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