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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103 | |
103 | |
104 | package JSON::XS; |
104 | package JSON::XS; |
105 | |
105 | |
106 | use strict; |
106 | use strict; |
107 | |
107 | |
108 | our $VERSION = '2.1'; |
108 | our $VERSION = '2.22'; |
109 | our @ISA = qw(Exporter); |
109 | our @ISA = qw(Exporter); |
110 | |
110 | |
111 | our @EXPORT = qw(encode_json decode_json to_json from_json); |
111 | our @EXPORT = qw(encode_json decode_json to_json from_json); |
112 | |
112 | |
113 | sub to_json($) { |
113 | sub to_json($) { |
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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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462 | Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>, |
462 | Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>, |
463 | resulting in an invalid JSON text: |
463 | resulting in an invalid JSON text: |
464 | |
464 | |
465 | JSON::XS->new->allow_nonref->encode ("Hello, World!") |
465 | JSON::XS->new->allow_nonref->encode ("Hello, World!") |
466 | => "Hello, World!" |
466 | => "Hello, World!" |
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467 | |
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468 | =item $json = $json->allow_unknown ([$enable]) |
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469 | |
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470 | =item $enabled = $json->get_allow_unknown |
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471 | |
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472 | If C<$enable> is true (or missing), then C<encode> will I<not> throw an |
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473 | exception when it encounters values it cannot represent in JSON (for |
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474 | example, filehandles) but instead will encode a JSON C<null> value. Note |
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475 | that blessed objects are not included here and are handled separately by |
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476 | c<allow_nonref>. |
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477 | |
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478 | If C<$enable> is false (the default), then C<encode> will throw an |
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479 | exception when it encounters anything it cannot encode as JSON. |
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480 | |
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481 | This option does not affect C<decode> in any way, and it is recommended to |
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482 | leave it off unless you know your communications partner. |
467 | |
483 | |
468 | =item $json = $json->allow_blessed ([$enable]) |
484 | =item $json = $json->allow_blessed ([$enable]) |
469 | |
485 | |
470 | =item $enabled = $json->get_allow_blessed |
486 | =item $enabled = $json->get_allow_blessed |
471 | |
487 | |
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612 | =item $json = $json->max_depth ([$maximum_nesting_depth]) |
628 | =item $json = $json->max_depth ([$maximum_nesting_depth]) |
613 | |
629 | |
614 | =item $max_depth = $json->get_max_depth |
630 | =item $max_depth = $json->get_max_depth |
615 | |
631 | |
616 | Sets the maximum nesting level (default C<512>) accepted while encoding |
632 | 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 |
633 | 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 |
634 | data structure, then the encoder and decoder will stop and croak at that |
619 | stop and croak at that point. |
635 | point. |
620 | |
636 | |
621 | 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 |
622 | 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<[> |
623 | characters without their matching closing parenthesis crossed to reach a |
639 | characters without their matching closing parenthesis crossed to reach a |
624 | given character in a string. |
640 | given character in a string. |
625 | |
641 | |
626 | 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 |
627 | that the object is only a single hash/object or array. |
643 | that the object is only a single hash/object or array. |
628 | |
644 | |
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 |
645 | If no argument is given, the highest possible setting will be used, which |
631 | 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. |
632 | |
651 | |
633 | 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. |
634 | |
653 | |
635 | =item $json = $json->max_size ([$maximum_string_size]) |
654 | =item $json = $json->max_size ([$maximum_string_size]) |
636 | |
655 | |
637 | =item $max_size = $json->get_max_size |
656 | =item $max_size = $json->get_max_size |
638 | |
657 | |
639 | 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 |
640 | 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> |
641 | 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 |
642 | 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 |
643 | effect on C<encode> (yet). |
662 | effect on C<encode> (yet). |
644 | |
663 | |
645 | 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 |
646 | power of two (so may be more than requested). If no argument is given, the |
665 | C<0> is specified). |
647 | limit check will be deactivated (same as when C<0> is specified). |
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648 | |
666 | |
649 | 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. |
650 | |
668 | |
651 | =item $json_text = $json->encode ($perl_scalar) |
669 | =item $json_text = $json->encode ($perl_scalar) |
652 | |
670 | |
… | |
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683 | =back |
701 | =back |
684 | |
702 | |
685 | |
703 | |
686 | =head1 INCREMENTAL PARSING |
704 | =head1 INCREMENTAL PARSING |
687 | |
705 | |
688 | [This section 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 |
706 | 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 |
707 | 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 |
708 | 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 |
709 | 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 |
710 | 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 |
711 | 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 |
712 | is much more efficient (and can be implemented with a minimum of method |
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713 | calls). |
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714 | |
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715 | 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 |
716 | has enough text to get a decisive result, using a very simple but |
698 | simple but truly incremental parser). |
717 | truly incremental parser. This means that it sometimes won't stop as |
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718 | early as the full parser, for example, it doesn't detect parenthese |
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719 | mismatches. The only thing it guarantees is that it starts decoding as |
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720 | soon as a syntactically valid JSON text has been seen. This means you need |
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721 | to set resource limits (e.g. C<max_size>) to ensure the parser will stop |
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722 | parsing in the presence if syntax errors. |
