| """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, |
| } |
| |
| |
| STRINGCHUNK = re.compile(r'(.*?)(["\\\x00-\x1f])', FLAGS) |
| BACKSLASH = { |
| '"': '"', '\\': '\\', '/': '/', |
| 'b': '\b', 'f': '\f', 'n': '\n', 'r': '\r', 't': '\t', |
| } |
| |
| def _decode_uXXXX(s, pos): |
| esc = s[pos + 1:pos + 5] |
| if len(esc) == 4 and esc[1] not in 'xX': |
| try: |
| return int(esc, 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) |
| end = _w(s, end).end() |
| nextchar = s[end:end + 1] |
| end += 1 |
| if nextchar != '"': |
| 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) |
| try: |
| if s[end] in _ws: |
| end += 1 |
| if s[end] in _ws: |
| end = _w(s, end + 1).end() |
| except IndexError: |
| pass |
| |
| return values, end |
| |
| |
| class JSONDecoder(object): |
| """Simple JSON <http://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 |
