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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.78 by root, Wed Dec 5 10:59:28 2007 UTC vs.
Revision 1.116 by root, Tue Feb 17 23:41:20 2009 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	JSON::XS - JSON serialising/deserialising, done correctly and fast	3	JSON::XS - JSON serialising/deserialising, done correctly and fast
		4
		5	=encoding utf-8
4		6
5	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
6	(http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html)	8	(http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html)
7		9
8	=head1 SYNOPSIS	10	=head1 SYNOPSIS
35	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
36	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.
37		39
38	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
39	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
40	overriden) with no overhead due to emulation (by inheritign constructor	42	overridden) with no overhead due to emulation (by inheriting constructor
41	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
42	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
43	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
44	require a C compiler when that is a problem.	46	require a C compiler when that is a problem.
45		47
…		…
47	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
48	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
49	their maintainers are unresponsive, gone missing, or not listening to bug	51	their maintainers are unresponsive, gone missing, or not listening to bug
50	reports for other reasons.	52	reports for other reasons.
51		53
52	See COMPARISON, below, for a comparison to some other JSON modules.
53
54	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
55	vice versa.	55	vice versa.
56		56
57	=head2 FEATURES	57	=head2 FEATURES
58		58
59	=over 4	59	=over 4
60		60
61	=item * correct Unicode handling	61	=item * correct Unicode handling
62		62
63	This module knows how to handle Unicode, and even documents how and when	63	This module knows how to handle Unicode, documents how and when it does
64	it does so.	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 datatypes 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, the deserialised data structure is identical on the Perl level.
70	(e.g. the string "2.0" doesn't suddenly become "2" just because it looks	70	(e.g. the string "2.0" doesn't suddenly become "2" just because it looks
71	like a number).	71	like a number). There minor I<are> exceptions to this, read the MAPPING
		72	section below to learn about those.
72		73
73	=item * strict checking of JSON correctness	74	=item * strict checking of JSON correctness
74		75
75	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,
76	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
77	feature).	78	feature).
78		79
79	=item * fast	80	=item * fast
80		81
81	Compared to other JSON modules, this module compares favourably in terms	82	Compared to other JSON modules and other serialisers such as Storable,
82	of speed, too.	83	this module usually compares favourably in terms of speed, too.
83		84
84	=item * simple to use	85	=item * simple to use
85		86
86	This module has both a simple functional interface as well as an OO	87	This module has both a simple functional interface as well as an object
87	interface.	88	oriented interface interface.
88		89
89	=item * reasonably versatile output formats	90	=item * reasonably versatile output formats
90		91
91	You can choose between the most compact guaranteed single-line format	92	You can choose between the most compact guaranteed-single-line format
92	possible (nice for simple line-based protocols), a pure-ascii format	93	possible (nice for simple line-based protocols), a pure-ASCII format
93	(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
94	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
95	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.
96		97
97	=back	98	=back
98		99
99	=cut	100	=cut
100		101
101	package JSON::XS;	102	package JSON::XS;
102		103
		104	no warnings;
103	use strict;	105	use strict;
104		106
105	our $VERSION = '2.01';	107	our $VERSION = '2.232';
106	our @ISA = qw(Exporter);	108	our @ISA = qw(Exporter);
107		109
108	our @EXPORT = qw(encode_json decode_json to_json from_json);	110	our @EXPORT = qw(encode_json decode_json to_json from_json);
109		111
110	sub to_json($) {	112	sub to_json($) {
…		…
134		136
135	This function call is functionally identical to:	137	This function call is functionally identical to:
136		138
137	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)	139	$json_text = JSON::XS->new->utf8->encode ($perl_scalar)
138		140
139	except being faster.	141	Except being faster.
140		142
141	=item $perl_scalar = decode_json $json_text	143	=item $perl_scalar = decode_json $json_text
142		144
143	The opposite of C<encode_json>: expects an UTF-8 (binary) string and tries	145	The opposite of C<encode_json>: expects an UTF-8 (binary) string and tries
144	to parse that as an UTF-8 encoded JSON text, returning the resulting	146	to parse that as an UTF-8 encoded JSON text, returning the resulting
…		…
146		148
147	This function call is functionally identical to:	149	This function call is functionally identical to:
148		150
149	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)	151	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
150		152
151	except being faster.	153	Except being faster.
152		154
153	=item $is_boolean = JSON::XS::is_bool $scalar	155	=item $is_boolean = JSON::XS::is_bool $scalar
154		156
155	Returns true if the passed scalar represents either JSON::XS::true or	157	Returns true if the passed scalar represents either JSON::XS::true or
156	JSON::XS::false, two constants that act like C<1> and C<0>, respectively	158	JSON::XS::false, two constants that act like C<1> and C<0>, respectively
…		…
174	This enables you to store Unicode characters as single characters in a	176	This enables you to store Unicode characters as single characters in a
175	Perl string - very natural.	177	Perl string - very natural.
176		178
177	=item 2. Perl does I<not> associate an encoding with your strings.	179	=item 2. Perl does I<not> associate an encoding with your strings.
178		180
179	Unless you force it to, e.g. when matching it against a regex, or printing	181	... until you force it to, e.g. when matching it against a regex, or
180	the scalar to a file, in which case Perl either interprets your string as	182	printing the scalar to a file, in which case Perl either interprets your
181	locale-encoded text, octets/binary, or as Unicode, depending on various	183	string as locale-encoded text, octets/binary, or as Unicode, depending
182	settings. In no case is an encoding stored together with your data, it is	184	on various settings. In no case is an encoding stored together with your
183	I<use> that decides encoding, not any magical metadata.	185	data, it is I<use> that decides encoding, not any magical meta data.
184		186
185	=item 3. The internal utf-8 flag has no meaning with regards to the	187	=item 3. The internal utf-8 flag has no meaning with regards to the
186	encoding of your string.	188	encoding of your string.
187		189
188	Just ignore that flag unless you debug a Perl bug, a module written in	190	Just ignore that flag unless you debug a Perl bug, a module written in
…		…
194		196
195	If you didn't know about that flag, just the better, pretend it doesn't	197	If you didn't know about that flag, just the better, pretend it doesn't
196	exist.	198	exist.
197		199
198	=item 4. A "Unicode String" is simply a string where each character can be	200	=item 4. A "Unicode String" is simply a string where each character can be
199	validly interpreted as a Unicode codepoint.	201	validly interpreted as a Unicode code point.
