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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.22 by root, Sun Mar 25 02:37:00 2007 UTC vs.
Revision 1.33 by root, Wed May 9 16:10:37 2007 UTC

…		…
86	package JSON::XS;	86	package JSON::XS;
87		87
88	use strict;	88	use strict;
89		89
90	BEGIN {	90	BEGIN {
91	our $VERSION = '0.8';	91	our $VERSION = '1.12';
92	our @ISA = qw(Exporter);	92	our @ISA = qw(Exporter);
93		93
94	our @EXPORT = qw(to_json from_json objToJson jsonToObj);	94	our @EXPORT = qw(to_json from_json objToJson jsonToObj);
95	require Exporter;	95	require Exporter;
96		96
…		…
128	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)	128	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
129		129
130	except being faster.	130	except being faster.
131		131
132	=back	132	=back
		133
133		134
134	=head1 OBJECT-ORIENTED INTERFACE	135	=head1 OBJECT-ORIENTED INTERFACE
135		136
136	The object oriented interface lets you configure your own encoding or	137	The object oriented interface lets you configure your own encoding or
137	decoding style, within the limits of supported formats.	138	decoding style, within the limits of supported formats.
…		…
153		154
154	If C<$enable> is true (or missing), then the C<encode> method will not	155	If C<$enable> is true (or missing), then the C<encode> method will not
155	generate characters outside the code range C<0..127> (which is ASCII). Any	156	generate characters outside the code range C<0..127> (which is ASCII). Any
156	unicode characters outside that range will be escaped using either a	157	unicode characters outside that range will be escaped using either a
157	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,	158	single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
158	as per RFC4627.	159	as per RFC4627. The resulting encoded JSON text can be treated as a native
		160	unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
		161	or any other superset of ASCII.
159		162
160	If C<$enable> is false, then the C<encode> method will not escape Unicode	163	If C<$enable> is false, then the C<encode> method will not escape Unicode
161	characters unless required by the JSON syntax. This results in a faster	164	characters unless required by the JSON syntax or other flags. This results
162	and more compact format.	165	in a faster and more compact format.
		166
		167	The main use for this flag is to produce JSON texts that can be
		168	transmitted over a 7-bit channel, as the encoded JSON texts will not
		169	contain any 8 bit characters.
163		170
164	JSON::XS->new->ascii (1)->encode ([chr 0x10401])	171	JSON::XS->new->ascii (1)->encode ([chr 0x10401])
165	=> ["\ud801\udc01"]	172	=> ["\ud801\udc01"]
		173
		174	=item $json = $json->latin1 ([$enable])
		175
		176	If C<$enable> is true (or missing), then the C<encode> method will encode
		177	the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
		178	outside the code range C<0..255>. The resulting string can be treated as a
		179	latin1-encoded JSON text or a native unicode string. The C<decode> method
		180	will not be affected in any way by this flag, as C<decode> by default
		181	expects unicode, which is a strict superset of latin1.
		182
		183	If C<$enable> is false, then the C<encode> method will not escape Unicode
		184	characters unless required by the JSON syntax or other flags.
		185
		186	The main use for this flag is efficiently encoding binary data as JSON
		187	text, as most octets will not be escaped, resulting in a smaller encoded
		188	size. The disadvantage is that the resulting JSON text is encoded
		189	in latin1 (and must correctly be treated as such when storing and
		190	transfering), a rare encoding for JSON. It is therefore most useful when
		191	you want to store data structures known to contain binary data efficiently
		192	in files or databases, not when talking to other JSON encoders/decoders.
		193
		194	JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
		195	=> ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
166		196
167	=item $json = $json->utf8 ([$enable])	197	=item $json = $json->utf8 ([$enable])
168		198
169	If C<$enable> is true (or missing), then the C<encode> method will encode	199	If C<$enable> is true (or missing), then the C<encode> method will encode
170	the JSON result into UTF-8, as required by many protocols, while the	200	the JSON result into UTF-8, as required by many protocols, while the
…		…
283	=> "Hello, World!"	313	=> "Hello, World!"
284		314
285	=item $json = $json->shrink ([$enable])	315	=item $json = $json->shrink ([$enable])
286		316
287	Perl usually over-allocates memory a bit when allocating space for	317	Perl usually over-allocates memory a bit when allocating space for
288	strings. This flag optionally resizes strings generated by either	318	strings. This flag optionally resizes strings generated by either
289	C<encode> or C<decode> to their minimum size possible. This can save	319	C<encode> or C<decode> to their minimum size possible. This can save
290	memory when your JSON texts are either very very long or you have many	320	memory when your JSON texts are either very very long or you have many
291	short strings. It will also try to downgrade any strings to octet-form	321	short strings. It will also try to downgrade any strings to octet-form
292	if possible: perl stores strings internally either in an encoding called	322	if possible: perl stores strings internally either in an encoding called
293	UTF-X or in octet-form. The latter cannot store everything but uses less	323	UTF-X or in octet-form. The latter cannot store everything but uses less
294	space in general.	324	space in general (and some buggy Perl or C code might even rely on that
		325	internal representation being used).
