Add path concatenation function

ozataman · Mar 18, 2013 · b2a464b · b2a464b
1 parent f44d79a
commit b2a464b
Showing 1 changed file with 13 additions and 0 deletions.
diff --git a/src/Snap/Extras/CoreUtils.hs b/src/Snap/Extras/CoreUtils.hs
@@ -20,6 +20,7 @@ module Snap.Extras.CoreUtils
     , undirify
     , maybeBadReq
     , fromMaybeM
+    , (-/-)
     ) where
 
 -------------------------------------------------------------------------------
@@ -169,3 +170,15 @@ maybeBadReq e f = fromMaybeM (badReq e) f
 fromMaybeM :: Monad m => m a -> m (Maybe a) -> m a
 fromMaybeM e f = maybe e return =<< f
 
+
+------------------------------------------------------------------------------
+-- | Concatenates two URL segments with a '/' between them.  To prevent double
+-- slashes, all trailing slashes are removed from the first path and all
+-- leading slashes are removed from the second path.
+(-/-) :: ByteString -> ByteString -> ByteString
+(-/-) a b = B.concat [revDrop a, "/", dropSlash b]
+  where
+    dropSlash = B.dropWhile (=='/')
+    revDrop = B.reverse . dropSlash . B.reverse
+
+