200		202
201	If you have UTF-8 encoded data, it is no longer a Unicode string, but a	203	If you have UTF-8 encoded data, it is no longer a Unicode string, but a
202	Unicode string encoded in UTF-8, giving you a binary string.	204	Unicode string encoded in UTF-8, giving you a binary string.
203		205
204	=item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string.	206	=item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string.
…		…
242		244
243	If C<$enable> is false, then the C<encode> method will not escape Unicode	245	If C<$enable> is false, then the C<encode> method will not escape Unicode
244	characters unless required by the JSON syntax or other flags. This results	246	characters unless required by the JSON syntax or other flags. This results
245	in a faster and more compact format.	247	in a faster and more compact format.
246		248
		249	See also the section I<ENCODING/CODESET FLAG NOTES> later in this
		250	document.
		251
247	The main use for this flag is to produce JSON texts that can be	252	The main use for this flag is to produce JSON texts that can be
248	transmitted over a 7-bit channel, as the encoded JSON texts will not	253	transmitted over a 7-bit channel, as the encoded JSON texts will not
249	contain any 8 bit characters.	254	contain any 8 bit characters.
250		255
251	JSON::XS->new->ascii (1)->encode ([chr 0x10401])	256	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
…		…
262	will not be affected in any way by this flag, as C<decode> by default	267	will not be affected in any way by this flag, as C<decode> by default
263	expects Unicode, which is a strict superset of latin1.	268	expects Unicode, which is a strict superset of latin1.
264		269
265	If C<$enable> is false, then the C<encode> method will not escape Unicode	270	If C<$enable> is false, then the C<encode> method will not escape Unicode
266	characters unless required by the JSON syntax or other flags.	271	characters unless required by the JSON syntax or other flags.
		272
		273	See also the section I<ENCODING/CODESET FLAG NOTES> later in this
		274	document.
267		275
268	The main use for this flag is efficiently encoding binary data as JSON	276	The main use for this flag is efficiently encoding binary data as JSON
269	text, as most octets will not be escaped, resulting in a smaller encoded	277	text, as most octets will not be escaped, resulting in a smaller encoded
270	size. The disadvantage is that the resulting JSON text is encoded	278	size. The disadvantage is that the resulting JSON text is encoded
271	in latin1 (and must correctly be treated as such when storing and	279	in latin1 (and must correctly be treated as such when storing and
…		…
290		298
291	If C<$enable> is false, then the C<encode> method will return the JSON	299	If C<$enable> is false, then the C<encode> method will return the JSON
292	string as a (non-encoded) Unicode string, while C<decode> expects thus a	300	string as a (non-encoded) Unicode string, while C<decode> expects thus a
293	Unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs	301	Unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs
294	to be done yourself, e.g. using the Encode module.	302	to be done yourself, e.g. using the Encode module.
		303
		304	See also the section I<ENCODING/CODESET FLAG NOTES> later in this
		305	document.
295		306
296	Example, output UTF-16BE-encoded JSON:	307	Example, output UTF-16BE-encoded JSON:
297		308
298	use Encode;	309	use Encode;
299	$jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);	310	$jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);
…		…
450	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,	461	Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,
451	resulting in an invalid JSON text:	462	resulting in an invalid JSON text:
452		463
453	JSON::XS->new->allow_nonref->encode ("Hello, World!")	464	JSON::XS->new->allow_nonref->encode ("Hello, World!")
454	=> "Hello, World!"	465	=> "Hello, World!"
		466
		467	=item $json = $json->allow_unknown ([$enable])
		468
		469	=item $enabled = $json->get_allow_unknown
		470
		471	If C<$enable> is true (or missing), then C<encode> will I<not> throw an
		472	exception when it encounters values it cannot represent in JSON (for
		473	example, filehandles) but instead will encode a JSON C<null> value. Note
		474	that blessed objects are not included here and are handled separately by
		475	c<allow_nonref>.
		476
		477	If C<$enable> is false (the default), then C<encode> will throw an
		478	exception when it encounters anything it cannot encode as JSON.
		479
		480	This option does not affect C<decode> in any way, and it is recommended to
		481	leave it off unless you know your communications partner.
455		482
456	=item $json = $json->allow_blessed ([$enable])	483	=item $json = $json->allow_blessed ([$enable])
457		484
458	=item $enabled = $json->get_allow_blessed	485	=item $enabled = $json->get_allow_blessed
459		486
…		…
600	=item $json = $json->max_depth ([$maximum_nesting_depth])	627	=item $json = $json->max_depth ([$maximum_nesting_depth])
601		628
602	=item $max_depth = $json->get_max_depth	629	=item $max_depth = $json->get_max_depth
603		630
604	Sets the maximum nesting level (default C<512>) accepted while encoding	631	Sets the maximum nesting level (default C<512>) accepted while encoding
605	or decoding. If the JSON text or Perl data structure has an equal or	632	or decoding. If a higher nesting level is detected in JSON text or a Perl
606	higher nesting level then this limit, then the encoder and decoder will	633	data structure, then the encoder and decoder will stop and croak at that
607	stop and croak at that point.	634	point.
608		635
609	Nesting level is defined by number of hash- or arrayrefs that the encoder	636	Nesting level is defined by number of hash- or arrayrefs that the encoder
610	needs to traverse to reach a given point or the number of C<{> or C<[>	637	needs to traverse to reach a given point or the number of C<{> or C<[>
611	characters without their matching closing parenthesis crossed to reach a	638	characters without their matching closing parenthesis crossed to reach a
612	given character in a string.	639	given character in a string.
613		640
614	Setting the maximum depth to one disallows any nesting, so that ensures	641	Setting the maximum depth to one disallows any nesting, so that ensures
615	that the object is only a single hash/object or array.	642	that the object is only a single hash/object or array.
616		643
617	The argument to C<max_depth> will be rounded up to the next highest power
618	of two. If no argument is given, the highest possible setting will be	644	If no argument is given, the highest possible setting will be used, which
619	used, which is rarely useful.	645	is rarely useful.
		646
		647	Note that nesting is implemented by recursion in C. The default value has
		648	been chosen to be as large as typical operating systems allow without
		649	crashing.
