1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
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3 | JSON::XS - JSON serialising/deserialising, done correctly and fast |
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4 | |
3 | =encoding utf-8 |
5 | =encoding utf-8 |
4 | |
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5 | JSON::XS - JSON serialising/deserialising, done correctly and fast |
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6 | |
6 | |
7 | 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 |
8 | (http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html) |
8 | (http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html) |
9 | |
9 | |
10 | =head1 SYNOPSIS |
10 | =head1 SYNOPSIS |
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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 | |
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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 | |
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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 |
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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 |
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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 |
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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. |
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628 | =item $json = $json->max_depth ([$maximum_nesting_depth]) |
628 | =item $json = $json->max_depth ([$maximum_nesting_depth]) |
629 | |
629 | |
630 | =item $max_depth = $json->get_max_depth |
630 | =item $max_depth = $json->get_max_depth |
631 | |
631 | |
632 | Sets the maximum nesting level (default C<512>) accepted while encoding |
632 | Sets the maximum nesting level (default C<512>) accepted while encoding |
633 | or decoding. If the JSON text or Perl data structure has an equal or |
633 | or decoding. If a higher nesting level is detected in JSON text or a Perl |
634 | higher nesting level then this limit, then the encoder and decoder will |
634 | data structure, then the encoder and decoder will stop and croak at that |
635 | stop and croak at that point. |
635 | point. |
636 | |
636 | |
637 | Nesting level is defined by number of hash- or arrayrefs that the encoder |
637 | Nesting level is defined by number of hash- or arrayrefs that the encoder |
638 | needs to traverse to reach a given point or the number of C<{> or C<[> |
638 | needs to traverse to reach a given point or the number of C<{> or C<[> |
639 | characters without their matching closing parenthesis crossed to reach a |
639 | characters without their matching closing parenthesis crossed to reach a |
640 | given character in a string. |
640 | given character in a string. |
641 | |
641 | |
642 | Setting the maximum depth to one disallows any nesting, so that ensures |
642 | Setting the maximum depth to one disallows any nesting, so that ensures |
643 | that the object is only a single hash/object or array. |
643 | that the object is only a single hash/object or array. |
644 | |
644 | |
645 | The argument to C<max_depth> will be rounded up to the next highest power |
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646 | of two. If no argument is given, the highest possible setting will be |
645 | If no argument is given, the highest possible setting will be used, which |
647 | used, which is rarely useful. |
646 | is rarely useful. |
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647 | |
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648 | Note that nesting is implemented by recursion in C. The default value has |
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649 | been chosen to be as large as typical operating systems allow without |
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650 | crashing. |
648 | |
651 | |
649 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
652 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
650 | |
653 | |
651 | =item $json = $json->max_size ([$maximum_string_size]) |
654 | =item $json = $json->max_size ([$maximum_string_size]) |
652 | |
655 | |
653 | =item $max_size = $json->get_max_size |
656 | =item $max_size = $json->get_max_size |
654 | |
657 | |
655 | Set the maximum length a JSON text may have (in bytes) where decoding is |
658 | Set the maximum length a JSON text may have (in bytes) where decoding is |
656 | being attempted. The default is C<0>, meaning no limit. When C<decode> |
659 | being attempted. The default is C<0>, meaning no limit. When C<decode> |
657 | is called on a string longer then this number of characters it will not |
660 | is called on a string that is longer then this many bytes, it will not |
658 | attempt to decode the string but throw an exception. This setting has no |
661 | attempt to decode the string but throw an exception. This setting has no |
659 | effect on C<encode> (yet). |
662 | effect on C<encode> (yet). |
660 | |
663 | |
661 | The argument to C<max_size> will be rounded up to the next B<highest> |
664 | If no argument is given, the limit check will be deactivated (same as when |
662 | power of two (so may be more than requested). If no argument is given, the |
