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monnier |
416 |
(* os-path-fn.sml
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*
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* COPYRIGHT (c) 1995 AT&T Bell Laboratories.
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*
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* A functorized implementation of the OS.Path structure.
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*
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* NOTE: these operations are currently not very efficient, since they
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* explode the path into its volume and arcs. A better implementation
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* would work "in situ."
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*
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*)
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local
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structure String = StringImp
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in
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functor OS_PathFn (OSPathBase : sig
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exception Path
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datatype arc_kind = Null | Parent | Current | Arc of string
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val classify : string -> arc_kind
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val parentArc : string
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val currentArc : string
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val validVolume : (bool * Substring.substring) -> bool
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val splitVolPath : string -> (bool * Substring.substring * Substring.substring)
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(* Split a string into the volume part and arcs part and note whether it
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* is absolute.
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* Note: it is guaranteed that this is never called with "".
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*)
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val joinVolPath : (bool * string * string) -> string
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(* join a volume and path; raise Path on invalid volumes *)
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val arcSepChar : char
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(* the character used to separate arcs (e.g., #"/" on UNIX) *)
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end) : OS_PATH = struct
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structure P = OSPathBase
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structure SS = Substring
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exception Path = P.Path
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val arcSepStr = String.str P.arcSepChar
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val parentArc = P.parentArc
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val currentArc = P.currentArc
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(* concatArcs is like List.@, except that a trailing empty arc in the
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* first argument is dropped.
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*)
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fun concatArcs ([], al2) = al2
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| concatArcs ([""], al2) = al2
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| concatArcs (a::al1, al2) = a :: concatArcs(al1, al2)
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fun validVolume {isAbs, vol} = P.validVolume(isAbs, SS.all vol)
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fun fromString "" = {isAbs = false, vol = "", arcs = []}
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| fromString p = let
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val fields = SS.fields (fn c => (c = P.arcSepChar))
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val (isAbs, vol, rest) = P.splitVolPath p
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in
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{ isAbs = isAbs,
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vol = SS.string vol,
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arcs = List.map SS.string (fields rest)
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}
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end
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fun toString {isAbs=false, vol, arcs="" :: _} = raise Path
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| toString {isAbs, vol, arcs} = let
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fun f [] = [""]
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| f [a] = [a]
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| f (a :: al) = a :: arcSepStr :: (f al)
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in
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String.concat(P.joinVolPath(isAbs, vol, "") :: f arcs)
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end
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fun getVolume p = #vol(fromString p)
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fun getParent p = let
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fun getParent' [] = [parentArc]
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| getParent' [a] = (case (P.classify a)
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of P.Current => [parentArc]
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| P.Parent => [parentArc, parentArc]
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| P.Null => [parentArc]
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| _ => []
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(* end case *))
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| getParent' (a :: al) = a :: getParent' al
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in
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case (fromString p)
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of {isAbs=true, vol, arcs=[""]} => p
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| {isAbs=true, vol, arcs} =>
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toString{isAbs = true, vol = vol, arcs = getParent' arcs}
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| {isAbs=false, vol, arcs} => (case (getParent' arcs)
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of [] => toString{isAbs=false, vol=vol, arcs=[currentArc]}
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| al' => toString{isAbs=false, vol=vol, arcs=al'}
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(* end case *))
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(* end case *)
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end
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fun splitDirFile p = let
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val {isAbs, vol, arcs} = fromString p
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fun split [] = ([], "")
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| split [f] = ([], f)
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| split (a :: al) = let val (d, f) = split al
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in
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(a :: d, f)
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end
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fun split' p = let val (d, f) = split p
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in
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{dir=toString{isAbs=isAbs, vol=vol, arcs=d}, file=f}
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end
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in
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split' arcs
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end
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fun joinDirFile {dir="", file} = file
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| joinDirFile {dir, file} = let
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val {isAbs, vol, arcs} = fromString dir
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in
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toString {isAbs=isAbs, vol=vol, arcs = concatArcs(arcs, [file])}
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end
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fun dir p = #dir(splitDirFile p)
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fun file p = #file(splitDirFile p)
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fun splitBaseExt p = let
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val {dir, file} = splitDirFile p
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val (file', ext') = SS.splitr (fn c => c <> #".") (SS.all file)
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val fileLen = SS.size file'
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val (file, ext) =
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if (fileLen <= 1) orelse (SS.isEmpty ext')
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then (file, NONE)
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else (SS.string(SS.trimr 1 file'), SOME(SS.string ext'))
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in
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{base = joinDirFile{dir=dir, file=file}, ext = ext}
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end
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fun joinBaseExt {base, ext=NONE} = base
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| joinBaseExt {base, ext=SOME ""} = base
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| joinBaseExt {base, ext=SOME ext} = let