620		650
621	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	651	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
622		652
623	=item $json = $json->max_size ([$maximum_string_size])	653	=item $json = $json->max_size ([$maximum_string_size])
624		654
625	=item $max_size = $json->get_max_size	655	=item $max_size = $json->get_max_size
626		656
627	Set the maximum length a JSON text may have (in bytes) where decoding is	657	Set the maximum length a JSON text may have (in bytes) where decoding is
628	being attempted. The default is C<0>, meaning no limit. When C<decode>	658	being attempted. The default is C<0>, meaning no limit. When C<decode>
629	is called on a string longer then this number of characters it will not	659	is called on a string that is longer then this many bytes, it will not
630	attempt to decode the string but throw an exception. This setting has no	660	attempt to decode the string but throw an exception. This setting has no
631	effect on C<encode> (yet).	661	effect on C<encode> (yet).
632		662
633	The argument to C<max_size> will be rounded up to the next B<highest>	663	If no argument is given, the limit check will be deactivated (same as when
634	power of two (so may be more than requested). If no argument is given, the	664	C<0> is specified).
635	limit check will be deactivated (same as when C<0> is specified).
636		665
637	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	666	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
638		667
639	=item $json_text = $json->encode ($perl_scalar)	668	=item $json_text = $json->encode ($perl_scalar)
640		669
…		…
669	=> ([], 3)	698	=> ([], 3)
670		699
671	=back	700	=back
672		701
673		702
		703	=head1 INCREMENTAL PARSING
		704
		705	In some cases, there is the need for incremental parsing of JSON
		706	texts. While this module always has to keep both JSON text and resulting
		707	Perl data structure in memory at one time, it does allow you to parse a
		708	JSON stream incrementally. It does so by accumulating text until it has
		709	a full JSON object, which it then can decode. This process is similar to
		710	using C<decode_prefix> to see if a full JSON object is available, but
		711	is much more efficient (and can be implemented with a minimum of method
		712	calls).
		713
		714	JSON::XS will only attempt to parse the JSON text once it is sure it
		715	has enough text to get a decisive result, using a very simple but
		716	truly incremental parser. This means that it sometimes won't stop as
		717	early as the full parser, for example, it doesn't detect parenthese
		718	mismatches. The only thing it guarantees is that it starts decoding as
		719	soon as a syntactically valid JSON text has been seen. This means you need
		720	to set resource limits (e.g. C<max_size>) to ensure the parser will stop
		721	parsing in the presence if syntax errors.
		722
		723	The following methods implement this incremental parser.
		724
		725	=over 4
		726
		727	=item [void, scalar or list context] = $json->incr_parse ([$string])
		728
		729	This is the central parsing function. It can both append new text and
		730	extract objects from the stream accumulated so far (both of these
		731	functions are optional).
		732
		733	If C<$string> is given, then this string is appended to the already
		734	existing JSON fragment stored in the C<$json> object.
		735
		736	After that, if the function is called in void context, it will simply
		737	return without doing anything further. This can be used to add more text
		738	in as many chunks as you want.
		739
		740	If the method is called in scalar context, then it will try to extract
		741	exactly I<one> JSON object. If that is successful, it will return this
		742	object, otherwise it will return C<undef>. If there is a parse error,
		743	this method will croak just as C<decode> would do (one can then use
		744	C<incr_skip> to skip the errornous part). This is the most common way of
		745	using the method.
		746
		747	And finally, in list context, it will try to extract as many objects
		748	from the stream as it can find and return them, or the empty list
		749	otherwise. For this to work, there must be no separators between the JSON
		750	objects or arrays, instead they must be concatenated back-to-back. If
		751	an error occurs, an exception will be raised as in the scalar context
		752	case. Note that in this case, any previously-parsed JSON texts will be
		753	lost.
		754
		755	=item $lvalue_string = $json->incr_text
		756
		757	This method returns the currently stored JSON fragment as an lvalue, that
		758	is, you can manipulate it. This I<only> works when a preceding call to
		759	C<incr_parse> in I<scalar context> successfully returned an object. Under
		760	all other circumstances you must not call this function (I mean it.
		761	although in simple tests it might actually work, it I<will> fail under
		762	real world conditions). As a special exception, you can also call this
		763	method before having parsed anything.
		764
		765	This function is useful in two cases: a) finding the trailing text after a
		766	JSON object or b) parsing multiple JSON objects separated by non-JSON text
		767	(such as commas).
		768
		769	=item $json->incr_skip
		770
		771	This will reset the state of the incremental parser and will remove
		772	the parsed text from the input buffer so far. This is useful after
		773	C<incr_parse> died, in which case the input buffer and incremental parser
		774	state is left unchanged, to skip the text parsed so far and to reset the
		775	parse state.
		776
		777	The difference to C<incr_reset> is that only text until the parse error
		778	occured is removed.
		779
		780	=item $json->incr_reset
		781
		782	This completely resets the incremental parser, that is, after this call,
		783	it will be as if the parser had never parsed anything.
		784
		785	This is useful if you want to repeatedly parse JSON objects and want to
		786	ignore any trailing data, which means you have to reset the parser after
		787	each successful decode.
		788
		789	=back
		790
		791	=head2 LIMITATIONS
		792
		793	All options that affect decoding are supported, except
		794	C<allow_nonref>. The reason for this is that it cannot be made to
		795	work sensibly: JSON objects and arrays are self-delimited, i.e. you can concatenate
		796	them back to back and still decode them perfectly. This does not hold true
		797	for JSON numbers, however.
		798
		799	For example, is the string C<1> a single JSON number, or is it simply the
		800	start of C<12>? Or is C<12> a single JSON number, or the concatenation
		801	of C<1> and C<2>? In neither case you can tell, and this is why JSON::XS
		802	takes the conservative route and disallows this case.
		803
		804	=head2 EXAMPLES
		805
		806	Some examples will make all this clearer. First, a simple example that
		807	works similarly to C<decode_prefix>: We want to decode the JSON object at
		808	the start of a string and identify the portion after the JSON object:
		809
		810	my $text = "[1,2,3] hello";
		811
		812	my $json = new JSON::XS;
		813
		814	my $obj = $json->incr_parse ($text)
		815	or die "expected JSON object or array at beginning of string";
		816
		817	my $tail = $json->incr_text;
		818	# $tail now contains " hello"
		819
		820	Easy, isn't it?
		821
		822	Now for a more complicated example: Imagine a hypothetical protocol where
		823	you read some requests from a TCP stream, and each request is a JSON
		824	array, without any separation between them (in fact, it is often useful to
		825	use newlines as "separators", as these get interpreted as whitespace at
		826	the start of the JSON text, which makes it possible to test said protocol
		827	with C<telnet>...).
