jpayne@68: """JSON token scanner
jpayne@68: """
jpayne@68: import re
jpayne@68: try:
jpayne@68:     from _json import make_scanner as c_make_scanner
jpayne@68: except ImportError:
jpayne@68:     c_make_scanner = None
jpayne@68: 
jpayne@68: __all__ = ['make_scanner']
jpayne@68: 
jpayne@68: NUMBER_RE = re.compile(
jpayne@68:     r'(-?(?:0|[1-9]\d*))(\.\d+)?([eE][-+]?\d+)?',
jpayne@68:     (re.VERBOSE | re.MULTILINE | re.DOTALL))
jpayne@68: 
jpayne@68: def py_make_scanner(context):
jpayne@68:     parse_object = context.parse_object
jpayne@68:     parse_array = context.parse_array
jpayne@68:     parse_string = context.parse_string
jpayne@68:     match_number = NUMBER_RE.match
jpayne@68:     strict = context.strict
jpayne@68:     parse_float = context.parse_float
jpayne@68:     parse_int = context.parse_int
jpayne@68:     parse_constant = context.parse_constant
jpayne@68:     object_hook = context.object_hook
jpayne@68:     object_pairs_hook = context.object_pairs_hook
jpayne@68:     memo = context.memo
jpayne@68: 
jpayne@68:     def _scan_once(string, idx):
jpayne@68:         try:
jpayne@68:             nextchar = string[idx]
jpayne@68:         except IndexError:
jpayne@68:             raise StopIteration(idx) from None
jpayne@68: 
jpayne@68:         if nextchar == '"':
jpayne@68:             return parse_string(string, idx + 1, strict)
jpayne@68:         elif nextchar == '{':
jpayne@68:             return parse_object((string, idx + 1), strict,
jpayne@68:                 _scan_once, object_hook, object_pairs_hook, memo)
jpayne@68:         elif nextchar == '[':
jpayne@68:             return parse_array((string, idx + 1), _scan_once)
jpayne@68:         elif nextchar == 'n' and string[idx:idx + 4] == 'null':
jpayne@68:             return None, idx + 4
jpayne@68:         elif nextchar == 't' and string[idx:idx + 4] == 'true':
jpayne@68:             return True, idx + 4
jpayne@68:         elif nextchar == 'f' and string[idx:idx + 5] == 'false':
jpayne@68:             return False, idx + 5
jpayne@68: 
jpayne@68:         m = match_number(string, idx)
jpayne@68:         if m is not None:
jpayne@68:             integer, frac, exp = m.groups()
jpayne@68:             if frac or exp:
jpayne@68:                 res = parse_float(integer + (frac or '') + (exp or ''))
jpayne@68:             else:
jpayne@68:                 res = parse_int(integer)
jpayne@68:             return res, m.end()
jpayne@68:         elif nextchar == 'N' and string[idx:idx + 3] == 'NaN':
jpayne@68:             return parse_constant('NaN'), idx + 3
jpayne@68:         elif nextchar == 'I' and string[idx:idx + 8] == 'Infinity':
jpayne@68:             return parse_constant('Infinity'), idx + 8
jpayne@68:         elif nextchar == '-' and string[idx:idx + 9] == '-Infinity':
jpayne@68:             return parse_constant('-Infinity'), idx + 9
jpayne@68:         else:
jpayne@68:             raise StopIteration(idx)
jpayne@68: 
jpayne@68:     def scan_once(string, idx):
jpayne@68:         try:
jpayne@68:             return _scan_once(string, idx)
jpayne@68:         finally:
jpayne@68:             memo.clear()
jpayne@68: 
jpayne@68:     return scan_once
jpayne@68: 
jpayne@68: make_scanner = c_make_scanner or py_make_scanner