third_party/simplejson/scanner.py

   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