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

Comparing JSON-XS/XS.pm (file contents):
Revision 1.21 by root, Sun Mar 25 02:32:40 2007 UTC vs.
Revision 1.24 by root, Thu Mar 29 01:27:36 2007 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use JSON::XS;	7	use JSON::XS;
8		8
9	# exported functions, croak on error	9	# exported functions, they croak on error
		10	# and expect/generate UTF-8
10		11
11	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;	12	$utf8_encoded_json_text = to_json $perl_hash_or_arrayref;
12	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;	13	$perl_hash_or_arrayref = from_json $utf8_encoded_json_text;
13		14
14	# objToJson and jsonToObj are exported for JSON	15	# objToJson and jsonToObj aliases to to_json and from_json
		16	# are exported for compatibility to the JSON module,
15	# compatibility, but should not be used in new code.	17	# but should not be used in new code.
16		18
17	# oo-interface	19	# OO-interface
18		20
19	$coder = JSON::XS->new->ascii->pretty->allow_nonref;	21	$coder = JSON::XS->new->ascii->pretty->allow_nonref;
20	$pretty_printed_unencoded = $coder->encode ($perl_scalar);	22	$pretty_printed_unencoded = $coder->encode ($perl_scalar);
21	$perl_scalar = $coder->decode ($unicode_json_text);	23	$perl_scalar = $coder->decode ($unicode_json_text);
22		24
…		…
126	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)	128	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
127		129
128	except being faster.	130	except being faster.
129		131
130	=back	132	=back
		133
131		134
132	=head1 OBJECT-ORIENTED INTERFACE	135	=head1 OBJECT-ORIENTED INTERFACE
133		136
134	The object oriented interface lets you configure your own encoding or	137	The object oriented interface lets you configure your own encoding or
135	decoding style, within the limits of supported formats.	138	decoding style, within the limits of supported formats.
…		…
281	=> "Hello, World!"	284	=> "Hello, World!"
282		285
283	=item $json = $json->shrink ([$enable])	286	=item $json = $json->shrink ([$enable])
284		287
285	Perl usually over-allocates memory a bit when allocating space for	288	Perl usually over-allocates memory a bit when allocating space for
286	strings. This flag optionally resizes strings generated by either	289	strings. This flag optionally resizes strings generated by either
287	C<encode> or C<decode> to their minimum size possible. This can save	290	C<encode> or C<decode> to their minimum size possible. This can save
288	memory when your JSON texts are either very very long or you have many	291	memory when your JSON texts are either very very long or you have many
289	short strings. It will also try to downgrade any strings to octet-form	292	short strings. It will also try to downgrade any strings to octet-form
290	if possible: perl stores strings internally either in an encoding called	293	if possible: perl stores strings internally either in an encoding called
291	UTF-X or in octet-form. The latter cannot store everything but uses less	294	UTF-X or in octet-form. The latter cannot store everything but uses less
292	space in general.	295	space in general (and some buggy Perl or C code might even rely on that
		296	internal representation being used).
293		297
		298	The actual definition of what shrink does might change in future versions,
		299	but it will always try to save space at the expense of time.
		300
294	If C<$enable> is true (or missing), the string returned by C<encode> will be shrunk-to-fit,	301	If C<$enable> is true (or missing), the string returned by C<encode> will
295	while all strings generated by C<decode> will also be shrunk-to-fit.	302	be shrunk-to-fit, while all strings generated by C<decode> will also be
		303	shrunk-to-fit.
296		304
297	If C<$enable> is false, then the normal perl allocation algorithms are used.	305	If C<$enable> is false, then the normal perl allocation algorithms are used.
298	If you work with your data, then this is likely to be faster.	306	If you work with your data, then this is likely to be faster.
299		307
300	In the future, this setting might control other things, such as converting	308	In the future, this setting might control other things, such as converting
301	strings that look like integers or floats into integers or floats	309	strings that look like integers or floats into integers or floats
302	internally (there is no difference on the Perl level), saving space.	310	internally (there is no difference on the Perl level), saving space.
		311
		312	=item $json = $json->max_depth ([$maximum_nesting_depth])
		313
		314	Sets the maximum nesting level (default C<8192>) accepted while encoding
		315	or decoding. If the JSON text or Perl data structure has an equal or
		316	higher nesting level then this limit, then the encoder and decoder will
		317	stop and croak at that point.
		318
		319	Nesting level is defined by number of hash- or arrayrefs that the encoder
		320	needs to traverse to reach a given point or the number of C<{> or C<[>
		321	characters without their matching closing parenthesis crossed to reach a
		322	given character in a string.
		323
		324	Setting the maximum depth to one disallows any nesting, so that ensures
		325	that the object is only a single hash/object or array.
		326