699 | |
723 | |
700 | The following two methods deal with this. |
724 | The following methods implement this incremental parser. |
701 | |
725 | |
702 | =over 4 |
726 | =over 4 |
703 | |
727 | |
704 | =item [void, scalar or list context] = $json->incr_parse ([$string]) |
728 | =item [void, scalar or list context] = $json->incr_parse ([$string]) |
705 | |
729 | |
… | |
… | |
727 | objects or arrays, instead they must be concatenated back-to-back. If |
751 | objects or arrays, instead they must be concatenated back-to-back. If |
728 | an error occurs, an exception will be raised as in the scalar context |
752 | an error occurs, an exception will be raised as in the scalar context |
729 | case. Note that in this case, any previously-parsed JSON texts will be |
753 | case. Note that in this case, any previously-parsed JSON texts will be |
730 | lost. |
754 | lost. |
731 | |
755 | |
732 | If there is a parse |
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733 | |
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734 | =item $lvalue_string = $json->incr_text |
756 | =item $lvalue_string = $json->incr_text |
735 | |
757 | |
736 | This method returns the currently stored JSON fragment as an lvalue, that |
758 | This method returns the currently stored JSON fragment as an lvalue, that |
737 | is, you can manipulate it. This I<only> works when a preceding call to |
759 | is, you can manipulate it. This I<only> works when a preceding call to |
738 | C<incr_parse> in I<scalar context> successfully returned an object. Under |
760 | C<incr_parse> in I<scalar context> successfully returned an object. Under |
… | |
… | |
742 | method before having parsed anything. |
764 | method before having parsed anything. |
743 | |
765 | |
744 | This function is useful in two cases: a) finding the trailing text after a |
766 | This function is useful in two cases: a) finding the trailing text after a |
745 | JSON object or b) parsing multiple JSON objects separated by non-JSON text |
767 | JSON object or b) parsing multiple JSON objects separated by non-JSON text |
746 | (such as commas). |
768 | (such as commas). |
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769 | |
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770 | =item $json->incr_skip |
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771 | |
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772 | This will reset the state of the incremental parser and will remove the |
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773 | parsed text from the input buffer. This is useful after C<incr_parse> |
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774 | died, in which case the input buffer and incremental parser state is left |
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775 | unchanged, to skip the text parsed so far and to reset the parse state. |
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776 | |
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777 | =item $json->incr_reset |
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778 | |
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779 | This completely resets the incremental parser, that is, after this call, |
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780 | it will be as if the parser had never parsed anything. |
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781 | |
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782 | This is useful if you want ot repeatedly parse JSON objects and want to |
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783 | ignore any trailing data, which means you have to reset the parser after |
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784 | each successful decode. |
747 | |
785 | |
748 | =back |
786 | =back |
749 | |
787 | |
750 | =head2 LIMITATIONS |
788 | =head2 LIMITATIONS |
751 | |
789 | |
… | |
… | |
992 | Other unblessed references are generally not allowed and will cause an |
1030 | Other unblessed references are generally not allowed and will cause an |
993 | exception to be thrown, except for references to the integers C<0> and |
1031 | exception to be thrown, except for references to the integers C<0> and |
994 | C<1>, which get turned into C<false> and C<true> atoms in JSON. You can |
1032 | C<1>, which get turned into C<false> and C<true> atoms in JSON. You can |
995 | also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. |
1033 | also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. |
996 | |
1034 | |
997 | encode_json [\0,JSON::XS::true] # yields [false,true] |
1035 | encode_json [\0, JSON::XS::true] # yields [false,true] |
998 | |
1036 | |
999 | =item JSON::XS::true, JSON::XS::false |
1037 | =item JSON::XS::true, JSON::XS::false |
1000 | |
1038 | |
1001 | These special values become JSON true and JSON false values, |
1039 | These special values become JSON true and JSON false values, |
1002 | respectively. You can also use C<\1> and C<\0> directly if you want. |
1040 | respectively. You can also use C<\1> and C<\0> directly if you want. |
… | |
… | |
1209 | |
1247 | |
1210 | First comes a comparison between various modules using |
1248 | First comes a comparison between various modules using |
1211 | a very short single-line JSON string (also available at |
1249 | a very short single-line JSON string (also available at |
1212 | L<http://dist.schmorp.de/misc/json/short.json>). |
1250 | L<http://dist.schmorp.de/misc/json/short.json>). |
1213 | |
1251 | |
1214 | {"method": "handleMessage", "params": ["user1", "we were just talking"], \ |
1252 | {"method": "handleMessage", "params": ["user1", |
1215 | "id": null, "array":[1,11,234,-5,1e5,1e7, true, false]} |
1253 | "we were just talking"], "id": null, "array":[1,11,234,-5,1e5,1e7, |
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1254 | true, false]} |
1216 | |
1255 | |
1217 | It shows the number of encodes/decodes per second (JSON::XS uses |
1256 | It shows the number of encodes/decodes per second (JSON::XS uses |
1218 | the functional interface, while JSON::XS/2 uses the OO interface |
1257 | the functional interface, while JSON::XS/2 uses the OO interface |
1219 | with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables |
1258 | with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables |
1220 | shrink). Higher is better: |
1259 | shrink). Higher is better: |
… | |
… | |
1318 | |
1357 | |
1319 | |
1358 | |
1320 | =head1 BUGS |
1359 | =head1 BUGS |
1321 | |
1360 | |
1322 | While the goal of this module is to be correct, that unfortunately does |
1361 | While the goal of this module is to be correct, that unfortunately does |
1323 | not mean it's bug-free, only that I think its design is bug-free. It is |
1362 | not mean it's bug-free, only that I think its design is bug-free. If you |
1324 | still relatively early in its development. If you keep reporting bugs they |
1363 | keep reporting bugs they will be fixed swiftly, though. |
1325 | will be fixed swiftly, though. |
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|
1326 | |
1364 | |
1327 | Please refrain from using rt.cpan.org or any other bug reporting |
1365 | Please refrain from using rt.cpan.org or any other bug reporting |
1328 | service. I put the contact address into my modules for a reason. |
1366 | service. I put the contact address into my modules for a reason. |
1329 | |
1367 | |
1330 | =cut |
1368 | =cut |