filepath-1.4.1.1: System/FilePath/Internal.hs
#if __GLASGOW_HASKELL__ >= 704
{-# LANGUAGE Safe #-}
#endif
{-# LANGUAGE PatternGuards #-}
-- This template expects CPP definitions for:
-- MODULE_NAME = Posix | Windows
-- IS_WINDOWS = False | True
-- |
-- Module : System.FilePath.MODULE_NAME
-- Copyright : (c) Neil Mitchell 2005-2014
-- License : BSD3
--
-- Maintainer : ndmitchell@gmail.com
-- Stability : stable
-- Portability : portable
--
-- A library for 'FilePath' manipulations, using MODULE_NAME style paths on
-- all platforms. Importing "System.FilePath" is usually better.
--
-- Given the example 'FilePath': @\/directory\/file.ext@
--
-- We can use the following functions to extract pieces.
--
-- * 'takeFileName' gives @\"file.ext\"@
--
-- * 'takeDirectory' gives @\"\/directory\"@
--
-- * 'takeExtension' gives @\".ext\"@
--
-- * 'dropExtension' gives @\"\/directory\/file\"@
--
-- * 'takeBaseName' gives @\"file\"@
--
-- And we could have built an equivalent path with the following expressions:
--
-- * @\"\/directory\" '</>' \"file.ext\"@.
--
-- * @\"\/directory\/file" '<.>' \"ext\"@.
--
-- * @\"\/directory\/file.txt" '-<.>' \"ext\"@.
--
-- Each function in this module is documented with several examples,
-- which are also used as tests.
--
-- Here are a few examples of using the @filepath@ functions together:
--
-- /Example 1:/ Find the possible locations of a Haskell module @Test@ imported from module @Main@:
--
-- @['replaceFileName' path_to_main \"Test\" '<.>' ext | ext <- [\"hs\",\"lhs\"] ]@
--
-- /Example 2:/ Download a file from @url@ and save it to disk:
--
-- @do let file = 'makeValid' url
-- System.IO.createDirectoryIfMissing True ('takeDirectory' file)@
--
-- /Example 3:/ Compile a Haskell file, putting the @.hi@ file under @interface@:
--
-- @'takeDirectory' file '</>' \"interface\" '</>' ('takeFileName' file '-<.>' \"hi\")@
--
-- References:
-- [1] <http://msdn.microsoft.com/en-us/library/windows/desktop/aa365247.aspx Naming Files, Paths and Namespaces> (Microsoft MSDN)
module System.FilePath.MODULE_NAME
(
-- * Separator predicates
FilePath,
pathSeparator, pathSeparators, isPathSeparator,
searchPathSeparator, isSearchPathSeparator,
extSeparator, isExtSeparator,
-- * @$PATH@ methods
splitSearchPath, getSearchPath,
-- * Extension functions
splitExtension,
takeExtension, replaceExtension, (-<.>), dropExtension, addExtension, hasExtension, (<.>),
splitExtensions, dropExtensions, takeExtensions, replaceExtensions,
stripExtension,
-- * Filename\/directory functions
splitFileName,
takeFileName, replaceFileName, dropFileName,
takeBaseName, replaceBaseName,
takeDirectory, replaceDirectory,
combine, (</>),
splitPath, joinPath, splitDirectories,
-- * Drive functions
splitDrive, joinDrive,
takeDrive, hasDrive, dropDrive, isDrive,
-- * Trailing slash functions
hasTrailingPathSeparator,
addTrailingPathSeparator,
dropTrailingPathSeparator,
-- * File name manipulations
normalise, equalFilePath,
makeRelative,
isRelative, isAbsolute,
isValid, makeValid
)
where
import Data.Char(toLower, toUpper, isAsciiLower, isAsciiUpper)
import Data.Maybe(isJust)
import Data.List(stripPrefix)
import System.Environment(getEnv)
infixr 7 <.>, -<.>
infixr 5 </>
---------------------------------------------------------------------
-- Platform Abstraction Methods (private)
-- | Is the operating system Unix or Linux like
isPosix :: Bool
isPosix = not isWindows
-- | Is the operating system Windows like
isWindows :: Bool
isWindows = IS_WINDOWS
---------------------------------------------------------------------
-- The basic functions
-- | The character that separates directories. In the case where more than
-- one character is possible, 'pathSeparator' is the \'ideal\' one.