		327	The argument to C<max_depth> will be rounded up to the next nearest power
		328	of two.
		329
		330	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
303		331
304	=item $json_text = $json->encode ($perl_scalar)	332	=item $json_text = $json->encode ($perl_scalar)
305		333
306	Converts the given Perl data structure (a simple scalar or a reference	334	Converts the given Perl data structure (a simple scalar or a reference
307	to a hash or array) to its JSON representation. Simple scalars will be	335	to a hash or array) to its JSON representation. Simple scalars will be
…		…
318	JSON numbers and strings become simple Perl scalars. JSON arrays become	346	JSON numbers and strings become simple Perl scalars. JSON arrays become
319	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes	347	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
320	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.	348	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
321		349
322	=back	350	=back
		351
323		352
324	=head1 MAPPING	353	=head1 MAPPING
325		354
326	This section describes how JSON::XS maps Perl values to JSON values and	355	This section describes how JSON::XS maps Perl values to JSON values and
327	vice versa. These mappings are designed to "do the right thing" in most	356	vice versa. These mappings are designed to "do the right thing" in most
…		…
438	=item circular data structures	467	=item circular data structures
439		468
440	Those will be encoded until memory or stackspace runs out.	469	Those will be encoded until memory or stackspace runs out.
441		470
442	=back	471	=back
		472
443		473
444	=head1 COMPARISON	474	=head1 COMPARISON
445		475
446	As already mentioned, this module was created because none of the existing	476	As already mentioned, this module was created because none of the existing
447	JSON modules could be made to work correctly. First I will describe the	477	JSON modules could be made to work correctly. First I will describe the
…		…
576	(such as JSON::PC) seem to decode faster than JSON::XS, but the result	606	(such as JSON::PC) seem to decode faster than JSON::XS, but the result
577	will be broken due to missing (or wrong) unicode handling. Others refuse	607	will be broken due to missing (or wrong) unicode handling. Others refuse
578	to decode or encode properly, so it was impossible to prepare a fair	608	to decode or encode properly, so it was impossible to prepare a fair
579	comparison table for that case.	609	comparison table for that case.
580		610
581	=head1 RESOURCE LIMITS
582		611
583	JSON::XS does not impose any limits on the size of JSON texts or Perl	612	=head1 SECURITY CONSIDERATIONS
584	values they represent - if your machine can handle it, JSON::XS will	613
585	encode or decode it. Future versions might optionally impose structure	614	When you are using JSON in a protocol, talking to untrusted potentially
586	depth and memory use resource limits.	615	hostile creatures requires relatively few measures.
		616
		617	First of all, your JSON decoder should be secure, that is, should not have
		618	any buffer overflows. Obviously, this module should ensure that and I am
		619	trying hard on making that true, but you never know.
		620
		621	Second, you need to avoid resource-starving attacks. That means you should
		622	limit the size of JSON texts you accept, or make sure then when your
		623	resources run out, thats just fine (e.g. by using a separate process that
		624	can crash safely). The size of a JSON text in octets or characters is
		625	usually a good indication of the size of the resources required to decode
		626	it into a Perl structure.
		627
		628	Third, JSON::XS recurses using the C stack when decoding objects and
		629	arrays. The C stack is a limited resource: for instance, on my amd64
		630	machine with 8MB of stack size I can decode around 180k nested arrays
		631	but only 14k nested JSON objects. If that is exceeded, the program
		632	crashes. Thats why the default nesting limit is set to 8192. If your
		633	process has a smaller stack, you should adjust this setting accordingly
		634	with the C<max_depth> method.
		635
		636	And last but least, something else could bomb you that I forgot to think
		637	of. In that case, you get to keep the pieces. I am alway sopen for hints,
		638	though...
		639
587		640
588	=head1 BUGS	641	=head1 BUGS
589		642
590	While the goal of this module is to be correct, that unfortunately does	643	While the goal of this module is to be correct, that unfortunately does
591	not mean its bug-free, only that I think its design is bug-free. It is	644	not mean its bug-free, only that I think its design is bug-free. It is
592	still very young and not well-tested. If you keep reporting bugs they will	645	still relatively early in its development. If you keep reporting bugs they
593	be fixed swiftly, though.	646	will be fixed swiftly, though.
594		647
595	=cut	648	=cut
596		649
597	1;	650	1;
598		651

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Comparing JSON-XS/XS.pm (file contents): Revision 1.21 by root, Sun Mar 25 02:32:40 2007 UTC vs. Revision 1.24 by root, Thu Mar 29 01:27:36 2007 UTC

Diff Legend

Comparing JSON-XS/XS.pm (file contents):
Revision 1.21 by root, Sun Mar 25 02:32:40 2007 UTC vs.
Revision 1.24 by root, Thu Mar 29 01:27:36 2007 UTC