| … | |
… | |
| 6 | |
6 | |
| 7 | use JSON::XS; |
7 | use JSON::XS; |
| 8 | |
8 | |
| 9 | =head1 DESCRIPTION |
9 | =head1 DESCRIPTION |
| 10 | |
10 | |
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11 | This module converts Perl data structures to JSON and vice versa. Its |
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12 | primary goal is to be I<correct> and its secondary goal is to be |
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13 | I<fast>. To reach the latter goal it was written in C. |
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14 | |
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15 | As this is the n-th-something JSON module on CPAN, what was the reason |
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16 | to write yet another JSON module? While it seems there are many JSON |
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17 | modules, none of them correctly handle all corner cases, and in most cases |
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18 | their maintainers are unresponsive, gone missing, or not listening to bug |
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19 | reports for other reasons. |
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20 | |
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21 | See COMPARISON, below, for a comparison to some other JSON modules. |
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22 | |
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23 | =head2 FEATURES |
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24 | |
| 11 | =over 4 |
25 | =over 4 |
| 12 | |
26 | |
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27 | =item * correct handling of unicode issues |
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28 | |
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29 | This module knows how to handle Unicode, and even documents how it does so. |
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30 | |
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31 | =item * round-trip integrity |
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32 | |
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33 | When you serialise a perl data structure using only datatypes supported |
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34 | by JSON, the deserialised data structure is identical on the Perl level. |
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35 | (e.g. the string "2.0" doesn't suddenly become "2"). |
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36 | |
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37 | =item * strict checking of JSON correctness |
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38 | |
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39 | There is no guessing, no generating of illegal JSON strings by default, |
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40 | and only JSON is accepted as input (the latter is a security feature). |
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41 | |
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42 | =item * fast |
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43 | |
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44 | compared to other JSON modules, this module compares favourably. |
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45 | |
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46 | =item * simple to use |
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47 | |
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48 | This module has both a simple functional interface as well as an OO |
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49 | interface. |
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50 | |
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51 | =item * reasonably versatile output formats |
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52 | |
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53 | You can choose between the most compact format possible, a pure-ascii |
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54 | format, or a pretty-printed format. Or you can combine those features in |
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55 | whatever way you like. |
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56 | |
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57 | =back |
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58 | |
| 13 | =cut |
59 | =cut |
| 14 | |
60 | |
| 15 | package JSON::XS; |
61 | package JSON::XS; |
| 16 | |
62 | |
| 17 | BEGIN { |
63 | BEGIN { |
| 18 | $VERSION = '0.1'; |
64 | $VERSION = '0.2'; |
| 19 | @ISA = qw(Exporter); |
65 | @ISA = qw(Exporter); |
| 20 | |
66 | |
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67 | @EXPORT = qw(to_json from_json); |
| 21 | require Exporter; |
68 | require Exporter; |
| 22 | |
69 | |
| 23 | require XSLoader; |
70 | require XSLoader; |
| 24 | XSLoader::load JSON::XS::, $VERSION; |
71 | XSLoader::load JSON::XS::, $VERSION; |
| 25 | } |
72 | } |
| 26 | |
73 | |
| 27 | =item |
74 | =head1 FUNCTIONAL INTERFACE |
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75 | |
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76 | The following convinience methods are provided by this module. They are |
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77 | exported by default: |
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78 | |
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79 | =over 4 |
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80 | |
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81 | =item $json_string = to_json $perl_scalar |
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82 | |
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83 | Converts the given Perl data structure (a simple scalar or a reference to |
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84 | a hash or array) to a UTF-8 encoded, binary string (that is, the string contains |
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85 | octets only). Croaks on error. |
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86 | |
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87 | This function call is functionally identical to C<< JSON::XS->new->utf8 |
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88 | (1)->encode ($perl_scalar) >>. |
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89 | |
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90 | =item $perl_scalar = from_json $json_string |
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91 | |
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92 | The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to |
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93 | parse that as an UTF-8 encoded JSON string, returning the resulting simple |
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94 | scalar or reference. Croaks on error. |
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95 | |
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96 | This function call is functionally identical to C<< JSON::XS->new->utf8 |
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97 | (1)->decode ($json_string) >>. |
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98 | |
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99 | =back |
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100 | |
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101 | =head1 OBJECT-ORIENTED INTERFACE |
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102 | |
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103 | The object oriented interface lets you configure your own encoding or |