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val {dir, file} = splitDirFile base
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in
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joinDirFile{dir=dir, file=String.concat[file, ".", ext]}
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end
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fun base p = #base(splitBaseExt p)
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fun ext p = #ext(splitBaseExt p)
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fun mkCanonical "" = currentArc
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| mkCanonical p = let
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fun scanArcs ([], []) = [P.Current]
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| scanArcs (l, []) = List.rev l
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| scanArcs ([], [""]) = [P.Null]
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| scanArcs (l, a::al) = (case (P.classify a)
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of P.Null => scanArcs(l, al)
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| P.Current => scanArcs(l, al)
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| P.Parent => (case l
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of (P.Arc _ :: r) => scanArcs(r, al)
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| _ => scanArcs(P.Parent::l, al)
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(* end case *))
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| a' => scanArcs(a' :: l, al)
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(* end case *))
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fun scanPath relPath = scanArcs([], relPath)
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fun mkArc (P.Arc a) = a
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| mkArc (P.Parent) = parentArc
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| mkArc _ = raise Fail "mkCanonical: impossible"
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fun filterArcs (true, P.Parent::r) = filterArcs (true, r)
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| filterArcs (true, []) = [""]
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| filterArcs (true, [P.Null]) = [""]
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| filterArcs (true, [P.Current]) = [""]
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| filterArcs (false, [P.Current]) = [currentArc]
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| filterArcs (_, al) = List.map mkArc al
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val {isAbs, vol, arcs} = fromString p
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in
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toString{
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isAbs=isAbs, vol=vol, arcs=filterArcs(isAbs, scanPath arcs)
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}
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end
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fun isCanonical p = (p = mkCanonical p)
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fun isAbsolute p = #isAbs(fromString p)
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fun isRelative p = Bool.not(#isAbs(fromString p))
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fun mkAbsolute {path, relativeTo} = (
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case (fromString path, fromString relativeTo)
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of (_, {isAbs=false, ...}) => raise Path
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| ({isAbs=true, ...}, _) => path
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| ({vol=v1, arcs=al1, ...}, {vol=v2, arcs=al2, ...}) => let
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fun mkCanon vol = mkCanonical(toString{
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isAbs=true, vol=vol, arcs=List.@(al2, al1)
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})
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in
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if (v1 = v2) then mkCanon v1
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else if (v1 = "") then mkCanon v2
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else if (v2 = "") then mkCanon v1
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else raise Path
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end
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(* end case *))
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fun mkRelative {path, relativeTo} =
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if (isAbsolute relativeTo)
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then if (isRelative path)
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then path
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else let
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val {vol=v1, arcs=al1, ...} = fromString path
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val {vol=v2, arcs=al2, ...} = fromString(mkCanonical relativeTo)
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fun strip (l, []) = mkArcs l
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| strip ([], l) = dotDot([], l)
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| strip (l1 as (x1::r1), l2 as (x2::r2)) = if (x1 = x2)
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then strip (r1, r2)
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else dotDot (l1, l2)
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and dotDot (al, []) = al
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| dotDot (al, _::r) = dotDot(parentArc :: al, r)
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and mkArcs [] = [currentArc]
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| mkArcs al = al
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in
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if (v1 <> v2)
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then raise Path
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else (case (al1, al2)
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of ([""], [""]) => currentArc
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| ([""], _) =>
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toString{isAbs=false, vol="", arcs=dotDot([], al2)}
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| _ =>
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toString{isAbs=false, vol="", arcs=strip(al1, al2)}
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(* end case *))
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end
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else raise Path
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fun isRoot path = (case (fromString path)
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of {isAbs=true, arcs=[""], ...} => true
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| _ => false
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(* end case *))
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fun concat (p1, p2) = (case (fromString p1, fromString p2)
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of (_, {isAbs=true, ...}) => raise Path
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| ({isAbs, vol=v1, arcs=al1}, {vol=v2, arcs=al2, ...}) =>
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if ((v2 = "") orelse (v1 = v2))
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then toString{isAbs=isAbs, vol=v1, arcs=concatArcs(al1, al2)}
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else raise Path
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(* end case *))
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blume |
1240 |
local
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fun fromUnixPath' up = let
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fun tr "." = P.currentArc
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| tr ".." = P.parentArc
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| tr arc = arc
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in
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case String.fields (fn c => c = #"/") up of
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"" :: arcs => { isAbs = true, vol = "", arcs = map tr arcs }
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| arcs => { isAbs = false, vol = "", arcs = map tr arcs }
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end
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fun toUnixPath' { isAbs, vol = "", arcs } =
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let fun tr arc =
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if arc = P.currentArc then "."
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else if arc = P.parentArc then ".."
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else if Char.contains arc #"/" then raise Path
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else arc
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in
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String.concatWith "/" (if isAbs then "" :: arcs else arcs)
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end
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| toUnixPath' _ = raise Path
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in
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val fromUnixPath = toString o fromUnixPath'
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val toUnixPath = toUnixPath' o fromString
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end
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monnier |
416 |
end
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end
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Parent Directory
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