		828
		829	Here is how you'd do it (it is trivial to write this in an event-based
		830	manner):
		831
		832	my $json = new JSON::XS;
		833
		834	# read some data from the socket
		835	while (sysread $socket, my $buf, 4096) {
		836
		837	# split and decode as many requests as possible
		838	for my $request ($json->incr_parse ($buf)) {
		839	# act on the $request
		840	}
		841	}
		842
		843	Another complicated example: Assume you have a string with JSON objects
		844	or arrays, all separated by (optional) comma characters (e.g. C<[1],[2],
		845	[3]>). To parse them, we have to skip the commas between the JSON texts,
		846	and here is where the lvalue-ness of C<incr_text> comes in useful:
		847
		848	my $text = "[1],[2], [3]";
		849	my $json = new JSON::XS;
		850
		851	# void context, so no parsing done
		852	$json->incr_parse ($text);
		853
		854	# now extract as many objects as possible. note the
		855	# use of scalar context so incr_text can be called.
		856	while (my $obj = $json->incr_parse) {
		857	# do something with $obj
		858
		859	# now skip the optional comma
		860	$json->incr_text =~ s/^ \s* , //x;
		861	}
		862
		863	Now lets go for a very complex example: Assume that you have a gigantic
		864	JSON array-of-objects, many gigabytes in size, and you want to parse it,
		865	but you cannot load it into memory fully (this has actually happened in
		866	the real world :).
		867
		868	Well, you lost, you have to implement your own JSON parser. But JSON::XS
		869	can still help you: You implement a (very simple) array parser and let
		870	JSON decode the array elements, which are all full JSON objects on their
		871	own (this wouldn't work if the array elements could be JSON numbers, for
		872	example):
		873
		874	my $json = new JSON::XS;
		875
		876	# open the monster
		877	open my $fh, "<bigfile.json"
		878	or die "bigfile: $!";
		879
		880	# first parse the initial "["
		881	for (;;) {
		882	sysread $fh, my $buf, 65536
		883	or die "read error: $!";
		884	$json->incr_parse ($buf); # void context, so no parsing
		885
		886	# Exit the loop once we found and removed(!) the initial "[".
		887	# In essence, we are (ab-)using the $json object as a simple scalar
		888	# we append data to.
		889	last if $json->incr_text =~ s/^ \s* \[ //x;
		890	}
		891
		892	# now we have the skipped the initial "[", so continue
		893	# parsing all the elements.
		894	for (;;) {
		895	# in this loop we read data until we got a single JSON object
		896	for (;;) {
		897	if (my $obj = $json->incr_parse) {
		898	# do something with $obj
		899	last;
		900	}
		901
		902	# add more data
		903	sysread $fh, my $buf, 65536
		904	or die "read error: $!";
		905	$json->incr_parse ($buf); # void context, so no parsing
		906	}
		907
		908	# in this loop we read data until we either found and parsed the
		909	# separating "," between elements, or the final "]"
		910	for (;;) {
		911	# first skip whitespace
		912	$json->incr_text =~ s/^\s*//;
		913
		914	# if we find "]", we are done
		915	if ($json->incr_text =~ s/^\]//) {
		916	print "finished.\n";
		917	exit;
		918	}
		919
		920	# if we find ",", we can continue with the next element
		921	if ($json->incr_text =~ s/^,//) {
		922	last;
		923	}
		924
		925	# if we find anything else, we have a parse error!
		926	if (length $json->incr_text) {
		927	die "parse error near ", $json->incr_text;
		928	}
		929
		930	# else add more data
		931	sysread $fh, my $buf, 65536
		932	or die "read error: $!";
		933	$json->incr_parse ($buf); # void context, so no parsing
		934	}
		935
		936	This is a complex example, but most of the complexity comes from the fact
		937	that we are trying to be correct (bear with me if I am wrong, I never ran
		938	the above example :).
		939
		940
		941
674	=head1 MAPPING	942	=head1 MAPPING
675		943
676	This section describes how JSON::XS maps Perl values to JSON values and	944	This section describes how JSON::XS maps Perl values to JSON values and
677	vice versa. These mappings are designed to "do the right thing" in most	945	vice versa. These mappings are designed to "do the right thing" in most
678	circumstances automatically, preserving round-tripping characteristics	946	circumstances automatically, preserving round-tripping characteristics
…		…
706		974
707	A JSON number becomes either an integer, numeric (floating point) or	975	A JSON number becomes either an integer, numeric (floating point) or
708	string scalar in perl, depending on its range and any fractional parts. On	976	string scalar in perl, depending on its range and any fractional parts. On
709	the Perl level, there is no difference between those as Perl handles all	977	the Perl level, there is no difference between those as Perl handles all
710	the conversion details, but an integer may take slightly less memory and	978	the conversion details, but an integer may take slightly less memory and
711	might represent more values exactly than (floating point) numbers.	979	might represent more values exactly than floating point numbers.
712		980
713	If the number consists of digits only, JSON::XS will try to represent	981	If the number consists of digits only, JSON::XS will try to represent
714	it as an integer value. If that fails, it will try to represent it as	982	it as an integer value. If that fails, it will try to represent it as
715	a numeric (floating point) value if that is possible without loss of	983	a numeric (floating point) value if that is possible without loss of
716	precision. Otherwise it will preserve the number as a string value.	984	precision. Otherwise it will preserve the number as a string value (in
		985	which case you lose roundtripping ability, as the JSON number will be
		986	re-encoded toa JSON string).
717		987
718	Numbers containing a fractional or exponential part will always be	988	Numbers containing a fractional or exponential part will always be
719	represented as numeric (floating point) values, possibly at a loss of	989	represented as numeric (floating point) values, possibly at a loss of
720	precision.	990	precision (in which case you might lose perfect roundtripping ability, but
721		991	the JSON number will still be re-encoded as a JSON number).
722	This might create round-tripping problems as numbers might become strings,
723	but as Perl is typeless there is no other way to do it.
