mirror of https://github.com/python/cpython
365 lines
13 KiB
Python
365 lines
13 KiB
Python
"""Implementation of JSONDecoder
|
|
"""
|
|
import re
|
|
|
|
from json import scanner
|
|
try:
|
|
from _json import scanstring as c_scanstring
|
|
except ImportError:
|
|
c_scanstring = None
|
|
|
|
__all__ = ['JSONDecoder', 'JSONDecodeError']
|
|
|
|
FLAGS = re.VERBOSE | re.MULTILINE | re.DOTALL
|
|
|
|
NaN = float('nan')
|
|
PosInf = float('inf')
|
|
NegInf = float('-inf')
|
|
|
|
|
|
class JSONDecodeError(ValueError):
|
|
"""Subclass of ValueError with the following additional properties:
|
|
|
|
msg: The unformatted error message
|
|
doc: The JSON document being parsed
|
|
pos: The start index of doc where parsing failed
|
|
lineno: The line corresponding to pos
|
|
colno: The column corresponding to pos
|
|
|
|
"""
|
|
# Note that this exception is used from _json
|
|
def __init__(self, msg, doc, pos):
|
|
lineno = doc.count('\n', 0, pos) + 1
|
|
colno = pos - doc.rfind('\n', 0, pos)
|
|
errmsg = '%s: line %d column %d (char %d)' % (msg, lineno, colno, pos)
|
|
ValueError.__init__(self, errmsg)
|
|
self.msg = msg
|
|
self.doc = doc
|
|
self.pos = pos
|
|
self.lineno = lineno
|
|
self.colno = colno
|
|
|
|
def __reduce__(self):
|
|
return self.__class__, (self.msg, self.doc, self.pos)
|
|
|
|
|
|
_CONSTANTS = {
|
|
'-Infinity': NegInf,
|
|
'Infinity': PosInf,
|
|
'NaN': NaN,
|
|
}
|
|
|
|
|
|
HEXDIGITS = re.compile(r'[0-9A-Fa-f]{4}', FLAGS)
|
|
STRINGCHUNK = re.compile(r'(.*?)(["\\\x00-\x1f])', FLAGS)
|
|
BACKSLASH = {
|
|
'"': '"', '\\': '\\', '/': '/',
|
|
'b': '\b', 'f': '\f', 'n': '\n', 'r': '\r', 't': '\t',
|
|
}
|
|
|
|
def _decode_uXXXX(s, pos, _m=HEXDIGITS.match):
|
|
esc = _m(s, pos + 1)
|
|
if esc is not None:
|
|
try:
|
|
return int(esc.group(), 16)
|
|
except ValueError:
|
|
pass
|
|
msg = "Invalid \\uXXXX escape"
|
|
raise JSONDecodeError(msg, s, pos)
|
|
|
|
def py_scanstring(s, end, strict=True,
|
|
_b=BACKSLASH, _m=STRINGCHUNK.match):
|
|
"""Scan the string s for a JSON string. End is the index of the
|
|
character in s after the quote that started the JSON string.
|
|
Unescapes all valid JSON string escape sequences and raises ValueError
|
|
on attempt to decode an invalid string. If strict is False then literal
|
|
control characters are allowed in the string.
|
|
|
|
Returns a tuple of the decoded string and the index of the character in s
|
|
after the end quote."""
|
|
chunks = []
|
|
_append = chunks.append
|
|
begin = end - 1
|
|
while 1:
|
|
chunk = _m(s, end)
|
|
if chunk is None:
|
|
raise JSONDecodeError("Unterminated string starting at", s, begin)
|
|
end = chunk.end()
|
|
content, terminator = chunk.groups()
|
|
# Content is contains zero or more unescaped string characters
|
|
if content:
|
|
_append(content)
|
|
# Terminator is the end of string, a literal control character,
|
|
# or a backslash denoting that an escape sequence follows
|
|
if terminator == '"':
|
|
break
|
|
elif terminator != '\\':
|
|
if strict:
|
|
#msg = "Invalid control character %r at" % (terminator,)
|
|
msg = "Invalid control character {0!r} at".format(terminator)
|
|
raise JSONDecodeError(msg, s, end)
|
|
else:
|
|
_append(terminator)
|
|
continue
|
|
try:
|
|
esc = s[end]
|
|
except IndexError:
|
|
raise JSONDecodeError("Unterminated string starting at",
|
|
s, begin) from None
|
|
# If not a unicode escape sequence, must be in the lookup table
|
|
if esc != 'u':
|
|
try:
|
|
char = _b[esc]
|
|
except KeyError:
|
|
msg = "Invalid \\escape: {0!r}".format(esc)
|
|
raise JSONDecodeError(msg, s, end)
|
|
end += 1
|
|
else:
|
|
uni = _decode_uXXXX(s, end)
|
|
end += 5
|
|
if 0xd800 <= uni <= 0xdbff and s[end:end + 2] == '\\u':
|
|
uni2 = _decode_uXXXX(s, end + 1)
|
|
if 0xdc00 <= uni2 <= 0xdfff:
|
|
uni = 0x10000 + (((uni - 0xd800) << 10) | (uni2 - 0xdc00))
|
|
end += 6
|
|
char = chr(uni)
|
|
_append(char)
|
|
return ''.join(chunks), end
