Move path stuff into a Utils module, and show basenames in metadata

fco2/Makefile

@@ -18,7 +18,8 @@ sources = \
 	SimplifyProcs.hs \
 	TLP.hs \
 	Types.hs \
-	Unnest.hs
+	Unnest.hs \
+	Utils.hs
 
 $(targets): $(sources)
 	ghc -fglasgow-exts -o fco --make Main

fco2/Metadata.hs

@@ -3,6 +3,8 @@ module Metadata where
 
 import Data.Generics
 
+import Utils
+
 data Meta = Meta {
     metaFile :: Maybe String,
     metaLine :: Int,
@@ -20,5 +22,5 @@ emptyMeta = Meta {
 instance Show Meta where
   show m =
       case metaFile m of
-        Just s -> s ++ ":" ++ show (metaLine m) ++ ":" ++ show (metaColumn m)
+        Just s -> basenamePath s ++ ":" ++ show (metaLine m) ++ ":" ++ show (metaColumn m)
         Nothing -> "no source position"

fco2/Parse.hs

@@ -19,6 +19,7 @@ import Metadata
 import ParseState
 import Pass
 import Types
+import Utils
 
 --{{{ setup stuff for Parsec
 type OccParser = GenParser Char ParseState
@@ -1416,16 +1417,6 @@ mangleModName mod
         then mod
         else mod ++ ".occ"
 
--- | Join a relative path to an existing path (i.e. if you're given foo/bar and
--- baz, return foo/baz).
-joinPath :: String -> String -> String
-joinPath base new
-    = case matchRegex pathRE base of
-        Just [dir] -> dir ++ new
-        Nothing -> new
-  where
-    pathRE = mkRegex "^(.*/)[^/]*$"
-
 type LoaderM a = StateT ParseState IO a
 
 -- | Load all the source files necessary for a program.

fco2/Utils.hs

@@ -0,0 +1,30 @@
+-- | Utility functions that aren't inherently related to FCO -- i.e. things
+-- that could be put into the standard library.
+module Utils where
+
+import Text.Regex
+
+-- | Split the directory and file components of a path.
+splitPath :: String -> (String, String)
+splitPath path
+    = case matchRegex dirRE path of
+        Just [dir, base] -> (if dir == "" then "." else dir, base)
+  where
+    dirRE = mkRegex "^(.*/)?([^/]*)$"
+
+-- | Return the directory containing a path.
+dirnamePath :: String -> String
+dirnamePath = fst . splitPath
+
+-- | Return a path without any leading directory components.
+basenamePath :: String -> String
+basenamePath = snd . splitPath
+
+-- | Join a relative path to an existing path (i.e. if you're given foo/bar and
+-- baz, return foo/baz).
+joinPath :: String -> String -> String
+joinPath base new
+    = case dirnamePath base of
+        "." -> new
+        dir -> dir ++ new
+