Python: CreateByteVector function in builder. (#4453)

python/flatbuffers/builder.py

@@ -421,6 +421,27 @@ class Builder(object):
 
         return self.EndVector(len(x))
 
+    def CreateByteVector(self, x):
+        """CreateString writes a byte vector."""
+
+        self.assertNotNested()
+        ## @cond FLATBUFFERS_INTERNAL
+        self.nested = True
+        ## @endcond
+
+        if not isinstance(x, compat.binary_types):
+            raise TypeError("non-byte vector passed to CreateByteVector")
+
+        self.Prep(N.UOffsetTFlags.bytewidth, len(x)*N.Uint8Flags.bytewidth)
+
+        l = UOffsetTFlags.py_type(len(x))
+        ## @cond FLATBUFFERS_INTERNAL
+        self.head = UOffsetTFlags.py_type(self.Head() - l)
+        ## @endcond
+        self.Bytes[self.Head():self.Head()+l] = x
+
+        return self.EndVector(len(x))
+
     ## @cond FLATBUFFERS_INTERNAL
     def assertNested(self):
         """

tests/py_test.py

@@ -459,6 +459,17 @@ class TestByteLayout(unittest.TestCase):
         self.assertBuilderEquals(b, [4, 0, 0, 0, 4, 5, 6, 7, 0, 0, 0, 0,
                                      3, 0, 0, 0, 1, 2, 3, 0])
 
+    def test_create_byte_vector(self):
+        b = flatbuffers.Builder(0)
+        b.CreateByteVector(b"")
+        # 0-byte pad:
+        self.assertBuilderEquals(b, [0, 0, 0, 0])
+
+        b = flatbuffers.Builder(0)
+        b.CreateByteVector(b"\x01\x02\x03")
+        # 1-byte pad:
+        self.assertBuilderEquals(b, [3, 0, 0, 0, 1, 2, 3, 0])
+
     def test_empty_vtable(self):
         b = flatbuffers.Builder(0)
         b.StartObject(0)
@@ -1226,6 +1237,13 @@ class TestExceptions(unittest.TestCase):
         assertRaises(self, lambda: b.CreateString(s),
                      flatbuffers.builder.IsNestedError)
 
+    def test_create_byte_vector_is_nested_error(self):
+        b = flatbuffers.Builder(0)
+        b.StartObject(0)
+        s = b'test1'
+        assertRaises(self, lambda: b.CreateByteVector(s),
+                     flatbuffers.builder.IsNestedError)
+
     def test_finished_bytes_error(self):
         b = flatbuffers.Builder(0)
         assertRaises(self, lambda: b.Output(),