--
-- > Windows: pathSeparator == '\\'
-- > Posix: pathSeparator == '/'
-- > isPathSeparator pathSeparator
pathSeparator :: Char
pathSeparator = if isWindows then '\\' else '/'
-- | The list of all possible separators.
--
-- > Windows: pathSeparators == ['\\', '/']
-- > Posix: pathSeparators == ['/']
-- > pathSeparator `elem` pathSeparators
pathSeparators :: [Char]
pathSeparators = if isWindows then "\\/" else "/"
-- | Rather than using @(== 'pathSeparator')@, use this. Test if something
-- is a path separator.
--
-- > isPathSeparator a == (a `elem` pathSeparators)
isPathSeparator :: Char -> Bool
isPathSeparator '/' = True
isPathSeparator '\\' = isWindows
isPathSeparator _ = False
-- | The character that is used to separate the entries in the $PATH environment variable.
--
-- > Windows: searchPathSeparator == ';'
-- > Posix: searchPathSeparator == ':'
searchPathSeparator :: Char
searchPathSeparator = if isWindows then ';' else ':'
-- | Is the character a file separator?
--
-- > isSearchPathSeparator a == (a == searchPathSeparator)
isSearchPathSeparator :: Char -> Bool
isSearchPathSeparator = (== searchPathSeparator)
-- | File extension character
--
-- > extSeparator == '.'
extSeparator :: Char
extSeparator = '.'
-- | Is the character an extension character?
--
-- > isExtSeparator a == (a == extSeparator)
isExtSeparator :: Char -> Bool
isExtSeparator = (== extSeparator)
---------------------------------------------------------------------
-- Path methods (environment $PATH)
-- | Take a string, split it on the 'searchPathSeparator' character.
-- Blank items are ignored on Windows, and converted to @.@ on Posix.
-- On Windows path elements are stripped of quotes.
--
-- Follows the recommendations in
-- <http://www.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html>
--
-- > Posix: splitSearchPath "File1:File2:File3" == ["File1","File2","File3"]
-- > Posix: splitSearchPath "File1::File2:File3" == ["File1",".","File2","File3"]
-- > Windows: splitSearchPath "File1;File2;File3" == ["File1","File2","File3"]
-- > Windows: splitSearchPath "File1;;File2;File3" == ["File1","File2","File3"]
-- > Windows: splitSearchPath "File1;\"File2\";File3" == ["File1","File2","File3"]
splitSearchPath :: String -> [FilePath]
splitSearchPath = f
where
f xs = case break isSearchPathSeparator xs of
(pre, [] ) -> g pre
(pre, _:post) -> g pre ++ f post
g "" = ["." | isPosix]
g ('\"':x@(_:_)) | isWindows && last x == '\"' = [init x]
g x = [x]
-- | Get a list of 'FilePath's in the $PATH variable.
getSearchPath :: IO [FilePath]
getSearchPath = fmap splitSearchPath (getEnv "PATH")
---------------------------------------------------------------------
-- Extension methods
-- | Split on the extension. 'addExtension' is the inverse.
