From 1e8e6816c9f74de6cb6ab735fc962c7dc8b67164 Mon Sep 17 00:00:00 2001
From: David Kerkeslager <kerkeslager@gmail.com>
Date: Sat, 24 Sep 2016 19:03:32 -0400
Subject: [PATCH] Added string serialization/deserialization

---
 serial/binary.py      | 36 ++++++++++++++++++++++++++++++++++++
 serial/test_binary.py |  4 ++++
 2 files changed, 40 insertions(+)

diff --git a/serial/binary.py b/serial/binary.py
index d362092..7ce58b7 100644
--- a/serial/binary.py
+++ b/serial/binary.py
@@ -14,6 +14,10 @@ TAG_INT8 = 0x10
 TAG_INT16 = 0x11
 TAG_INT32 = 0x12
 TAG_INT64 = 0x13
+TAG_BINARY = 0x20
+TAG_UTF8 = 0x21
+TAG_UTF16 = 0x22
+TAG_UTF32 = 0x23
 
 TaggedObject = collections.namedtuple(
     'TaggedObject',
@@ -41,6 +45,15 @@ def _make_struct_serializer(fmt):
 
     return serializer
 
+def _make_string_serializer(encoder):
+    packer = functools.partial(struct.pack, '!BI')
+
+    def serializer(to):
+        encoded = encoder(to.instance)
+        return packer(to.tag, len(encoded)) + encoded
+
+    return serializer
+
 _TAGS_TO_SERIALIZERS = {
     TAG_NULL: _make_tag_only_serializer(TAG_NULL, None),
     TAG_TRUE: _make_tag_only_serializer(TAG_TRUE, True),
@@ -53,6 +66,10 @@ _TAGS_TO_SERIALIZERS = {
     TAG_INT16: _make_struct_serializer('h'),
     TAG_INT32: _make_struct_serializer('i'),
     TAG_INT64: _make_struct_serializer('q'),
+    TAG_BINARY: _make_string_serializer(lambda s: s),
+    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')),
 }
 
 def serialize(to):
@@ -76,6 +93,21 @@ def _make_struct_deserializer(tag, fmt):
 
     return parser
 
+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))
+
+    return parser
+
 _TAGS_TO_PARSERS = {
     TAG_NULL: _make_tag_only_parser(TAG_NULL, None),
     TAG_TRUE: _make_tag_only_parser(TAG_TRUE, True),
@@ -88,6 +120,10 @@ _TAGS_TO_PARSERS = {
     TAG_INT16: _make_struct_deserializer(TAG_INT16, 'h'),
     TAG_INT32: _make_struct_deserializer(TAG_INT32, 'i'),
     TAG_INT64: _make_struct_deserializer(TAG_INT64, 'q'),
+    TAG_BINARY: _make_string_deserializer(TAG_BINARY, lambda b: b),
+    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')),
 }
 
 def deserialize(b):
diff --git a/serial/test_binary.py b/serial/test_binary.py
index 0463dda..8bc3811 100644
--- a/serial/test_binary.py
+++ b/serial/test_binary.py
@@ -22,6 +22,10 @@ EXAMPLE_REPRESENTATIONS = [
     (binary.TAG_INT16, -2, b'\x11\xff\xfe'),
     (binary.TAG_INT32, -2, b'\x12\xff\xff\xff\xfe'),
     (binary.TAG_INT64, -2, b'\x13\xff\xff\xff\xff\xff\xff\xff\xfe'),
+    (binary.TAG_BINARY, b'\xde\xad\xbe\xef', b'\x20\x00\x00\x00\x04\xde\xad\xbe\xef'),
+    (binary.TAG_UTF8, 'Lol!', b'\x21\x00\x00\x00\x04Lol!'),
+    (binary.TAG_UTF16, 'かわ', b'\x22\x00\x00\x00\x06\xff\xfeK0\x8f0'),
+    (binary.TAG_UTF32, 'æ¼¢', b'\x23\x00\x00\x00\x08\xff\xfe\x00\x00"o\x00\x00'),
 ]
 
 class SerializeTests(unittest.TestCase):
-- 
2.20.1