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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49 | to write yet another JSON module? While it seems there are many JSON |
49 | to write yet another JSON module? While it seems there are many JSON |
50 | modules, none of them correctly handle all corner cases, and in most cases |
50 | modules, none of them correctly handle all corner cases, and in most cases |
51 | their maintainers are unresponsive, gone missing, or not listening to bug |
51 | their maintainers are unresponsive, gone missing, or not listening to bug |
52 | reports for other reasons. |
52 | reports for other reasons. |
53 | |
53 | |
54 | See COMPARISON, below, for a comparison to some other JSON modules. |
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55 | |
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56 | See MAPPING, below, on how JSON::XS maps perl values to JSON values and |
54 | See MAPPING, below, on how JSON::XS maps perl values to JSON values and |
57 | vice versa. |
55 | vice versa. |
58 | |
56 | |
59 | =head2 FEATURES |
57 | =head2 FEATURES |
60 | |
58 | |
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65 | This module knows how to handle Unicode, documents how and when it does |
63 | This module knows how to handle Unicode, documents how and when it does |
66 | so, and even documents what "correct" means. |
64 | so, and even documents what "correct" means. |
67 | |
65 | |
68 | =item * round-trip integrity |
66 | =item * round-trip integrity |
69 | |
67 | |
70 | When you serialise a perl data structure using only datatypes supported |
68 | 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. |
69 | 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 |
70 | (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 |
71 | like a number). There minor I<are> exceptions to this, read the MAPPING |
74 | section below to learn about those. |
72 | section below to learn about those. |
75 | |
73 | |
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84 | Compared to other JSON modules and other serialisers such as Storable, |
82 | Compared to other JSON modules and other serialisers such as Storable, |
85 | this module usually compares favourably in terms of speed, too. |
83 | this module usually compares favourably in terms of speed, too. |
86 | |
84 | |
87 | =item * simple to use |
85 | =item * simple to use |
88 | |
86 | |
89 | This module has both a simple functional interface as well as an objetc |
87 | This module has both a simple functional interface as well as an object |
90 | oriented interface interface. |
88 | oriented interface interface. |
91 | |
89 | |
92 | =item * reasonably versatile output formats |
90 | =item * reasonably versatile output formats |
93 | |
91 | |
94 | You can choose between the most compact guaranteed-single-line format |
92 | You can choose between the most compact guaranteed-single-line format |
95 | possible (nice for simple line-based protocols), a pure-ascii format |
93 | 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 |
94 | (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 |
95 | 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. |
96 | stuff). Or you can combine those features in whatever way you like. |
99 | |
97 | |
100 | =back |
98 | =back |
101 | |
99 | |
102 | =cut |
100 | =cut |
103 | |
101 | |
104 | package JSON::XS; |
102 | package JSON::XS; |
105 | |
103 | |
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104 | no warnings; |
106 | use strict; |
105 | use strict; |
107 | |
106 | |
108 | our $VERSION = '2.1'; |
107 | our $VERSION = '2.231'; |
109 | our @ISA = qw(Exporter); |
108 | our @ISA = qw(Exporter); |
110 | |
109 | |
111 | our @EXPORT = qw(encode_json decode_json to_json from_json); |
110 | our @EXPORT = qw(encode_json decode_json to_json from_json); |
112 | |
111 | |
113 | sub to_json($) { |
112 | sub to_json($) { |
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137 | |
136 | |
138 | This function call is functionally identical to: |
137 | This function call is functionally identical to: |
139 | |
138 | |
140 | $json_text = JSON::XS->new->utf8->encode ($perl_scalar) |
139 | $json_text = JSON::XS->new->utf8->encode ($perl_scalar) |
141 | |
140 | |
142 | except being faster. |
141 | Except being faster. |
143 | |
142 | |
144 | =item $perl_scalar = decode_json $json_text |
143 | =item $perl_scalar = decode_json $json_text |
145 | |
144 | |
146 | The opposite of C<encode_json>: expects an UTF-8 (binary) string and tries |
145 | 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 |
146 | to parse that as an UTF-8 encoded JSON text, returning the resulting |
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149 | |
148 | |
150 | This function call is functionally identical to: |
149 | This function call is functionally identical to: |
151 | |
150 | |
152 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) |
151 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) |
153 | |
152 | |
154 | except being faster. |
153 | Except being faster. |
155 | |
154 | |
156 | =item $is_boolean = JSON::XS::is_bool $scalar |
155 | =item $is_boolean = JSON::XS::is_bool $scalar |
157 | |
156 | |
158 | Returns true if the passed scalar represents either JSON::XS::true or |
157 | 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 |
158 | JSON::XS::false, two constants that act like C<1> and C<0>, respectively |
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197 | |
196 | |
