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1 """ |
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2 Implementation of JSONEncoder |
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3 """ |
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4 import re |
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5 try: |
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6 from simplejson import _speedups |
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7 except ImportError: |
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8 _speedups = None |
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9 |
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10 ESCAPE = re.compile(r'[\x00-\x19\\"\b\f\n\r\t]') |
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11 ESCAPE_ASCII = re.compile(r'([\\"/]|[^\ -~])') |
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12 ESCAPE_DCT = { |
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13 # escape all forward slashes to prevent </script> attack |
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14 '/': '\\/', |
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15 '\\': '\\\\', |
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16 '"': '\\"', |
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17 '\b': '\\b', |
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18 '\f': '\\f', |
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19 '\n': '\\n', |
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20 '\r': '\\r', |
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21 '\t': '\\t', |
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22 } |
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23 for i in range(0x20): |
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24 ESCAPE_DCT.setdefault(chr(i), '\\u%04x' % (i,)) |
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25 |
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26 # assume this produces an infinity on all machines (probably not guaranteed) |
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27 INFINITY = float('1e66666') |
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28 |
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29 def floatstr(o, allow_nan=True): |
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30 # Check for specials. Note that this type of test is processor- and/or |
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31 # platform-specific, so do tests which don't depend on the internals. |
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32 |
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33 if o != o: |
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34 text = 'NaN' |
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35 elif o == INFINITY: |
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36 text = 'Infinity' |
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37 elif o == -INFINITY: |
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38 text = '-Infinity' |
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39 else: |
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40 return repr(o) |
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41 |
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42 if not allow_nan: |
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43 raise ValueError("Out of range float values are not JSON compliant: %r" |
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44 % (o,)) |
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45 |
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46 return text |
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47 |
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48 |
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49 def encode_basestring(s): |
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50 """ |
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51 Return a JSON representation of a Python string |
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52 """ |
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53 def replace(match): |
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54 return ESCAPE_DCT[match.group(0)] |
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55 return '"' + ESCAPE.sub(replace, s) + '"' |
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56 |
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57 def encode_basestring_ascii(s): |
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58 def replace(match): |
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59 s = match.group(0) |
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60 try: |
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61 return ESCAPE_DCT[s] |
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62 except KeyError: |
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63 n = ord(s) |
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64 if n < 0x10000: |
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65 return '\\u%04x' % (n,) |
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66 else: |
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67 # surrogate pair |
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68 n -= 0x10000 |
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69 s1 = 0xd800 | ((n >> 10) & 0x3ff) |
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70 s2 = 0xdc00 | (n & 0x3ff) |
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71 return '\\u%04x\\u%04x' % (s1, s2) |
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72 return '"' + str(ESCAPE_ASCII.sub(replace, s)) + '"' |
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73 |
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74 try: |
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75 encode_basestring_ascii = _speedups.encode_basestring_ascii |
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76 _need_utf8 = True |
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77 except AttributeError: |
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78 _need_utf8 = False |
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79 |
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80 class JSONEncoder(object): |
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81 """ |
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82 Extensible JSON <http://json.org> encoder for Python data structures. |
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83 |
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84 Supports the following objects and types by default: |
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85 |
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86 +-------------------+---------------+ |
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87 | Python | JSON | |
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88 +===================+===============+ |
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89 | dict | object | |
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90 +-------------------+---------------+ |
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91 | list, tuple | array | |
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92 +-------------------+---------------+ |
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93 | str, unicode | string | |
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94 +-------------------+---------------+ |
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95 | int, long, float | number | |
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96 +-------------------+---------------+ |
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97 | True | true | |
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98 +-------------------+---------------+ |
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99 | False | false | |
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100 +-------------------+---------------+ |
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101 | None | null | |
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102 +-------------------+---------------+ |
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103 |
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104 To extend this to recognize other objects, subclass and implement a |
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105 ``.default()`` method with another method that returns a serializable |
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106 object for ``o`` if possible, otherwise it should call the superclass |
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107 implementation (to raise ``TypeError``). |
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108 """ |
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109 __all__ = ['__init__', 'default', 'encode', 'iterencode'] |
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110 item_separator = ', ' |
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111 key_separator = ': ' |
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112 def __init__(self, skipkeys=False, ensure_ascii=True, |
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113 check_circular=True, allow_nan=True, sort_keys=False, |
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114 indent=None, separators=None, encoding='utf-8'): |
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115 """ |
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116 Constructor for JSONEncoder, with sensible defaults. |
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117 |
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118 If skipkeys is False, then it is a TypeError to attempt |
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119 encoding of keys that are not str, int, long, float or None. If |
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120 skipkeys is True, such items are simply skipped. |
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121 |
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122 If ensure_ascii is True, the output is guaranteed to be str |
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123 objects with all incoming unicode characters escaped. If |
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124 ensure_ascii is false, the output will be unicode object. |
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125 |
