Adding GF.Infra.Location and GF.Text.Pretty (forgot to 'darcs add' them before)

src/compiler/GF/Infra/Location.hs

@@ -0,0 +1,31 @@
+module GF.Infra.Location where
+import GF.Text.Pretty
+
+class HasSourcePath a where sourcePath :: a -> FilePath
+
+data Location 
+  = NoLoc
+  | Local Int Int
+  | External FilePath Location
+  deriving (Show,Eq,Ord)
+
+-- | Attaching location information
+data L a = L Location a deriving Show
+
+instance Functor L where fmap f (L loc x) = L loc (f x)
+
+unLoc :: L a -> a
+unLoc (L _ x) = x
+
+noLoc = L NoLoc
+
+ppLocation :: FilePath -> Location -> Doc
+ppLocation fpath NoLoc          = pp fpath
+ppLocation fpath (External p l) = ppLocation p l
+ppLocation fpath (Local b e)
+  | b == e    = fpath <> ":" <> b
+  | otherwise = fpath <> ":" <> b <> "-" <> e
+
+
+ppL (L loc x) msg = hang (ppLocation "" loc<>":") 4
+                         ("In"<+>x<>":"<+>msg)