--
-- > splitExtension "/directory/path.ext" == ("/directory/path",".ext")
-- > uncurry (++) (splitExtension x) == x
-- > Valid x => uncurry addExtension (splitExtension x) == x
-- > splitExtension "file.txt" == ("file",".txt")
-- > splitExtension "file" == ("file","")
-- > splitExtension "file/file.txt" == ("file/file",".txt")
-- > splitExtension "file.txt/boris" == ("file.txt/boris","")
-- > splitExtension "file.txt/boris.ext" == ("file.txt/boris",".ext")
-- > splitExtension "file/path.txt.bob.fred" == ("file/path.txt.bob",".fred")
-- > splitExtension "file/path.txt/" == ("file/path.txt/","")
splitExtension :: FilePath -> (String, String)
splitExtension x = case nameDot of
"" -> (x,"")
_ -> (dir ++ init nameDot, extSeparator : ext)
where
(dir,file) = splitFileName_ x
(nameDot,ext) = breakEnd isExtSeparator file
-- | Get the extension of a file, returns @\"\"@ for no extension, @.ext@ otherwise.
--
-- > takeExtension "/directory/path.ext" == ".ext"
-- > takeExtension x == snd (splitExtension x)
-- > Valid x => takeExtension (addExtension x "ext") == ".ext"
-- > Valid x => takeExtension (replaceExtension x "ext") == ".ext"
takeExtension :: FilePath -> String
takeExtension = snd . splitExtension
-- | Remove the current extension and add another, equivalent to 'replaceExtension'.
--
-- > "/directory/path.txt" -<.> "ext" == "/directory/path.ext"
-- > "/directory/path.txt" -<.> ".ext" == "/directory/path.ext"
-- > "foo.o" -<.> "c" == "foo.c"
(-<.>) :: FilePath -> String -> FilePath
(-<.>) = replaceExtension
-- | Set the extension of a file, overwriting one if already present, equivalent to '-<.>'.
--
-- > replaceExtension "/directory/path.txt" "ext" == "/directory/path.ext"
-- > replaceExtension "/directory/path.txt" ".ext" == "/directory/path.ext"
-- > replaceExtension "file.txt" ".bob" == "file.bob"
-- > replaceExtension "file.txt" "bob" == "file.bob"
-- > replaceExtension "file" ".bob" == "file.bob"
-- > replaceExtension "file.txt" "" == "file"
-- > replaceExtension "file.fred.bob" "txt" == "file.fred.txt"
-- > replaceExtension x y == addExtension (dropExtension x) y
replaceExtension :: FilePath -> String -> FilePath
replaceExtension x y = dropExtension x <.> y
-- | Add an extension, even if there is already one there, equivalent to 'addExtension'.
--
-- > "/directory/path" <.> "ext" == "/directory/path.ext"
-- > "/directory/path" <.> ".ext" == "/directory/path.ext"
(<.>) :: FilePath -> String -> FilePath
(<.>) = addExtension
-- | Remove last extension, and the \".\" preceding it.
--
-- > dropExtension "/directory/path.ext" == "/directory/path"
-- > dropExtension x == fst (splitExtension x)
dropExtension :: FilePath -> FilePath
dropExtension = fst . splitExtension
-- | Add an extension, even if there is already one there, equivalent to '<.>'.
--
-- > addExtension "/directory/path" "ext" == "/directory/path.ext"
-- > addExtension "file.txt" "bib" == "file.txt.bib"
-- > addExtension "file." ".bib" == "file..bib"
-- > addExtension "file" ".bib" == "file.bib"
-- > addExtension "/" "x" == "/.x"
-- > addExtension x "" == x
-- > Valid x => takeFileName (addExtension (addTrailingPathSeparator x) "ext") == ".ext"
-- > Windows: addExtension "\\\\share" ".txt" == "\\\\share\\.txt"
addExtension :: FilePath -> String -> FilePath
addExtension file "" = file
addExtension file xs@(x:_) = joinDrive a res
where
res = if isExtSeparator x then b ++ xs
else b ++ [extSeparator] ++ xs
(a,b) = splitDrive file
-- | Does the given filename have an extension?
