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- """JSON token scanner
- """
- import re
- try:
- from _json 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
- strict = context.strict
- parse_float = context.parse_float
- parse_int = context.parse_int
- parse_constant = context.parse_constant
- object_hook = context.object_hook
- object_pairs_hook = context.object_pairs_hook
- memo = context.memo
- def _scan_once(string, idx):
- try:
- nextchar = string[idx]
- except IndexError:
- raise StopIteration(idx) from None
- if nextchar == '"':
- return parse_string(string, idx + 1, strict)
- elif nextchar == '{':
- return parse_object((string, idx + 1), strict,
- _scan_once, object_hook, object_pairs_hook, memo)
- 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(idx)
- def scan_once(string, idx):
- try:
- return _scan_once(string, idx)
- finally:
- memo.clear()
- return scan_once
- make_scanner = c_make_scanner or py_make_scanner
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