724		992
725	=item true, false	993	=item true, false
726		994
727	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,	995	These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
728	respectively. They are overloaded to act almost exactly like the numbers	996	respectively. They are overloaded to act almost exactly like the numbers
…		…
765	Other unblessed references are generally not allowed and will cause an	1033	Other unblessed references are generally not allowed and will cause an
766	exception to be thrown, except for references to the integers C<0> and	1034	exception to be thrown, except for references to the integers C<0> and
767	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can	1035	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
768	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.	1036	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
769		1037
770	encode_json [\0,JSON::XS::true] # yields [false,true]	1038	encode_json [\0, JSON::XS::true] # yields [false,true]
771		1039
772	=item JSON::XS::true, JSON::XS::false	1040	=item JSON::XS::true, JSON::XS::false
773		1041
774	These special values become JSON true and JSON false values,	1042	These special values become JSON true and JSON false values,
775	respectively. You can also use C<\1> and C<\0> directly if you want.	1043	respectively. You can also use C<\1> and C<\0> directly if you want.
776		1044
777	=item blessed objects	1045	=item blessed objects
778		1046
779	Blessed objects are not allowed. JSON::XS currently tries to encode their	1047	Blessed objects are not directly representable in JSON. See the
780	underlying representation (hash- or arrayref), but this behaviour might	1048	C<allow_blessed> and C<convert_blessed> methods on various options on
781	change in future versions.	1049	how to deal with this: basically, you can choose between throwing an
		1050	exception, encoding the reference as if it weren't blessed, or provide
		1051	your own serialiser method.
782		1052
783	=item simple scalars	1053	=item simple scalars
784		1054
785	Simple Perl scalars (any scalar that is not a reference) are the most	1055	Simple Perl scalars (any scalar that is not a reference) are the most
786	difficult objects to encode: JSON::XS will encode undefined scalars as	1056	difficult objects to encode: JSON::XS will encode undefined scalars as
787	JSON null value, scalars that have last been used in a string context	1057	JSON C<null> values, scalars that have last been used in a string context
788	before encoding as JSON strings and anything else as number value:	1058	before encoding as JSON strings, and anything else as number value:
789		1059
790	# dump as number	1060	# dump as number
791	encode_json [2] # yields [2]	1061	encode_json [2] # yields [2]
792	encode_json [-3.0e17] # yields [-3e+17]	1062	encode_json [-3.0e17] # yields [-3e+17]
793	my $value = 5; encode_json [$value] # yields [5]	1063	my $value = 5; encode_json [$value] # yields [5]
…		…
811	my $x = "3"; # some variable containing a string	1081	my $x = "3"; # some variable containing a string
812	$x += 0; # numify it, ensuring it will be dumped as a number	1082	$x += 0; # numify it, ensuring it will be dumped as a number
813	$x *= 1; # same thing, the choice is yours.	1083	$x *= 1; # same thing, the choice is yours.
814		1084
815	You can not currently force the type in other, less obscure, ways. Tell me	1085	You can not currently force the type in other, less obscure, ways. Tell me
816	if you need this capability.	1086	if you need this capability (but don't forget to explain why it's needed
		1087	:).
817		1088
818	=back	1089	=back
819		1090
820		1091
821	=head1 COMPARISON	1092	=head1 ENCODING/CODESET FLAG NOTES
822		1093
823	As already mentioned, this module was created because none of the existing	1094	The interested reader might have seen a number of flags that signify
824	JSON modules could be made to work correctly. First I will describe the	1095	encodings or codesets - C<utf8>, C<latin1> and C<ascii>. There seems to be
825	problems (or pleasures) I encountered with various existing JSON modules,	1096	some confusion on what these do, so here is a short comparison:
826	followed by some benchmark values. JSON::XS was designed not to suffer	1097
827	from any of these problems or limitations.	1098	C<utf8> controls whether the JSON text created by C<encode> (and expected
		1099	by C<decode>) is UTF-8 encoded or not, while C<latin1> and C<ascii> only
		1100	control whether C<encode> escapes character values outside their respective
		1101	codeset range. Neither of these flags conflict with each other, although
		1102	some combinations make less sense than others.
		1103
		1104	Care has been taken to make all flags symmetrical with respect to
		1105	C<encode> and C<decode>, that is, texts encoded with any combination of
		1106	these flag values will be correctly decoded when the same flags are used
		1107	- in general, if you use different flag settings while encoding vs. when
		1108	decoding you likely have a bug somewhere.
		1109
		1110	Below comes a verbose discussion of these flags. Note that a "codeset" is
		1111	simply an abstract set of character-codepoint pairs, while an encoding
		1112	takes those codepoint numbers and I<encodes> them, in our case into
		1113	octets. Unicode is (among other things) a codeset, UTF-8 is an encoding,
		1114	and ISO-8859-1 (= latin 1) and ASCII are both codesets I<and> encodings at
		1115	the same time, which can be confusing.
828		1116
829	=over 4	1117	=over 4
830		1118
831	=item JSON 1.07	1119	=item C<utf8> flag disabled
832		1120
833	Slow (but very portable, as it is written in pure Perl).	1121	When C<utf8> is disabled (the default), then C<encode>/C<decode> generate
		1122	and expect Unicode strings, that is, characters with high ordinal Unicode
		1123	values (> 255) will be encoded as such characters, and likewise such
		1124	characters are decoded as-is, no canges to them will be done, except
		1125	"(re-)interpreting" them as Unicode codepoints or Unicode characters,
		1126	respectively (to Perl, these are the same thing in strings unless you do
		1127	funny/weird/dumb stuff).
834		1128
835	Undocumented/buggy Unicode handling (how JSON handles Unicode values is	1129	This is useful when you want to do the encoding yourself (e.g. when you
836	undocumented. One can get far by feeding it Unicode strings and doing	1130	want to have UTF-16 encoded JSON texts) or when some other layer does
837	en-/decoding oneself, but Unicode escapes are not working properly).	1131	the encoding for you (for example, when printing to a terminal using a
		1132	filehandle that transparently encodes to UTF-8 you certainly do NOT want
		1133	to UTF-8 encode your data first and have Perl encode it another time).
838		1134
839	No round-tripping (strings get clobbered if they look like numbers, e.g.	1135	=item C<utf8> flag enabled
840	the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will
841	decode into the number 2.
842		1136
843	=item JSON::PC 0.01	1137	If the C<utf8>-flag is enabled, C<encode>/C<decode> will encode all
		1138	characters using the corresponding UTF-8 multi-byte sequence, and will
		1139	expect your input strings to be encoded as UTF-8, that is, no "character"
		1140	of the input string must have any value > 255, as UTF-8 does not allow
		1141	that.
