From 07d76f810ece3b43bb837e81ceb3a8b441348ba3 Mon Sep 17 00:00:00 2001
From: David Kerkeslager <kerkeslager@gmail.com>
Date: Fri, 30 Sep 2016 12:11:43 -0400
Subject: [PATCH] Implemented tuple serialization

---
 serial/binary.py      | 62 +++++++++++++++++++++++++++++++++++--------
 serial/test_binary.py | 32 +++++++++++++++-------
 2 files changed, 73 insertions(+), 21 deletions(-)

diff --git a/serial/binary.py b/serial/binary.py
index 7ce58b7..fabcd47 100644
--- a/serial/binary.py
+++ b/serial/binary.py
@@ -18,6 +18,7 @@ TAG_BINARY = 0x20
 TAG_UTF8 = 0x21
 TAG_UTF16 = 0x22
 TAG_UTF32 = 0x23
+TAG_TUPLE = 0x30
 
 TaggedObject = collections.namedtuple(
     'TaggedObject',
@@ -54,6 +55,16 @@ def _make_string_serializer(encoder):
 
     return serializer
 
+def _serialize_tuple(to):
+    assert isinstance(to.instance, tuple)
+
+    payload = b''.join(serialize(item) for item in to.instance)
+
+    fmt = '!BI'
+
+    return struct.pack('!BI', TAG_TUPLE, len(payload)) + payload
+
+
 _TAGS_TO_SERIALIZERS = {
     TAG_NULL: _make_tag_only_serializer(TAG_NULL, None),
     TAG_TRUE: _make_tag_only_serializer(TAG_TRUE, True),
@@ -70,6 +81,7 @@ _TAGS_TO_SERIALIZERS = {
     TAG_UTF8: _make_string_serializer(lambda s: s.encode('utf-8')),
     TAG_UTF16: _make_string_serializer(lambda s: s.encode('utf-16')),
     TAG_UTF32: _make_string_serializer(lambda s: s.encode('utf-32')),
+    TAG_TUPLE: _serialize_tuple,
 }
 
 def serialize(to):
@@ -77,7 +89,7 @@ def serialize(to):
 
 def _make_tag_only_parser(tag, value):
     def parser(b):
-        return TaggedObject(tag = tag, instance = value)
+        return 0, TaggedObject(tag = tag, instance = value)
 
     return parser
 
@@ -89,25 +101,48 @@ def _make_struct_deserializer(tag, fmt):
     def parser(b):
         b = b.read(size)
         assert len(b) == size
-        return TaggedObject(tag = tag, instance = unpacker(b)[0])
+        return size, TaggedObject(tag = tag, instance = unpacker(b)[0])
 
     return parser
 
+_LENGTH_FMT = '!I'
+_LENGTH_FMT_SIZE = struct.calcsize(_LENGTH_FMT)
+
+def _read_length_then_payload(b):
+    length_b = b.read(_LENGTH_FMT_SIZE)
+    assert len(length_b) == _LENGTH_FMT_SIZE
+    length = struct.unpack(_LENGTH_FMT, length_b)[0]
+
+    payload = b.read(length)
+    assert len(payload) == length
+    return _LENGTH_FMT_SIZE + length, payload
+
 def _make_string_deserializer(tag, decoder):
     fmt = '!I'
     size = struct.calcsize(fmt)
     unpacker = functools.partial(struct.unpack, fmt)
 
     def parser(b):
-        length_b = b.read(size)
-        assert len(length_b) == size
-        length = unpacker(length_b)[0]
-        s = b.read(length)
-        assert len(s) == length
-        return TaggedObject(tag = tag, instance = decoder(s))
+        bytes_read, payload = _read_length_then_payload(b)
+        return bytes_read, TaggedObject(tag = tag, instance = decoder(payload))
 
     return parser
 
+def _deserialize_tuple(b):
+    bytes_read, payload = _read_length_then_payload(b)
+
+    payload_stream = io.BytesIO(payload)
+
+    total_bytes_read = 0
+    instance = []
+
+    while total_bytes_read < len(payload):
+        partial_bytes_read, item = _deserialize_partial(payload_stream)
+        total_bytes_read += partial_bytes_read
+        instance.append(item)
+
+    return bytes_read, TaggedObject(tag = TAG_TUPLE, instance = tuple(instance))
+
 _TAGS_TO_PARSERS = {
     TAG_NULL: _make_tag_only_parser(TAG_NULL, None),
     TAG_TRUE: _make_tag_only_parser(TAG_TRUE, True),
@@ -124,15 +159,20 @@ _TAGS_TO_PARSERS = {
     TAG_UTF8: _make_string_deserializer(TAG_UTF8, lambda b: b.decode('utf-8')),
     TAG_UTF16: _make_string_deserializer(TAG_UTF16, lambda b: b.decode('utf-16')),
     TAG_UTF32: _make_string_deserializer(TAG_UTF32, lambda b: b.decode('utf-32')),
+    TAG_TUPLE: _deserialize_tuple,
 }
 
+def _deserialize_partial(b):
+    tag = b.read(1)
+    assert len(tag) == 1
+    bytes_read, to = _TAGS_TO_PARSERS[tag[0]](b)
+    return bytes_read + 1, to
+
 def deserialize(b):
     if isinstance(b, bytes):
         b = io.BytesIO(b)
 
-    tag = b.read(1)[0]
-
-    result = _TAGS_TO_PARSERS[tag](b)
+    bytes_read, result = _deserialize_partial(b)
 
     remainder = b.read()
 
diff --git a/serial/test_binary.py b/serial/test_binary.py
index 95652cb..4da6e1b 100644
--- a/serial/test_binary.py
+++ b/serial/test_binary.py
@@ -26,22 +26,34 @@ EXAMPLE_REPRESENTATIONS = [
     (binary.TaggedObject(binary.TAG_UTF8, 'Lol!'), b'\x21\x00\x00\x00\x04Lol!'),
     (binary.TaggedObject(binary.TAG_UTF16, 'かわ'), b'\x22\x00\x00\x00\x06\xff\xfeK0\x8f0'),
     (binary.TaggedObject(binary.TAG_UTF32, 'æ¼¢'), b'\x23\x00\x00\x00\x08\xff\xfe\x00\x00"o\x00\x00'),
+    (
+        binary.TaggedObject(
+            binary.TAG_TUPLE,
+            (
+                binary.TaggedObject(
+                    binary.TAG_TRUE,
+                    True,
+                ),
+                binary.TaggedObject(
+                    binary.TAG_UINT8,
+                    7,
+                ),
+            ),
+        ),
+        b'\x30\x00\x00\x00\x03\x01\x03\x07'
+    ),
 ]
 
 class SerializeTests(unittest.TestCase):
     def test_serialize(self):
-        for tagged_object, representation in EXAMPLE_REPRESENTATIONS:
-            self.assertEqual(
-                binary.serialize(tagged_object),
-                representation,
-            )
+        for tagged_object, expected in EXAMPLE_REPRESENTATIONS:
+            actual = binary.serialize(tagged_object)
+            self.assertEqual(expected, actual)
 
 class DeserializeTests(unittest.TestCase):
     def test_deserialize(self):
-        for tagged_object, representation in EXAMPLE_REPRESENTATIONS:
-            self.assertEqual(
-                binary.deserialize(representation),
-                tagged_object,
-            )
+        for expected, representation in EXAMPLE_REPRESENTATIONS:
+            actual = binary.deserialize(representation)
+            self.assertEqual(expected, actual)
 
 unittest.main()
-- 
2.20.1