… | |
… | |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use JSON::XS; |
7 | use JSON::XS; |
8 | |
8 | |
9 | # exported functions, croak on error |
9 | # exported functions, they croak on error |
|
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10 | # and expect/generate UTF-8 |
10 | |
11 | |
11 | $utf8_encoded_json_text = to_json $perl_hash_or_arrayref; |
12 | $utf8_encoded_json_text = to_json $perl_hash_or_arrayref; |
12 | $perl_hash_or_arrayref = from_json $utf8_encoded_json_text; |
13 | $perl_hash_or_arrayref = from_json $utf8_encoded_json_text; |
13 | |
14 | |
|
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15 | # objToJson and jsonToObj aliases to to_json and from_json |
|
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16 | # are exported for compatibility to the JSON module, |
|
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17 | # but should not be used in new code. |
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18 | |
14 | # oo-interface |
19 | # OO-interface |
15 | |
20 | |
16 | $coder = JSON::XS->new->ascii->pretty->allow_nonref; |
21 | $coder = JSON::XS->new->ascii->pretty->allow_nonref; |
17 | $pretty_printed_unencoded = $coder->encode ($perl_scalar); |
22 | $pretty_printed_unencoded = $coder->encode ($perl_scalar); |
18 | $perl_scalar = $coder->decode ($unicode_json_text); |
23 | $perl_scalar = $coder->decode ($unicode_json_text); |
19 | |
24 | |
… | |
… | |
36 | |
41 | |
37 | =head2 FEATURES |
42 | =head2 FEATURES |
38 | |
43 | |
39 | =over 4 |
44 | =over 4 |
40 | |
45 | |
41 | =item * correct handling of unicode issues |
46 | =item * correct unicode handling |
42 | |
47 | |
43 | This module knows how to handle Unicode, and even documents how and when |
48 | This module knows how to handle Unicode, and even documents how and when |
44 | it does so. |
49 | it does so. |
45 | |
50 | |
46 | =item * round-trip integrity |
51 | =item * round-trip integrity |
47 | |
52 | |
48 | When you serialise a perl data structure using only datatypes supported |
53 | When you serialise a perl data structure using only datatypes supported |
49 | by JSON, the deserialised data structure is identical on the Perl level. |
54 | by JSON, the deserialised data structure is identical on the Perl level. |
50 | (e.g. the string "2.0" doesn't suddenly become "2"). |
55 | (e.g. the string "2.0" doesn't suddenly become "2" just because it looks |
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56 | like a number). |
51 | |
57 | |
52 | =item * strict checking of JSON correctness |
58 | =item * strict checking of JSON correctness |
53 | |
59 | |
54 | There is no guessing, no generating of illegal JSON strings by default, |
60 | There is no guessing, no generating of illegal JSON texts by default, |
55 | and only JSON is accepted as input by default (the latter is a security |
61 | and only JSON is accepted as input by default (the latter is a security |
56 | feature). |
62 | feature). |
57 | |
63 | |
58 | =item * fast |
64 | =item * fast |
59 | |
65 | |
… | |
… | |
66 | interface. |
72 | interface. |
67 | |
73 | |
68 | =item * reasonably versatile output formats |
74 | =item * reasonably versatile output formats |
69 | |
75 | |
70 | You can choose between the most compact guarenteed single-line format |
76 | You can choose between the most compact guarenteed single-line format |
71 | possible (nice for simple line-based protocols), a pure-ascii format (for |
77 | possible (nice for simple line-based protocols), a pure-ascii format |
72 | when your transport is not 8-bit clean), or a pretty-printed format (for |
78 | (for when your transport is not 8-bit clean, still supports the whole |
73 | when you want to read that stuff). Or you can combine those features in |
79 | unicode range), or a pretty-printed format (for when you want to read that |
74 | whatever way you like. |
80 | stuff). Or you can combine those features in whatever way you like. |
75 | |
81 | |
76 | =back |
82 | =back |
77 | |
83 | |
78 | =cut |
84 | =cut |
79 | |
85 | |
80 | package JSON::XS; |
86 | package JSON::XS; |
81 | |
87 | |
|
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88 | use strict; |
|
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89 | |
82 | BEGIN { |
90 | BEGIN { |
83 | $VERSION = '0.31'; |
91 | our $VERSION = '1.23'; |
84 | @ISA = qw(Exporter); |
92 | our @ISA = qw(Exporter); |
85 | |
93 | |
86 | @EXPORT = qw(to_json from_json); |
94 | our @EXPORT = qw(to_json from_json objToJson jsonToObj); |
87 | require Exporter; |
95 | require Exporter; |
88 | |
96 | |
89 | require XSLoader; |
97 | require XSLoader; |
90 | XSLoader::load JSON::XS::, $VERSION; |
98 | XSLoader::load JSON::XS::, $VERSION; |
91 | } |
99 | } |
… | |
… | |
95 | The following convinience methods are provided by this module. They are |
103 | The following convinience methods are provided by this module. They are |
96 | exported by default: |
104 | exported by default: |
97 | |
105 | |
98 | =over 4 |
106 | =over 4 |
99 | |
107 | |
100 | =item $json_string = to_json $perl_scalar |
108 | =item $json_text = to_json $perl_scalar |
101 | |
109 | |
102 | Converts the given Perl data structure (a simple scalar or a reference to |
110 | Converts the given Perl data structure (a simple scalar or a reference to |
103 | a hash or array) to a UTF-8 encoded, binary string (that is, the string contains |