198 | If you didn't know about that flag, just the better, pretend it doesn't |
197 | If you didn't know about that flag, just the better, pretend it doesn't |
199 | exist. |
198 | exist. |
200 | |
199 | |
201 | =item 4. A "Unicode String" is simply a string where each character can be |
200 | =item 4. A "Unicode String" is simply a string where each character can be |
202 | validly interpreted as a Unicode codepoint. |
201 | validly interpreted as a Unicode code point. |
203 | |
202 | |
204 | If you have UTF-8 encoded data, it is no longer a Unicode string, but a |
203 | 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. |
204 | Unicode string encoded in UTF-8, giving you a binary string. |
206 | |
205 | |
207 | =item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string. |
206 | =item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string. |
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462 | Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>, |
461 | Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>, |
463 | resulting in an invalid JSON text: |
462 | resulting in an invalid JSON text: |
464 | |
463 | |
465 | JSON::XS->new->allow_nonref->encode ("Hello, World!") |
464 | JSON::XS->new->allow_nonref->encode ("Hello, World!") |
466 | => "Hello, World!" |
465 | => "Hello, World!" |
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466 | |
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467 | =item $json = $json->allow_unknown ([$enable]) |
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468 | |
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469 | =item $enabled = $json->get_allow_unknown |
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470 | |
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471 | If C<$enable> is true (or missing), then C<encode> will I<not> throw an |
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472 | exception when it encounters values it cannot represent in JSON (for |
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473 | example, filehandles) but instead will encode a JSON C<null> value. Note |
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474 | that blessed objects are not included here and are handled separately by |
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475 | c<allow_nonref>. |
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476 | |
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477 | If C<$enable> is false (the default), then C<encode> will throw an |
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478 | exception when it encounters anything it cannot encode as JSON. |
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479 | |
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480 | This option does not affect C<decode> in any way, and it is recommended to |
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481 | leave it off unless you know your communications partner. |
467 | |
482 | |
468 | =item $json = $json->allow_blessed ([$enable]) |
483 | =item $json = $json->allow_blessed ([$enable]) |
469 | |
484 | |
470 | =item $enabled = $json->get_allow_blessed |
485 | =item $enabled = $json->get_allow_blessed |
471 | |
486 | |
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612 | =item $json = $json->max_depth ([$maximum_nesting_depth]) |
627 | =item $json = $json->max_depth ([$maximum_nesting_depth]) |
613 | |
628 | |
614 | =item $max_depth = $json->get_max_depth |
629 | =item $max_depth = $json->get_max_depth |
615 | |
630 | |
616 | Sets the maximum nesting level (default C<512>) accepted while encoding |
631 | Sets the maximum nesting level (default C<512>) accepted while encoding |
617 | or decoding. If the JSON text or Perl data structure has an equal or |
632 | or decoding. If a higher nesting level is detected in JSON text or a Perl |
618 | higher nesting level then this limit, then the encoder and decoder will |
633 | data structure, then the encoder and decoder will stop and croak at that |
619 | stop and croak at that point. |
634 | point. |
620 | |
635 | |
621 | Nesting level is defined by number of hash- or arrayrefs that the encoder |
636 | Nesting level is defined by number of hash- or arrayrefs that the encoder |
622 | needs to traverse to reach a given point or the number of C<{> or C<[> |
637 | needs to traverse to reach a given point or the number of C<{> or C<[> |
623 | characters without their matching closing parenthesis crossed to reach a |
638 | characters without their matching closing parenthesis crossed to reach a |
624 | given character in a string. |
639 | given character in a string. |
625 | |
640 | |
626 | Setting the maximum depth to one disallows any nesting, so that ensures |
641 | Setting the maximum depth to one disallows any nesting, so that ensures |
627 | that the object is only a single hash/object or array. |
642 | that the object is only a single hash/object or array. |
628 | |
643 | |
629 | The argument to C<max_depth> will be rounded up to the next highest power |
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630 | of two. If no argument is given, the highest possible setting will be |
644 | If no argument is given, the highest possible setting will be used, which |
631 | used, which is rarely useful. |
645 | is rarely useful. |
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646 | |
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647 | Note that nesting is implemented by recursion in C. The default value has |
