… | |
… | |
37 | primary goal is to be I<correct> and its secondary goal is to be |
37 | primary goal is to be I<correct> and its secondary goal is to be |
38 | I<fast>. To reach the latter goal it was written in C. |
38 | I<fast>. To reach the latter goal it was written in C. |
39 | |
39 | |
40 | Beginning with version 2.0 of the JSON module, when both JSON and |
40 | Beginning with version 2.0 of the JSON module, when both JSON and |
41 | JSON::XS are installed, then JSON will fall back on JSON::XS (this can be |
41 | JSON::XS are installed, then JSON will fall back on JSON::XS (this can be |
42 | overriden) with no overhead due to emulation (by inheritign constructor |
42 | overridden) with no overhead due to emulation (by inheriting constructor |
43 | and methods). If JSON::XS is not available, it will fall back to the |
43 | and methods). If JSON::XS is not available, it will fall back to the |
44 | compatible JSON::PP module as backend, so using JSON instead of JSON::XS |
44 | compatible JSON::PP module as backend, so using JSON instead of JSON::XS |
45 | gives you a portable JSON API that can be fast when you need and doesn't |
45 | gives you a portable JSON API that can be fast when you need and doesn't |
46 | require a C compiler when that is a problem. |
46 | require a C compiler when that is a problem. |
47 | |
47 | |
… | |
… | |
65 | This module knows how to handle Unicode, documents how and when it does |
65 | This module knows how to handle Unicode, documents how and when it does |
66 | so, and even documents what "correct" means. |
66 | so, and even documents what "correct" means. |
67 | |
67 | |
68 | =item * round-trip integrity |
68 | =item * round-trip integrity |
69 | |
69 | |
70 | When you serialise a perl data structure using only datatypes supported |
70 | When you serialise a perl data structure using only data types supported |
71 | by JSON, the deserialised data structure is identical on the Perl level. |
71 | by JSON, the deserialised data structure is identical on the Perl level. |
72 | (e.g. the string "2.0" doesn't suddenly become "2" just because it looks |
72 | (e.g. the string "2.0" doesn't suddenly become "2" just because it looks |
73 | like a number). There minor I<are> exceptions to this, read the MAPPING |
73 | like a number). There minor I<are> exceptions to this, read the MAPPING |
74 | section below to learn about those. |
74 | section below to learn about those. |
75 | |
75 | |
… | |
… | |
84 | Compared to other JSON modules and other serialisers such as Storable, |
84 | Compared to other JSON modules and other serialisers such as Storable, |
85 | this module usually compares favourably in terms of speed, too. |
85 | this module usually compares favourably in terms of speed, too. |
86 | |
86 | |
87 | =item * simple to use |
87 | =item * simple to use |
88 | |
88 | |
89 | This module has both a simple functional interface as well as an objetc |
89 | This module has both a simple functional interface as well as an object |
90 | oriented interface interface. |
90 | oriented interface interface. |
91 | |
91 | |
92 | =item * reasonably versatile output formats |
92 | =item * reasonably versatile output formats |
93 | |
93 | |
94 | You can choose between the most compact guaranteed-single-line format |
94 | You can choose between the most compact guaranteed-single-line format |
95 | possible (nice for simple line-based protocols), a pure-ascii format |
95 | possible (nice for simple line-based protocols), a pure-ASCII format |
96 | (for when your transport is not 8-bit clean, still supports the whole |
96 | (for when your transport is not 8-bit clean, still supports the whole |
97 | Unicode range), or a pretty-printed format (for when you want to read that |
97 | Unicode range), or a pretty-printed format (for when you want to read that |
98 | stuff). Or you can combine those features in whatever way you like. |
98 | stuff). Or you can combine those features in whatever way you like. |
99 | |
99 | |
100 | =back |
100 | =back |
… | |
… | |
137 | |
137 | |
138 | This function call is functionally identical to: |
138 | This function call is functionally identical to: |
139 | |
139 | |
140 | $json_text = JSON::XS->new->utf8->encode ($perl_scalar) |
140 | $json_text = JSON::XS->new->utf8->encode ($perl_scalar) |
141 | |
141 | |
142 | except being faster. |
142 | Except being faster. |
143 | |
143 | |
144 | =item $perl_scalar = decode_json $json_text |