665 | C<0> is specified). |
663 | limit check will be deactivated (same as when C<0> is specified). |
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664 | |
666 | |
665 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
667 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
666 | |
668 | |
667 | =item $json_text = $json->encode ($perl_scalar) |
669 | =item $json_text = $json->encode ($perl_scalar) |
668 | |
670 | |
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698 | |
700 | |
699 | =back |
701 | =back |
700 | |
702 | |
701 | |
703 | |
702 | =head1 INCREMENTAL PARSING |
704 | =head1 INCREMENTAL PARSING |
703 | |
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704 | [This section and the API it details is still EXPERIMENTAL] |
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705 | |
705 | |
706 | 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 |
707 | 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 |
708 | 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 |
709 | 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 |
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764 | This will reset the state of the incremental parser and will remove the |
764 | This will reset the state of the incremental parser and will remove the |
765 | parsed text from the input buffer. This is useful after C<incr_parse> |
765 | parsed text from the input buffer. This is useful after C<incr_parse> |
766 | died, in which case the input buffer and incremental parser state is left |
766 | died, in which case the input buffer and incremental parser state is left |
767 | unchanged, to skip the text parsed so far and to reset the parse state. |
767 | unchanged, to skip the text parsed so far and to reset the parse state. |
768 | |
768 | |
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769 | =item $json->incr_reset |
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770 | |
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771 | This completely resets the incremental parser, that is, after this call, |
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772 | it will be as if the parser had never parsed anything. |
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773 | |
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774 | This is useful if you want ot repeatedly parse JSON objects and want to |
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775 | ignore any trailing data, which means you have to reset the parser after |
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776 | each successful decode. |
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777 | |
769 | =back |
778 | =back |
770 | |
779 | |
771 | =head2 LIMITATIONS |
780 | =head2 LIMITATIONS |
772 | |
781 | |
773 | All options that affect decoding are supported, except |
782 | All options that affect decoding are supported, except |
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1013 | Other unblessed references are generally not allowed and will cause an |
1022 | Other unblessed references are generally not allowed and will cause an |
1014 | exception to be thrown, except for references to the integers C<0> and |
1023 | exception to be thrown, except for references to the integers C<0> and |
1015 | C<1>, which get turned into C<false> and C<true> atoms in JSON. You can |
1024 | C<1>, which get turned into C<false> and C<true> atoms in JSON. You can |
1016 | also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. |
1025 | also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. |
1017 | |
1026 | |
1018 | encode_json [\0,JSON::XS::true] # yields [false,true] |
1027 | encode_json [\0, JSON::XS::true] # yields [false,true] |
1019 | |
1028 | |
1020 | =item JSON::XS::true, JSON::XS::false |
1029 | =item JSON::XS::true, JSON::XS::false |
1021 | |
1030 | |
1022 | These special values become JSON true and JSON false values, |
1031 | These special values become JSON true and JSON false values, |
1023 | respectively. You can also use C<\1> and C<\0> directly if you want. |
1032 | respectively. You can also use C<\1> and C<\0> directly if you want. |
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1340 | |
1349 | |
1341 | |
1350 | |
1342 | =head1 BUGS |
1351 | =head1 BUGS |
1343 | |
1352 | |
1344 | While the goal of this module is to be correct, that unfortunately does |
1353 | While the goal of this module is to be correct, that unfortunately does |
1345 | not mean it's bug-free, only that I think its design is bug-free. It is |
1354 | not mean it's bug-free, only that I think its design is bug-free. If you |
1346 | still relatively early in its development. If you keep reporting bugs they |
1355 | keep reporting bugs they will be fixed swiftly, though. |
1347 | will be fixed swiftly, though. |
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1348 | |
1356 | |
1349 | Please refrain from using rt.cpan.org or any other bug reporting |
1357 | Please refrain from using rt.cpan.org or any other bug reporting |
1350 | service. I put the contact address into my modules for a reason. |
1358 | service. I put the contact address into my modules for a reason. |
1351 | |
1359 | |
1352 | =cut |
1360 | =cut |