|
|
|
|
|
|
# Use speedup if available
|
|
scanstring = c_scanstring or py_scanstring
|
|
|
|
WHITESPACE = re.compile(r'[ \t\n\r]*', FLAGS)
|
|
WHITESPACE_STR = ' \t\n\r'
|
|
|
|
|
|
def JSONObject(s_and_end, strict, scan_once, object_hook, object_pairs_hook,
|
|
memo=None, _w=WHITESPACE.match, _ws=WHITESPACE_STR):
|
|
s, end = s_and_end
|
|
pairs = []
|
|
pairs_append = pairs.append
|
|
# Backwards compatibility
|
|
if memo is None:
|
|
memo = {}
|
|
memo_get = memo.setdefault
|
|
# Use a slice to prevent IndexError from being raised, the following
|
|
# check will raise a more specific ValueError if the string is empty
|
|
nextchar = s[end:end + 1]
|
|
# Normally we expect nextchar == '"'
|
|
if nextchar != '"':
|
|
if nextchar in _ws:
|
|
end = _w(s, end).end()
|
|
nextchar = s[end:end + 1]
|
|
# Trivial empty object
|
|
if nextchar == '}':
|
|
if object_pairs_hook is not None:
|
|
result = object_pairs_hook(pairs)
|
|
return result, end + 1
|
|
pairs = {}
|
|
if object_hook is not None:
|
|
pairs = object_hook(pairs)
|
|
return pairs, end + 1
|
|
elif nextchar != '"':
|
|
raise JSONDecodeError(
|
|
"Expecting property name enclosed in double quotes", s, end)
|
|
end += 1
|
|
while True:
|
|
key, end = scanstring(s, end, strict)
|
|
key = memo_get(key, key)
|
|
# To skip some function call overhead we optimize the fast paths where
|
|
# the JSON key separator is ": " or just ":".
|
|
if s[end:end + 1] != ':':
|
|
end = _w(s, end).end()
|
|
if s[end:end + 1] != ':':
|
|
raise JSONDecodeError("Expecting ':' delimiter", s, end)
|
|
end += 1
|
|
|
|
try:
|
|
if s[end] in _ws:
|
|
end += 1
|
|
if s[end] in _ws:
|
|
end = _w(s, end + 1).end()
|
|
except IndexError:
|
|
pass
|
|
|
|
try:
|
|
value, end = scan_once(s, end)
|
|
except StopIteration as err:
|
|
raise JSONDecodeError("Expecting value", s, err.value) from None
|
|
pairs_append((key, value))
|
|
try:
|
|
nextchar = s[end]
|
|
if nextchar in _ws:
|
|
end = _w(s, end + 1).end()
|
|
nextchar = s[end]
|
|
except IndexError:
|
|
nextchar = ''
|
|
end += 1
|
|
|
|
if nextchar == '}':
|
|
break
|
|
elif nextchar != ',':
|
|
raise JSONDecodeError("Expecting ',' delimiter", s, end - 1)
|
|
comma_idx = end - 1
|
|
end = _w(s, end).end()
|
|
nextchar = s[end:end + 1]
|
|
end += 1
|
|
if nextchar != '"':
|
|
if nextchar == '}':
|
|
raise JSONDecodeError("Illegal trailing comma before end of object", s, comma_idx)
|
|
raise JSONDecodeError(
|
|
"Expecting property name enclosed in double quotes", s, end - 1)
|
|
if object_pairs_hook is not None:
|
|
result = object_pairs_hook(pairs)
|
|
return result, end
|
|
pairs = dict(pairs)
|
|
if object_hook is not None:
|
|
pairs = object_hook(pairs)
|
|
return pairs, end
|
|
|
|
def JSONArray(s_and_end, scan_once, _w=WHITESPACE.match, _ws=WHITESPACE_STR):
|
|
s, end = s_and_end
|
|
values = []
|
|
nextchar = s[end:end + 1]
|
|
if nextchar in _ws:
|
|
end = _w(s, end + 1).end()
|
|
nextchar = s[end:end + 1]
|
|
# Look-ahead for trivial empty array
|
|
if nextchar == ']':
|
|
return values, end + 1
|
|
_append = values.append
|
|
while True:
|
|
try:
|
|
value, end = scan_once(s, end)
|
|
except StopIteration as err:
|
|
raise JSONDecodeError("Expecting value", s, err.value) from None
|
|
_append(value)
|
|
nextchar = s[end:end + 1]
|
|
if nextchar in _ws:
|
|
end = _w(s, end + 1).end()
|
|
nextchar = s[end:end + 1]
|
|
end += 1
|
|
if nextchar == ']':
|
|
break
|
|
elif nextchar != ',':
|
|
raise JSONDecodeError("Expecting ',' delimiter", s, end - 1)
|
|
comma_idx = end - 1
|
|
try:
|
|
if s[end] in _ws:
|
|
end += 1
|
|
if s[end] in _ws:
|
|
end = _w(s, end + 1).end()
|
|
nextchar = s[end:end + 1]
|
|
except IndexError:
|
|
pass
|
|
if nextchar == ']':
|
|
raise JSONDecodeError("Illegal trailing comma before end of array", s, comma_idx)
|
|
|
|
return values, end
|
|
|
|
|
|
class JSONDecoder(object):
|
|
"""Simple JSON <https://json.org> decoder
|
|
|
|
