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 | |
106 | use strict; |
104 | use common::sense; |
107 | |
105 | |
108 | our $VERSION = '2.1'; |
106 | our $VERSION = '2.24'; |
109 | our @ISA = qw(Exporter); |
107 | our @ISA = qw(Exporter); |
110 | |
108 | |
111 | our @EXPORT = qw(encode_json decode_json to_json from_json); |
109 | our @EXPORT = qw(encode_json decode_json to_json from_json); |
112 | |
110 | |
113 | sub to_json($) { |
111 | sub to_json($) { |
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137 | |
135 | |
138 | This function call is functionally identical to: |
136 | This function call is functionally identical to: |
139 | |
137 | |
140 | $json_text = JSON::XS->new->utf8->encode ($perl_scalar) |
138 | $json_text = JSON::XS->new->utf8->encode ($perl_scalar) |
141 | |
139 | |
142 | except being faster. |
140 | Except being faster. |
143 | |
141 | |
144 | =item $perl_scalar = decode_json $json_text |
142 | =item $perl_scalar = decode_json $json_text |
145 | |
143 | |
146 | The opposite of C<encode_json>: expects an UTF-8 (binary) string and tries |
144 | 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 |
145 | to parse that as an UTF-8 encoded JSON text, returning the resulting |
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149 | |
147 | |
150 | This function call is functionally identical to: |
148 | This function call is functionally identical to: |
151 | |
149 | |
152 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) |
150 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) |
153 | |
151 | |
154 | except being faster. |
152 | Except being faster. |
155 | |
153 | |
156 | =item $is_boolean = JSON::XS::is_bool $scalar |
154 | =item $is_boolean = JSON::XS::is_bool $scalar |
157 | |
155 | |
158 | Returns true if the passed scalar represents either JSON::XS::true or |
156 | 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 |
157 | JSON::XS::false, two constants that act like C<1> and C<0>, respectively |
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197 | |
195 | |
198 | If you didn't know about that flag, just the better, pretend it doesn't |
196 | If you didn't know about that flag, just the better, pretend it doesn't |
199 | exist. |
197 | exist. |
200 | |
198 | |
201 | =item 4. A "Unicode String" is simply a string where each character can be |
199 | =item 4. A "Unicode String" is simply a string where each character can be |
202 | validly interpreted as a Unicode codepoint. |
200 | validly interpreted as a Unicode code point. |
203 | |
201 | |
204 | If you have UTF-8 encoded data, it is no longer a Unicode string, but a |
202 | 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. |
203 | Unicode string encoded in UTF-8, giving you a binary string. |
206 | |
204 | |
207 | =item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string. |
205 | =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>, |
460 | Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>, |
463 | resulting in an invalid JSON text: |
461 | resulting in an invalid JSON text: |
464 | |
462 | |
465 | JSON::XS->new->allow_nonref->encode ("Hello, World!") |
463 | JSON::XS->new->allow_nonref->encode ("Hello, World!") |
466 | => "Hello, World!" |
464 | => "Hello, World!" |
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465 | |
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466 | =item $json = $json->allow_unknown ([$enable]) |
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467 | |
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468 | =item $enabled = $json->get_allow_unknown |
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469 | |
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470 | If C<$enable> is true (or missing), then C<encode> will I<not> throw an |
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471 | exception when it encounters values it cannot represent in JSON (for |
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472 | example, filehandles) but instead will encode a JSON C<null> value. Note |
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473 | that blessed objects are not included here and are handled separately by |
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474 | c<allow_nonref>. |
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475 | |
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476 | If C<$enable> is false (the default), then C<encode> will throw an |
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477 | exception when it encounters anything it cannot encode as JSON. |