111 | a hash or array) to a UTF-8 encoded, binary string (that is, the string contains |
104 | octets only). Croaks on error. |
112 | octets only). Croaks on error. |
105 | |
113 | |
106 | This function call is functionally identical to C<< JSON::XS->new->utf8->encode ($perl_scalar) >>. |
114 | This function call is functionally identical to: |
107 | |
115 | |
|
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116 | $json_text = JSON::XS->new->utf8->encode ($perl_scalar) |
|
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117 | |
|
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118 | except being faster. |
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119 | |
108 | =item $perl_scalar = from_json $json_string |
120 | =item $perl_scalar = from_json $json_text |
109 | |
121 | |
110 | The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to |
122 | The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to |
111 | parse that as an UTF-8 encoded JSON string, returning the resulting simple |
123 | parse that as an UTF-8 encoded JSON text, returning the resulting simple |
112 | scalar or reference. Croaks on error. |
124 | scalar or reference. Croaks on error. |
113 | |
125 | |
114 | This function call is functionally identical to C<< JSON::XS->new->utf8->decode ($json_string) >>. |
126 | This function call is functionally identical to: |
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127 | |
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128 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) |
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129 | |
|
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130 | except being faster. |
115 | |
131 | |
116 | =back |
132 | =back |
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133 | |
117 | |
134 | |
118 | =head1 OBJECT-ORIENTED INTERFACE |
135 | =head1 OBJECT-ORIENTED INTERFACE |
119 | |
136 | |
120 | The object oriented interface lets you configure your own encoding or |
137 | The object oriented interface lets you configure your own encoding or |
121 | decoding style, within the limits of supported formats. |
138 | decoding style, within the limits of supported formats. |
… | |
… | |
128 | strings. All boolean flags described below are by default I<disabled>. |
145 | strings. All boolean flags described below are by default I<disabled>. |
129 | |
146 | |
130 | The mutators for flags all return the JSON object again and thus calls can |
147 | The mutators for flags all return the JSON object again and thus calls can |
131 | be chained: |
148 | be chained: |
132 | |
149 | |
133 | my $json = JSON::XS->new->utf8(1)->space_after(1)->encode ({a => [1,2]}) |
150 | my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]}) |
134 | => {"a": [1, 2]} |
151 | => {"a": [1, 2]} |
135 | |
152 | |
136 | =item $json = $json->ascii ([$enable]) |
153 | =item $json = $json->ascii ([$enable]) |
137 | |
154 | |
138 | If C<$enable> is true (or missing), then the C<encode> method will |
155 | If C<$enable> is true (or missing), then the C<encode> method will not |
139 | not generate characters outside the code range C<0..127>. Any unicode |
156 | generate characters outside the code range C<0..127> (which is ASCII). Any |
140 | characters outside that range will be escaped using either a single |
157 | unicode characters outside that range will be escaped using either a |
141 | \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, as per |
158 | single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, |
142 | RFC4627. |
159 | as per RFC4627. The resulting encoded JSON text can be treated as a native |
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160 | unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string, |
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161 | or any other superset of ASCII. |
143 | |
162 | |
144 | If C<$enable> is false, then the C<encode> method will not escape Unicode |
163 | If C<$enable> is false, then the C<encode> method will not escape Unicode |
145 | characters unless necessary. |
164 | characters unless required by the JSON syntax or other flags. This results |
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165 | in a faster and more compact format. |
146 | |
166 | |
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167 | The main use for this flag is to produce JSON texts that can be |
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168 | transmitted over a 7-bit channel, as the encoded JSON texts will not |
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169 | contain any 8 bit characters. |
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170 | |
147 | JSON::XS->new->ascii (1)->encode (chr 0x10401) |
171 | JSON::XS->new->ascii (1)->encode ([chr 0x10401]) |
148 | => \ud801\udc01 |
172 | => ["\ud801\udc01"] |
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173 | |
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174 | =item $json = $json->latin1 ([$enable]) |
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175 | |
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176 | If C<$enable> is true (or missing), then the C<encode> method will encode |
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177 | the resulting JSON text as latin1 (or iso-8859-1), escaping any characters |
