JSON-XS/XS.pm

=head1 NAME

JSON::XS - JSON serialising/deserialising, done correctly and fast

=head1 SYNOPSIS

 use JSON::XS;

=head1 DESCRIPTION

This module converts Perl data structures to JSON and vice versa. Its
primary goal is to be I<correct> and its secondary goal is to be
I<fast>. To reach the latter goal it was written in C.

As this is the n-th-something JSON module on CPAN, what was the reason
to write yet another JSON module? While it seems there are many JSON
modules, none of them correctly handle all corner cases, and in most cases
their maintainers are unresponsive, gone missing, or not listening to bug
reports for other reasons.

See COMPARISON, below, for a comparison to some other JSON modules.

=head2 FEATURES

=over 4

=item * correct handling of unicode issues

This module knows how to handle Unicode, and even documents how it does so.

=item * round-trip integrity

When you serialise a perl data structure using only datatypes supported
by JSON, the deserialised data structure is identical on the Perl level.
(e.g. the string "2.0" doesn't suddenly become "2").

=item * strict checking of JSON correctness

There is no guessing, no generating of illegal JSON strings by default,
and only JSON is accepted as input (the latter is a security feature).

=item * fast

compared to other JSON modules, this module compares favourably.

=item * simple to use

This module has both a simple functional interface as well as an OO
interface.

=item * reasonably versatile output formats

You can choose between the most compact format possible, a pure-ascii
format, or a pretty-printed format. Or you can combine those features in
whatever way you like.

=back

=cut

package JSON::XS;

BEGIN {
   $VERSION = '0.1';
   @ISA = qw(Exporter);

   @EXPORT = qw(to_json from_json);
   require Exporter;

   require XSLoader;
   XSLoader::load JSON::XS::, $VERSION;
}

=head1 FUNCTIONAL INTERFACE

The following convinience methods are provided by this module. They are
exported by default:

=over 4

=item $json_string = to_json $perl_scalar

Converts the given Perl data structure (a simple scalar or a reference to
a hash or array) to a UTF-8 encoded, binary string (that is, the string contains
octets only). Croaks on error.

This function call is functionally identical to C<< JSON::XS->new->utf8
(1)->encode ($perl_scalar) >>.

=item $perl_scalar = from_json $json_string

The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to
parse that as an UTF-8 encoded JSON string, returning the resulting simple
scalar or reference. Croaks on error.

This function call is functionally identical to C<< JSON::XS->new->utf8
(1)->decode ($json_string) >>.

=back

=head1 OBJECT-ORIENTED INTERFACE

The object oriented interface lets you configure your own encoding or
decoding style, within the limits of supported formats.

=over 4

=item $json = new JSON::XS

Creates a new JSON::XS object that can be used to de/encode JSON
strings. All boolean flags described below are by default I<disabled>.

The mutators for flags all return the JSON object again and thus calls can
be chained:

   my $json = JSON::XS->new->utf8(1)->pretty(1)->encode ({a => [1,2]})
   => {"a" : [1, 2]}

=item $json = $json->ascii ($enable)

If C<$enable> is true, then the C<encode> method will not generate
characters outside the code range C<0..127>. Any unicode characters
outside that range will be escaped using either a single \uXXXX (BMP
characters) or a double \uHHHH\uLLLLL escape sequence, as per RFC4627.

If C<$enable> is false, then the C<encode> method will not escape Unicode
characters unless necessary.

=item $json = $json->utf8 ($enable)

If C<$enable> is true, then the C<encode> method will encode the JSON
string into UTF-8, as required by many protocols, while the C<decode>
method expects to be handled an UTF-8-encoded string.  Please note that
UTF-8-encoded strings do not contain any characters outside the range
C<0..255>, they are thus useful for bytewise/binary I/O.

If C<$enable> is false, then the C<encode> method will return the JSON
string as a (non-encoded) unicode string, while C<decode> expects thus a
unicode string.  Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs
to be done yourself, e.g. using the Encode module.

=item $json = $json->pretty ($enabla)

This enables (or disables) all of the C<indent>, C<space_before> and
C<space_after> (and in the future possibly more) settings in one call to
generate the most readable (or most compact) form possible.

=item $json = $json->indent ($enable)

If C<$enable> is true, then the C<encode> method will use a multiline
format as output, putting every array member or object/hash key-value pair
into its own line, identing them properly.

If C<$enable> is false, no newlines or indenting will be produced, and the
resulting JSON strings is guarenteed not to contain any C<newlines>.

This setting has no effect when decoding JSON strings.

=item $json = $json->space_before ($enable)

If C<$enable> is true, then the C<encode> method will add an extra
optional space before the C<:> separating keys from values in JSON objects.

If C<$enable> is false, then the C<encode> method will not add any extra
space at those places.