844		1142
845	Very fast.	1143	The C<utf8> flag therefore switches between two modes: disabled means you
		1144	will get a Unicode string in Perl, enabled means you get an UTF-8 encoded
		1145	octet/binary string in Perl.
846		1146
847	Undocumented/buggy Unicode handling.	1147	=item C<latin1> or C<ascii> flags enabled
848		1148
849	No round-tripping.	1149	With C<latin1> (or C<ascii>) enabled, C<encode> will escape characters
		1150	with ordinal values > 255 (> 127 with C<ascii>) and encode the remaining
		1151	characters as specified by the C<utf8> flag.
850		1152
851	Has problems handling many Perl values (e.g. regex results and other magic	1153	If C<utf8> is disabled, then the result is also correctly encoded in those
852	values will make it croak).	1154	character sets (as both are proper subsets of Unicode, meaning that a
		1155	Unicode string with all character values < 256 is the same thing as a
		1156	ISO-8859-1 string, and a Unicode string with all character values < 128 is
		1157	the same thing as an ASCII string in Perl).
853		1158
854	Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>	1159	If C<utf8> is enabled, you still get a correct UTF-8-encoded string,
855	which is not a valid JSON text.	1160	regardless of these flags, just some more characters will be escaped using
		1161	C<\uXXXX> then before.
856		1162
857	Unmaintained (maintainer unresponsive for many months, bugs are not	1163	Note that ISO-8859-1-I<encoded> strings are not compatible with UTF-8
858	getting fixed).	1164	encoding, while ASCII-encoded strings are. That is because the ISO-8859-1
		1165	encoding is NOT a subset of UTF-8 (despite the ISO-8859-1 I<codeset> being
		1166	a subset of Unicode), while ASCII is.
859		1167
860	=item JSON::Syck 0.21	1168	Surprisingly, C<decode> will ignore these flags and so treat all input
		1169	values as governed by the C<utf8> flag. If it is disabled, this allows you
		1170	to decode ISO-8859-1- and ASCII-encoded strings, as both strict subsets of
		1171	Unicode. If it is enabled, you can correctly decode UTF-8 encoded strings.
861		1172
862	Very buggy (often crashes).	1173	So neither C<latin1> nor C<ascii> are incompatible with the C<utf8> flag -
		1174	they only govern when the JSON output engine escapes a character or not.
863		1175
864	Very inflexible (no human-readable format supported, format pretty much	1176	The main use for C<latin1> is to relatively efficiently store binary data
865	undocumented. I need at least a format for easy reading by humans and a	1177	as JSON, at the expense of breaking compatibility with most JSON decoders.
866	single-line compact format for use in a protocol, and preferably a way to
867	generate ASCII-only JSON texts).
868		1178
869	Completely broken (and confusingly documented) Unicode handling (Unicode	1179	The main use for C<ascii> is to force the output to not contain characters
870	escapes are not working properly, you need to set ImplicitUnicode to	1180	with values > 127, which means you can interpret the resulting string
871	I<different> values on en- and decoding to get symmetric behaviour).	1181	as UTF-8, ISO-8859-1, ASCII, KOI8-R or most about any character set and
872		1182	8-bit-encoding, and still get the same data structure back. This is useful
873	No round-tripping (simple cases work, but this depends on whether the scalar	1183	when your channel for JSON transfer is not 8-bit clean or the encoding
874	value was used in a numeric context or not).	1184	might be mangled in between (e.g. in mail), and works because ASCII is a
875		1185	proper subset of most 8-bit and multibyte encodings in use in the world.
876	Dumping hashes may skip hash values depending on iterator state.
877
878	Unmaintained (maintainer unresponsive for many months, bugs are not
879	getting fixed).
880
881	Does not check input for validity (i.e. will accept non-JSON input and
882	return "something" instead of raising an exception. This is a security
883	issue: imagine two banks transferring money between each other using
884	JSON. One bank might parse a given non-JSON request and deduct money,
885	while the other might reject the transaction with a syntax error. While a
886	good protocol will at least recover, that is extra unnecessary work and
887	the transaction will still not succeed).
888
889	=item JSON::DWIW 0.04
890
891	Very fast. Very natural. Very nice.
892
893	Undocumented Unicode handling (but the best of the pack. Unicode escapes
894	still don't get parsed properly).
895
896	Very inflexible.
897
898	No round-tripping.
899
900	Does not generate valid JSON texts (key strings are often unquoted, empty keys
901	result in nothing being output)
902
903	Does not check input for validity.
904		1186
905	=back	1187	=back
906		1188
907		1189
		1190	=head2 JSON and ECMAscript
		1191
		1192	JSON syntax is based on how literals are represented in javascript (the
		1193	not-standardised predecessor of ECMAscript) which is presumably why it is
		1194	called "JavaScript Object Notation".
		1195
		1196	However, JSON is not a subset (and also not a superset of course) of
		1197	ECMAscript (the standard) or javascript (whatever browsers actually
		1198	implement).
		1199
		1200	If you want to use javascript's C<eval> function to "parse" JSON, you
		1201	might run into parse errors for valid JSON texts, or the resulting data
		1202	structure might not be queryable:
		1203
		1204	One of the problems is that U+2028 and U+2029 are valid characters inside
		1205	JSON strings, but are not allowed in ECMAscript string literals, so the
		1206	following Perl fragment will not output something that can be guaranteed
		1207	to be parsable by javascript's C<eval>:
		1208
		1209	use JSON::XS;
		1210
		1211	print encode_json [chr 0x2028];
		1212
		1213	The right fix for this is to use a proper JSON parser in your javascript
		1214	programs, and not rely on C<eval>.
		1215
		1216	If this is not an option, you can, as a stop-gap measure, simply encode to
		1217	ASCII-only JSON:
		1218
		1219	use JSON::XS;
		1220
		1221	print JSON::XS->new->ascii->encode ([chr 0x2028]);
		1222
		1223	And if you are concerned about the size of the resulting JSON text, you
		1224	can run some regexes to only escape U+2028 and U+2029:
		1225
		1226	use JSON::XS;
		1227
		1228	my $json = JSON::XS->new->utf8->encode ([chr 0x2028]);
		1229	$json =~ s/\xe2\x80\xa8/\\u2028/g; # escape U+2028
		1230	$json =~ s/\xe2\x80\xa9/\\u2029/g; # escape U+2029
		1231	print $json;
		1232
		1233	This works because U+2028/U+2029 are not allowed outside of strings and
		1234	are not used for syntax, so replacing them unconditionally just works.