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178 | outside the code range C<0..255>. The resulting string can be treated as a |
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179 | latin1-encoded JSON text or a native unicode string. The C<decode> method |
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180 | will not be affected in any way by this flag, as C<decode> by default |
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181 | expects unicode, which is a strict superset of latin1. |
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182 | |
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183 | If C<$enable> is false, then the C<encode> method will not escape Unicode |
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184 | characters unless required by the JSON syntax or other flags. |
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185 | |
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186 | The main use for this flag is efficiently encoding binary data as JSON |
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187 | text, as most octets will not be escaped, resulting in a smaller encoded |
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188 | size. The disadvantage is that the resulting JSON text is encoded |
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189 | in latin1 (and must correctly be treated as such when storing and |
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190 | transfering), a rare encoding for JSON. It is therefore most useful when |
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191 | you want to store data structures known to contain binary data efficiently |
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192 | in files or databases, not when talking to other JSON encoders/decoders. |
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193 | |
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194 | JSON::XS->new->latin1->encode (["\x{89}\x{abc}"] |
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195 | => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not) |
149 | |
196 | |
150 | =item $json = $json->utf8 ([$enable]) |
197 | =item $json = $json->utf8 ([$enable]) |
151 | |
198 | |
152 | If C<$enable> is true (or missing), then the C<encode> method will encode |
199 | If C<$enable> is true (or missing), then the C<encode> method will encode |
153 | the JSON string into UTF-8, as required by many protocols, while the |
200 | the JSON result into UTF-8, as required by many protocols, while the |
154 | C<decode> method expects to be handled an UTF-8-encoded string. Please |
201 | C<decode> method expects to be handled an UTF-8-encoded string. Please |
155 | note that UTF-8-encoded strings do not contain any characters outside the |
202 | note that UTF-8-encoded strings do not contain any characters outside the |
156 | range C<0..255>, they are thus useful for bytewise/binary I/O. |
203 | range C<0..255>, they are thus useful for bytewise/binary I/O. In future |
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204 | versions, enabling this option might enable autodetection of the UTF-16 |
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205 | and UTF-32 encoding families, as described in RFC4627. |
157 | |
206 | |
158 | If C<$enable> is false, then the C<encode> method will return the JSON |
207 | If C<$enable> is false, then the C<encode> method will return the JSON |
159 | string as a (non-encoded) unicode string, while C<decode> expects thus a |
208 | string as a (non-encoded) unicode string, while C<decode> expects thus a |
160 | unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs |
209 | unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs |
161 | to be done yourself, e.g. using the Encode module. |
210 | to be done yourself, e.g. using the Encode module. |
162 | |
211 | |
163 | Example, output UTF-16-encoded JSON: |
212 | Example, output UTF-16BE-encoded JSON: |
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213 | |
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214 | use Encode; |
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215 | $jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object); |
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216 | |
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217 | Example, decode UTF-32LE-encoded JSON: |
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218 | |
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219 | use Encode; |
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220 | $object = JSON::XS->new->decode (decode "UTF-32LE", $jsontext); |
164 | |
221 | |
165 | =item $json = $json->pretty ([$enable]) |
222 | =item $json = $json->pretty ([$enable]) |
166 | |
223 | |
167 | This enables (or disables) all of the C<indent>, C<space_before> and |
224 | This enables (or disables) all of the C<indent>, C<space_before> and |
168 | C<space_after> (and in the future possibly more) flags in one call to |
225 | C<space_after> (and in the future possibly more) flags in one call to |
… | |
… | |
184 | If C<$enable> is true (or missing), then the C<encode> method will use a multiline |
241 | If C<$enable> is true (or missing), then the C<encode> method will use a multiline |
185 | format as output, putting every array member or object/hash key-value pair |
242 | format as output, putting every array member or object/hash key-value pair |