This setting has no effect when decoding JSON strings. You will also most
likely combine this setting with C<space_after>.

=item $json = $json->space_after ($enable)

If C<$enable> is true, then the C<encode> method will add an extra
optional space after the C<:> separating keys from values in JSON objects
and extra whitespace after the C<,> separating key-value pairs and array
members.

If C<$enable> is false, then the C<encode> method will not add any extra
space at those places.

This setting has no effect when decoding JSON strings.

=item $json = $json->canonical ($enable)

If C<$enable> is true, then the C<encode> method will output JSON objects
by sorting their keys. This is adding a comparatively high overhead.

If C<$enable> is false, then the C<encode> method will output key-value
pairs in the order Perl stores them (which will likely change between runs
of the same script).

This option is useful if you want the same data structure to be encoded as
the same JSON string (given the same overall settings). If it is disabled,
the same hash migh be encoded differently even if contains the same data,
as key-value pairs have no inherent ordering in Perl.

This setting has no effect when decoding JSON strings.

=item $json_string = $json->encode ($perl_scalar)

Converts the given Perl data structure (a simple scalar or a reference
to a hash or array) to its JSON representation. Simple scalars will be
converted into JSON string or number sequences, while references to arrays
become JSON arrays and references to hashes become JSON objects. Undefined
Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>
nor C<false> values will be generated.

=item $perl_scalar = $json->decode ($json_string)

The opposite of C<encode>: expects a JSON string and tries to parse it,
returning the resulting simple scalar or reference. Croaks on error.

JSON numbers and strings become simple Perl scalars. JSON arrays become
Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.

=back

=cut

1;

