small optimisation

diff --git a/Utility/Tmp.hs b/Utility/Tmp.hs
index df6673eadd78c33f1bb6d41f22ce25875dcdb5c2..332b949048326d671658d22e5164bdceb9020ee0 100644 (file)
--- a/Utility/Tmp.hs
+++ b/Utility/Tmp.hs
@@ -126,17 +126,20 @@ relatedTemplate' f
        {- Some filesystems like FAT have issues with filenames
         - ending in ".", and others like VFAT don't allow a
         - filename to end with trailing whitespace, so avoid
-        - truncating a filename to end that way. -}
-       fixend p =
-               {- B.dropWhileEnd doesn't take wide characters
-                - into account, but is fast, so use it to check
-                - the common case. -}
-               let p' = B.dropWhileEnd disallowed p
-               in if p' == p 
-                       then p
-                       else toRawFilePath $ reverse $
+        - truncating a filename to end that way.
+        -
+        - Checking with unsnoc for the path to end with a disallowed
+        - character doesn't take wide characters into account,
+        - so will have false positives, but it is fast.
+        -}
+       fixend p = case B.unsnoc p of
+               Just (_, c) | disallowed c -> 
+                       -- Convert to String to take wide characters into
+                       -- account.
+                       toRawFilePath $ reverse $
                                dropWhile (disallowed . fromIntegral . ord) $
                                reverse $ fromRawFilePath p
+               _ -> p
        dot = fromIntegral (ord '.')
        disallowed c = c == dot || isSpace (chr (fromIntegral c))
 #else