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