| """ |
| Implementation of JSONDecoder |
| """ |
| import re |
| |
| from simplejson.scanner import Scanner, pattern |
| |
| FLAGS = re.VERBOSE | re.MULTILINE | re.DOTALL |
| |
| def _floatconstants(): |
| import struct |
| import sys |
| _BYTES = '7FF80000000000007FF0000000000000'.decode('hex') |
| if sys.byteorder != 'big': |
| _BYTES = _BYTES[:8][::-1] + _BYTES[8:][::-1] |
| nan, inf = struct.unpack('dd', _BYTES) |
| return nan, inf, -inf |
| |
| NaN, PosInf, NegInf = _floatconstants() |
| |
| def linecol(doc, pos): |
| lineno = doc.count('\n', 0, pos) + 1 |
| if lineno == 1: |
| colno = pos |
| else: |
| colno = pos - doc.rindex('\n', 0, pos) |
| return lineno, colno |
| |
| def errmsg(msg, doc, pos, end=None): |
| lineno, colno = linecol(doc, pos) |
| if end is None: |
| return '%s: line %d column %d (char %d)' % (msg, lineno, colno, pos) |
| endlineno, endcolno = linecol(doc, end) |
| return '%s: line %d column %d - line %d column %d (char %d - %d)' % ( |
| msg, lineno, colno, endlineno, endcolno, pos, end) |
| |
| _CONSTANTS = { |
| '-Infinity': NegInf, |
| 'Infinity': PosInf, |
| 'NaN': NaN, |
| 'true': True, |
| 'false': False, |
| 'null': None, |
| } |
| |
| def JSONConstant(match, context, c=_CONSTANTS): |
| return c[match.group(0)], None |
| pattern('(-?Infinity|NaN|true|false|null)')(JSONConstant) |
| |
| def JSONNumber(match, context): |
| match = JSONNumber.regex.match(match.string, *match.span()) |
| integer, frac, exp = match.groups() |
| if frac or exp: |
| res = float(integer + (frac or '') + (exp or '')) |
| else: |
| res = int(integer) |
| return res, None |
| pattern(r'(-?(?:0|[1-9]\d*))(\.\d+)?([eE][-+]?\d+)?')(JSONNumber) |
| |
| STRINGCHUNK = re.compile(r'(.*?)(["\\])', FLAGS) |
| BACKSLASH = { |
| '"': u'"', '\\': u'\\', '/': u'/', |
| 'b': u'\b', 'f': u'\f', 'n': u'\n', 'r': u'\r', 't': u'\t', |
| } |
| |
| DEFAULT_ENCODING = "utf-8" |
| |
| def scanstring(s, end, encoding=None, _b=BACKSLASH, _m=STRINGCHUNK.match): |
| if encoding is None: |
| encoding = DEFAULT_ENCODING |
| chunks = [] |
| _append = chunks.append |
| begin = end - 1 |
| while 1: |
| chunk = _m(s, end) |
| if chunk is None: |
| raise ValueError( |
| errmsg("Unterminated string starting at", s, begin)) |
| end = chunk.end() |
| content, terminator = chunk.groups() |
| if content: |
| if not isinstance(content, unicode): |
| content = unicode(content, encoding) |
| _append(content) |
| if terminator == '"': |
| break |
| try: |
| esc = s[end] |
| except IndexError: |
| raise ValueError( |
| errmsg("Unterminated string starting at", s, begin)) |
| if esc != 'u': |
| try: |
| m = _b[esc] |
| except KeyError: |
| raise ValueError( |
| errmsg("Invalid \\escape: %r" % (esc,), s, end)) |
| end += 1 |
| else: |
| esc = s[end + 1:end + 5] |
| try: |
| m = unichr(int(esc, 16)) |
| if len(esc) != 4 or not esc.isalnum(): |
| raise ValueError |
| except ValueError: |
| raise ValueError(errmsg("Invalid \\uXXXX escape", s, end)) |
| end += 5 |
| _append(m) |
| return u''.join(chunks), end |
| |
| def JSONString(match, context): |
| encoding = getattr(context, 'encoding', None) |
| return scanstring(match.string, match.end(), encoding) |
| pattern(r'"')(JSONString) |
| |
| WHITESPACE = re.compile(r'\s*', FLAGS) |
| |
| def JSONObject(match, context, _w=WHITESPACE.match): |
| pairs = {} |
| s = match.string |
| end = _w(s, match.end()).end() |
| nextchar = s[end:end + 1] |
| # trivial empty object |
| if nextchar == '}': |
| return pairs, end + 1 |
| if nextchar != '"': |
| raise ValueError(errmsg("Expecting property name", s, end)) |
| end += 1 |
| encoding = getattr(context, 'encoding', None) |
| iterscan = JSONScanner.iterscan |
