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