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Diffstat (limited to 'lib/simplejson/decoder.py')
| -rw-r--r-- | lib/simplejson/decoder.py | 421 | 
1 files changed, 421 insertions, 0 deletions
| diff --git a/lib/simplejson/decoder.py b/lib/simplejson/decoder.py new file mode 100644 index 000000000..e5496d6e7 --- /dev/null +++ b/lib/simplejson/decoder.py @@ -0,0 +1,421 @@ +"""Implementation of JSONDecoder +""" +import re +import sys +import struct + +from simplejson.scanner import make_scanner +def _import_c_scanstring(): +    try: +        from simplejson._speedups import scanstring +        return scanstring +    except ImportError: +        return None +c_scanstring = _import_c_scanstring() + +__all__ = ['JSONDecoder'] + +FLAGS = re.VERBOSE | re.MULTILINE | re.DOTALL + +def _floatconstants(): +    _BYTES = '7FF80000000000007FF0000000000000'.decode('hex') +    # The struct module in Python 2.4 would get frexp() out of range here +    # when an endian is specified in the format string. Fixed in Python 2.5+ +    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() + + +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 +    end: The end index of doc where parsing failed (may be None) +    lineno: The line corresponding to pos +    colno: The column corresponding to pos +    endlineno: The line corresponding to end (may be None) +    endcolno: The column corresponding to end (may be None) + +    """ +    def __init__(self, msg, doc, pos, end=None): +        ValueError.__init__(self, errmsg(msg, doc, pos, end=end)) +        self.msg = msg +        self.doc = doc +        self.pos = pos +        self.end = end +        self.lineno, self.colno = linecol(doc, pos) +        if end is not None: +            self.endlineno, self.endcolno = linecol(doc, end) +        else: +            self.endlineno, self.endcolno = None, None + + +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): +    # Note that this function is called from _speedups +    lineno, colno = linecol(doc, pos) +    if end is None: +        #fmt = '{0}: line {1} column {2} (char {3})' +        #return fmt.format(msg, lineno, colno, pos) +        fmt = '%s: line %d column %d (char %d)' +        return fmt % (msg, lineno, colno, pos) +    endlineno, endcolno = linecol(doc, end) +    #fmt = '{0}: line {1} column {2} - line {3} column {4} (char {5} - {6})' +    #return fmt.format(msg, lineno, colno, endlineno, endcolno, pos, end) +    fmt = '%s: line %d column %d - line %d column %d (char %d - %d)' +    return fmt % (msg, lineno, colno, endlineno, endcolno, pos, end) + + +_CONSTANTS = { +    '-Infinity': NegInf, +    'Infinity': PosInf, +    'NaN': NaN, +} + +STRINGCHUNK = re.compile(r'(.*?)(["\\\x00-\x1f])', 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 py_scanstring(s, end, encoding=None, 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.""" +    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 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: +            if not isinstance(content, unicode): +                content = unicode(content, encoding) +            _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) +        # If not a unicode escape sequence, must be in the lookup table +        if esc != 'u': +            try: +                char = _b[esc] +            except KeyError: +                msg = "Invalid \\escape: " + repr(esc) +                raise JSONDecodeError(msg, s, end) +            end += 1 +        else: +            # Unicode escape sequence +            esc = s[end + 1:end + 5] +            next_end = end + 5 +            if len(esc) != 4: +                msg = "Invalid \\uXXXX escape" +                raise JSONDecodeError(msg, s, end) +            uni = int(esc, 16) +            # Check for surrogate pair on UCS-4 systems +            if 0xd800 <= uni <= 0xdbff and sys.maxunicode > 65535: +                msg = "Invalid \\uXXXX\\uXXXX surrogate pair" +                if not s[end + 5:end + 7] == '\\u': +                    raise JSONDecodeError(msg, s, end) +                esc2 = s[end + 7:end + 11] +                if len(esc2) != 4: +                    raise JSONDecodeError(msg, s, end) +                uni2 = int(esc2, 16) +                uni = 0x10000 + (((uni - 0xd800) << 10) | (uni2 - 0xdc00)) +                next_end += 6 +            char = unichr(uni) +            end = next_end +        # Append the unescaped character +        _append(char) +    return u''.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, end), encoding, strict, scan_once, object_hook, +        object_pairs_hook, memo=None, +        _w=WHITESPACE.match, _ws=WHITESPACE_STR): +    # Backwards compatibility +    if memo is None: +        memo = {} +    memo_get = memo.setdefault +    pairs = [] +    # 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", s, end) +    end += 1 +    while True: +        key, end = scanstring(s, end, encoding, 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: +            raise JSONDecodeError("Expecting object", s, end) +        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) + +        try: +            nextchar = s[end] +            if nextchar in _ws: +                end += 1 +                nextchar = s[end] +                if nextchar in _ws: +                    end = _w(s, end + 1).end() +                    nextchar = s[end] +        except IndexError: +            nextchar = '' + +        end += 1 +        if nextchar != '"': +            raise JSONDecodeError("Expecting property name", 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, end), scan_once, _w=WHITESPACE.match, _ws=WHITESPACE_STR): +    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: +            raise JSONDecodeError("Expecting object", s, end) +        _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) + +        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        | 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. + +    """ + +    def __init__(self, encoding=None, object_hook=None, parse_float=None, +            parse_int=None, parse_constant=None, strict=True, +            object_pairs_hook=None): +        """ +        *encoding* determines the encoding used to interpret any +        :class:`str` objects decoded by this instance (``'utf-8'`` by +        default).  It has no effect when decoding :class:`unicode` objects. + +        Note that currently only encodings that are a superset of ASCII work, +        strings of other encodings should be passed in as :class:`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 :class:`dict`.  This can be used to provide custom +        deserializations (e.g. to support JSON-RPC class hinting). + +        *object_pairs_hook* is an optional function that will be called with +        the result of any object literal decode with an ordered list of pairs. +        The return value of *object_pairs_hook* will be used instead of the +        :class:`dict`.  This feature can be used to implement custom decoders +        that rely on the order that the key and value pairs are decoded (for +        example, :func:`collections.OrderedDict` will remember the order of +        insertion). 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. :class:`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. :class:`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. + +        *strict* controls the parser's behavior when it encounters an +        invalid control character in a string. The default setting of +        ``True`` means that unescaped control characters are parse errors, if +        ``False`` then control characters will be allowed in strings. + +        """ +        self.encoding = encoding +        self.object_hook = object_hook +        self.object_pairs_hook = object_pairs_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.parse_object = JSONObject +        self.parse_array = JSONArray +        self.parse_string = scanstring +        self.memo = {} +        self.scan_once = make_scanner(self) + +    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 JSONDecodeError("Extra data", s, end, len(s)) +        return obj + +    def raw_decode(self, s, idx=0): +        """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. + +        """ +        try: +            obj, end = self.scan_once(s, idx) +        except StopIteration: +            raise JSONDecodeError("No JSON object could be decoded", s, idx) +        return obj, end | 
