::DWIW/DS \| 1647.927 \| 2673.916 \|
1120	JSON::DWIW \| 825.228 \| 1082.513 \|	1378	JSON::DWIW/FJ \| 1630.249 \| 2596.128 \|
1121	JSON::PC \| 3571.444 \| 2394.829 \|
1122	JSON::PP \| 210.987 \| 32.574 \|	1379	JSON::PP \| 400.640 \| 62.311 \|
1123	JSON::Syck \| 552.551 \| 787.544 \|	1380	JSON::Syck \| 1481.040 \| 1524.869 \|
1124	JSON::XS \| 5780.463 \| 4854.519 \|	1381	JSON::XS \| 20661.596 \| 9541.183 \|
1125	JSON::XS/2 \| 3869.998 \| 4798.975 \|	1382	JSON::XS/2 \| 10683.403 \| 9416.938 \|
1126	JSON::XS/3 \| 5862.880 \| 4798.975 \|	1383	JSON::XS/3 \| 20661.596 \| 9400.054 \|
1127	Storable \| 4445.002 \| 5235.027 \|	1384	Storable \| 19765.806 \| 10000.725 \|
1128	-----------+------------+------------+	1385	--------------+------------+------------+
1129		1386
1130	Again, JSON::XS leads by far (except for Storable which non-surprisingly	1387	Again, JSON::XS leads by far (except for Storable which non-surprisingly
1131	decodes faster).	1388	decodes a bit faster).
1132		1389
1133	On large strings containing lots of high Unicode characters, some modules	1390	On large strings containing lots of high Unicode characters, some modules
1134	(such as JSON::PC) seem to decode faster than JSON::XS, but the result	1391	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
1135	will be broken due to missing (or wrong) Unicode handling. Others refuse	1392	will be broken due to missing (or wrong) Unicode handling. Others refuse
1136	to decode or encode properly, so it was impossible to prepare a fair	1393	to decode or encode properly, so it was impossible to prepare a fair
…		…
1162	to free the temporary). If that is exceeded, the program crashes. To be	1419	to free the temporary). If that is exceeded, the program crashes. To be
1163	conservative, the default nesting limit is set to 512. If your process	1420	conservative, the default nesting limit is set to 512. If your process
1164	has a smaller stack, you should adjust this setting accordingly with the	1421	has a smaller stack, you should adjust this setting accordingly with the
1165	C<max_depth> method.	1422	C<max_depth> method.
1166		1423
1167	And last but least, something else could bomb you that I forgot to think	1424	Something else could bomb you, too, that I forgot to think of. In that
1168	of. In that case, you get to keep the pieces. I am always open for hints,	1425	case, you get to keep the pieces. I am always open for hints, though...
1169	though...	1426
		1427	Also keep in mind that JSON::XS might leak contents of your Perl data
		1428	structures in its error messages, so when you serialise sensitive
		1429	information you might want to make sure that exceptions thrown by JSON::XS
		1430	will not end up in front of untrusted eyes.
1170		1431
1171	If you are using JSON::XS to return packets to consumption	1432	If you are using JSON::XS to return packets to consumption
1172	by JavaScript scripts in a browser you should have a look at	1433	by JavaScript scripts in a browser you should have a look at
1173	L<http://jpsykes.com/47/practical-csrf-and-json-security> to see whether	1434	L<http://blog.archive.jpsykes.com/47/practical-csrf-and-json-security/> to
1174	you are vulnerable to some common attack vectors (which really are browser	1435	see whether you are vulnerable to some common attack vectors (which really
1175	design bugs, but it is still you who will have to deal with it, as major	1436	are browser design bugs, but it is still you who will have to deal with
1176	browser developers care only for features, not about getting security	1437	it, as major browser developers care only for features, not about getting
1177	right).	1438	security right).
1178		1439
1179		1440
1180	=head1 THREADS	1441	=head1 THREADS
1181		1442
1182	This module is I<not> guaranteed to be thread safe and there are no	1443	This module is I<not> guaranteed to be thread safe and there are no
1183	plans to change this until Perl gets thread support (as opposed to the	1444	plans to change this until Perl gets thread support (as opposed to the
1184	horribly slow so-called "threads" which are simply slow and bloated	1445	horribly slow so-called "threads" which are simply slow and bloated
1185	process simulations - use fork, its I<much> faster, cheaper, better).	1446	process simulations - use fork, it's I<much> faster, cheaper, better).
1186		1447
1187	(It might actually work, but you have been warned).	1448	(It might actually work, but you have been warned).
1188		1449
1189		1450
		1451	=head1 THE PERILS OF SETLOCALE
		1452
		1453	Sometimes people avoid the Perl locale support and directly call the
		1454	system's setlocale function with C<LC_ALL>.
		1455
		1456	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
		1458	print C<1>, and JSON::XS might output illegal JSON as JSON::XS relies on
		1459	perl to stringify numbers).
		1460
		1461	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>.
		1463
		1464	If you need C<LC_NUMERIC>, you should enable it only around the code that
		1465	actually needs it (avoiding stringification of numbers), and restore it
		1466	afterwards.
		1467
		1468
1190	=head1 BUGS	1469	=head1 BUGS
1191		1470
1192	While the goal of this module is to be correct, that unfortunately does	1471	While the goal of this module is to be correct, that unfortunately does
1193	not mean its bug-free, only that I think its design is bug-free. It is	1472	not mean it's bug-free, only that I think its design is bug-free. If you
1194	still relatively early in its development. If you keep reporting bugs they	1473	keep reporting bugs they will be fixed swiftly, though.
1195	will be fixed swiftly, though.
1196		1474
1197	Please refrain from using rt.cpan.org or any other bug reporting	1475	Please refrain from using rt.cpan.org or any other bug reporting
1198	service. I put the contact address into my modules for a reason.	1476	service. I put the contact address into my modules for a reason.
1199		1477
1200	=cut	1478	=cut
…		…
1220	"--" => sub { $_[0] = ${$_[0]} - 1 },	1498	"--" => sub { $_[0] = ${$_[0]} - 1 },
1221	fallback => 1;	1499	fallback => 1;
1222		1500
1223	1;	1501	1;
1224		1502
		1503	=head1 SEE ALSO
		1504
		1505	The F<json_xs> command line utility for quick experiments.
		1506
1225	=head1 AUTHOR	1507	=head1 AUTHOR
1226		1508
1227	Marc Lehmann <schmorp@schmorp.de>	1509	Marc Lehmann <schmorp@schmorp.de>
1228	http://home.schmorp.de/	1510	http://home.schmorp.de/
1229		1511

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Comparing JSON-XS/XS.pm (file contents): Revision 1.84 by root, Wed Mar 19 02:52:15 2008 UTC vs. Revision 1.139 by root, Thu May 23 09:31:32 2013 UTC

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Comparing JSON-XS/XS.pm (file contents):
Revision 1.84 by root, Wed Mar 19 02:52:15 2008 UTC vs.
Revision 1.139 by root, Thu May 23 09:31:32 2013 UTC