--
-- > hasExtension "/directory/path.ext" == True
-- > hasExtension "/directory/path" == False
-- > null (takeExtension x) == not (hasExtension x)
hasExtension :: FilePath -> Bool
hasExtension = any isExtSeparator . takeFileName
-- | Drop the given extension from a FilePath, and the @\".\"@ preceding it.
-- Returns 'Nothing' if the FilePath does not have the given extension, or
-- 'Just' and the part before the extension if it does.
--
-- This function can be more predictable than 'dropExtensions', especially if the filename
-- might itself contain @.@ characters.
--
-- > stripExtension "hs.o" "foo.x.hs.o" == Just "foo.x"
-- > stripExtension "hi.o" "foo.x.hs.o" == Nothing
-- > dropExtension x == fromJust (stripExtension (takeExtension x) x)
-- > dropExtensions x == fromJust (stripExtension (takeExtensions x) x)
-- > stripExtension ".c.d" "a.b.c.d" == Just "a.b"
-- > stripExtension ".c.d" "a.b..c.d" == Just "a.b."
-- > stripExtension "baz" "foo.bar" == Nothing
-- > stripExtension "bar" "foobar" == Nothing
-- > stripExtension "" x == Just x
stripExtension :: String -> FilePath -> Maybe FilePath
stripExtension [] path = Just path
stripExtension ext@(x:_) path = stripSuffix dotExt path
where dotExt = if isExtSeparator x then ext else '.':ext
-- | Split on all extensions.
--
-- > splitExtensions "/directory/path.ext" == ("/directory/path",".ext")
-- > splitExtensions "file.tar.gz" == ("file",".tar.gz")
-- > uncurry (++) (splitExtensions x) == x
-- > Valid x => uncurry addExtension (splitExtensions x) == x
-- > splitExtensions "file.tar.gz" == ("file",".tar.gz")
splitExtensions :: FilePath -> (FilePath, String)
splitExtensions x = (a ++ c, d)
where
(a,b) = splitFileName_ x
(c,d) = break isExtSeparator b
-- | Drop all extensions.
--
-- > dropExtensions "/directory/path.ext" == "/directory/path"
-- > dropExtensions "file.tar.gz" == "file"
-- > not $ hasExtension $ dropExtensions x
-- > not $ any isExtSeparator $ takeFileName $ dropExtensions x
dropExtensions :: FilePath -> FilePath
dropExtensions = fst . splitExtensions
-- | Get all extensions.
--
-- > takeExtensions "/directory/path.ext" == ".ext"
-- > takeExtensions "file.tar.gz" == ".tar.gz"
takeExtensions :: FilePath -> String
takeExtensions = snd . splitExtensions
-- | Replace all extensions of a file with a new extension. Note
-- that 'replaceExtension' and 'addExtension' both work for adding
-- multiple extensions, so only required when you need to drop
-- all extensions first.
--
-- > replaceExtensions "file.fred.bob" "txt" == "file.txt"
-- > replaceExtensions "file.fred.bob" "tar.gz" == "file.tar.gz"
replaceExtensions :: FilePath -> String -> FilePath
replaceExtensions x y = dropExtensions x <.> y
---------------------------------------------------------------------
-- Drive methods
-- | Is the given character a valid drive letter?
-- only a-z and A-Z are letters, not isAlpha which is more unicodey
isLetter :: Char -> Bool
isLetter x = isAsciiLower x || isAsciiUpper x
-- | Split a path into a drive and a path.
-- On Posix, \/ is a Drive.
