Make invalid value explicit.

python/fusion_engine_client/parsers/file_index.py

@@ -125,8 +125,15 @@ class FileIndex(object):
 
     _DTYPE = np.dtype([('time', '<f8'), ('type', '<u2'), ('offset', '<u8'), ('message_index', '<u8')])
 
-    def __init__(self, index_path: str = None, data_path: str = None, delete_on_error=True,
-                 data: Union[np.ndarray, list] = None, t0: Timestamp = None, enum_class = MessageType):
+    def __init__(self,
+                 index_path: str = None,
+                 data_path: str = None,
+                 delete_on_error=True,
+                 data: Union[np.ndarray,
+                             list] = None,
+                 t0: Timestamp = None,
+                 enum_class=MessageType,
+                 enum_class_invalid=MessageType.INVALID):
         """!
         @brief Construct a new @ref FileIndex instance.
 
@@ -139,8 +146,10 @@ def __init__(self, index_path: str = None, data_path: str = None, delete_on_erro
                `.p1log` file. For internal use.
         @param t0 The P1 time corresponding with the start of the `.p1log` file, if known. For internal use.
         @param enum_class The @ref IntEnum class used to identify the messages.
+        @param enum_class_invalid The value of enum_class to use for invalid entries.
         """
         self.enum_class = enum_class
+        self.enum_class_invalid = enum_class_invalid
         if data is None:
             self._data = None
         else:
@@ -195,7 +204,7 @@ def load(self, index_path, data_path=None, delete_on_error=True):
             if not os.path.exists(data_path):
                 # If the user didn't explicitly set data_path and the default file doesn't exist, it is not considered
                 # an error.
-                if self._data['type'][-1] == self.enum_class.INVALID:
+                if self._data['type'][-1] == self.enum_class_invalid:
                     self._data = self._data[:-1]
                 return
         elif not os.path.exists(data_path):
@@ -220,7 +229,7 @@ def load(self, index_path, data_path=None, delete_on_error=True):
             # Get the last entry in the index. If its message type is INVALID, it's a special marker at the end of the
             # index file indicating the size of the binary data file when the index was created. If it exists, we can
             # use it to check if the data file size has changed.
-            if self.type[-1] == self.enum_class.INVALID:
+            if self.type[-1] == self.enum_class_invalid:
                 expected_data_file_size = self.offset[-1]
                 self._data = self._data[:-1]
 
@@ -271,9 +280,9 @@ def save(self, index_path: str, data_path: str):
         if len(self._data) > 0:
             # Append an EOF marker at the end of the data if data_path is specified.
             data = self._data
-            if data['type'][-1] != self.enum_class.INVALID and data_path is not None:
+            if data['type'][-1] != self.enum_class_invalid and data_path is not None:
                 file_size_bytes = os.stat(data_path).st_size
-                data = np.append(data, np.array((np.nan, self.enum_class.INVALID, file_size_bytes, -1),
+                data = np.append(data, np.array((np.nan, self.enum_class_invalid, file_size_bytes, -1),
                                                 dtype=FileIndex._DTYPE))
 
             raw_data = FileIndex._to_raw(data)
@@ -489,6 +498,7 @@ class FileIndexBuilder(object):
 
     This class can be used to construct a @ref FileIndex and a corresponding `.p1i` file when reading a `.p1log` file.
     """
+
     def __init__(self):
         self.raw_data = []