186 | into its own line, identing them properly. |
243 | into its own line, identing them properly. |
187 | |
244 | |
188 | If C<$enable> is false, no newlines or indenting will be produced, and the |
245 | If C<$enable> is false, no newlines or indenting will be produced, and the |
189 | resulting JSON strings is guarenteed not to contain any C<newlines>. |
246 | resulting JSON text is guarenteed not to contain any C<newlines>. |
190 | |
247 | |
191 | This setting has no effect when decoding JSON strings. |
248 | This setting has no effect when decoding JSON texts. |
192 | |
249 | |
193 | =item $json = $json->space_before ([$enable]) |
250 | =item $json = $json->space_before ([$enable]) |
194 | |
251 | |
195 | If C<$enable> is true (or missing), then the C<encode> method will add an extra |
252 | If C<$enable> is true (or missing), then the C<encode> method will add an extra |
196 | optional space before the C<:> separating keys from values in JSON objects. |
253 | optional space before the C<:> separating keys from values in JSON objects. |
197 | |
254 | |
198 | If C<$enable> is false, then the C<encode> method will not add any extra |
255 | If C<$enable> is false, then the C<encode> method will not add any extra |
199 | space at those places. |
256 | space at those places. |
200 | |
257 | |
201 | This setting has no effect when decoding JSON strings. You will also most |
258 | This setting has no effect when decoding JSON texts. You will also |
202 | likely combine this setting with C<space_after>. |
259 | most likely combine this setting with C<space_after>. |
203 | |
260 | |
204 | Example, space_before enabled, space_after and indent disabled: |
261 | Example, space_before enabled, space_after and indent disabled: |
205 | |
262 | |
206 | {"key" :"value"} |
263 | {"key" :"value"} |
207 | |
264 | |
… | |
… | |
213 | members. |
270 | members. |
214 | |
271 | |
215 | If C<$enable> is false, then the C<encode> method will not add any extra |
272 | If C<$enable> is false, then the C<encode> method will not add any extra |
216 | space at those places. |
273 | space at those places. |
217 | |
274 | |
218 | This setting has no effect when decoding JSON strings. |
275 | This setting has no effect when decoding JSON texts. |
219 | |
276 | |
220 | Example, space_before and indent disabled, space_after enabled: |
277 | Example, space_before and indent disabled, space_after enabled: |
221 | |
278 | |
222 | {"key": "value"} |
279 | {"key": "value"} |
223 | |
280 | |
… | |
… | |
229 | If C<$enable> is false, then the C<encode> method will output key-value |
286 | If C<$enable> is false, then the C<encode> method will output key-value |
230 | pairs in the order Perl stores them (which will likely change between runs |
287 | pairs in the order Perl stores them (which will likely change between runs |
231 | of the same script). |
288 | of the same script). |
232 | |
289 | |
233 | This option is useful if you want the same data structure to be encoded as |
290 | This option is useful if you want the same data structure to be encoded as |
234 | the same JSON string (given the same overall settings). If it is disabled, |
291 | the same JSON text (given the same overall settings). If it is disabled, |
235 | the same hash migh be encoded differently even if contains the same data, |
292 | the same hash migh be encoded differently even if contains the same data, |
236 | as key-value pairs have no inherent ordering in Perl. |
293 | as key-value pairs have no inherent ordering in Perl. |
237 | |
294 | |
238 | This setting has no effect when decoding JSON strings. |
295 | This setting has no effect when decoding JSON texts. |
239 | |
296 | |
240 | =item $json = $json->allow_nonref ([$enable]) |
297 | =item $json = $json->allow_nonref ([$enable]) |
241 | |
298 | |
242 | If C<$enable> is true (or missing), then the C<encode> method can convert a |
299 | If C<$enable> is true (or missing), then the C<encode> method can convert a |
243 | non-reference into its corresponding string, number or null JSON value, |
300 | non-reference into its corresponding string, number or null JSON value, |
244 | which is an extension to RFC4627. Likewise, C<decode> will accept those JSON |
301 | which is an extension to RFC4627. Likewise, C<decode> will accept those JSON |
245 | values instead of croaking. |
302 | values instead of croaking. |
246 | |
303 | |
247 | If C<$enable> is false, then the C<encode> method will croak if it isn't |
304 | If C<$enable> is false, then the C<encode> method will croak if it isn't |
248 | passed an arrayref or hashref, as JSON strings must either be an object |
305 | passed an arrayref or hashref, as JSON texts must either be an object |
249 | or array. Likewise, C<decode> will croak if given something that is not a |
306 | or array. Likewise, C<decode> will croak if given something that is not a |
250 | JSON object or array. |
307 | JSON object or array. |
251 | |
308 | |
252 | Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>, |
309 | Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>, |
253 | resulting in an invalid JSON text: |
310 | resulting in an invalid JSON text: |
… | |
… | |
256 | => "Hello, World!" |
313 | => "Hello, World!" |
257 | |
314 | |
258 | =item $json = $json->shrink ([$enable]) |
315 | =item $json = $json->shrink ([$enable]) |
259 | |
316 | |