		1235
		1236	Note, however, that fixing the broken JSON parser is better than working
		1237	around it in every other generator. The above regexes should work well in
		1238	other languages, as long as they operate on UTF-8. It is equally valid to
		1239	replace all occurences of U+2028/2029 directly by their \\u-escaped forms
		1240	in unicode texts, so they can simply be used to fix any parsers relying on
		1241	C<eval> by first applying the regexes on the encoded texts.
		1242
		1243	Note also that the above only works for U+2028 and U+2029 and thus
		1244	only for fully ECMAscript-compliant parsers. Many existing javascript
		1245	implementations misparse other characters as well. Best rely on a good
		1246	JSON parser, such as Douglas Crockfords F<json2.js>, which escapes the
		1247	above and many more problematic characters properly before passing them
		1248	into C<eval>.
		1249
		1250	Another problem is that some javascript implementations reserve
		1251	some property names for their own purposes (which probably makes
		1252	them non-ECMAscript-compliant). For example, Iceweasel reserves the
		1253	C<__proto__> property name for it's own purposes.
		1254
		1255	If that is a problem, you could parse try to filter the resulting JSON
		1256	output for these property strings, e.g.:
		1257
		1258	$json =~ s/"__proto__"\s*:/"__proto__renamed":/g;
		1259
		1260	This works because C<__proto__> is not valid outside of strings, so every
		1261	occurence of C<"__proto__"\s*:> must be a string used as property name.
		1262
		1263	If you know of other incompatibilities, please let me know.
		1264
		1265
908	=head2 JSON and YAML	1266	=head2 JSON and YAML
909		1267
910	You often hear that JSON is a subset (or a close subset) of YAML. This is,	1268	You often hear that JSON is a subset of YAML. This is, however, a mass
911	however, a mass hysteria and very far from the truth. In general, there is	1269	hysteria(*) and very far from the truth (as of the time of this writing),
912	no way to configure JSON::XS to output a data structure as valid YAML.	1270	so let me state it clearly: I<in general, there is no way to configure
		1271	JSON::XS to output a data structure as valid YAML> that works in all
		1272	cases.
913		1273
914	If you really must use JSON::XS to generate YAML, you should use this	1274	If you really must use JSON::XS to generate YAML, you should use this
915	algorithm (subject to change in future versions):	1275	algorithm (subject to change in future versions):
916		1276
917	my $to_yaml = JSON::XS->new->utf8->space_after (1);	1277	my $to_yaml = JSON::XS->new->utf8->space_after (1);
918	my $yaml = $to_yaml->encode ($ref) . "\n";	1278	my $yaml = $to_yaml->encode ($ref) . "\n";
919		1279
920	This will usually generate JSON texts that also parse as valid	1280	This will I<usually> generate JSON texts that also parse as valid
921	YAML. Please note that YAML has hardcoded limits on (simple) object key	1281	YAML. Please note that YAML has hardcoded limits on (simple) object key
922	lengths that JSON doesn't have, so you should make sure that your hash	1282	lengths that JSON doesn't have and also has different and incompatible
		1283	unicode handling, so you should make sure that your hash keys are
923	keys are noticeably shorter than the 1024 characters YAML allows.	1284	noticeably shorter than the 1024 "stream characters" YAML allows and that
		1285	you do not have characters with codepoint values outside the Unicode BMP
		1286	(basic multilingual page). YAML also does not allow C<\/> sequences in
		1287	strings (which JSON::XS does not I<currently> generate, but other JSON
		1288	generators might).
924		1289
925	There might be other incompatibilities that I am not aware of. In general	1290	There might be other incompatibilities that I am not aware of (or the YAML
		1291	specification has been changed yet again - it does so quite often). In
926	you should not try to generate YAML with a JSON generator or vice versa,	1292	general you should not try to generate YAML with a JSON generator or vice
927	or try to parse JSON with a YAML parser or vice versa: chances are high	1293	versa, or try to parse JSON with a YAML parser or vice versa: chances are
928	that you will run into severe interoperability problems.	1294	high that you will run into severe interoperability problems when you
		1295	least expect it.
		1296
		1297	=over 4
		1298
		1299	=item (*)
		1300
		1301	I have been pressured multiple times by Brian Ingerson (one of the
		1302	authors of the YAML specification) to remove this paragraph, despite him
		1303	acknowledging that the actual incompatibilities exist. As I was personally
		1304	bitten by this "JSON is YAML" lie, I refused and said I will continue to
		1305	educate people about these issues, so others do not run into the same
		1306	problem again and again. After this, Brian called me a (quote)I<complete
		1307	and worthless idiot>(unquote).
		1308
		1309	In my opinion, instead of pressuring and insulting people who actually
		1310	clarify issues with YAML and the wrong statements of some of its
		1311	proponents, I would kindly suggest reading the JSON spec (which is not
		1312	that difficult or long) and finally make YAML compatible to it, and
		1313	educating users about the changes, instead of spreading lies about the
		1314	real compatibility for many I<years> and trying to silence people who
		1315	point out that it isn't true.
		1316
		1317	=back
929		1318
930		1319
931	=head2 SPEED	1320	=head2 SPEED
932		1321
933	It seems that JSON::XS is surprisingly fast, as shown in the following	1322	It seems that JSON::XS is surprisingly fast, as shown in the following
934	tables. They have been generated with the help of the C<eg/bench> program	1323	tables. They have been generated with the help of the C<eg/bench> program
935	in the JSON::XS distribution, to make it easy to compare on your own	1324	in the JSON::XS distribution, to make it easy to compare on your own
936	system.	1325	system.
937		1326
938	First comes a comparison between various modules using a very short	1327	First comes a comparison between various modules using
939	single-line JSON string:	1328	a very short single-line JSON string (also available at
		1329	L<http://dist.schmorp.de/misc/json/short.json>).
940		1330
941	{"method": "handleMessage", "params": ["user1", "we were just talking"], \	1331	{"method": "handleMessage", "params": ["user1",
942	"id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}	1332	"we were just talking"], "id": null, "array":[1,11,234,-5,1e5,1e7,
		1333	true, false]}
943		1334
944	It shows the number of encodes/decodes per second (JSON::XS uses	1335	It shows the number of encodes/decodes per second (JSON::XS uses
945	the functional interface, while JSON::XS/2 uses the OO interface	1336	the functional interface, while JSON::XS/2 uses the OO interface
946	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables	1337	with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
947	shrink). Higher is better:	1338	shrink). Higher is better:
…		…
963	about three times faster on decoding, and over forty times faster	1354	about three times faster on decoding, and over forty times faster
964	than JSON, even with pretty-printing and key sorting. It also compares	1355	than JSON, even with pretty-printing and key sorting. It also compares
965	favourably to Storable for small amounts of data.	1356	favourably to Storable for small amounts of data.