--
-- > uncurry (++) (splitDrive x) == x
-- > Windows: splitDrive "file" == ("","file")
-- > Windows: splitDrive "c:/file" == ("c:/","file")
-- > Windows: splitDrive "c:\\file" == ("c:\\","file")
-- > Windows: splitDrive "\\\\shared\\test" == ("\\\\shared\\","test")
-- > Windows: splitDrive "\\\\shared" == ("\\\\shared","")
-- > Windows: splitDrive "\\\\?\\UNC\\shared\\file" == ("\\\\?\\UNC\\shared\\","file")
-- > Windows: splitDrive "\\\\?\\UNCshared\\file" == ("\\\\?\\","UNCshared\\file")
-- > Windows: splitDrive "\\\\?\\d:\\file" == ("\\\\?\\d:\\","file")
-- > Windows: splitDrive "/d" == ("","/d")
-- > Posix: splitDrive "/test" == ("/","test")
-- > Posix: splitDrive "//test" == ("//","test")
-- > Posix: splitDrive "test/file" == ("","test/file")
-- > Posix: splitDrive "file" == ("","file")
splitDrive :: FilePath -> (FilePath, FilePath)
splitDrive x | isPosix = span (== '/') x
splitDrive x | Just y <- readDriveLetter x = y
splitDrive x | Just y <- readDriveUNC x = y
splitDrive x | Just y <- readDriveShare x = y
splitDrive x = ("",x)
addSlash :: FilePath -> FilePath -> (FilePath, FilePath)
addSlash a xs = (a++c,d)
where (c,d) = span isPathSeparator xs
-- See [1].
-- "\\?\D:\<path>" or "\\?\UNC\<server>\<share>"
readDriveUNC :: FilePath -> Maybe (FilePath, FilePath)
readDriveUNC (s1:s2:'?':s3:xs) | all isPathSeparator [s1,s2,s3] =
case map toUpper xs of
('U':'N':'C':s4:_) | isPathSeparator s4 ->
let (a,b) = readDriveShareName (drop 4 xs)
in Just (s1:s2:'?':s3:take 4 xs ++ a, b)
_ -> case readDriveLetter xs of
-- Extended-length path.
Just (a,b) -> Just (s1:s2:'?':s3:a,b)
Nothing -> Nothing
readDriveUNC _ = Nothing
{- c:\ -}
readDriveLetter :: String -> Maybe (FilePath, FilePath)
readDriveLetter (x:':':y:xs) | isLetter x && isPathSeparator y = Just $ addSlash [x,':'] (y:xs)
readDriveLetter (x:':':xs) | isLetter x = Just ([x,':'], xs)
readDriveLetter _ = Nothing
{- \\sharename\ -}
readDriveShare :: String -> Maybe (FilePath, FilePath)
readDriveShare (s1:s2:xs) | isPathSeparator s1 && isPathSeparator s2 =
Just (s1:s2:a,b)
where (a,b) = readDriveShareName xs
readDriveShare _ = Nothing
{- assume you have already seen \\ -}
{- share\bob -> "share\", "bob" -}
readDriveShareName :: String -> (FilePath, FilePath)
readDriveShareName name = addSlash a b
where (a,b) = break isPathSeparator name
-- | Join a drive and the rest of the path.
--
-- > Valid x => uncurry joinDrive (splitDrive x) == x
-- > Windows: joinDrive "C:" "foo" == "C:foo"
-- > Windows: joinDrive "C:\\" "bar" == "C:\\bar"
-- > Windows: joinDrive "\\\\share" "foo" == "\\\\share\\foo"
-- > Windows: joinDrive "/:" "foo" == "/:\\foo"
joinDrive :: FilePath -> FilePath -> FilePath
joinDrive = combineAlways
-- | Get the drive from a filepath.
--
-- > takeDrive x == fst (splitDrive x)
takeDrive :: FilePath -> FilePath
takeDrive = fst . splitDrive
-- | Delete the drive, if it exists.
--
-- > dropDrive x == snd (splitDrive x)
dropDrive :: FilePath -> FilePath
dropDrive = snd . splitDrive
-- | Does a path have a drive.