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104 | decoding style, within the limits of supported formats. |
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105 | |
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106 | =over 4 |
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107 | |
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108 | =item $json = new JSON::XS |
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109 | |
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110 | Creates a new JSON::XS object that can be used to de/encode JSON |
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111 | strings. All boolean flags described below are by default I<disabled>. |
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112 | |
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113 | The mutators for flags all return the JSON object again and thus calls can |
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114 | be chained: |
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115 | |
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116 | my $json = JSON::XS->new->utf8(1)->space_after(1)->encode ({a => [1,2]}) |
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117 | => {"a": [1, 2]} |
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118 | |
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119 | =item $json = $json->ascii ([$enable]) |
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120 | |
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121 | If C<$enable> is true (or missing), then the C<encode> method will |
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122 | not generate characters outside the code range C<0..127>. Any unicode |
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123 | characters outside that range will be escaped using either a single |
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124 | \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, as per |
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125 | RFC4627. |
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126 | |
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127 | If C<$enable> is false, then the C<encode> method will not escape Unicode |
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128 | characters unless necessary. |
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129 | |
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130 | JSON::XS->new->ascii (1)->encode (chr 0x10401) |
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131 | => \ud801\udc01 |
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132 | |
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133 | =item $json = $json->utf8 ([$enable]) |
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134 | |
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135 | If C<$enable> is true (or missing), then the C<encode> method will encode |
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136 | the JSON string into UTF-8, as required by many protocols, while the |
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137 | C<decode> method expects to be handled an UTF-8-encoded string. Please |
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138 | note that UTF-8-encoded strings do not contain any characters outside the |
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139 | range C<0..255>, they are thus useful for bytewise/binary I/O. |
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140 | |
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141 | If C<$enable> is false, then the C<encode> method will return the JSON |
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142 | string as a (non-encoded) unicode string, while C<decode> expects thus a |
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143 | unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs |
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144 | to be done yourself, e.g. using the Encode module. |
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145 | |
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146 | =item $json = $json->pretty ([$enable]) |
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147 | |
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148 | This enables (or disables) all of the C<indent>, C<space_before> and |
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149 | C<space_after> (and in the future possibly more) flags in one call to |
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150 | generate the most readable (or most compact) form possible. |
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151 | |
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152 | my $json = JSON::XS->new->pretty(1)->encode ({a => [1,2]}) |
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153 | => |
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154 | { |
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155 | "a" : [ |
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156 | 1, |
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157 | 2 |
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158 | ] |
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159 | } |
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160 | |
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161 | =item $json = $json->indent ([$enable]) |
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162 | |
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163 | If C<$enable> is true (or missing), then the C<encode> method will use a multiline |
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164 | format as output, putting every array member or object/hash key-value pair |
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165 | into its own line, identing them properly. |
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166 | |
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167 | If C<$enable> is false, no newlines or indenting will be produced, and the |
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168 | resulting JSON strings is guarenteed not to contain any C<newlines>. |
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169 | |
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170 | This setting has no effect when decoding JSON strings. |
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171 | |
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172 | =item $json = $json->space_before ([$enable]) |
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173 | |
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174 | If C<$enable> is true (or missing), then the C<encode> method will add an extra |
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175 | optional space before the C<:> separating keys from values in JSON objects. |
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176 | |
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177 | If C<$enable> is false, then the C<encode> method will not add any extra |
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178 | space at those places. |
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179 | |
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180 | This setting has no effect when decoding JSON strings. You will also most |
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181 | likely combine this setting with C<space_after>. |
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182 | |
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183 | =item $json = $json->space_after ([$enable]) |
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184 | |
