"""JSON token scanner

"""

import re

try:

    from simplejson._speedups import make_scanner as c_make_scanner

except ImportError:

    c_make_scanner = None

__all__ = ['make_scanner']

NUMBER_RE = re.compile(

    r'(-?(?:0|[1-9]\d*))(\.\d+)?([eE][-+]?\d+)?',

    (re.VERBOSE | re.MULTILINE | re.DOTALL))

def py_make_scanner(context):

    parse_object = context.parse_object

    parse_array = context.parse_array

    parse_string = context.parse_string

    match_number = NUMBER_RE.match

    encoding = context.encoding

    strict = context.strict

    parse_float = context.parse_float

    parse_int = context.parse_int

    parse_constant = context.parse_constant

    object_hook = context.object_hook

    def _scan_once(string, idx):

        try:

            nextchar = string[idx]

        except IndexError:

            raise StopIteration

        if nextchar == '"':

            return parse_string(string, idx + 1, encoding, strict)

        elif nextchar == '{':

            return parse_object((string, idx + 1), encoding, strict, _scan_once, object_hook)

        elif nextchar == '[':

            return parse_array((string, idx + 1), _scan_once)

        elif nextchar == 'n' and string[idx:idx + 4] == 'null':

            return None, idx + 4

        elif nextchar == 't' and string[idx:idx + 4] == 'true':

            return True, idx + 4

        elif nextchar == 'f' and string[idx:idx + 5] == 'false':

            return False, idx + 5

        m = match_number(string, idx)

        if m is not None:

            integer, frac, exp = m.groups()

            if frac or exp:

                res = parse_float(integer + (frac or '') + (exp or ''))

            else:

                res = parse_int(integer)

            return res, m.end()

        elif nextchar == 'N' and string[idx:idx + 3] == 'NaN':

            return parse_constant('NaN'), idx + 3

        elif nextchar == 'I' and string[idx:idx + 8] == 'Infinity':

            return parse_constant('Infinity'), idx + 8

        elif nextchar == '-' and string[idx:idx + 9] == '-Infinity':

            return parse_constant('-Infinity'), idx + 9

        else:

            raise StopIteration

    return _scan_once

make_scanner = c_make_scanner or py_make_scanner