cpython/Lib/json/encoder.py at 3.5 · python/cpython · GitHub

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"""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(repr(o) + " 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.__str__,

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 __str__, 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(), key=lambda kv: kv[0])

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("key " + repr(key) + " is not a string")

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

cpython/Lib/json/encoder.py at 3.5 · python/cpython · GitHub

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