Add eventFilePath and eventSourceIsSelf

src/System/INotify.hsc

@@ -26,6 +26,8 @@ module System.INotify
     , withINotify
     , addWatch
     , removeWatch
+    , eventFilePath
+    , eventSourceIsSelf
     , INotify
     , WatchDescriptor
     , Event(..)
@@ -139,6 +141,40 @@ data Event =
     | Unknown FDEvent
     deriving (Eq, Show)
 
+-- | The file path that generated an event.
+--
+-- The value is @Nothing@ when no file path generated the event
+-- (e.g. @QOverflow@) or if the event source is self (a path for which a
+-- watch was explicitly added).
+eventFilePath :: Event -> Maybe RawFilePath
+eventFilePath event = case event of
+    Accessed _ mfp -> mfp
+    Modified _ mfp -> mfp
+    Attributes _  mfp -> mfp
+    Closed _ mfp _ -> mfp
+    Opened _ mfp -> mfp
+    MovedOut _ fp _ -> Just fp
+    MovedIn _ fp _ -> Just fp
+    Created _ fp -> Just fp
+    Deleted _ fp -> Just fp
+    _ -> Nothing
+
+-- | Whether the source of the event is a root @WatchDescriptor@.
+--
+-- For example if there is watch added for @dir/@, watching for @DeleteSelf@
+-- and @Create@ event varieties, then:
+--
+--   * for the event generated by creating the file @dir/some_file@,
+--     @eventSourceIsSelf event == False@.
+--   * for the event generated by deleting @dir/@,
+--     @eventSourceIsSelf event == True@
+eventSourceIsSelf :: Event -> Bool
+eventSourceIsSelf event = case event of
+    MovedSelf _ -> True
+    DeletedSelf -> True
+    Unmounted -> True
+    _ -> False
+
 data EventVariety
     = Access
     | Modify