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      1 """JSON token scanner
      2 """
      3 import re
      4 def _import_c_make_scanner():
      5     try:
      6         from simplejson._speedups import make_scanner
      7         return make_scanner
      8     except ImportError:
      9         return None
     10 c_make_scanner = _import_c_make_scanner()
     11 
     12 __all__ = ['make_scanner']
     13 
     14 NUMBER_RE = re.compile(
     15     r'(-?(?:0|[1-9]\d*))(\.\d+)?([eE][-+]?\d+)?',
     16     (re.VERBOSE | re.MULTILINE | re.DOTALL))
     17 
     18 def 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 
     77 make_scanner = c_make_scanner or py_make_scanner
     78