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185 | If C<$enable> is true (or missing), then the C<encode> method will add an extra |
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186 | optional space after the C<:> separating keys from values in JSON objects |
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187 | and extra whitespace after the C<,> separating key-value pairs and array |
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188 | members. |
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189 | |
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190 | If C<$enable> is false, then the C<encode> method will not add any extra |
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191 | space at those places. |
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192 | |
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193 | This setting has no effect when decoding JSON strings. |
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194 | |
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195 | =item $json = $json->canonical ([$enable]) |
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196 | |
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197 | If C<$enable> is true (or missing), then the C<encode> method will output JSON objects |
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198 | by sorting their keys. This is adding a comparatively high overhead. |
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199 | |
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200 | If C<$enable> is false, then the C<encode> method will output key-value |
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201 | pairs in the order Perl stores them (which will likely change between runs |
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202 | of the same script). |
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203 | |
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204 | This option is useful if you want the same data structure to be encoded as |
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205 | the same JSON string (given the same overall settings). If it is disabled, |
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206 | the same hash migh be encoded differently even if contains the same data, |
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207 | as key-value pairs have no inherent ordering in Perl. |
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208 | |
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209 | This setting has no effect when decoding JSON strings. |
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210 | |
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211 | =item $json = $json->allow_nonref ([$enable]) |
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212 | |
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213 | If C<$enable> is true (or missing), then the C<encode> method can convert a |
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214 | non-reference into its corresponding string, number or null JSON value, |
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215 | which is an extension to RFC4627. Likewise, C<decode> will accept those JSON |
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216 | values instead of croaking. |
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217 | |
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218 | If C<$enable> is false, then the C<encode> method will croak if it isn't |
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219 | passed an arrayref or hashref, as JSON strings must either be an object |
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220 | or array. Likewise, C<decode> will croak if given something that is not a |
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221 | JSON object or array. |
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222 | |
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223 | =item $json = $json->shrink ([$enable]) |
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224 | |
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225 | Perl usually over-allocates memory a bit when allocating space for |
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226 | strings. This flag optionally resizes strings generated by either |
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227 | C<encode> or C<decode> to their minimum size possible. This can save |
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228 | memory when your JSON strings are either very very long or you have many |
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229 | short strings. |
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230 | |
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231 | If C<$enable> is true (or missing), the string returned by C<encode> will be shrunk-to-fit, |
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232 | while all strings generated by C<decode> will also be shrunk-to-fit. |
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233 | |
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234 | If C<$enable> is false, then the normal perl allocation algorithms are used. |
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235 | If you work with your data, then this is likely to be faster. |
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236 | |
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237 | In the future, this setting might control other things, such as converting |
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238 | strings that look like integers or floats into integers or floats |
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239 | internally (there is no difference on the Perl level), saving space. |
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240 | |
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241 | =item $json_string = $json->encode ($perl_scalar) |
|
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242 | |
|
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243 | Converts the given Perl data structure (a simple scalar or a reference |
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244 | to a hash or array) to its JSON representation. Simple scalars will be |
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245 | converted into JSON string or number sequences, while references to arrays |
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246 | become JSON arrays and references to hashes become JSON objects. Undefined |
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247 | Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true> |
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248 | nor C<false> values will be generated. |
|
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249 | |
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250 | =item $perl_scalar = $json->decode ($json_string) |
|
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251 | |
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252 | The opposite of C<encode>: expects a JSON string and tries to parse it, |
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253 | returning the resulting simple scalar or reference. Croaks on error. |
|
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254 | |
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255 | JSON numbers and strings become simple Perl scalars. JSON arrays become |
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256 | Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes |
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257 | C<1>, C<false> becomes C<0> and C<null> becomes C<undef>. |
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258 | |
