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1#!/usr/bin/env python3
2# Copyright (c) Facebook, Inc. and its affiliates. (http://www.facebook.com)
3# WARNING: This is mostly a copy of code from the cpython library.
4# flake8: noqa
5# fmt: off
6# isort:skip_file
7"""Implementation of JSONDecoder
8"""
9import re
10from _json import JSONDecodeError, loads as _loads
11
12from _builtins import _unimplemented
13
14__all__ = ['JSONDecoder', 'JSONDecodeError']
15
16
17NaN = float('nan')
18PosInf = float('inf')
19NegInf = float('-inf')
20
21_CONSTANTS = {
22 '-Infinity': NegInf,
23 'Infinity': PosInf,
24 'NaN': NaN,
25}
26
27
28class JSONDecoder(object):
29 """Simple JSON <http://json.org> decoder
30
31 Performs the following translations in decoding by default:
32
33 +---------------+-------------------+
34 | JSON | Python |
35 +===============+===================+
36 | object | dict |
37 +---------------+-------------------+
38 | array | list |
39 +---------------+-------------------+
40 | string | str |
41 +---------------+-------------------+
42 | number (int) | int |
43 +---------------+-------------------+
44 | number (real) | float |
45 +---------------+-------------------+
46 | true | True |
47 +---------------+-------------------+
48 | false | False |
49 +---------------+-------------------+
50 | null | None |
51 +---------------+-------------------+
52
53 It also understands ``NaN``, ``Infinity``, and ``-Infinity`` as
54 their corresponding ``float`` values, which is outside the JSON spec.
55
56 """
57
58 def __init__(self, *, object_hook=None, parse_float=None,
59 parse_int=None, parse_constant=None, strict=True,
60 object_pairs_hook=None):
61 """``object_hook``, if specified, will be called with the result
62 of every JSON object decoded and its return value will be used in
63 place of the given ``dict``. This can be used to provide custom
64 deserializations (e.g. to support JSON-RPC class hinting).
65
66 ``object_pairs_hook``, if specified will be called with the result of
67 every JSON object decoded with an ordered list of pairs. The return
68 value of ``object_pairs_hook`` will be used instead of the ``dict``.
69 This feature can be used to implement custom decoders.
70 If ``object_hook`` is also defined, the ``object_pairs_hook`` takes
71 priority.
72
73 ``parse_float``, if specified, will be called with the string
74 of every JSON float to be decoded. By default this is equivalent to
75 float(num_str). This can be used to use another datatype or parser
76 for JSON floats (e.g. decimal.Decimal).
77
78 ``parse_int``, if specified, will be called with the string
79 of every JSON int to be decoded. By default this is equivalent to
80 int(num_str). This can be used to use another datatype or parser
81 for JSON integers (e.g. float).
82
83 ``parse_constant``, if specified, will be called with one of the
84 following strings: -Infinity, Infinity, NaN.
85 This can be used to raise an exception if invalid JSON numbers
86 are encountered.
87
88 If ``strict`` is false (true is the default), then control
89 characters will be allowed inside strings. Control characters in
90 this context are those with character codes in the 0-31 range,
91 including ``'\\t'`` (tab), ``'\\n'``, ``'\\r'`` and ``'\\0'``.
92 """
93 self.object_hook = object_hook
94 self.parse_float = parse_float or float
95 self.parse_int = parse_int or int
96 self.parse_constant = parse_constant or _CONSTANTS.__getitem__
97 self.strict = strict
98 self.object_pairs_hook = object_pairs_hook
99
100
101 def decode(self, s):
102 """Return the Python representation of ``s`` (a ``str`` instance
103 containing a JSON document).
104
105 """
106 parse_float = self.parse_float
107 if parse_float is float:
108 parse_float = None
109 parse_int = self.parse_int
110 if parse_int is int:
111 parse_int = None
112 parse_constant = self.parse_constant
113 if parse_constant == _CONSTANTS.__getitem__:
114 parse_constant = None
115 return _loads(s, object_hook=self.object_hook, parse_float=parse_float,
116 parse_int=parse_int, parse_constant=parse_constant,
117 object_pairs_hook=self.object_pairs_hook, strict=self.strict)
118
119 def raw_decode(self, s, idx=0):
120 """Decode a JSON document from ``s`` (a ``str`` beginning with
121 a JSON document) and return a 2-tuple of the Python
122 representation and the index in ``s`` where the document ended.
123
124 This can be used to decode a JSON document from a string that may
125 have extraneous data at the end.
126
127 """
128 _unimplemented()