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478 | |
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479 | This option does not affect C<decode> in any way, and it is recommended to |
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480 | leave it off unless you know your communications partner. |
467 | |
481 | |
468 | =item $json = $json->allow_blessed ([$enable]) |
482 | =item $json = $json->allow_blessed ([$enable]) |
469 | |
483 | |
470 | =item $enabled = $json->get_allow_blessed |
484 | =item $enabled = $json->get_allow_blessed |
471 | |
485 | |
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612 | =item $json = $json->max_depth ([$maximum_nesting_depth]) |
626 | =item $json = $json->max_depth ([$maximum_nesting_depth]) |
613 | |
627 | |
614 | =item $max_depth = $json->get_max_depth |
628 | =item $max_depth = $json->get_max_depth |
615 | |
629 | |
616 | Sets the maximum nesting level (default C<512>) accepted while encoding |
630 | 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 |
631 | 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 |
632 | data structure, then the encoder and decoder will stop and croak at that |
619 | stop and croak at that point. |
633 | point. |
620 | |
634 | |
621 | Nesting level is defined by number of hash- or arrayrefs that the encoder |
635 | 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<[> |
636 | 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 |
637 | characters without their matching closing parenthesis crossed to reach a |
624 | given character in a string. |
638 | given character in a string. |
625 | |
639 | |
626 | Setting the maximum depth to one disallows any nesting, so that ensures |
640 | Setting the maximum depth to one disallows any nesting, so that ensures |
627 | that the object is only a single hash/object or array. |
641 | that the object is only a single hash/object or array. |
628 | |
642 | |
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 |
643 | If no argument is given, the highest possible setting will be used, which |
631 | used, which is rarely useful. |
644 | is rarely useful. |
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645 | |
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646 | Note that nesting is implemented by recursion in C. The default value has |
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647 | been chosen to be as large as typical operating systems allow without |
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648 | crashing. |
632 | |
649 | |
633 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
650 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
634 | |
651 | |
635 | =item $json = $json->max_size ([$maximum_string_size]) |
652 | =item $json = $json->max_size ([$maximum_string_size]) |
636 | |
653 | |
637 | =item $max_size = $json->get_max_size |
654 | =item $max_size = $json->get_max_size |
638 | |
655 | |
639 | Set the maximum length a JSON text may have (in bytes) where decoding is |
656 | 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> |
657 | 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 |
658 | 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 |
659 | attempt to decode the string but throw an exception. This setting has no |
643 | effect on C<encode> (yet). |
660 | effect on C<encode> (yet). |
644 | |
661 | |
645 | The argument to C<max_size> will be rounded up to the next B<highest> |
662 | 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 |
663 | C<0> is specified). |
647 | limit check will be deactivated (same as when C<0> is specified). |
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648 | |
664 | |
649 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
665 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
650 | |
666 | |
651 | =item $json_text = $json->encode ($perl_scalar) |
667 | =item $json_text = $json->encode ($perl_scalar) |
652 | |
668 | |
… | |
… | |
683 | =back |
699 | =back |
684 | |
700 | |
685 | |
701 | |
686 | =head1 INCREMENTAL PARSING |
702 | =head1 INCREMENTAL PARSING |
687 | |
703 | |
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 |
704 | 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 |
705 | 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 |
706 | 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 |
707 | 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 |
708 | 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 |
709 | 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 |
710 | is much more efficient (and can be implemented with a minimum of method |