Performs the following translations in decoding by default:
|
|
|
|
+---------------+-------------------+
|
|
| JSON | Python |
|
|
+===============+===================+
|
|
| object | dict |
|
|
+---------------+-------------------+
|
|
| array | list |
|
|
+---------------+-------------------+
|
|
| string | str |
|
|
+---------------+-------------------+
|
|
| number (int) | int |
|
|
+---------------+-------------------+
|
|
| number (real) | float |
|
|
+---------------+-------------------+
|
|
| true | True |
|
|
+---------------+-------------------+
|
|
| false | False |
|
|
+---------------+-------------------+
|
|
| null | None |
|
|
+---------------+-------------------+
|
|
|
|
It also understands ``NaN``, ``Infinity``, and ``-Infinity`` as
|
|
their corresponding ``float`` values, which is outside the JSON spec.
|
|
|
|
"""
|
|
|
|
def __init__(self, *, object_hook=None, parse_float=None,
|
|
parse_int=None, parse_constant=None, strict=True,
|
|
object_pairs_hook=None):
|
|
"""``object_hook``, if specified, will be called with the result
|
|
of every JSON object decoded and its return value will be used in
|
|
place of the given ``dict``. This can be used to provide custom
|
|
deserializations (e.g. to support JSON-RPC class hinting).
|
|
|
|
``object_pairs_hook``, if specified will be called with the result of
|
|
every JSON object decoded with an ordered list of pairs. The return
|
|
value of ``object_pairs_hook`` will be used instead of the ``dict``.
|
|
This feature can be used to implement custom decoders.
|
|
If ``object_hook`` is also defined, the ``object_pairs_hook`` takes
|
|
priority.
|
|
|
|
``parse_float``, if specified, will be called with the string
|
|
of every JSON float to be decoded. By default this is equivalent to
|
|
float(num_str). This can be used to use another datatype or parser
|
|
for JSON floats (e.g. decimal.Decimal).
|
|
|
|
``parse_int``, if specified, will be called with the string
|
|
of every JSON int to be decoded. By default this is equivalent to
|
|
int(num_str). This can be used to use another datatype or parser
|
|
for JSON integers (e.g. float).
|
|
|
|
``parse_constant``, if specified, will be called with one of the
|
|
following strings: -Infinity, Infinity, NaN.
|
|
This can be used to raise an exception if invalid JSON numbers
|
|
are encountered.
|
|
|
|
If ``strict`` is false (true is the default), then control
|
|
characters will be allowed inside strings. Control characters in
|
|
this context are those with character codes in the 0-31 range,
|
|
including ``'\\t'`` (tab), ``'\\n'``, ``'\\r'`` and ``'\\0'``.
|
|
"""
|
|
self.object_hook = object_hook
|
|
self.parse_float = parse_float or float
|
|
self.parse_int = parse_int or int
|
|
self.parse_constant = parse_constant or _CONSTANTS.__getitem__
|
|
self.strict = strict
|
|
self.object_pairs_hook = object_pairs_hook
|
|
self.parse_object = JSONObject
|
|
self.parse_array = JSONArray
|
|
self.parse_string = scanstring
|
|
self.memo = {}
|
|
self.scan_once = scanner.make_scanner(self)
|
|
|
|
|
|
def decode(self, s, _w=WHITESPACE.match):
|
|
"""Return the Python representation of ``s`` (a ``str`` instance
|
|
containing a JSON document).
|
|
|
|
"""
|
|
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
|
|
end = _w(s, end).end()
|
|
if end != len(s):
|
|
raise JSONDecodeError("Extra data", s, end)
|
|
return obj
|
|
|
|
def raw_decode(self, s, idx=0):
|
|
"""Decode a JSON document from ``s`` (a ``str`` beginning with
|
|
a JSON document) and return a 2-tuple of the Python
|
|
representation and the index in ``s`` where the document ended.
|
|
|
|
This can be used to decode a JSON document from a string that may
|
|
have extraneous data at the end.
|
|
|
|
"""
|
|
try:
|
|
obj, end = self.scan_once(s, idx)
|
|
except StopIteration as err:
|
|
raise JSONDecodeError("Expecting value", s, err.value) from None
|
|
return obj, end
|