260 | Perl usually over-allocates memory a bit when allocating space for |
317 | Perl usually over-allocates memory a bit when allocating space for |
261 | strings. This flag optionally resizes strings generated by either |
318 | strings. This flag optionally resizes strings generated by either |
262 | C<encode> or C<decode> to their minimum size possible. This can save |
319 | C<encode> or C<decode> to their minimum size possible. This can save |
263 | memory when your JSON strings are either very very long or you have many |
320 | memory when your JSON texts are either very very long or you have many |
264 | short strings. It will also try to downgrade any strings to octet-form |
321 | short strings. It will also try to downgrade any strings to octet-form |
265 | if possible: perl stores strings internally either in an encoding called |
322 | if possible: perl stores strings internally either in an encoding called |
266 | UTF-X or in octet-form. The latter cannot store everything but uses less |
323 | UTF-X or in octet-form. The latter cannot store everything but uses less |
267 | space in general. |
324 | space in general (and some buggy Perl or C code might even rely on that |
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325 | internal representation being used). |
268 | |
326 | |
|
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327 | The actual definition of what shrink does might change in future versions, |
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328 | but it will always try to save space at the expense of time. |
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329 | |
269 | If C<$enable> is true (or missing), the string returned by C<encode> will be shrunk-to-fit, |
330 | If C<$enable> is true (or missing), the string returned by C<encode> will |
270 | while all strings generated by C<decode> will also be shrunk-to-fit. |
331 | be shrunk-to-fit, while all strings generated by C<decode> will also be |
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332 | shrunk-to-fit. |
271 | |
333 | |
272 | If C<$enable> is false, then the normal perl allocation algorithms are used. |
334 | If C<$enable> is false, then the normal perl allocation algorithms are used. |
273 | If you work with your data, then this is likely to be faster. |
335 | If you work with your data, then this is likely to be faster. |
274 | |
336 | |
275 | In the future, this setting might control other things, such as converting |
337 | In the future, this setting might control other things, such as converting |
276 | strings that look like integers or floats into integers or floats |
338 | strings that look like integers or floats into integers or floats |
277 | internally (there is no difference on the Perl level), saving space. |
339 | internally (there is no difference on the Perl level), saving space. |
278 | |
340 | |
|
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341 | =item $json = $json->max_depth ([$maximum_nesting_depth]) |
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342 | |
|
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343 | Sets the maximum nesting level (default C<512>) accepted while encoding |
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344 | or decoding. If the JSON text or Perl data structure has an equal or |
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345 | higher nesting level then this limit, then the encoder and decoder will |
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346 | stop and croak at that point. |
|
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347 | |
|
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348 | Nesting level is defined by number of hash- or arrayrefs that the encoder |
|
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349 | needs to traverse to reach a given point or the number of C<{> or C<[> |
|
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350 | characters without their matching closing parenthesis crossed to reach a |
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351 | given character in a string. |
|
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352 | |
|
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353 | Setting the maximum depth to one disallows any nesting, so that ensures |
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354 | that the object is only a single hash/object or array. |
|
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355 | |
|
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356 | The argument to C<max_depth> will be rounded up to the next nearest power |
|
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357 | of two. |
|
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358 | |
|
|
359 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
|
|
360 | |
279 | =item $json_string = $json->encode ($perl_scalar) |
361 | =item $json_text = $json->encode ($perl_scalar) |
280 | |
362 | |
281 | Converts the given Perl data structure (a simple scalar or a reference |
363 | Converts the given Perl data structure (a simple scalar or a reference |
282 | to a hash or array) to its JSON representation. Simple scalars will be |
364 | to a hash or array) to its JSON representation. Simple scalars will be |
283 | converted into JSON string or number sequences, while references to arrays |
