Rework the OS.Path implementation to allow for multiple arc separator

characters.  For Windows, we now recognize #"/" as a valid arc sepatator,
which addresses issue #280 (Support forward-slash ("/") as a separator
in the Windows implementation of OS.Path).

base/system/Basis/Implementation/OS/os-path-fn.sml

@@ -27,12 +27,17 @@ functor OS_PathFn (OSPathBase : sig
     val splitVolPath : string -> (bool * Substring.substring * Substring.substring)
 	(* Split a string into the volume part and arcs part and note whether it
 	 * is absolute.
-	 * Note: it is guaranteed that this is never called with "".
+	 * Note: it is guaranteed that this function is never called with "".
 	 *)
     val joinVolPath : (bool * string * string) -> string
 	(* join a volume and path; raise Path on invalid volumes *)
-    val arcSepChar : char
-	(* the character used to separate arcs (e.g., #"/" on UNIX) *)
+    val arcSep : string
+	(* the arc separator (e.g., "/" on UNIX) *)
+    val isArchSepChar : char -> bool
+        (* a predicate to test if a character is an arc separator; by using a predicate
+         * for this purpose, we allow for multiple separator characters (e.g., both
+         * forward and backward slashs are valid on Windows.
+         *)
     val sameVol : string * string -> bool
 
   end) : OS_PATH = struct
@@ -46,8 +51,6 @@ functor OS_PathFn (OSPathBase : sig
   (* check an arc to see if it is valid and raise InvalidArc if not *)
     fun checkArc arc = if P.validArc arc then arc else raise InvalidArc
 
-    val arcSepStr = String.str P.arcSepChar
-
     val parentArc = P.parentArc
     val currentArc = P.currentArc
 
@@ -62,7 +65,7 @@ functor OS_PathFn (OSPathBase : sig
 
     fun fromString "" = {isAbs = false, vol = "", arcs = []}
       | fromString p = let
-	  val fields = SS.fields (fn c => (c = P.arcSepChar))
+	  val fields = SS.fields P.isArchSepChar
 	  val (isAbs, vol, rest) = P.splitVolPath p
 	  in
 	    { isAbs = isAbs,
@@ -75,7 +78,7 @@ functor OS_PathFn (OSPathBase : sig
       | toString {isAbs, vol, arcs} = let
 	  fun f [] = [""]
 	    | f [a] = [checkArc a]
-	    | f (a :: al) = (checkArc a) :: arcSepStr :: (f al)
+	    | f (a :: al) = (checkArc a) :: P.arcSep :: (f al)
 	  in
 	    if validVolume{isAbs=isAbs, vol=vol}
 	      then String.concat(P.joinVolPath(isAbs, vol, "") :: f arcs)
@@ -127,7 +130,7 @@ functor OS_PathFn (OSPathBase : sig
 	  end
     fun dir p = #dir(splitDirFile p)
     fun file p = #file(splitDirFile p)
-    
+
     fun splitBaseExt p = let
 	  val {dir, file} = splitDirFile p
 	  val (file', ext') = SS.splitr (fn c => c <> #".") (SS.full file)
@@ -161,7 +164,7 @@ functor OS_PathFn (OSPathBase : sig
 		      of (P.Arc _ :: r) => scanArcs(r, al)
 		       | _ => scanArcs(P.Parent::l, al)
 		     (* end case *))
-		  | a' => scanArcs(a' :: l, al) 
+		  | a' => scanArcs(a' :: l, al)
 		(* end case *))
 	  fun scanPath relPath = scanArcs([], relPath)
 	  fun mkArc (P.Arc a) = a

base/system/Basis/Implementation/Unix/os-path.sml

@@ -47,7 +47,9 @@ structure OS_Path = OS_PathFn (
       | joinVolPath (false, "", s) = s
       | joinVolPath _ = raise Path (* invalid volume *)
 
-    val arcSepChar = #"/"
+    val arcSep = "/"
+
+    fun isArchSepChar #"/" = true | isArchSepChar _ = false
 
     fun sameVol (v1, v2: string) = v1 = v2
 

base/system/Basis/Implementation/Win32/os-filesys.sml

@@ -39,11 +39,11 @@ structure OS_FileSys : OS_FILE_SYS =
     fun openDir s = let
 	  fun rse' s = rse "openDir" s
 	  val _ = not (isDir s) andalso rse' "invalid directory"
-	  fun mkValidDir s = if (S.sub(s,S.size s - 1) <> W32G.arcSepChar)
-		then s^(S.str W32G.arcSepChar)
-		else s
+	  fun mkValidDir s = if WG.isArchSepChar(S.sub(s, S.size s - 1))
+		then s
+                else s ^ W32G.arcSep
 	  val p = (mkValidDir s)^"*"
-	  val (h,firstName) = W32FS.findFirstFile p
+	  val (h, firstName) = W32FS.findFirstFile p
 	  in
 	    if not (Handle.isValid h)
 	      then rse' "cannot find first file"

base/system/Basis/Implementation/Win32/os-path.sml

@@ -35,29 +35,28 @@ structure OS_Path = OS_PathFn (
 
       val volSepChar = #":"
 
-      val arcSepChar = W32G.arcSepChar
-      val arcSep = S.str arcSepChar
+      val arcSep = W32G.arcSep
+      val isArchSepChar = W32G.isArchSepChar
 
-      fun volPresent vol = 
+      fun volPresent vol =
           (String.size vol >= 2) andalso
 	  (C.isAlpha(S.sub(vol,0)) andalso (S.sub(vol,1) = volSepChar))
 
-      fun validVolume (_,vol) = 
+      fun validVolume (_,vol) =
 	  (SS.isEmpty vol) orelse volPresent(SS.string vol)
 
       val emptySS    = SS.full ""
 
-      fun splitPath (vol, s) = 
-	  if (SS.size s >= 1) andalso (SS.sub(s, 0) = arcSepChar) then
-	       (true, vol, SS.triml 1 s)
-	  else (false, vol, s)
+      fun splitPath (vol, s) = if (SS.size s > 0) andalso W32G.isArcSepChar(SS.sub(s, 0))
+            then (true, vol, SS.triml 1 s)
+	    else (false, vol, s)
 
       fun splitVolPath "" = (false, emptySS, emptySS)
-	| splitVolPath s = 
-	  if volPresent s then splitPath (SS.splitAt (SS.full s, 2))
-	  else splitPath (emptySS, SS.full s)
+	| splitVolPath s = if volPresent s
+            then splitPath (SS.splitAt (SS.full s, 2))
+	    else splitPath (emptySS, SS.full s)
 
-      fun joinVolPath arg = 
+      fun joinVolPath arg =
 	  let fun checkVol vol = if (volPresent vol) then vol else raise Path
 	      fun aux (true,"","") = arcSep
 		| aux (true,"",s) = arcSep^s

base/system/Basis/Implementation/Win32/win32-general.sig

@@ -15,7 +15,8 @@ signature WIN32_GENERAL =
 
     val isValidHandle : hndl -> bool
 
-    val arcSepChar : char
+    val arcSep : string
+    val isArchSepChar : char -> bool
 
     val cfun : string -> string -> 'a -> 'b
     val getConst : string -> string -> word

base/system/Basis/Implementation/Win32/win32-general.sml

@@ -16,7 +16,10 @@ structure Win32_General : WIN32_GENERAL =
 
     val isValidHandle = Handle.isValid
 
-    val arcSepChar = #"\\"
+    val arcSep = "\\"
+    fun isArchSepChar #"/" = true
+      | isArchSepChar #"\\" = true
+      | isArchSepChar _ = false
 
     val cfun = CInterface.c_function