Add text serialization for null, booleans, and integers

[sandbox] / serial / serial / text.py

diff --git a/serial/serial/text.py b/serial/serial/text.py
new file mode 100644 (file)
index 0000000..cf2bedc
--- /dev/null
+++ b/serial/serial/text.py
@@ -0,0 +1,109 @@
+import re
+
+from . import tags
+
+def _make_literal_serializer(expected_value, literal):
+    def serializer(to):
+        assert to.instance is expected_value
+        return literal
+
+    return serializer
+
+def _make_integer_serializer(lower_bound, upper_bound, suffix):
+    def _serializer(to):
+        assert lower_bound <= to.instance and to.instance < upper_bound
+        return '{}{}'.format(to.instance, suffix)
+
+    return _serializer
+
+def _make_unsigned_integer_serializer(bit_length):
+    return _make_integer_serializer(0, 2 << (bit_length - 1), 'u{}'.format(bit_length))
+
+def _make_signed_integer_serializer(bit_length):
+    upper_bound = 2 << (bit_length - 2)
+    lower_bound = -upper_bound
+    return _make_integer_serializer(lower_bound, upper_bound, 'i{}'.format(bit_length))
+
+_SERIALIZERS = {
+    tags.NULL: _make_literal_serializer(None, 'null'),
+    tags.TRUE: _make_literal_serializer(True, 'true'),
+    tags.FALSE: _make_literal_serializer(False, 'false'),
+    tags.UINT8: _make_unsigned_integer_serializer(8),
+    tags.UINT16: _make_unsigned_integer_serializer(16),
+    tags.UINT32: _make_unsigned_integer_serializer(32),
+    tags.UINT64: _make_unsigned_integer_serializer(64),
+    tags.INT8: _make_signed_integer_serializer(8),
+    tags.INT16: _make_signed_integer_serializer(16),
+    tags.INT32: _make_signed_integer_serializer(32),
+    tags.INT64: _make_signed_integer_serializer(64),
+}
+
+def serialize(to):
+    return _SERIALIZERS[to.tag](to)
+
+def _make_literal_deserializer(tag, instance, literal):
+    def _deserializer(s):
+        if s.startswith(literal):
+            return True, tags.TaggedObject(tag = tag, instance = instance), s[len(literal):]
+
+        return False, None, None
+
+    return _deserializer
+
+def _make_regex_deserializer(tag, decoder, regex):
+    matcher = re.compile(regex).match
+
+    def _deserializer(s):
+        match = matcher(s)
+
+        if match is None:
+            return False, None, None
+
+        return True, tags.TaggedObject(tag = tag, instance = decoder(match)), s[match.end():]
+
+    return _deserializer
+
+def _make_unsigned_int_deserializer(tag, bit_length):
+    bound = 2 << (bit_length - 1)
+
+    def _decoder(match):
+        result = int(match.group(1))
+        assert result < bound
+        return result
+
+    return _make_regex_deserializer(tag, _decoder, r'(\d+)' + 'u{}'.format(bit_length))
+
+def _make_signed_int_deserializer(tag, bit_length):
+    upper_bound = 2 << (bit_length - 2)
+    lower_bound = -upper_bound
+
+    def _decoder(match):
+        result = int(match.group(1))
+        assert lower_bound <= result and result < upper_bound
+        return result
+
+    return _make_regex_deserializer(tag, _decoder, r'(-?\d+)' + 'i{}'.format(bit_length))
+
+_DESERIALIZERS = [
+    _make_literal_deserializer(tags.NULL, None, 'null'),
+    _make_literal_deserializer(tags.TRUE, True, 'true'),
+    _make_literal_deserializer(tags.FALSE, False, 'false'),
+    _make_unsigned_int_deserializer(tags.UINT8, 8),
+    _make_unsigned_int_deserializer(tags.UINT16, 16),
+    _make_unsigned_int_deserializer(tags.UINT32, 32),
+    _make_unsigned_int_deserializer(tags.UINT64, 64),
+    _make_signed_int_deserializer(tags.INT8, 8),
+    _make_signed_int_deserializer(tags.INT16, 16),
+    _make_signed_int_deserializer(tags.INT32, 32),
+    _make_signed_int_deserializer(tags.INT64, 64),
+]
+
+def deserialize(s):
+    for deserializer in _DESERIALIZERS:
+        succeeded, result, remaining = deserializer(s)
+
+        if succeeded:
+            assert remaining == ''
+            return result
+
+    raise Exception()