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711 | calls). |
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712 | |
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713 | 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 |
714 | has enough text to get a decisive result, using a very simple but |
698 | simple but truly incremental parser). |
715 | truly incremental parser. This means that it sometimes won't stop as |
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716 | early as the full parser, for example, it doesn't detect parenthese |
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717 | mismatches. The only thing it guarantees is that it starts decoding as |
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718 | soon as a syntactically valid JSON text has been seen. This means you need |
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719 | to set resource limits (e.g. C<max_size>) to ensure the parser will stop |
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720 | parsing in the presence if syntax errors. |
699 | |
721 | |
700 | The following two methods deal with this. |
722 | The following methods implement this incremental parser. |
701 | |
723 | |
702 | =over 4 |
724 | =over 4 |
703 | |
725 | |
704 | =item [void, scalar or list context] = $json->incr_parse ([$string]) |
726 | =item [void, scalar or list context] = $json->incr_parse ([$string]) |
705 | |
727 | |
… | |
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714 | return without doing anything further. This can be used to add more text |
736 | return without doing anything further. This can be used to add more text |
715 | in as many chunks as you want. |
737 | in as many chunks as you want. |
716 | |
738 | |
717 | If the method is called in scalar context, then it will try to extract |
739 | If the method is called in scalar context, then it will try to extract |
718 | exactly I<one> JSON object. If that is successful, it will return this |
740 | exactly I<one> JSON object. If that is successful, it will return this |
719 | object, otherwise it will return C<undef>. This is the most common way of |
741 | object, otherwise it will return C<undef>. If there is a parse error, |
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742 | this method will croak just as C<decode> would do (one can then use |
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743 | C<incr_skip> to skip the errornous part). This is the most common way of |
720 | using the method. |
744 | using the method. |
721 | |
745 | |
722 | And finally, in list context, it will try to extract as many objects |
746 | And finally, in list context, it will try to extract as many objects |
723 | from the stream as it can find and return them, or the empty list |
747 | from the stream as it can find and return them, or the empty list |
724 | otherwise. For this to work, there must be no separators between the JSON |
748 | otherwise. For this to work, there must be no separators between the JSON |
725 | objects or arrays, instead they must be concatenated back-to-back. |
749 | objects or arrays, instead they must be concatenated back-to-back. If |
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750 | an error occurs, an exception will be raised as in the scalar context |
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751 | case. Note that in this case, any previously-parsed JSON texts will be |
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752 | lost. |
726 | |
753 | |
727 | =item $lvalue_string = $json->incr_text |
754 | =item $lvalue_string = $json->incr_text |
728 | |
755 | |
729 | This method returns the currently stored JSON fragment as an lvalue, that |
756 | This method returns the currently stored JSON fragment as an lvalue, that |
730 | is, you can manipulate it. This I<only> works when a preceding call to |
757 | is, you can manipulate it. This I<only> works when a preceding call to |
… | |
… | |
735 | method before having parsed anything. |
762 | method before having parsed anything. |
736 | |
763 | |
737 | This function is useful in two cases: a) finding the trailing text after a |
764 | This function is useful in two cases: a) finding the trailing text after a |
738 | JSON object or b) parsing multiple JSON objects separated by non-JSON text |
765 | JSON object or b) parsing multiple JSON objects separated by non-JSON text |
739 | (such as commas). |
766 | (such as commas). |
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767 | |
