"""Implementation of JSONEncoder """ import re try: from _json import encode_basestring_ascii as c_encode_basestring_ascii except ImportError: c_encode_basestring_ascii = None try: from _json import encode_basestring as c_encode_basestring except ImportError: c_encode_basestring = None try: from _json import make_encoder as c_make_encoder except ImportError: c_make_encoder = None ESCAPE = re.compile(r'[\x00-\x1f\\"\b\f\n\r\t]') ESCAPE_ASCII = re.compile(r'([\\"]|[^\ -~])') HAS_UTF8 = re.compile(b'[\x80-\xff]') ESCAPE_DCT = { '\\': '\\\\', '"': '\\"', '\b': '\\b', '\f': '\\f', '\n': '\\n', '\r': '\\r', '\t': '\\t', } for i in range(0x20): ESCAPE_DCT.setdefault(chr(i), '\\u{0:04x}'.format(i)) #ESCAPE_DCT.setdefault(chr(i), '\\u%04x' % (i,)) INFINITY = float('inf') def py_encode_basestring(s): """Return a JSON representation of a Python string """ def replace(match): return ESCAPE_DCT[match.group(0)] return '"' + ESCAPE.sub(replace, s) + '"' encode_basestring = (c_encode_basestring or py_encode_basestring) def py_encode_basestring_ascii(s): """Return an ASCII-only JSON representation of a Python string """ def replace(match): s = match.group(0) try: return ESCAPE_DCT[s] except KeyError: n = ord(s) if n < 0x10000: return '\\u{0:04x}'.format(n) #return '\\u%04x' % (n,) else: # surrogate pair n -= 0x10000 s1 = 0xd800 | ((n >> 10) & 0x3ff) s2 = 0xdc00 | (n & 0x3ff) return '\\u{0:04x}\\u{1:04x}'.format(s1, s2) return '"' + ESCAPE_ASCII.sub(replace, s) + '"' encode_basestring_ascii = ( c_encode_basestring_ascii or py_encode_basestring_ascii) class JSONEncoder(object): """Extensible JSON <http://json.org> encoder for Python data structures. Supports the following objects and types by default: +-------------------+---------------+ | Python | JSON | +===================+===============+ | dict | object | +-------------------+---------------+ | list, tuple | array | +-------------------+---------------+ | str | string | +-------------------+---------------+ | int, float | number | +-------------------+---------------+ | True | true | +-------------------+---------------+ | False | false | +-------------------+---------------+ | None | null | +-------------------+---------------+ To extend this to recognize other objects, subclass and implement a ``.default()`` method with another method that returns a serializable object for ``o`` if possible, otherwise it should call the superclass implementation (to raise ``TypeError``). """ item_separator = ', ' key_separator = ': ' def __init__(self, *, skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, sort_keys=False, indent=None, separators=None, default=None): """Constructor for JSONEncoder, with sensible defaults. If skipkeys is false, then it is a TypeError to attempt encoding of keys that are not str, int, float or None. If skipkeys is True, such items are simply skipped. If ensure_ascii is true, the output is guaranteed to be str objects with all incoming non-ASCII characters escaped. If ensure_ascii is false, the output can contain non-ASCII characters. If check_circular is true, then lists, dicts, and custom encoded objects will be checked for circular references during encoding to prevent an infinite recursion (which would cause an OverflowError). Otherwise, no such check takes place. If allow_nan is true, then NaN, Infinity, and -Infinity will be encoded as such. This behavior is not JSON specification compliant, but is consistent with most JavaScript based encoders and decoders. Otherwise, it will be a ValueError to encode such floats. If sort_keys is true, then the output of dictionaries will be sorted by key; this is useful for regression tests to ensure that JSON serializations can be compared on a day-to-day basis. If indent is a non-negative integer, then JSON array elements and object members will be pretty-printed with that indent level. An indent level of 0 will only insert newlines. None is the most compact representation. If specified, separators should be an (item_separator, key_separator) tuple. The default is (', ', ': ') if *indent* is ``None`` and (',', ': ') otherwise. To get the most compact JSON representation, you should specify (',', ':') to eliminate whitespace. If specified, default is a function that gets called for objects that can't otherwise be serialized. It should return a JSON encodable version of the object or raise a ``TypeError``. """ self.skipkeys = skipkeys self.ensure_ascii = ensure_ascii self.check_circular = check_circular self.allow_nan = allow_nan self.sort_keys = sort_keys self.indent = indent if separators is not None: self.item_separator, self.key_separator = separators elif indent is not None: self.item_separator = ',' if default is not None: self.default = default def default(self, o): """Implement this method in a subclass such that it returns a serializable object for ``o``, or calls the base implementation (to raise a ``TypeError``). For example, to support arbitrary iterators, you could implement default like this:: def default(self, o): try: iterable = iter(o) except TypeError: pass else: return list(iterable) # Let the base class default method raise the TypeError return JSONEncoder.default(self, o) """ raise TypeError(f'Object of type {o.__class__.__name__} ' f'is not JSON serializable') def encode(self, o): """Return a JSON string representation of a Python data structure. >>> from json.encoder import JSONEncoder >>> JSONEncoder().encode({"foo": ["bar", "baz"]}) '{"foo": ["bar", "baz"]}' """ # This is for extremely simple cases and benchmarks. if isinstance(o, str): if self.ensure_ascii: return encode_basestring_ascii(o) else: return encode_basestring(o) # This doesn't pass the iterator directly to ''.join() because the # exceptions aren't as detailed. The list call should be roughly # equivalent to the PySequence_Fast that ''.join() would do. chunks = self.iterencode(o, _one_shot=True) if not isinstance(chunks, (list, tuple)): chunks = list(chunks) return ''.join(chunks) def iterencode(self, o, _one_shot=False): """Encode the given object and yield each string representation as available. For example:: for chunk in JSONEncoder().iterencode(bigobject): mysocket.write(chunk) """ if self.check_circular: markers = {} else: markers = None if self.ensure_ascii: _encoder = encode_basestring_ascii else: _encoder = encode_basestring def floatstr(o, allow_nan=self.allow_nan, _repr=float.