295		326
		327	The actual definition of what shrink does might change in future versions,
		328	but it will always try to save space at the expense of time.
		329
296	If C<$enable> is true (or missing), the string returned by C<encode> will be shrunk-to-fit,	330	If C<$enable> is true (or missing), the string returned by C<encode> will
297	while all strings generated by C<decode> will also be shrunk-to-fit.	331	be shrunk-to-fit, while all strings generated by C<decode> will also be
		332	shrunk-to-fit.
298		333
299	If C<$enable> is false, then the normal perl allocation algorithms are used.	334	If C<$enable> is false, then the normal perl allocation algorithms are used.
300	If you work with your data, then this is likely to be faster.	335	If you work with your data, then this is likely to be faster.
301		336
302	In the future, this setting might control other things, such as converting	337	In the future, this setting might control other things, such as converting
303	strings that look like integers or floats into integers or floats	338	strings that look like integers or floats into integers or floats
304	internally (there is no difference on the Perl level), saving space.	339	internally (there is no difference on the Perl level), saving space.
		340
		341	=item $json = $json->max_depth ([$maximum_nesting_depth])
		342
		343	Sets the maximum nesting level (default C<512>) accepted while encoding
		344	or decoding. If the JSON text or Perl data structure has an equal or
		345	higher nesting level then this limit, then the encoder and decoder will
		346	stop and croak at that point.
		347
		348	Nesting level is defined by number of hash- or arrayrefs that the encoder
		349	needs to traverse to reach a given point or the number of C<{> or C<[>
		350	characters without their matching closing parenthesis crossed to reach a
		351	given character in a string.
		352
		353	Setting the maximum depth to one disallows any nesting, so that ensures
		354	that the object is only a single hash/object or array.
		355
		356	The argument to C<max_depth> will be rounded up to the next nearest power
		357	of two.
		358
		359	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
305		360
306	=item $json_text = $json->encode ($perl_scalar)	361	=item $json_text = $json->encode ($perl_scalar)
307		362
308	Converts the given Perl data structure (a simple scalar or a reference	363	Converts the given Perl data structure (a simple scalar or a reference
309	to a hash or array) to its JSON representation. Simple scalars will be	364	to a hash or array) to its JSON representation. Simple scalars will be
…		…
321	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes	376	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
322	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.	377	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
323		378
324	=back	379	=back
325		380
		381
326	=head1 MAPPING	382	=head1 MAPPING
327		383
328	This section describes how JSON::XS maps Perl values to JSON values and	384	This section describes how JSON::XS maps Perl values to JSON values and
329	vice versa. These mappings are designed to "do the right thing" in most	385	vice versa. These mappings are designed to "do the right thing" in most
330	circumstances automatically, preserving round-tripping characteristics	386	circumstances automatically, preserving round-tripping characteristics
…		…
383	=over 4	439	=over 4
384		440
385	=item hash references	441	=item hash references
386		442
387	Perl hash references become JSON objects. As there is no inherent ordering	443	Perl hash references become JSON objects. As there is no inherent ordering
388	in hash keys, they will usually be encoded in a pseudo-random order that	444	in hash keys (or JSON objects), they will usually be encoded in a
389	can change between runs of the same program but stays generally the same	445	pseudo-random order that can change between runs of the same program but
390	within a single run of a program. JSON::XS can optionally sort the hash	446	stays generally the same within a single run of a program. JSON::XS can
391	keys (determined by the I<canonical> flag), so the same datastructure	447	optionally sort the hash keys (determined by the I<canonical> flag), so
392	will serialise to the same JSON text (given same settings and version of	448	the same datastructure will serialise to the same JSON text (given same
393	JSON::XS), but this incurs a runtime overhead.	449	settings and version of JSON::XS), but this incurs a runtime overhead
		450	and is only rarely useful, e.g. when you want to compare some JSON text
		451	against another for equality.