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768 | =item $json->incr_skip |
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769 | |
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770 | This will reset the state of the incremental parser and will remove |
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771 | the parsed text from the input buffer so far. This is useful after |
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772 | C<incr_parse> died, in which case the input buffer and incremental parser |
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773 | state is left unchanged, to skip the text parsed so far and to reset the |
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774 | parse state. |
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775 | |
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776 | The difference to C<incr_reset> is that only text until the parse error |
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777 | occured is removed. |
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778 | |
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779 | =item $json->incr_reset |
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780 | |
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781 | This completely resets the incremental parser, that is, after this call, |
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782 | it will be as if the parser had never parsed anything. |
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783 | |
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784 | This is useful if you want to repeatedly parse JSON objects and want to |
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785 | ignore any trailing data, which means you have to reset the parser after |
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786 | each successful decode. |
740 | |
787 | |
741 | =back |
788 | =back |
742 | |
789 | |
743 | =head2 LIMITATIONS |
790 | =head2 LIMITATIONS |
744 | |
791 | |
… | |
… | |
985 | Other unblessed references are generally not allowed and will cause an |
1032 | Other unblessed references are generally not allowed and will cause an |
986 | exception to be thrown, except for references to the integers C<0> and |
1033 | exception to be thrown, except for references to the integers C<0> and |
987 | C<1>, which get turned into C<false> and C<true> atoms in JSON. You can |
1034 | C<1>, which get turned into C<false> and C<true> atoms in JSON. You can |
988 | also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. |
1035 | also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. |
989 | |
1036 | |
990 | encode_json [\0,JSON::XS::true] # yields [false,true] |
1037 | encode_json [\0, JSON::XS::true] # yields [false,true] |
991 | |
1038 | |
992 | =item JSON::XS::true, JSON::XS::false |
1039 | =item JSON::XS::true, JSON::XS::false |
993 | |
1040 | |
994 | These special values become JSON true and JSON false values, |
1041 | These special values become JSON true and JSON false values, |
995 | respectively. You can also use C<\1> and C<\0> directly if you want. |
1042 | respectively. You can also use C<\1> and C<\0> directly if you want. |
… | |
… | |
1137 | proper subset of most 8-bit and multibyte encodings in use in the world. |
1184 | proper subset of most 8-bit and multibyte encodings in use in the world. |
1138 | |
1185 | |
1139 | =back |
1186 | =back |
1140 | |
1187 | |
1141 | |
1188 | |
1142 | =head1 COMPARISON |
1189 | =head2 JSON and ECMAscript |
1143 | |
1190 | |
1144 | As already mentioned, this module was created because none of the existing |
1191 | JSON syntax is based on how literals are represented in javascript (the |
1145 | JSON modules could be made to work correctly. First I will describe the |
1192 | not-standardised predecessor of ECMAscript) which is presumably why it is |
1146 | problems (or pleasures) I encountered with various existing JSON modules, |
1193 | called "JavaScript Object Notation". |
1147 | followed by some benchmark values. JSON::XS was designed not to suffer |
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1148 | from any of these problems or limitations. |
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1149 | |
1194 | |
1150 | =over 4 |
1195 | However, JSON is not a subset (and also not a superset of course) of |
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1196 | ECMAscript (the standard) or javascript (whatever browsers actually |
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1197 | implement). |
1151 | |
1198 | |