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648 | been chosen to be as large as typical operating systems allow without |
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649 | crashing. |
632 | |
650 | |
633 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
651 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
634 | |
652 | |
635 | =item $json = $json->max_size ([$maximum_string_size]) |
653 | =item $json = $json->max_size ([$maximum_string_size]) |
636 | |
654 | |
637 | =item $max_size = $json->get_max_size |
655 | =item $max_size = $json->get_max_size |
638 | |
656 | |
639 | Set the maximum length a JSON text may have (in bytes) where decoding is |
657 | Set the maximum length a JSON text may have (in bytes) where decoding is |
640 | being attempted. The default is C<0>, meaning no limit. When C<decode> |
658 | being attempted. The default is C<0>, meaning no limit. When C<decode> |
641 | is called on a string longer then this number of characters it will not |
659 | is called on a string that is longer then this many bytes, it will not |
642 | attempt to decode the string but throw an exception. This setting has no |
660 | attempt to decode the string but throw an exception. This setting has no |
643 | effect on C<encode> (yet). |
661 | effect on C<encode> (yet). |
644 | |
662 | |
645 | The argument to C<max_size> will be rounded up to the next B<highest> |
663 | If no argument is given, the limit check will be deactivated (same as when |
646 | power of two (so may be more than requested). If no argument is given, the |
664 | C<0> is specified). |
647 | limit check will be deactivated (same as when C<0> is specified). |
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648 | |
665 | |
649 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
666 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
650 | |
667 | |
651 | =item $json_text = $json->encode ($perl_scalar) |
668 | =item $json_text = $json->encode ($perl_scalar) |
652 | |
669 | |
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683 | =back |
700 | =back |
684 | |
701 | |
685 | |
702 | |
686 | =head1 INCREMENTAL PARSING |
703 | =head1 INCREMENTAL PARSING |
687 | |
704 | |
688 | [This section and the API it details is still EXPERIMENTAL] |
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689 | |
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690 | In some cases, there is the need for incremental parsing of JSON |
705 | In some cases, there is the need for incremental parsing of JSON |
691 | texts. While this module always has to keep both JSON text and resulting |
706 | texts. While this module always has to keep both JSON text and resulting |
692 | Perl data structure in memory at one time, it does allow you to parse a |
707 | Perl data structure in memory at one time, it does allow you to parse a |
693 | JSON stream incrementally. It does so by accumulating text until it has |
708 | JSON stream incrementally. It does so by accumulating text until it has |
694 | a full JSON object, which it then can decode. This process is similar to |
709 | a full JSON object, which it then can decode. This process is similar to |
695 | using C<decode_prefix> to see if a full JSON object is available, but is |
710 | using C<decode_prefix> to see if a full JSON object is available, but |
696 | much more efficient (JSON::XS will only attempt to parse the JSON text |
711 | is much more efficient (and can be implemented with a minimum of method |
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712 | calls). |
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713 | |
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714 | JSON::XS will only attempt to parse the JSON text once it is sure it |
697 | once it is sure it has enough text to get a decisive result, using a very |
715 | has enough text to get a decisive result, using a very simple but |
698 | simple but truly incremental parser). |
716 | truly incremental parser. This means that it sometimes won't stop as |
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717 | early as the full parser, for example, it doesn't detect parenthese |
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718 | mismatches. The only thing it guarantees is that it starts decoding as |
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719 | soon as a syntactically valid JSON text has been seen. This means you need |
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720 | to set resource limits (e.g. C<max_size>) to ensure the parser will stop |
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721 | parsing in the presence if syntax errors. |
699 | |
722 | |
700 | The following two methods deal with this. |
723 | The following methods implement this incremental parser. |
701 | |
724 | |
702 | =over 4 |
725 | =over 4 |
703 | |
726 | |
704 | =item [void, scalar or list context] = $json->incr_parse ([$string]) |
727 | =item [void, scalar or list context] = $json->incr_parse ([$string]) |
705 | |
728 | |
… | |
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743 | JSON object or b) parsing multiple JSON objects separated by non-JSON text |
766 | JSON object or b) parsing multiple JSON objects separated by non-JSON text |
744 | (such as commas). |
767 | (such as commas). |
745 | |
768 | |
746 | =item $json->incr_skip |
769 | =item $json->incr_skip |
747 | |
770 | |
748 | This will reset the state of the incremental parser and will remove the |