144 | =item $perl_scalar = decode_json $json_text |
145 | |
145 | |
146 | The opposite of C<encode_json>: expects an UTF-8 (binary) string and tries |
146 | The opposite of C<encode_json>: expects an UTF-8 (binary) string and tries |
147 | to parse that as an UTF-8 encoded JSON text, returning the resulting |
147 | to parse that as an UTF-8 encoded JSON text, returning the resulting |
… | |
… | |
149 | |
149 | |
150 | This function call is functionally identical to: |
150 | This function call is functionally identical to: |
151 | |
151 | |
152 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) |
152 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) |
153 | |
153 | |
154 | except being faster. |
154 | Except being faster. |
155 | |
155 | |
156 | =item $is_boolean = JSON::XS::is_bool $scalar |
156 | =item $is_boolean = JSON::XS::is_bool $scalar |
157 | |
157 | |
158 | Returns true if the passed scalar represents either JSON::XS::true or |
158 | Returns true if the passed scalar represents either JSON::XS::true or |
159 | JSON::XS::false, two constants that act like C<1> and C<0>, respectively |
159 | JSON::XS::false, two constants that act like C<1> and C<0>, respectively |
… | |
… | |
197 | |
197 | |
198 | If you didn't know about that flag, just the better, pretend it doesn't |
198 | If you didn't know about that flag, just the better, pretend it doesn't |
199 | exist. |
199 | exist. |
200 | |
200 | |
201 | =item 4. A "Unicode String" is simply a string where each character can be |
201 | =item 4. A "Unicode String" is simply a string where each character can be |
202 | validly interpreted as a Unicode codepoint. |
202 | validly interpreted as a Unicode code point. |
203 | |
203 | |
204 | If you have UTF-8 encoded data, it is no longer a Unicode string, but a |
204 | If you have UTF-8 encoded data, it is no longer a Unicode string, but a |
205 | Unicode string encoded in UTF-8, giving you a binary string. |
205 | Unicode string encoded in UTF-8, giving you a binary string. |
206 | |
206 | |
207 | =item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string. |
207 | =item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string. |
… | |
… | |
701 | =back |
701 | =back |
702 | |
702 | |
703 | |
703 | |
704 | =head1 INCREMENTAL PARSING |
704 | =head1 INCREMENTAL PARSING |
705 | |
705 | |
706 | [This section and the API it details is still EXPERIMENTAL] |
|
|
707 | |
|
|
708 | In some cases, there is the need for incremental parsing of JSON |
706 | In some cases, there is the need for incremental parsing of JSON |
709 | texts. While this module always has to keep both JSON text and resulting |
707 | texts. While this module always has to keep both JSON text and resulting |
710 | Perl data structure in memory at one time, it does allow you to parse a |
708 | Perl data structure in memory at one time, it does allow you to parse a |
711 | JSON stream incrementally. It does so by accumulating text until it has |
709 | JSON stream incrementally. It does so by accumulating text until it has |
712 | a full JSON object, which it then can decode. This process is similar to |
710 | a full JSON object, which it then can decode. This process is similar to |
… | |
… | |
1015 | Other unblessed references are generally not allowed and will cause an |
1013 | Other unblessed references are generally not allowed and will cause an |
1016 | exception to be thrown, except for references to the integers C<0> and |
1014 | exception to be thrown, except for references to the integers C<0> and |
1017 | C<1>, which get turned into C<false> and C<true> atoms in JSON. You can |
1015 | C<1>, which get turned into C<false> and C<true> atoms in JSON. You can |
1018 | also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. |
1016 | also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. |
1019 | |
1017 | |
1020 | encode_json [\0,JSON::XS::true] # yields [false,true] |
1018 | encode_json [\0, JSON::XS::true] # yields [false,true] |
1021 | |
1019 | |
1022 | =item JSON::XS::true, JSON::XS::false |
1020 | =item JSON::XS::true, JSON::XS::false |
1023 | |
1021 | |
1024 | These special values become JSON true and JSON false values, |
1022 | These special values become JSON true and JSON false values, |
1025 | respectively. You can also use C<\1> and C<\0> directly if you want. |
1023 | respectively. You can also use C<\1> and C<\0> directly if you want. |