966		1357
967	Using a longer test string (roughly 18KB, generated from Yahoo! Locals	1358	Using a longer test string (roughly 18KB, generated from Yahoo! Locals
968	search API (http://nanoref.com/yahooapis/mgPdGg):	1359	search API (L<http://dist.schmorp.de/misc/json/long.json>).
969		1360
970	module \| encode \| decode \|	1361	module \| encode \| decode \|
971	-----------\|------------\|------------\|	1362	-----------\|------------\|------------\|
972	JSON 1.x \| 55.260 \| 34.971 \|	1363	JSON 1.x \| 55.260 \| 34.971 \|
973	JSON::DWIW \| 825.228 \| 1082.513 \|	1364	JSON::DWIW \| 825.228 \| 1082.513 \|
…		…
1010		1401
1011	Third, JSON::XS recurses using the C stack when decoding objects and	1402	Third, JSON::XS recurses using the C stack when decoding objects and
1012	arrays. The C stack is a limited resource: for instance, on my amd64	1403	arrays. The C stack is a limited resource: for instance, on my amd64
1013	machine with 8MB of stack size I can decode around 180k nested arrays but	1404	machine with 8MB of stack size I can decode around 180k nested arrays but
1014	only 14k nested JSON objects (due to perl itself recursing deeply on croak	1405	only 14k nested JSON objects (due to perl itself recursing deeply on croak
1015	to free the temporary). If that is exceeded, the program crashes. to be	1406	to free the temporary). If that is exceeded, the program crashes. To be
1016	conservative, the default nesting limit is set to 512. If your process	1407	conservative, the default nesting limit is set to 512. If your process
1017	has a smaller stack, you should adjust this setting accordingly with the	1408	has a smaller stack, you should adjust this setting accordingly with the
1018	C<max_depth> method.	1409	C<max_depth> method.
1019		1410
1020	And last but least, something else could bomb you that I forgot to think	1411	Something else could bomb you, too, that I forgot to think of. In that
1021	of. In that case, you get to keep the pieces. I am always open for hints,	1412	case, you get to keep the pieces. I am always open for hints, though...
1022	though...	1413
		1414	Also keep in mind that JSON::XS might leak contents of your Perl data
		1415	structures in its error messages, so when you serialise sensitive
		1416	information you might want to make sure that exceptions thrown by JSON::XS
		1417	will not end up in front of untrusted eyes.
1023		1418
1024	If you are using JSON::XS to return packets to consumption	1419	If you are using JSON::XS to return packets to consumption
1025	by JavaScript scripts in a browser you should have a look at	1420	by JavaScript scripts in a browser you should have a look at
1026	L<http://jpsykes.com/47/practical-csrf-and-json-security> to see whether	1421	L<http://jpsykes.com/47/practical-csrf-and-json-security> to see whether
1027	you are vulnerable to some common attack vectors (which really are browser	1422	you are vulnerable to some common attack vectors (which really are browser
1028	design bugs, but it is still you who will have to deal with it, as major	1423	design bugs, but it is still you who will have to deal with it, as major
1029	browser developers care only for features, not about doing security	1424	browser developers care only for features, not about getting security
1030	right).	1425	right).
1031		1426
1032		1427
1033	=head1 THREADS	1428	=head1 THREADS
1034		1429
1035	This module is I<not> guaranteed to be thread safe and there are no	1430	This module is I<not> guaranteed to be thread safe and there are no
1036	plans to change this until Perl gets thread support (as opposed to the	1431	plans to change this until Perl gets thread support (as opposed to the
1037	horribly slow so-called "threads" which are simply slow and bloated	1432	horribly slow so-called "threads" which are simply slow and bloated
1038	process simulations - use fork, its I<much> faster, cheaper, better).	1433	process simulations - use fork, it's I<much> faster, cheaper, better).
1039		1434
1040	(It might actually work, but you have been warned).	1435	(It might actually work, but you have been warned).
1041		1436
1042		1437
1043	=head1 BUGS	1438	=head1 BUGS
1044		1439
1045	While the goal of this module is to be correct, that unfortunately does	1440	While the goal of this module is to be correct, that unfortunately does
1046	not mean its bug-free, only that I think its design is bug-free. It is	1441	not mean it's bug-free, only that I think its design is bug-free. If you
1047	still relatively early in its development. If you keep reporting bugs they	1442	keep reporting bugs they will be fixed swiftly, though.
1048	will be fixed swiftly, though.
1049		1443
1050	Please refrain from using rt.cpan.org or any other bug reporting	1444	Please refrain from using rt.cpan.org or any other bug reporting
1051	service. I put the contact address into my modules for a reason.	1445	service. I put the contact address into my modules for a reason.
1052		1446
1053	=cut	1447	=cut
…		…
1073	"--" => sub { $_[0] = ${$_[0]} - 1 },	1467	"--" => sub { $_[0] = ${$_[0]} - 1 },
1074	fallback => 1;	1468	fallback => 1;
1075		1469
1076	1;	1470	1;
1077		1471
		1472	=head1 SEE ALSO
		1473
		1474	The F<json_xs> command line utility for quick experiments.
		1475
1078	=head1 AUTHOR	1476	=head1 AUTHOR
1079		1477
1080	Marc Lehmann <schmorp@schmorp.de>	1478	Marc Lehmann <schmorp@schmorp.de>
1081	http://home.schmorp.de/	1479	http://home.schmorp.de/
1082		1480

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Comparing JSON-XS/XS.pm (file contents): Revision 1.78 by root, Wed Dec 5 10:59:28 2007 UTC vs. Revision 1.116 by root, Tue Feb 17 23:41:20 2009 UTC

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Comparing JSON-XS/XS.pm (file contents):
Revision 1.78 by root, Wed Dec 5 10:59:28 2007 UTC vs.
Revision 1.116 by root, Tue Feb 17 23:41:20 2009 UTC