diff --git a/simplejson/decoder.py b/simplejson/decoder.py
new file mode 100644
index 0000000..4cf4015
--- /dev/null
+++ b/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, pos)
+        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
+            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