start converting from System.Directory to System.OsPath

This is the start of a long road, got the first few files to compile
after this large change.

Sponsored-by: mycroft

Utility/OsPath.hs

@@ -7,51 +7,68 @@
 
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE PackageImports #-}
+{-# LANGUAGE TypeSynonymInstances, FlexibleInstances #-}
 {-# OPTIONS_GHC -fno-warn-tabs #-}
 
 module Utility.OsPath (
 	OsPath,
 	OsString,
+	literalOsPath,
 	toOsPath,
 	fromOsPath,
 ) where
 
 import Utility.FileSystemEncoding
-
 #ifdef WITH_OSPATH
 import System.OsPath
 import "os-string" System.OsString.Internal.Types
 import qualified Data.ByteString.Short as S
+#else
+import qualified Data.ByteString as S
+#endif
+
+class OsPathConv t where
+	toOsPath :: t -> OsPath
+	fromOsPath :: OsPath -> t
+
+instance OsPathConv FilePath where
+	toOsPath = toOsPath . toRawFilePath
+	fromOsPath = fromRawFilePath . fromOsPath
+
+{- Used for string constants. -}
+literalOsPath :: String -> OsPath
+literalOsPath = toOsPath
+
+#ifdef WITH_OSPATH
+instance OsPathConv RawFilePath where
+	toOsPath = bytesToOsPath
+	fromOsPath = bytesFromOsPath
 
 {- Unlike System.OsString.fromBytes, on Windows this does not ensure a
  - valid USC-2LE encoding. The input ByteString must be in a valid encoding
  - already or uses of the OsPath will fail. -}
-toOsPath :: RawFilePath -> OsPath
+bytesToOsPath :: RawFilePath -> OsPath
 #if defined(mingw32_HOST_OS)
-toOsPath = OsString . WindowsString . S.toShort
+bytesToOsPath = OsString . WindowsString . S.toShort
 #else
-toOsPath = OsString . PosixString . S.toShort
+bytesToOsPath = OsString . PosixString . S.toShort
 #endif
 
-fromOsPath :: OsPath -> RawFilePath
+bytesFromOsPath :: OsPath -> RawFilePath
 #if defined(mingw32_HOST_OS)
-fromOsPath = S.fromShort . getWindowsString . getOsString
+bytesFromOsPath = S.fromShort . getWindowsString . getOsString
 #else
-fromOsPath = S.fromShort . getPosixString . getOsString
+bytesFromOsPath = S.fromShort . getPosixString . getOsString
 #endif
 
 #else
-{- When not building with WITH_OSPATH, use FilePath. This allows
- - using functions from legacy FilePath libraries interchangeably with
- - newer OsPath libraries.
+{- When not building with WITH_OSPATH, use RawFilePath.
  -}
-type OsPath = FilePath
+type OsPath = RawFilePath
 
-type OsString = String
+type OsString = S.ByteString
 
-toOsPath :: RawFilePath -> OsPath
-toOsPath = fromRawFilePath
-
-fromOsPath :: OsPath -> RawFilePath
-fromOsPath = toRawFilePath
+instance OsPathConv RawFilePath where
+	toOsPath = id
+	fromOsPath = id
 #endif