1152 | =item JSON 2.xx |
1199 | If you want to use javascript's C<eval> function to "parse" JSON, you |
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1200 | might run into parse errors for valid JSON texts, or the resulting data |
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1201 | structure might not be queryable: |
1153 | |
1202 | |
1154 | A marvellous piece of engineering, this module either uses JSON::XS |
1203 | One of the problems is that U+2028 and U+2029 are valid characters inside |
1155 | directly when available (so will be 100% compatible with it, including |
1204 | JSON strings, but are not allowed in ECMAscript string literals, so the |
1156 | speed), or it uses JSON::PP, which is basically JSON::XS translated to |
1205 | following Perl fragment will not output something that can be guaranteed |
1157 | Pure Perl, which should be 100% compatible with JSON::XS, just a bit |
1206 | to be parsable by javascript's C<eval>: |
1158 | slower. |
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1159 | |
1207 | |
1160 | You cannot really lose by using this module, especially as it tries very |
1208 | use JSON::XS; |
1161 | hard to work even with ancient Perl versions, while JSON::XS does not. |
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1162 | |
1209 | |
1163 | =item JSON 1.07 |
1210 | print encode_json [chr 0x2028]; |
1164 | |
1211 | |
1165 | Slow (but very portable, as it is written in pure Perl). |
1212 | The right fix for this is to use a proper JSON parser in your javascript |
|
|
1213 | programs, and not rely on C<eval> (see for example Douglas Crockford's |
|
|
1214 | F<json2.js> parser). |
1166 | |
1215 | |
1167 | Undocumented/buggy Unicode handling (how JSON handles Unicode values is |
1216 | If this is not an option, you can, as a stop-gap measure, simply encode to |
1168 | undocumented. One can get far by feeding it Unicode strings and doing |
1217 | ASCII-only JSON: |
1169 | en-/decoding oneself, but Unicode escapes are not working properly). |
|
|
1170 | |
1218 | |
1171 | No round-tripping (strings get clobbered if they look like numbers, e.g. |
1219 | use JSON::XS; |
1172 | the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will |
|
|
1173 | decode into the number 2. |
|
|
1174 | |
1220 | |
1175 | =item JSON::PC 0.01 |
1221 | print JSON::XS->new->ascii->encode ([chr 0x2028]); |
1176 | |
1222 | |
1177 | Very fast. |
1223 | Note that this will enlarge the resulting JSON text quite a bit if you |
|
|
1224 | have many non-ASCII characters. You might be tempted to run some regexes |
|
|
1225 | to only escape U+2028 and U+2029, e.g.: |
1178 | |
1226 | |
1179 | Undocumented/buggy Unicode handling. |
1227 | # DO NOT USE THIS! |
|
|
1228 | my $json = JSON::XS->new->utf8->encode ([chr 0x2028]); |
|
|
1229 | $json =~ s/\xe2\x80\xa8/\\u2028/g; # escape U+2028 |
|
|
1230 | $json =~ s/\xe2\x80\xa9/\\u2029/g; # escape U+2029 |
|
|
1231 | print $json; |
1180 | |
1232 | |
1181 | No round-tripping. |
1233 | Note that I<this is a bad idea>: the above only works for U+2028 and |
|
|
1234 | U+2029 and thus only for fully ECMAscript-compliant parsers. Many existing |
|
|
1235 | javascript implementations, however, have issues with other characters as |
|
|
1236 | well - using C<eval> naively simply I<will> cause problems. |
1182 | |
1237 | |
1183 | Has problems handling many Perl values (e.g. regex results and other magic |
1238 | Another problem is that some javascript implementations reserve |
1184 | values will make it croak). |
1239 | some property names for their own purposes (which probably makes |
|
|
1240 | them non-ECMAscript-compliant). For example, Iceweasel reserves the |
|
|
1241 | C<__proto__> property name for it's own purposes. |
1185 | |
1242 | |
1186 | Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}> |
1243 | If that is a problem, you could parse try to filter the resulting JSON |
1187 | which is not a valid JSON text. |
1244 | output for these property strings, e.g.: |
1188 | |
1245 | |
1189 | Unmaintained (maintainer unresponsive for many months, bugs are not |
1246 | $json =~ s/"__proto__"\s*:/"__proto__renamed":/g; |
1190 | getting fixed). |
|
|
1191 | |
1247 | |
1192 | =item JSON::Syck 0.21 |
1248 | This works because C<__proto__> is not valid outside of strings, so every |
|
|
1249 | occurence of C<"__proto__"\s*:> must be a string used as property name. |
1193 | |
1250 | |
1194 | Very buggy (often crashes). |
1251 | If you know of other incompatibilities, please let me know. |
1195 | |
|
|
1196 | Very inflexible (no human-readable format supported, format pretty much |