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126 If check_circular is True, then lists, dicts, and custom encoded |
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127 objects will be checked for circular references during encoding to |
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128 prevent an infinite recursion (which would cause an OverflowError). |
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129 Otherwise, no such check takes place. |
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130 |
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131 If allow_nan is True, then NaN, Infinity, and -Infinity will be |
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132 encoded as such. This behavior is not JSON specification compliant, |
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133 but is consistent with most JavaScript based encoders and decoders. |
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134 Otherwise, it will be a ValueError to encode such floats. |
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135 |
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136 If sort_keys is True, then the output of dictionaries will be |
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137 sorted by key; this is useful for regression tests to ensure |
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138 that JSON serializations can be compared on a day-to-day basis. |
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139 |
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140 If indent is a non-negative integer, then JSON array |
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141 elements and object members will be pretty-printed with that |
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142 indent level. An indent level of 0 will only insert newlines. |
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143 None is the most compact representation. |
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144 |
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145 If specified, separators should be a (item_separator, key_separator) |
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146 tuple. The default is (', ', ': '). To get the most compact JSON |
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147 representation you should specify (',', ':') to eliminate whitespace. |
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148 |
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149 If encoding is not None, then all input strings will be |
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150 transformed into unicode using that encoding prior to JSON-encoding. |
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151 The default is UTF-8. |
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152 """ |
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153 |
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154 self.skipkeys = skipkeys |
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155 self.ensure_ascii = ensure_ascii |
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156 self.check_circular = check_circular |
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157 self.allow_nan = allow_nan |
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158 self.sort_keys = sort_keys |
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159 self.indent = indent |
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160 self.current_indent_level = 0 |
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161 if separators is not None: |
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162 self.item_separator, self.key_separator = separators |
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163 self.encoding = encoding |
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164 |
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165 def _newline_indent(self): |
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166 return '\n' + (' ' * (self.indent * self.current_indent_level)) |
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167 |
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168 def _iterencode_list(self, lst, markers=None): |
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169 if not lst: |
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170 yield '[]' |
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171 return |
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172 if markers is not None: |
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173 markerid = id(lst) |
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174 if markerid in markers: |
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175 raise ValueError("Circular reference detected") |
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176 markers[markerid] = lst |
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177 yield '[' |
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178 if self.indent is not None: |
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179 self.current_indent_level += 1 |
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180 newline_indent = self._newline_indent() |
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181 separator = self.item_separator + newline_indent |
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182 yield newline_indent |
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183 else: |
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184 newline_indent = None |
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185 separator = self.item_separator |
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186 first = True |
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187 for value in lst: |
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188 if first: |
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189 first = False |
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190 else: |
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191 yield separator |
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192 for chunk in self._iterencode(value, markers): |
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193 yield chunk |
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194 if newline_indent is not None: |
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195 self.current_indent_level -= 1 |
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196 yield self._newline_indent() |
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197 yield ']' |
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198 if markers is not None: |
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199 del markers[markerid] |
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200 |
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201 def _iterencode_dict(self, dct, markers=None): |
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202 if not dct: |
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203 yield '{}' |
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204 return |
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205 if markers is not None: |
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206 markerid = id(dct) |
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207 if markerid in markers: |
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208 raise ValueError("Circular reference detected") |
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209 markers[markerid] = dct |
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210 yield '{' |
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211 key_separator = self.key_separator |
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212 if self.indent is not None: |
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213 self.current_indent_level += 1 |
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214 newline_indent = self._newline_indent() |
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215 item_separator = self.item_separator + newline_indent |
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216 yield newline_indent |
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217 else: |
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218 newline_indent = None |
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219 item_separator = self.item_separator |
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220 first = True |
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221 if self.ensure_ascii: |
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222 encoder = encode_basestring_ascii |
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223 else: |
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224 encoder = encode_basestring |
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225 allow_nan = self.allow_nan |
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226 if self.sort_keys: |
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227 keys = dct.keys() |
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228 keys.sort() |
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229 items = [(k, dct[k]) for k in keys] |
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230 else: |
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231 items = dct.iteritems() |
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232 _encoding = self.encoding |
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233 _do_decode = (_encoding is not None |
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234 and not (_need_utf8 and _encoding == 'utf-8')) |
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235 for key, value in items: |
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236 if isinstance(key, str): |
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237 if _do_decode: |
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238 key = key.decode(_encoding) |
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239 elif isinstance(key, basestring): |
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240 pass |
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241 # JavaScript is weakly typed for these, so it makes sense to |
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242 # also allow them. Many encoders seem to do something like this. |
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243 elif isinstance(key, float): |
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244 key = floatstr(key, allow_nan) |