365 | converted into JSON string or number sequences, while references to arrays |
284 | become JSON arrays and references to hashes become JSON objects. Undefined |
366 | become JSON arrays and references to hashes become JSON objects. Undefined |
285 | Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true> |
367 | Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true> |
286 | nor C<false> values will be generated. |
368 | nor C<false> values will be generated. |
287 | |
369 | |
288 | =item $perl_scalar = $json->decode ($json_string) |
370 | =item $perl_scalar = $json->decode ($json_text) |
289 | |
371 | |
290 | The opposite of C<encode>: expects a JSON string and tries to parse it, |
372 | The opposite of C<encode>: expects a JSON text and tries to parse it, |
291 | returning the resulting simple scalar or reference. Croaks on error. |
373 | returning the resulting simple scalar or reference. Croaks on error. |
292 | |
374 | |
293 | JSON numbers and strings become simple Perl scalars. JSON arrays become |
375 | JSON numbers and strings become simple Perl scalars. JSON arrays become |
294 | Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes |
376 | Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes |
295 | C<1>, C<false> becomes C<0> and C<null> becomes C<undef>. |
377 | C<1>, C<false> becomes C<0> and C<null> becomes C<undef>. |
296 | |
378 | |
|
|
379 | =item ($perl_scalar, $characters) = $json->decode_prefix ($json_text) |
|
|
380 | |
|
|
381 | This works like the C<decode> method, but instead of raising an exception |
|
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382 | when there is trailing garbage after the first JSON object, it will |
|
|
383 | silently stop parsing there and return the number of characters consumed |
|
|
384 | so far. |
|
|
385 | |
|
|
386 | This is useful if your JSON texts are not delimited by an outer protocol |
|
|
387 | (which is not the brightest thing to do in the first place) and you need |
|
|
388 | to know where the JSON text ends. |
|
|
389 | |
|
|
390 | JSON::XS->new->decode_prefix ("[1] the tail") |
|
|
391 | => ([], 3) |
|
|
392 | |
297 | =back |
393 | =back |
|
|
394 | |
298 | |
395 | |
299 | =head1 MAPPING |
396 | =head1 MAPPING |
300 | |
397 | |
301 | This section describes how JSON::XS maps Perl values to JSON values and |
398 | This section describes how JSON::XS maps Perl values to JSON values and |
302 | vice versa. These mappings are designed to "do the right thing" in most |
399 | vice versa. These mappings are designed to "do the right thing" in most |
… | |
… | |
356 | =over 4 |
453 | =over 4 |
357 | |
454 | |
358 | =item hash references |
455 | =item hash references |
359 | |
456 | |
360 | Perl hash references become JSON objects. As there is no inherent ordering |
457 | Perl hash references become JSON objects. As there is no inherent ordering |
361 | in hash keys, they will usually be encoded in a pseudo-random order that |
458 | in hash keys (or JSON objects), they will usually be encoded in a |
362 | can change between runs of the same program but stays generally the same |
459 | pseudo-random order that can change between runs of the same program but |
363 | within a single run of a program. JSON::XS can optionally sort the hash |
460 | stays generally the same within a single run of a program. JSON::XS can |
364 | keys (determined by the I<canonical> flag), so the same datastructure |
461 | optionally sort the hash keys (determined by the I<canonical> flag), so |
365 | will serialise to the same JSON text (given same settings and version of |
462 | the same datastructure will serialise to the same JSON text (given same |
366 | JSON::XS), but this incurs a runtime overhead. |
463 | settings and version of JSON::XS), but this incurs a runtime overhead |
|
|
464 | and is only rarely useful, e.g. when you want to compare some JSON text |
|
|
465 | against another for equality. |
367 | |
466 | |
368 | =item array references |
467 | =item array references |
369 | |
468 | |
370 | Perl array references become JSON arrays. |
469 | Perl array references become JSON arrays. |
|
|
470 | |
|
|
471 | =item other references |
|
|
472 | |
|
|
473 | Other unblessed references are generally not allowed and will cause an |
|
|
474 | exception to be thrown, except for references to the integers C<0> and |
|
|
475 | C<1>, which get turned into C<false> and C<true> atoms in JSON. You can |
|
|
476 | also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. |
|
|
477 | |
|
|
478 | to_json [\0,JSON::XS::true] # yields [false,true] |
371 | |
479 | |
372 | =item blessed objects |
480 | =item blessed objects |
373 | |
481 | |
374 | Blessed objects are not allowed. JSON::XS currently tries to encode their |
482 | Blessed objects are not allowed. JSON::XS currently tries to encode their |
375 | underlying representation (hash- or arrayref), but this behaviour might |
483 | underlying representation (hash- or arrayref), but this behaviour might |
… | |
… | |
408 | $x *= 1; # same thing, the choise is yours. |
516 | $x *= 1; # same thing, the choise is yours. |
409 | |
517 | |
410 | You can not currently output JSON booleans or force the type in other, |
518 | You can not currently output JSON booleans or force the type in other, |
411 | less obscure, ways. Tell me if you need this capability. |
519 | less obscure, ways. Tell me if you need this capability. |