771 | This will reset the state of the incremental parser and will remove |
749 | parsed text from the input buffer. This is useful after C<incr_parse> |
772 | the parsed text from the input buffer so far. This is useful after |
750 | died, in which case the input buffer and incremental parser state is left |
773 | C<incr_parse> died, in which case the input buffer and incremental parser |
751 | unchanged, to skip the text parsed so far and to reset the parse state. |
774 | state is left unchanged, to skip the text parsed so far and to reset the |
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775 | parse state. |
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776 | |
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777 | The difference to C<incr_reset> is that only text until the parse error |
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778 | occured is removed. |
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779 | |
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780 | =item $json->incr_reset |
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781 | |
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782 | This completely resets the incremental parser, that is, after this call, |
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783 | it will be as if the parser had never parsed anything. |
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784 | |
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785 | This is useful if you want to repeatedly parse JSON objects and want to |
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786 | ignore any trailing data, which means you have to reset the parser after |
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787 | each successful decode. |
752 | |
788 | |
753 | =back |
789 | =back |
754 | |
790 | |
755 | =head2 LIMITATIONS |
791 | =head2 LIMITATIONS |
756 | |
792 | |
… | |
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997 | Other unblessed references are generally not allowed and will cause an |
1033 | Other unblessed references are generally not allowed and will cause an |
998 | exception to be thrown, except for references to the integers C<0> and |
1034 | exception to be thrown, except for references to the integers C<0> and |
999 | C<1>, which get turned into C<false> and C<true> atoms in JSON. You can |
1035 | C<1>, which get turned into C<false> and C<true> atoms in JSON. You can |
1000 | also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. |
1036 | also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. |
1001 | |
1037 | |
1002 | encode_json [\0,JSON::XS::true] # yields [false,true] |
1038 | encode_json [\0, JSON::XS::true] # yields [false,true] |
1003 | |
1039 | |
1004 | =item JSON::XS::true, JSON::XS::false |
1040 | =item JSON::XS::true, JSON::XS::false |
1005 | |
1041 | |
1006 | These special values become JSON true and JSON false values, |
1042 | These special values become JSON true and JSON false values, |
1007 | respectively. You can also use C<\1> and C<\0> directly if you want. |
1043 | respectively. You can also use C<\1> and C<\0> directly if you want. |
… | |
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1214 | |
1250 | |
1215 | First comes a comparison between various modules using |
1251 | First comes a comparison between various modules using |
1216 | a very short single-line JSON string (also available at |
1252 | a very short single-line JSON string (also available at |
1217 | L<http://dist.schmorp.de/misc/json/short.json>). |
1253 | L<http://dist.schmorp.de/misc/json/short.json>). |
1218 | |
1254 | |
1219 | {"method": "handleMessage", "params": ["user1", "we were just talking"], \ |
1255 | {"method": "handleMessage", "params": ["user1", |
1220 | "id": null, "array":[1,11,234,-5,1e5,1e7, true, false]} |
1256 | "we were just talking"], "id": null, "array":[1,11,234,-5,1e5,1e7, |
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1257 | true, false]} |
1221 | |
1258 | |
1222 | It shows the number of encodes/decodes per second (JSON::XS uses |
1259 | It shows the number of encodes/decodes per second (JSON::XS uses |
1223 | the functional interface, while JSON::XS/2 uses the OO interface |
1260 | the functional interface, while JSON::XS/2 uses the OO interface |
1224 | with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables |
1261 | with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables |
1225 | shrink). Higher is better: |
1262 | shrink). Higher is better: |
… | |
… | |
1323 | |
1360 | |
1324 | |
1361 | |
1325 | =head1 BUGS |
1362 | =head1 BUGS |
1326 | |
1363 | |
1327 | While the goal of this module is to be correct, that unfortunately does |
1364 | While the goal of this module is to be correct, that unfortunately does |
1328 | not mean it's bug-free, only that I think its design is bug-free. It is |
1365 | not mean it's bug-free, only that I think its design is bug-free. If you |
1329 | still relatively early in its development. If you keep reporting bugs they |
1366 | keep reporting bugs they will be fixed swiftly, though. |
1330 | will be fixed swiftly, though. |
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1331 | |
1367 | |
1332 | Please refrain from using rt.cpan.org or any other bug reporting |
1368 | Please refrain from using rt.cpan.org or any other bug reporting |
1333 | service. I put the contact address into my modules for a reason. |
1369 | service. I put the contact address into my modules for a reason. |
1334 | |
1370 | |
1335 | =cut |
1371 | =cut |