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245 elif isinstance(key, (int, long)): |
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246 key = str(key) |
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247 elif key is True: |
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248 key = 'true' |
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249 elif key is False: |
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250 key = 'false' |
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251 elif key is None: |
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252 key = 'null' |
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253 elif self.skipkeys: |
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254 continue |
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255 else: |
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256 raise TypeError("key %r is not a string" % (key,)) |
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257 if first: |
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258 first = False |
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259 else: |
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260 yield item_separator |
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261 yield encoder(key) |
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262 yield key_separator |
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263 for chunk in self._iterencode(value, markers): |
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264 yield chunk |
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265 if newline_indent is not None: |
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266 self.current_indent_level -= 1 |
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267 yield self._newline_indent() |
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268 yield '}' |
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269 if markers is not None: |
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270 del markers[markerid] |
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271 |
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272 def _iterencode(self, o, markers=None): |
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273 if isinstance(o, basestring): |
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274 if self.ensure_ascii: |
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275 encoder = encode_basestring_ascii |
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276 else: |
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277 encoder = encode_basestring |
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278 _encoding = self.encoding |
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279 if (_encoding is not None and isinstance(o, str) |
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280 and not (_need_utf8 and _encoding == 'utf-8')): |
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281 o = o.decode(_encoding) |
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282 yield encoder(o) |
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283 elif o is None: |
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284 yield 'null' |
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285 elif o is True: |
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286 yield 'true' |
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287 elif o is False: |
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288 yield 'false' |
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289 elif isinstance(o, (int, long)): |
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290 yield str(o) |
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291 elif isinstance(o, float): |
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292 yield floatstr(o, self.allow_nan) |
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293 elif isinstance(o, (list, tuple)): |
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294 for chunk in self._iterencode_list(o, markers): |
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295 yield chunk |
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296 elif isinstance(o, dict): |
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297 for chunk in self._iterencode_dict(o, markers): |
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298 yield chunk |
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299 else: |
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300 if markers is not None: |
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301 markerid = id(o) |
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302 if markerid in markers: |
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303 raise ValueError("Circular reference detected") |
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304 markers[markerid] = o |
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305 for chunk in self._iterencode_default(o, markers): |
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306 yield chunk |
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307 if markers is not None: |
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308 del markers[markerid] |
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309 |
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310 def _iterencode_default(self, o, markers=None): |
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311 newobj = self.default(o) |
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312 return self._iterencode(newobj, markers) |
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313 |
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314 def default(self, o): |
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315 """ |
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316 Implement this method in a subclass such that it returns |
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317 a serializable object for ``o``, or calls the base implementation |
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318 (to raise a ``TypeError``). |
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319 |
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320 For example, to support arbitrary iterators, you could |
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321 implement default like this:: |
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322 |
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323 def default(self, o): |
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324 try: |
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325 iterable = iter(o) |
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326 except TypeError: |
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327 pass |
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328 else: |
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329 return list(iterable) |
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330 return JSONEncoder.default(self, o) |
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331 """ |
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332 raise TypeError("%r is not JSON serializable" % (o,)) |
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333 |
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334 def encode(self, o): |
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335 """ |
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336 Return a JSON string representation of a Python data structure. |
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337 |
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338 >>> JSONEncoder().encode({"foo": ["bar", "baz"]}) |
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339 '{"foo":["bar", "baz"]}' |
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340 """ |
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341 # This is for extremely simple cases and benchmarks... |
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342 if isinstance(o, basestring): |
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343 if isinstance(o, str): |
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344 _encoding = self.encoding |
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345 if (_encoding is not None |
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346 and not (_encoding == 'utf-8' and _need_utf8)): |
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347 o = o.decode(_encoding) |
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348 return encode_basestring_ascii(o) |
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349 # This doesn't pass the iterator directly to ''.join() because it |
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350 # sucks at reporting exceptions. It's going to do this internally |
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351 # anyway because it uses PySequence_Fast or similar. |
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352 chunks = list(self.iterencode(o)) |
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353 return ''.join(chunks) |
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354 |
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355 def iterencode(self, o): |
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356 """ |
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357 Encode the given object and yield each string |
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358 representation as available. |
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359 |
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360 For example:: |
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361 |
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362 for chunk in JSONEncoder().iterencode(bigobject): |
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363 mysocket.write(chunk) |
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364 """ |
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365 if self.check_circular: |
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366 markers = {} |
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367 else: |
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368 markers = None |
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369 return self._iterencode(o, markers) |
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370 |
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371 __all__ = ['JSONEncoder'] |