|
|
1197 | undocumented. I need at least a format for easy reading by humans and a |
|
|
1198 | single-line compact format for use in a protocol, and preferably a way to |
|
|
1199 | generate ASCII-only JSON texts). |
|
|
1200 | |
|
|
1201 | Completely broken (and confusingly documented) Unicode handling (Unicode |
|
|
1202 | escapes are not working properly, you need to set ImplicitUnicode to |
|
|
1203 | I<different> values on en- and decoding to get symmetric behaviour). |
|
|
1204 | |
|
|
1205 | No round-tripping (simple cases work, but this depends on whether the scalar |
|
|
1206 | value was used in a numeric context or not). |
|
|
1207 | |
|
|
1208 | Dumping hashes may skip hash values depending on iterator state. |
|
|
1209 | |
|
|
1210 | Unmaintained (maintainer unresponsive for many months, bugs are not |
|
|
1211 | getting fixed). |
|
|
1212 | |
|
|
1213 | Does not check input for validity (i.e. will accept non-JSON input and |
|
|
1214 | return "something" instead of raising an exception. This is a security |
|
|
1215 | issue: imagine two banks transferring money between each other using |
|
|
1216 | JSON. One bank might parse a given non-JSON request and deduct money, |
|
|
1217 | while the other might reject the transaction with a syntax error. While a |
|
|
1218 | good protocol will at least recover, that is extra unnecessary work and |
|
|
1219 | the transaction will still not succeed). |
|
|
1220 | |
|
|
1221 | =item JSON::DWIW 0.04 |
|
|
1222 | |
|
|
1223 | Very fast. Very natural. Very nice. |
|
|
1224 | |
|
|
1225 | Undocumented Unicode handling (but the best of the pack. Unicode escapes |
|
|
1226 | still don't get parsed properly). |
|
|
1227 | |
|
|
1228 | Very inflexible. |
|
|
1229 | |
|
|
1230 | No round-tripping. |
|
|
1231 | |
|
|
1232 | Does not generate valid JSON texts (key strings are often unquoted, empty keys |
|
|
1233 | result in nothing being output) |
|
|
1234 | |
|
|
1235 | Does not check input for validity. |
|
|
1236 | |
|
|
1237 | =back |
|
|
1238 | |
1252 | |
1239 | |
1253 | |
1240 | =head2 JSON and YAML |
1254 | =head2 JSON and YAML |
1241 | |
1255 | |
1242 | You often hear that JSON is a subset of YAML. This is, however, a mass |
1256 | You often hear that JSON is a subset of YAML. This is, however, a mass |
… | |
… | |
1300 | |
1314 | |
1301 | First comes a comparison between various modules using |
1315 | First comes a comparison between various modules using |
1302 | a very short single-line JSON string (also available at |
1316 | a very short single-line JSON string (also available at |
1303 | L<http://dist.schmorp.de/misc/json/short.json>). |
1317 | L<http://dist.schmorp.de/misc/json/short.json>). |
1304 | |
1318 | |
1305 | {"method": "handleMessage", "params": ["user1", "we were just talking"], \ |
1319 | {"method": "handleMessage", "params": ["user1", |
1306 | "id": null, "array":[1,11,234,-5,1e5,1e7, true, false]} |
1320 | "we were just talking"], "id": null, "array":[1,11,234,-5,1e5,1e7, |
|
|
1321 | true, false]} |
1307 | |
1322 | |
1308 | It shows the number of encodes/decodes per second (JSON::XS uses |
1323 | It shows the number of encodes/decodes per second (JSON::XS uses |
1309 | the functional interface, while JSON::XS/2 uses the OO interface |
1324 | the functional interface, while JSON::XS/2 uses the OO interface |
1310 | with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables |
1325 | with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables |
1311 | shrink). Higher is better: |
1326 | shrink). Higher is better: |
… | |
… | |
1409 | |
1424 | |
1410 | |
1425 | |
1411 | =head1 BUGS |
1426 | =head1 BUGS |
1412 | |
1427 | |
1413 | While the goal of this module is to be correct, that unfortunately does |
1428 | While the goal of this module is to be correct, that unfortunately does |
1414 | not mean it's bug-free, only that I think its design is bug-free. It is |
1429 | not mean it's bug-free, only that I think its design is bug-free. If you |
1415 | still relatively early in its development. If you keep reporting bugs they |
1430 | keep reporting bugs they will be fixed swiftly, though. |
1416 | will be fixed swiftly, though. |
|
|
1417 | |
1431 | |
1418 | Please refrain from using rt.cpan.org or any other bug reporting |
1432 | Please refrain from using rt.cpan.org or any other bug reporting |
1419 | service. I put the contact address into my modules for a reason. |
1433 | service. I put the contact address into my modules for a reason. |
1420 | |
1434 | |
1421 | =cut |
1435 | =cut |