code.kerkeslager.com Git - sandbox/blob - serial/serial/text.py

   1 import re
   2
   3 from . import tags
   4
   5 def _make_literal_serializer(expected_value, literal):
   6     def serializer(to):
   7         assert to.instance is expected_value
   8         return literal
   9
  10     return serializer
  11
  12 def _make_integer_serializer(lower_bound, upper_bound, suffix):
  13     def _serializer(to):
  14         assert lower_bound <= to.instance and to.instance < upper_bound
  15         return '{}{}'.format(to.instance, suffix)
  16
  17     return _serializer
  18
  19 def _make_unsigned_integer_serializer(bit_length):
  20     return _make_integer_serializer(0, 2 << (bit_length - 1), 'u{}'.format(bit_length))
  21
  22 def _make_signed_integer_serializer(bit_length):
  23     upper_bound = 2 << (bit_length - 2)
  24     lower_bound = -upper_bound
  25     return _make_integer_serializer(lower_bound, upper_bound, 'i{}'.format(bit_length))
  26
  27 _SERIALIZERS = {
  28     tags.NULL: _make_literal_serializer(None, 'null'),
  29     tags.TRUE: _make_literal_serializer(True, 'true'),
  30     tags.FALSE: _make_literal_serializer(False, 'false'),
  31     tags.UINT8: _make_unsigned_integer_serializer(8),
  32     tags.UINT16: _make_unsigned_integer_serializer(16),
  33     tags.UINT32: _make_unsigned_integer_serializer(32),
  34     tags.UINT64: _make_unsigned_integer_serializer(64),
  35     tags.INT8: _make_signed_integer_serializer(8),
  36     tags.INT16: _make_signed_integer_serializer(16),
  37     tags.INT32: _make_signed_integer_serializer(32),
  38     tags.INT64: _make_signed_integer_serializer(64),
  39 }
  40
  41 def serialize(to):
  42     return _SERIALIZERS[to.tag](to)
  43
  44 def _make_literal_deserializer(tag, instance, literal):
  45     def _deserializer(s):
  46         if s.startswith(literal):
  47             return True, tags.TaggedObject(tag = tag, instance = instance), s[len(literal):]
  48
  49         return False, None, None
  50
  51     return _deserializer
  52
  53 def _make_regex_deserializer(tag, decoder, regex):
  54     matcher = re.compile(regex).match
  55
  56     def _deserializer(s):
  57         match = matcher(s)
  58
  59         if match is None:
  60             return False, None, None
  61
  62         return True, tags.TaggedObject(tag = tag, instance = decoder(match)), s[match.end():]
  63
  64     return _deserializer
  65
  66 def _make_unsigned_int_deserializer(tag, bit_length):
  67     bound = 2 << (bit_length - 1)
  68
  69     def _decoder(match):
  70         result = int(match.group(1))
  71         assert result < bound
  72         return result
  73
  74     return _make_regex_deserializer(tag, _decoder, r'(\d+)' + 'u{}'.format(bit_length))
  75
  76 def _make_signed_int_deserializer(tag, bit_length):
  77     upper_bound = 2 << (bit_length - 2)
  78     lower_bound = -upper_bound
  79
  80     def _decoder(match):
  81         result = int(match.group(1))
  82         assert lower_bound <= result and result < upper_bound
  83         return result
  84
  85     return _make_regex_deserializer(tag, _decoder, r'(-?\d+)' + 'i{}'.format(bit_length))
  86
  87 _DESERIALIZERS = [
  88     _make_literal_deserializer(tags.NULL, None, 'null'),
  89     _make_literal_deserializer(tags.TRUE, True, 'true'),
  90     _make_literal_deserializer(tags.FALSE, False, 'false'),
  91     _make_unsigned_int_deserializer(tags.UINT8, 8),
  92     _make_unsigned_int_deserializer(tags.UINT16, 16),
  93     _make_unsigned_int_deserializer(tags.UINT32, 32),
  94     _make_unsigned_int_deserializer(tags.UINT64, 64),
  95     _make_signed_int_deserializer(tags.INT8, 8),
  96     _make_signed_int_deserializer(tags.INT16, 16),
  97     _make_signed_int_deserializer(tags.INT32, 32),
  98     _make_signed_int_deserializer(tags.INT64, 64),
  99 ]
 100
 101 def deserialize(s):
 102     for deserializer in _DESERIALIZERS:
 103         succeeded, result, remaining = deserializer(s)
 104
 105         if succeeded:
 106             assert remaining == ''
 107             return result
 108
 109     raise Exception()