=head1 AUTHOR

 Marc Lehmann <schmorp@schmorp.de>
 http://home.schmorp.de/

=cut

Revision:	1.2
Committed:	Thu Mar 22 17:28:50 2007 UTC (17 years, 2 months ago) by root
Branch:	MAIN
Changes since 1.1:	+188 -25 lines
Log Message:	added preliminary documentation
#	Content
1	=head1 NAME
2
3	JSON::XS - JSON serialising/deserialising, done correctly and fast
4
5	=head1 SYNOPSIS
6
7	use JSON::XS;
8
9	=head1 DESCRIPTION
10
11	This module converts Perl data structures to JSON and vice versa. Its
12	primary goal is to be I<correct> and its secondary goal is to be
13	I<fast>. To reach the latter goal it was written in C.
14
15	As this is the n-th-something JSON module on CPAN, what was the reason
16	to write yet another JSON module? While it seems there are many JSON
17	modules, none of them correctly handle all corner cases, and in most cases
18	their maintainers are unresponsive, gone missing, or not listening to bug
19	reports for other reasons.
20
21	See COMPARISON, below, for a comparison to some other JSON modules.
22
23	=head2 FEATURES
24
25	=over 4
26
27	=item * correct handling of unicode issues
28
29	This module knows how to handle Unicode, and even documents how it does so.
30
31	=item * round-trip integrity
32
33	When you serialise a perl data structure using only datatypes supported
34	by JSON, the deserialised data structure is identical on the Perl level.
35	(e.g. the string "2.0" doesn't suddenly become "2").
36
37	=item * strict checking of JSON correctness
38
39	There is no guessing, no generating of illegal JSON strings by default,
40	and only JSON is accepted as input (the latter is a security feature).
41
42	=item * fast
43
44	compared to other JSON modules, this module compares favourably.
45
46	=item * simple to use
47
48	This module has both a simple functional interface as well as an OO
49	interface.
50
51	=item * reasonably versatile output formats
52
53	You can choose between the most compact format possible, a pure-ascii
54	format, or a pretty-printed format. Or you can combine those features in
55	whatever way you like.
56
57	=back
58
59	=cut
60
61	package JSON::XS;
62
63	BEGIN {
64	$VERSION = '0.1';
65	@ISA = qw(Exporter);
66
67	@EXPORT = qw(to_json from_json);
68	require Exporter;
69
70	require XSLoader;
71	XSLoader::load JSON::XS::, $VERSION;
72	}
73
74	=head1 FUNCTIONAL INTERFACE
75
76	The following convinience methods are provided by this module. They are
77	exported by default:
78
79	=over 4
80
81	=item $json_string = to_json $perl_scalar
82
83	Converts the given Perl data structure (a simple scalar or a reference to
84	a hash or array) to a UTF-8 encoded, binary string (that is, the string contains
85	octets only). Croaks on error.
86
87	This function call is functionally identical to C<< JSON::XS->new->utf8
88	(1)->encode ($perl_scalar) >>.
89
90	=item $perl_scalar = from_json $json_string
91
92	The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to
93	parse that as an UTF-8 encoded JSON string, returning the resulting simple
94	scalar or reference. Croaks on error.
95
96	This function call is functionally identical to C<< JSON::XS->new->utf8
97	(1)->decode ($json_string) >>.
98
99	=back
100
101	=head1 OBJECT-ORIENTED INTERFACE
102
103	The object oriented interface lets you configure your own encoding or
104	decoding style, within the limits of supported formats.
105
106	=over 4
107
108	=item $json = new JSON::XS
109
110	Creates a new JSON::XS object that can be used to de/encode JSON
111	strings. All boolean flags described below are by default I<disabled>.
112
113	The mutators for flags all return the JSON object again and thus calls can
114	be chained:
115
116	my $json = JSON::XS->new->utf8(1)->pretty(1)->encode ({a => [1,2]})
117	=> {"a" : [1, 2]}
118
119	=item $json = $json->ascii ($enable)
120
121	If C<$enable> is true, then the C<encode> method will not generate
122	characters outside the code range C<0..127>. Any unicode characters
123	outside that range will be escaped using either a single \uXXXX (BMP
124	characters) or a double \uHHHH\uLLLLL escape sequence, as per RFC4627.
125
126	If C<$enable> is false, then the C<encode> method will not escape Unicode
127	characters unless necessary.
128
129	=item $json = $json->utf8 ($enable)
130
131	If C<$enable> is true, then the C<encode> method will encode the JSON
132	string into UTF-8, as required by many protocols, while the C<decode>
133	method expects to be handled an UTF-8-encoded string. Please note that
134	UTF-8-encoded strings do not contain any characters outside the range
135	C<0..255>, they are thus useful for bytewise/binary I/O.
136
137	If C<$enable> is false, then the C<encode> method will return the JSON
138	string as a (non-encoded) unicode string, while C<decode> expects thus a
139	unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs
140	to be done yourself, e.g. using the Encode module.
141
142	=item $json = $json->pretty ($enabla)
143
144	This enables (or disables) all of the C<indent>, C<space_before> and
145	C<space_after> (and in the future possibly more) settings in one call to
146	generate the most readable (or most compact) form possible.
147
148	=item $json = $json->indent ($enable)
149
150	If C<$enable> is true, then the C<encode> method will use a multiline
151	format as output, putting every array member or object/hash key-value pair
152	into its own line, identing them properly.
153
154	If C<$enable> is false, no newlines or indenting will be produced, and the
155	resulting JSON strings is guarenteed not to contain any C<newlines>.
156
157	This setting has no effect when decoding JSON strings.
158
159	=item $json = $json->space_before ($enable)
160
161	If C<$enable> is true, then the C<encode> method will add an extra
162	optional space before the C<:> separating keys from values in JSON objects.
163
164	If C<$enable> is false, then the C<encode> method will not add any extra
165	space at those places.
166
167	This setting has no effect when decoding JSON strings. You will also most
168	likely combine this setting with C<space_after>.
169
170	=item $json = $json->space_after ($enable)
171
172	If C<$enable> is true, then the C<encode> method will add an extra
173	optional space after the C<:> separating keys from values in JSON objects
174	and extra whitespace after the C<,> separating key-value pairs and array
175	members.
176
177	If C<$enable> is false, then the C<encode> method will not add any extra
178	space at those places.
179
180	This setting has no effect when decoding JSON strings.
181
182	=item $json = $json->canonical ($enable)
183
184	If C<$enable> is true, then the C<encode> method will output JSON objects
185	by sorting their keys. This is adding a comparatively high overhead.
186
187	If C<$enable> is false, then the C<encode> method will output key-value
188	pairs in the order Perl stores them (which will likely change between runs
189	of the same script).
190
191	This option is useful if you want the same data structure to be encoded as
192	the same JSON string (given the same overall settings). If it is disabled,
193	the same hash migh be encoded differently even if contains the same data,
194	as key-value pairs have no inherent ordering in Perl.
195
196	This setting has no effect when decoding JSON strings.
197
198	=item $json_string = $json->encode ($perl_scalar)
199
200	Converts the given Perl data structure (a simple scalar or a reference
201	to a hash or array) to its JSON representation. Simple scalars will be
202	converted into JSON string or number sequences, while references to arrays
203	become JSON arrays and references to hashes become JSON objects. Undefined
204	Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>
205	nor C<false> values will be generated.
206
207	=item $perl_scalar = $json->decode ($json_string)
208
209	The opposite of C<encode>: expects a JSON string and tries to parse it,
210	returning the resulting simple scalar or reference. Croaks on error.
211
212	JSON numbers and strings become simple Perl scalars. JSON arrays become
213	Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
214	C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
215
216	=back
217
218	=cut
219
220	1;
221
222	=head1 AUTHOR
223
224	Marc Lehmann <schmorp@schmorp.de>
225	http://home.schmorp.de/
226
227	=cut
228