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259 | =back |
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260 | |
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261 | =head1 COMPARISON |
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262 | |
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263 | As already mentioned, this module was created because none of the existing |
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264 | JSON modules could be made to work correctly. First I will describe the |
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265 | problems (or pleasures) I encountered with various existing JSON modules, |
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266 | followed by some benchmark values. JSON::XS was designed not to suffer |
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267 | from any of these problems or limitations. |
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268 | |
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269 | =over 4 |
|
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270 | |
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271 | =item JSON 1.07 |
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272 | |
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273 | Slow (but very portable, as it is written in pure Perl). |
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274 | |
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275 | Undocumented/buggy Unicode handling (how JSON handles unicode values is |
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276 | undocumented. One can get far by feeding it unicode strings and doing |
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277 | en-/decoding oneself, but unicode escapes are not working properly). |
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278 | |
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279 | No roundtripping (strings get clobbered if they look like numbers, e.g. |
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280 | the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will |
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281 | decode into the number 2. |
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282 | |
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283 | =item JSON::PC 0.01 |
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284 | |
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285 | Very fast. |
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286 | |
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287 | Undocumented/buggy Unicode handling. |
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288 | |
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289 | No roundtripping. |
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290 | |
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291 | Has problems handling many Perl values (e.g. regex results and other magic |
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292 | values will make it croak). |
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293 | |
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294 | Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}> |
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295 | which is not a valid JSON string. |
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296 | |
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297 | Unmaintained (maintainer unresponsive for many months, bugs are not |
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298 | getting fixed). |
|
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299 | |
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300 | =item JSON::Syck 0.21 |
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301 | |
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302 | Very buggy (often crashes). |
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303 | |
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304 | Very inflexible (no human-readable format supported, format pretty much |
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305 | undocumented. I need at least a format for easy reading by humans and a |
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306 | single-line compact format for use in a protocol, and preferably a way to |
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307 | generate ASCII-only JSON strings). |
|
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308 | |
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309 | Completely broken (and confusingly documented) Unicode handling (unicode |
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310 | escapes are not working properly, you need to set ImplicitUnicode to |
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311 | I<different> values on en- and decoding to get symmetric behaviour). |
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312 | |
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313 | No roundtripping (simple cases work, but this depends on wether the scalar |
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314 | value was used in a numeric context or not). |
|
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315 | |
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316 | Dumping hashes may skip hash values depending on iterator state. |
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317 | |
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318 | Unmaintained (maintainer unresponsive for many months, bugs are not |
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319 | getting fixed). |
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320 | |
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321 | Does not check input for validity (i.e. will accept non-JSON input and |
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322 | return "something" instead of raising an exception. This is a security |
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323 | issue: imagine two banks transfering money between each other using |
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324 | JSON. One bank might parse a given non-JSON request and deduct money, |
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325 | while the other might reject the transaction with a syntax error. While a |
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326 | good protocol will at least recover, that is extra unnecessary work and |
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327 | the transaction will still not succeed). |
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328 | |
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329 | =item JSON::DWIW 0.04 |
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330 | |
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331 | Very fast. Very natural. Very nice. |
|
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332 | |
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333 | Undocumented unicode handling (but the best of the pack. Unicode escapes |
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334 | still don't get parsed properly). |
|
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335 | |
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336 | Very inflexible. |
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337 | |
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338 | No roundtripping. |
|
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339 | |
|
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340 | Does not generate valid JSON (key strings are often unquoted, empty keys |
