add Encoding::num_bytes_to_encode_code_point()

src/core/Encoding.cc

@@ -156,3 +156,41 @@ uint32_t Encoding::decode(Type type, const uint8_t * encoded)
 
     return 0u;
 }
+
+uint8_t Encoding::num_bytes_to_encode_code_point(uint32_t code_point, Type type)
+{
+    switch (type)
+    {
+    case UTF_8:
+        if (code_point <= 0x7Fu)
+        {
+            return 1u;
+        }
+        else if (code_point <= 0x7FFu)
+        {
+            return 2u;
+        }
+        else if (code_point <= 0xFFFFu)
+        {
+            return 3u;
+        }
+        else if (code_point <= 0x1FFFFFu)
+        {
+            return 4u;
+        }
+        else if (code_point <= 0x3FFFFFFu)
+        {
+            return 5u;
+        }
+        else
+        {
+            return 6u;
+        }
+        break;
+    case CP_1252:
+        return 1u;
+        break;
+    }
+
+    return 0u;
+}