412 | |
520 | |
413 | =item circular data structures |
|
|
414 | |
|
|
415 | Those will be encoded until memory or stackspace runs out. |
|
|
416 | |
|
|
417 | =back |
521 | =back |
|
|
522 | |
418 | |
523 | |
419 | =head1 COMPARISON |
524 | =head1 COMPARISON |
420 | |
525 | |
421 | As already mentioned, this module was created because none of the existing |
526 | As already mentioned, this module was created because none of the existing |
422 | JSON modules could be made to work correctly. First I will describe the |
527 | JSON modules could be made to work correctly. First I will describe the |
… | |
… | |
448 | |
553 | |
449 | Has problems handling many Perl values (e.g. regex results and other magic |
554 | Has problems handling many Perl values (e.g. regex results and other magic |
450 | values will make it croak). |
555 | values will make it croak). |
451 | |
556 | |
452 | Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}> |
557 | Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}> |
453 | which is not a valid JSON string. |
558 | which is not a valid JSON text. |
454 | |
559 | |
455 | Unmaintained (maintainer unresponsive for many months, bugs are not |
560 | Unmaintained (maintainer unresponsive for many months, bugs are not |
456 | getting fixed). |
561 | getting fixed). |
457 | |
562 | |
458 | =item JSON::Syck 0.21 |
563 | =item JSON::Syck 0.21 |
… | |
… | |
460 | Very buggy (often crashes). |
565 | Very buggy (often crashes). |
461 | |
566 | |
462 | Very inflexible (no human-readable format supported, format pretty much |
567 | Very inflexible (no human-readable format supported, format pretty much |
463 | undocumented. I need at least a format for easy reading by humans and a |
568 | undocumented. I need at least a format for easy reading by humans and a |
464 | single-line compact format for use in a protocol, and preferably a way to |
569 | single-line compact format for use in a protocol, and preferably a way to |
465 | generate ASCII-only JSON strings). |
570 | generate ASCII-only JSON texts). |
466 | |
571 | |
467 | Completely broken (and confusingly documented) Unicode handling (unicode |
572 | Completely broken (and confusingly documented) Unicode handling (unicode |
468 | escapes are not working properly, you need to set ImplicitUnicode to |
573 | escapes are not working properly, you need to set ImplicitUnicode to |
469 | I<different> values on en- and decoding to get symmetric behaviour). |
574 | I<different> values on en- and decoding to get symmetric behaviour). |
470 | |
575 | |
… | |
… | |
493 | |
598 | |
494 | Very inflexible. |
599 | Very inflexible. |
495 | |
600 | |
496 | No roundtripping. |
601 | No roundtripping. |
497 | |
602 | |
498 | Does not generate valid JSON (key strings are often unquoted, empty keys |
603 | Does not generate valid JSON texts (key strings are often unquoted, empty keys |
499 | result in nothing being output) |
604 | result in nothing being output) |
500 | |
605 | |
501 | Does not check input for validity. |
606 | Does not check input for validity. |
502 | |
607 | |
503 | =back |
608 | =back |
… | |
… | |
507 | It seems that JSON::XS is surprisingly fast, as shown in the following |
612 | It seems that JSON::XS is surprisingly fast, as shown in the following |
508 | tables. They have been generated with the help of the C<eg/bench> program |
613 | tables. They have been generated with the help of the C<eg/bench> program |
509 | in the JSON::XS distribution, to make it easy to compare on your own |
614 | in the JSON::XS distribution, to make it easy to compare on your own |
510 | system. |
615 | system. |
511 | |
616 | |
512 | First comes a comparison between various modules using a very short JSON |
617 | First comes a comparison between various modules using a very short |
513 | string (83 bytes), showing the number of encodes/decodes per second |
618 | single-line JSON string: |
514 | (JSON::XS is the functional interface, while JSON::XS/2 is the OO |
619 | |
|
|
620 | {"method": "handleMessage", "params": ["user1", "we were just talking"], \ |
|
|
621 | "id": null, "array":[1,11,234,-5,1e5,1e7, true, false]} |
|
|
622 | |
|
|
623 | It shows the number of encodes/decodes per second (JSON::XS uses the |
|
|
624 | functional interface, while JSON::XS/2 uses the OO interface with |
515 | interface with pretty-printing and hashkey sorting enabled). Higher is |
625 | pretty-printing and hashkey sorting enabled). Higher is better: |
516 | better: |
|
|
517 | |
626 | |
518 | module | encode | decode | |
627 | module | encode | decode | |
519 | -----------|------------|------------| |
628 | -----------|------------|------------| |
520 | JSON | 14006 | 6820 | |
629 | JSON | 7645.468 | 4208.613 | |
521 | JSON::DWIW | 200937 | 120386 | |
630 | JSON::DWIW | 68534.379 | 79437.576 | |
522 | JSON::PC | 85065 | 129366 | |
631 | JSON::PC | 65948.176 | 78251.940 | |
523 | JSON::Syck | 59898 | 44232 | |
632 | JSON::Syck | 23379.621 | 28416.694 | |
524 | JSON::XS | 1171478 | 342435 | |
633 | JSON::XS | 388361.481 | 199728.762 | |
525 | JSON::XS/2 | 730760 | 328714 | |
634 | JSON::XS/2 | 218453.333 | 192399.266 | |
|
|
635 | JSON::XS/3 | 338250.323 | 192399.266 | |
|
|
636 | Storable | 15732.573 | 28571.553 | |
526 | -----------+------------+------------+ |
637 | -----------+------------+------------+ |
527 | |
638 | |