__repr__, _inf=INFINITY, _neginf=-INFINITY): # Check for specials. Note that this type of test is processor # and/or platform-specific, so do tests which don't depend on the # internals. if o != o: text = 'NaN' elif o == _inf: text = 'Infinity' elif o == _neginf: text = '-Infinity' else: return _repr(o) if not allow_nan: raise ValueError( "Out of range float values are not JSON compliant: " + repr(o)) return text if (_one_shot and c_make_encoder is not None and self.indent is None): _iterencode = c_make_encoder( markers, self.default, _encoder, self.indent, self.key_separator, self.item_separator, self.sort_keys, self.skipkeys, self.allow_nan) else: _iterencode = _make_iterencode( markers, self.default, _encoder, self.indent, floatstr, self.key_separator, self.item_separator, self.sort_keys, self.skipkeys, _one_shot) return _iterencode(o, 0) def _make_iterencode(markers, _default, _encoder, _indent, _floatstr, _key_separator, _item_separator, _sort_keys, _skipkeys, _one_shot, ## HACK: hand-optimized bytecode; turn globals into locals ValueError=ValueError, dict=dict, float=float, id=id, int=int, isinstance=isinstance, list=list, str=str, tuple=tuple, _intstr=int.__repr__, ): if _indent is not None and not isinstance(_indent, str): _indent = ' ' * _indent def _iterencode_list(lst, _current_indent_level): if not lst: yield '[]' return if markers is not None: markerid = id(lst) if markerid in markers: raise ValueError("Circular reference detected") markers[markerid] = lst buf = '[' if _indent is not None: _current_indent_level += 1 newline_indent = '\n' + _indent * _current_indent_level separator = _item_separator + newline_indent buf += newline_indent else: newline_indent = None separator = _item_separator first = True for value in lst: if first: first = False else: buf = separator if isinstance(value, str): yield buf + _encoder(value) elif value is None: yield buf + 'null' elif value is True: yield buf + 'true' elif value is False: yield buf + 'false' elif isinstance(value, int): # Subclasses of int/float may override __repr__, but we still # want to encode them as integers/floats in JSON. One example # within the standard library is IntEnum. yield buf + _intstr(value) elif isinstance(value, float): # see comment above for int yield buf + _floatstr(value) else: yield buf if isinstance(value, (list, tuple)): chunks = _iterencode_list(value, _current_indent_level) elif isinstance(value, dict): chunks = _iterencode_dict(value, _current_indent_level) else: chunks = _iterencode(value, _current_indent_level) yield from chunks if newline_indent is not None: _current_indent_level -= 1 yield '\n' + _indent * _current_indent_level yield ']' if markers is not None: del markers[markerid] def _iterencode_dict(dct, _current_indent_level): if not dct: yield '{}' return if markers is not None: markerid = id(dct) if markerid in markers: raise ValueError("Circular reference detected") markers[markerid] = dct yield '{' if _indent is not None: _current_indent_level += 1 newline_indent = '\n' + _indent * _current_indent_level item_separator = _item_separator + newline_indent yield newline_indent else: newline_indent = None item_separator = _item_separator first = True if _sort_keys: items = sorted(dct.items()) else: items = dct.items() for key, value in items: if isinstance(key, str): pass # JavaScript is weakly typed for these, so it makes sense to # also allow them. Many encoders seem to do something like this. elif isinstance(key, float): # see comment for int/float in _make_iterencode key = _floatstr(key) elif key is True: key = 'true' elif key is False: key = 'false' elif key is None: key = 'null' elif isinstance(key, int): # see comment for int/float in _make_iterencode key = _intstr(key) elif _skipkeys: continue else: raise TypeError(f'keys must be str, int, float, bool or None, ' f'not {key.__class__.__name__}') if first: first = False else: yield item_separator yield _encoder(key) yield _key_separator if isinstance(value, str): yield _encoder(value) elif value is None: yield 'null' elif value is True: yield 'true' elif value is False: yield 'false' elif isinstance(value, int): # see comment for int/float in _make_iterencode yield _intstr(value) elif isinstance(value, float): # see comment for int/float in _make_iterencode yield _floatstr(value) else: if isinstance(value, (list, tuple)): chunks = _iterencode_list(value, _current_indent_level) elif isinstance(value, dict): chunks = _iterencode_dict(value, _current_indent_level) else: chunks = _iterencode(value, _current_indent_level) yield from chunks if newline_indent is not None: _current_indent_level -= 1 yield '\n' + _indent * _current_indent_level yield '}' if markers is not None: del markers[markerid] def _iterencode(o, _current_indent_level): if isinstance(o, str): yield _encoder(o) elif o is None: yield 'null' elif o is True: yield 'true' elif o is False: yield 'false' elif isinstance(o, int): # see comment for int/float in _make_iterencode yield _intstr(o) elif isinstance(o, float): # see comment for int/float in _make_iterencode yield _floatstr(o) elif isinstance(o, (list, tuple)): yield from _iterencode_list(o, _current_indent_level) elif isinstance(o, dict): yield from _iterencode_dict(o, _current_indent_level) else: if markers is not None: markerid = id(o) if markerid in markers: raise ValueError("Circular reference detected") markers[markerid] = o o = _default(o) yield from _iterencode(o, _current_indent_level) if markers is not None: del markers[markerid] return _iterencode