394		452
395	=item array references	453	=item array references
396		454
397	Perl array references become JSON arrays.	455	Perl array references become JSON arrays.
		456
		457	=item other references
		458
		459	Other unblessed references are generally not allowed and will cause an
		460	exception to be thrown, except for references to the integers C<0> and
		461	C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
		462	also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
		463
		464	to_json [\0,JSON::XS::true] # yields [false,true]
398		465
399	=item blessed objects	466	=item blessed objects
400		467
401	Blessed objects are not allowed. JSON::XS currently tries to encode their	468	Blessed objects are not allowed. JSON::XS currently tries to encode their
402	underlying representation (hash- or arrayref), but this behaviour might	469	underlying representation (hash- or arrayref), but this behaviour might
…		…
435	$x *= 1; # same thing, the choise is yours.	502	$x *= 1; # same thing, the choise is yours.
436		503
437	You can not currently output JSON booleans or force the type in other,	504	You can not currently output JSON booleans or force the type in other,
438	less obscure, ways. Tell me if you need this capability.	505	less obscure, ways. Tell me if you need this capability.
439		506
440	=item circular data structures
441
442	Those will be encoded until memory or stackspace runs out.
443
444	=back	507	=back
		508
445		509
446	=head1 COMPARISON	510	=head1 COMPARISON
447		511
448	As already mentioned, this module was created because none of the existing	512	As already mentioned, this module was created because none of the existing
449	JSON modules could be made to work correctly. First I will describe the	513	JSON modules could be made to work correctly. First I will describe the
…		…
578	(such as JSON::PC) seem to decode faster than JSON::XS, but the result	642	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
579	will be broken due to missing (or wrong) unicode handling. Others refuse	643	will be broken due to missing (or wrong) unicode handling. Others refuse
580	to decode or encode properly, so it was impossible to prepare a fair	644	to decode or encode properly, so it was impossible to prepare a fair
581	comparison table for that case.	645	comparison table for that case.
582		646
583	=head1 RESOURCE LIMITS
584		647
585	JSON::XS does not impose any limits on the size of JSON texts or Perl	648	=head1 SECURITY CONSIDERATIONS
586	values they represent - if your machine can handle it, JSON::XS will	649
587	encode or decode it. Future versions might optionally impose structure	650	When you are using JSON in a protocol, talking to untrusted potentially
588	depth and memory use resource limits.	651	hostile creatures requires relatively few measures.
		652
		653	First of all, your JSON decoder should be secure, that is, should not have
		654	any buffer overflows. Obviously, this module should ensure that and I am
		655	trying hard on making that true, but you never know.
		656
		657	Second, you need to avoid resource-starving attacks. That means you should
		658	limit the size of JSON texts you accept, or make sure then when your
		659	resources run out, thats just fine (e.g. by using a separate process that
		660	can crash safely). The size of a JSON text in octets or characters is
		661	usually a good indication of the size of the resources required to decode
		662	it into a Perl structure.
		663
		664	Third, JSON::XS recurses using the C stack when decoding objects and
		665	arrays. The C stack is a limited resource: for instance, on my amd64
		666	machine with 8MB of stack size I can decode around 180k nested arrays but
		667	only 14k nested JSON objects (due to perl itself recursing deeply on croak
		668	to free the temporary). If that is exceeded, the program crashes. to be
		669	conservative, the default nesting limit is set to 512. If your process
		670	has a smaller stack, you should adjust this setting accordingly with the
		671	C<max_depth> method.
		672
		673	And last but least, something else could bomb you that I forgot to think
		674	of. In that case, you get to keep the pieces. I am always open for hints,
		675	though...
		676
589		677
590	=head1 BUGS	678	=head1 BUGS
591		679
592	While the goal of this module is to be correct, that unfortunately does	680	While the goal of this module is to be correct, that unfortunately does
593	not mean its bug-free, only that I think its design is bug-free. It is	681	not mean its bug-free, only that I think its design is bug-free. It is
594	still very young and not well-tested. If you keep reporting bugs they will	682	still relatively early in its development. If you keep reporting bugs they
595	be fixed swiftly, though.	683	will be fixed swiftly, though.
596		684
597	=cut	685	=cut
		686
		687	sub true() { \1 }
		688	sub false() { \0 }
598		689
599	1;	690	1;
600		691
601	=head1 AUTHOR	692	=head1 AUTHOR
602		693

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Comparing JSON-XS/XS.pm (file contents): Revision 1.22 by root, Sun Mar 25 02:37:00 2007 UTC vs. Revision 1.33 by root, Wed May 9 16:10:37 2007 UTC

Diff Legend

Comparing JSON-XS/XS.pm (file contents):
Revision 1.22 by root, Sun Mar 25 02:37:00 2007 UTC vs.
Revision 1.33 by root, Wed May 9 16:10:37 2007 UTC