1"""JSON token scanner
2"""
3import re
4def _import_c_make_scanner():
5    try:
6        from simplejson._speedups import make_scanner
7        return make_scanner
8    except ImportError:
9        return None
10c_make_scanner = _import_c_make_scanner()
11
12__all__ = ['make_scanner']
13
14NUMBER_RE = re.compile(
15    r'(-?(?:0|[1-9]\d*))(\.\d+)?([eE][-+]?\d+)?',
16    (re.VERBOSE | re.MULTILINE | re.DOTALL))
17
18def py_make_scanner(context):
19    parse_object = context.parse_object
20    parse_array = context.parse_array
21    parse_string = context.parse_string
22    match_number = NUMBER_RE.match
23    encoding = context.encoding
24    strict = context.strict
25    parse_float = context.parse_float
26    parse_int = context.parse_int
27    parse_constant = context.parse_constant
28    object_hook = context.object_hook
29    object_pairs_hook = context.object_pairs_hook
30    memo = context.memo
31
32    def _scan_once(string, idx):
33        try:
34            nextchar = string[idx]
35        except IndexError:
36            raise StopIteration
37
38        if nextchar == '"':
39            return parse_string(string, idx + 1, encoding, strict)
40        elif nextchar == '{':
41            return parse_object((string, idx + 1), encoding, strict,
42                _scan_once, object_hook, object_pairs_hook, memo)
43        elif nextchar == '[':
44            return parse_array((string, idx + 1), _scan_once)
45        elif nextchar == 'n' and string[idx:idx + 4] == 'null':
46            return None, idx + 4
47        elif nextchar == 't' and string[idx:idx + 4] == 'true':
48            return True, idx + 4
49        elif nextchar == 'f' and string[idx:idx + 5] == 'false':
50            return False, idx + 5
51
52        m = match_number(string, idx)
53        if m is not None:
54            integer, frac, exp = m.groups()
55            if frac or exp:
56                res = parse_float(integer + (frac or '') + (exp or ''))
57            else:
58                res = parse_int(integer)
59            return res, m.end()
60        elif nextchar == 'N' and string[idx:idx + 3] == 'NaN':
61            return parse_constant('NaN'), idx + 3
62        elif nextchar == 'I' and string[idx:idx + 8] == 'Infinity':
63            return parse_constant('Infinity'), idx + 8
64        elif nextchar == '-' and string[idx:idx + 9] == '-Infinity':
65            return parse_constant('-Infinity'), idx + 9
66        else:
67            raise StopIteration
68
69    def scan_once(string, idx):
70        try:
71            return _scan_once(string, idx)
72        finally:
73            memo.clear()
74
75    return scan_once
76
77make_scanner = c_make_scanner or py_make_scanner
78