| while True: |
| key, end = scanstring(s, end, encoding) |
| end = _w(s, end).end() |
| if s[end:end + 1] != ':': |
| raise ValueError(errmsg("Expecting : delimiter", s, end)) |
| end = _w(s, end + 1).end() |
| try: |
| value, end = iterscan(s, idx=end, context=context).next() |
| except StopIteration: |
| raise ValueError(errmsg("Expecting object", s, end)) |
| pairs[key] = value |
| end = _w(s, end).end() |
| nextchar = s[end:end + 1] |
| end += 1 |
| if nextchar == '}': |
| break |
| if nextchar != ',': |
| raise ValueError(errmsg("Expecting , delimiter", s, end - 1)) |
| end = _w(s, end).end() |
| nextchar = s[end:end + 1] |
| end += 1 |
| if nextchar != '"': |
| raise ValueError(errmsg("Expecting property name", s, end - 1)) |
| object_hook = getattr(context, 'object_hook', None) |
| if object_hook is not None: |
| pairs = object_hook(pairs) |
| return pairs, end |
| pattern(r'{')(JSONObject) |
| |
| def JSONArray(match, context, _w=WHITESPACE.match): |
| values = [] |
| s = match.string |
| end = _w(s, match.end()).end() |
| # look-ahead for trivial empty array |
| nextchar = s[end:end + 1] |
| if nextchar == ']': |
| return values, end + 1 |
| iterscan = JSONScanner.iterscan |
| while True: |
| try: |
| value, end = iterscan(s, idx=end, context=context).next() |
| except StopIteration: |
| raise ValueError(errmsg("Expecting object", s, end)) |
| values.append(value) |
| end = _w(s, end).end() |
| nextchar = s[end:end + 1] |
| end += 1 |
| if nextchar == ']': |
| break |
| if nextchar != ',': |
| raise ValueError(errmsg("Expecting , delimiter", s, end)) |
| end = _w(s, end).end() |
| return values, end |
| pattern(r'\[')(JSONArray) |
| |
| ANYTHING = [ |
| JSONObject, |
| JSONArray, |
| JSONString, |
| JSONConstant, |
| JSONNumber, |
| ] |
| |
| JSONScanner = Scanner(ANYTHING) |
| |
| class JSONDecoder(object): |
| """ |
| Simple JSON <http://json.org> decoder |
| |
| Performs the following translations in decoding: |
| |
| +---------------+-------------------+ |
| | JSON | Python | |
| +===============+===================+ |
| | object | dict | |
| +---------------+-------------------+ |
| | array | list | |
| +---------------+-------------------+ |
| | string | unicode | |
| +---------------+-------------------+ |
| | number (int) | int, long | |
| +---------------+-------------------+ |
| | 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. |
| """ |
| |
| _scanner = Scanner(ANYTHING) |
| __all__ = ['__init__', 'decode', 'raw_decode'] |
| |
| def __init__(self, encoding=None, object_hook=None): |
| """ |
| ``encoding`` determines the encoding used to interpret any ``str`` |
| objects decoded by this instance (utf-8 by default). It has no |
| effect when decoding ``unicode`` objects. |
| |
| Note that currently only encodings that are a superset of ASCII work, |
| strings of other encodings should be passed in as ``unicode``. |
| |
| ``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). |
| """ |
| self.encoding = encoding |
| self.object_hook = object_hook |
| |
| def decode(self, s, _w=WHITESPACE.match): |
| """ |
| Return the Python representation of ``s`` (a ``str`` or ``unicode`` |
| 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 ValueError(errmsg("Extra data", s, end, len(s))) |
| return obj |
| |
| def raw_decode(self, s, **kw): |
| """ |
| Decode a JSON document from ``s`` (a ``str`` or ``unicode`` 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. |
| """ |
| kw.setdefault('context', self) |
| try: |
| obj, end = self._scanner.iterscan(s, **kw).next() |
| except StopIteration: |
| raise ValueError("No JSON object could be decoded") |
| return obj, end |
| |
| __all__ = ['JSONDecoder'] |