528 | That is, JSON::XS is 6 times faster than than JSON::DWIW and about 80 |
639 | That is, JSON::XS is about five times faster than JSON::DWIW on encoding, |
|
|
640 | about three times faster on decoding, and over fourty times faster |
529 | times faster than JSON, even with pretty-printing and key sorting. |
641 | than JSON, even with pretty-printing and key sorting. It also compares |
|
|
642 | favourably to Storable for small amounts of data. |
530 | |
643 | |
531 | Using a longer test string (roughly 18KB, generated from Yahoo! Locals |
644 | Using a longer test string (roughly 18KB, generated from Yahoo! Locals |
532 | search API (http://nanoref.com/yahooapis/mgPdGg): |
645 | search API (http://nanoref.com/yahooapis/mgPdGg): |
533 | |
646 | |
534 | module | encode | decode | |
647 | module | encode | decode | |
535 | -----------|------------|------------| |
648 | -----------|------------|------------| |
536 | JSON | 673 | 38 | |
649 | JSON | 254.685 | 37.665 | |
537 | JSON::DWIW | 5271 | 770 | |
650 | JSON::DWIW | 1014.244 | 1087.678 | |
538 | JSON::PC | 9901 | 2491 | |
651 | JSON::PC | 3602.116 | 2307.352 | |
539 | JSON::Syck | 2360 | 786 | |
652 | JSON::Syck | 558.035 | 776.263 | |
540 | JSON::XS | 37398 | 3202 | |
653 | JSON::XS | 5747.196 | 3543.684 | |
541 | JSON::XS/2 | 13765 | 3153 | |
654 | JSON::XS/2 | 3968.121 | 3589.170 | |
|
|
655 | JSON::XS/3 | 6105.246 | 3561.134 | |
|
|
656 | Storable | 4456.337 | 5320.020 | |
542 | -----------+------------+------------+ |
657 | -----------+------------+------------+ |
543 | |
658 | |
544 | Again, JSON::XS leads by far in the encoding case, while still beating |
659 | Again, JSON::XS leads by far. |
545 | every other module in the decoding case. |
|
|
546 | |
660 | |
547 | On large strings containing lots of unicode characters, some modules |
661 | On large strings containing lots of high unicode characters, some modules |
548 | (such as JSON::PC) decode faster than JSON::XS, but the result will be |
662 | (such as JSON::PC) seem to decode faster than JSON::XS, but the result |
549 | broken due to missing unicode handling. Others refuse to decode or encode |
663 | will be broken due to missing (or wrong) unicode handling. Others refuse |
550 | properly, so it was impossible to prepare a fair comparison table for that |
664 | to decode or encode properly, so it was impossible to prepare a fair |
551 | case. |
665 | comparison table for that case. |
552 | |
666 | |
553 | =head1 RESOURCE LIMITS |
|
|
554 | |
667 | |
555 | JSON::XS does not impose any limits on the size of JSON texts or Perl |
668 | =head1 SECURITY CONSIDERATIONS |
556 | values they represent - if your machine can handle it, JSON::XS will |
669 | |
557 | encode or decode it. Future versions might optionally impose structure |
670 | When you are using JSON in a protocol, talking to untrusted potentially |
558 | depth and memory use resource limits. |
671 | hostile creatures requires relatively few measures. |
|
|
672 | |
|
|
673 | First of all, your JSON decoder should be secure, that is, should not have |
|
|
674 | any buffer overflows. Obviously, this module should ensure that and I am |
|
|
675 | trying hard on making that true, but you never know. |
|
|
676 | |
|
|
677 | Second, you need to avoid resource-starving attacks. That means you should |
|
|
678 | limit the size of JSON texts you accept, or make sure then when your |
|
|
679 | resources run out, thats just fine (e.g. by using a separate process that |
|
|
680 | can crash safely). The size of a JSON text in octets or characters is |
|
|
681 | usually a good indication of the size of the resources required to decode |
|
|
682 | it into a Perl structure. |
|
|
683 | |
|
|
684 | Third, JSON::XS recurses using the C stack when decoding objects and |
|
|
685 | arrays. The C stack is a limited resource: for instance, on my amd64 |
|
|
686 | machine with 8MB of stack size I can decode around 180k nested arrays but |
|
|
687 | only 14k nested JSON objects (due to perl itself recursing deeply on croak |
|
|
688 | to free the temporary). If that is exceeded, the program crashes. to be |
|
|
689 | conservative, the default nesting limit is set to 512. If your process |
|
|
690 | has a smaller stack, you should adjust this setting accordingly with the |
|
|
691 | C<max_depth> method. |
|
|
692 | |
|
|
693 | And last but least, something else could bomb you that I forgot to think |
|
|
694 | of. In that case, you get to keep the pieces. I am always open for hints, |
|
|
695 | though... |
|
|
696 | |
559 | |
697 | |
560 | =head1 BUGS |
698 | =head1 BUGS |
561 | |
699 | |
562 | While the goal of this module is to be correct, that unfortunately does |
700 | While the goal of this module is to be correct, that unfortunately does |
563 | not mean its bug-free, only that I think its design is bug-free. It is |
701 | not mean its bug-free, only that I think its design is bug-free. It is |
564 | still very young and not well-tested. If you keep reporting bugs they will |
702 | still relatively early in its development. If you keep reporting bugs they |
565 | be fixed swiftly, though. |
703 | will be fixed swiftly, though. |
566 | |
704 | |
567 | =cut |
705 | =cut |
|
|
706 | |
|
|
707 | sub true() { \1 } |
|
|
708 | sub false() { \0 } |
568 | |
709 | |
569 | 1; |
710 | 1; |
570 | |
711 | |
571 | =head1 AUTHOR |
712 | =head1 AUTHOR |
572 | |
713 | |