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341 | result in nothing being output) |
|
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342 | |
|
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343 | Does not check input for validity. |
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344 | |
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345 | =back |
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346 | |
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347 | =head2 SPEED |
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348 | |
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349 | It seems that JSON::XS is surprisingly fast, as shown in the following |
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350 | tables. They have been generated with the help of the C<eg/bench> program |
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351 | in the JSON::XS distribution, to make it easy to compare on your own |
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352 | system. |
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353 | |
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354 | First is a comparison between various modules using a very simple JSON |
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355 | string, showing the number of encodes/decodes per second (JSON::XS is |
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356 | the functional interface, while JSON::XS/2 is the OO interface with |
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357 | pretty-printing and hashkey sorting enabled). |
|
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358 | |
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359 | module | encode | decode | |
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360 | -----------|------------|------------| |
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361 | JSON | 14006 | 6820 | |
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362 | JSON::DWIW | 200937 | 120386 | |
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363 | JSON::PC | 85065 | 129366 | |
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364 | JSON::Syck | 59898 | 44232 | |
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365 | JSON::XS | 1171478 | 342435 | |
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366 | JSON::XS/2 | 730760 | 328714 | |
|
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367 | -----------+------------+------------+ |
|
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368 | |
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369 | That is, JSON::XS is 6 times faster than than JSON::DWIW and about 80 |
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370 | times faster than JSON, even with pretty-printing and key sorting. |
|
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371 | |
|
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372 | Using a longer test string (roughly 8KB, generated from Yahoo! Locals |
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373 | search API (http://nanoref.com/yahooapis/mgPdGg): |
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374 | |
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375 | module | encode | decode | |
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376 | -----------|------------|------------| |
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377 | JSON | 673 | 38 | |
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378 | JSON::DWIW | 5271 | 770 | |
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379 | JSON::PC | 9901 | 2491 | |
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380 | JSON::Syck | 2360 | 786 | |
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381 | JSON::XS | 37398 | 3202 | |
|
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382 | JSON::XS/2 | 13765 | 3153 | |
|
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383 | -----------+------------+------------+ |
|
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384 | |
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385 | Again, JSON::XS leads by far in the encoding case, while still beating |
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386 | every other module in the decoding case. |
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387 | |
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388 | Last example is an almost 8MB large hash with many large binary values |
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389 | (PNG files), resulting in a lot of escaping: |
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390 | |
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391 | =head1 BUGS |
|
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392 | |
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393 | While the goal of this module is to be correct, that unfortunately does |
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394 | not mean its bug-free, only that I think its design is bug-free. It is |
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395 | still very young and not well-tested. If you keep reporting bugs they will |
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396 | be fixed swiftly, though. |
| 28 | |
397 | |
| 29 | =cut |
398 | =cut |
| 30 | |
399 | |
| 31 | use JSON::DWIW; |
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| 32 | use Benchmark; |
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| 33 | |
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| 34 | use utf8; |
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| 35 | #my $json = '{"ü":1,"a":[1,{"3":4},2],"b":5,"üü":2}'; |
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| 36 | my $json = '{"test":9555555555555555555,"hu" : -1e+5, "arr" : [ 1,2,3,4,5]}'; |
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| 37 | |
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| 38 | my $js = JSON::XS->new; |
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| 39 | warn $js->indent (0); |
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| 40 | warn $js->canonical (0); |
|
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| 41 | warn $js->ascii (0); |
|
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| 42 | warn $js->space_after (0); |
|
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| 43 | use Data::Dumper; |
|
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| 44 | warn Dumper $js->decode ($json); |
|
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| 45 | warn Dumper $js->encode ($js->decode ($json)); |
|
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| 46 | #my $x = {"üü" => 2, "ü" => 1, "a" => [1,{3,4},2], b => 5}; |
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| 47 | |
|
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| 48 | #my $js2 = JSON::DWIW->new; |
|
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| 49 | # |
|
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| 50 | #timethese 200000, { |
|
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| 51 | # a => sub { $js->encode ($x) }, |
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| 52 | # b => sub { $js2->to_json ($x) }, |
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| 53 | #}; |
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| 54 | |
|
|
| 55 | 1; |
400 | 1; |
| 56 | |
|
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| 57 | =back |
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| 58 | |
401 | |
| 59 | =head1 AUTHOR |
402 | =head1 AUTHOR |
| 60 | |
403 | |
| 61 | Marc Lehmann <schmorp@schmorp.de> |
404 | Marc Lehmann <schmorp@schmorp.de> |
| 62 | http://home.schmorp.de/ |
405 | http://home.schmorp.de/ |