--
-- > not (hasDrive x) == null (takeDrive x)
-- > Posix: hasDrive "/foo" == True
-- > Windows: hasDrive "C:\\foo" == True
-- > Windows: hasDrive "C:foo" == True
-- > hasDrive "foo" == False
-- > hasDrive "" == False
hasDrive :: FilePath -> Bool
hasDrive = not . null . takeDrive
-- | Is an element a drive
--
-- > Posix: isDrive "/" == True
-- > Posix: isDrive "/foo" == False
-- > Windows: isDrive "C:\\" == True
-- > Windows: isDrive "C:\\foo" == False
-- > isDrive "" == False
isDrive :: FilePath -> Bool
isDrive x = not (null x) && null (dropDrive x)
---------------------------------------------------------------------
-- Operations on a filepath, as a list of directories
-- | Split a filename into directory and file. '</>' is the inverse.
-- The first component will often end with a trailing slash.
--
-- > splitFileName "/directory/file.ext" == ("/directory/","file.ext")
-- > Valid x => uncurry (</>) (splitFileName x) == x || fst (splitFileName x) == "./"
-- > Valid x => isValid (fst (splitFileName x))
-- > splitFileName "file/bob.txt" == ("file/", "bob.txt")
-- > splitFileName "file/" == ("file/", "")
-- > splitFileName "bob" == ("./", "bob")
-- > Posix: splitFileName "/" == ("/","")
-- > Windows: splitFileName "c:" == ("c:","")
splitFileName :: FilePath -> (String, String)
splitFileName x = (if null dir then "./" else dir, name)
where
(dir, name) = splitFileName_ x
-- version of splitFileName where, if the FilePath has no directory
-- component, the returned directory is "" rather than "./". This
-- is used in cases where we are going to combine the returned
-- directory to make a valid FilePath, and having a "./" appear would
-- look strange and upset simple equality properties. See
-- e.g. replaceFileName.
splitFileName_ :: FilePath -> (String, String)
splitFileName_ x = (drv ++ dir, file)
where
(drv,pth) = splitDrive x
(dir,file) = breakEnd isPathSeparator pth
-- | Set the filename.
--
-- > replaceFileName "/directory/other.txt" "file.ext" == "/directory/file.ext"
-- > Valid x => replaceFileName x (takeFileName x) == x
replaceFileName :: FilePath -> String -> FilePath
replaceFileName x y = a </> y where (a,_) = splitFileName_ x
-- | Drop the filename. Unlike 'takeDirectory', this function will leave
-- a trailing path separator on the directory.
--
-- > dropFileName "/directory/file.ext" == "/directory/"
-- > dropFileName x == fst (splitFileName x)
dropFileName :: FilePath -> FilePath
dropFileName = fst . splitFileName
-- | Get the file name.
--
-- > takeFileName "/directory/file.ext" == "file.ext"
-- > takeFileName "test/" == ""
-- > takeFileName x `isSuffixOf` x
-- > takeFileName x == snd (splitFileName x)
-- > Valid x => takeFileName (replaceFileName x "fred") == "fred"
-- > Valid x => takeFileName (x </> "fred") == "fred"
-- > Valid x => isRelative (takeFileName x)
takeFileName :: FilePath -> FilePath
takeFileName = snd . splitFileName
-- | Get the base name, without an extension or path.
--
-- > takeBaseName "/directory/file.ext" == "file"
-- > takeBaseName "file/test.txt" == "test"
-- > takeBaseName "dave.ext" == "dave"
-- > takeBaseName "" == ""
-- > takeBaseName "test" == "test"
-- > takeBaseName (addTrailingPathSeparator x) == ""
-- > takeBaseName "file/file.tar.gz" == "file.tar"
takeBaseName :: FilePath -> String
takeBaseName = dropExtension . takeFileName
-- | Set the base name.
--
-- > replaceBaseName "/directory/other.ext" "file" == "/directory/file.ext"
-- > replaceBaseName "file/test.txt" "bob" == "file/bob.txt"
-- > replaceBaseName "fred" "bill" == "bill"
-- > replaceBaseName "/dave/fred/bob.gz.tar" "new" == "/dave/fred/new.tar"
-- > Valid x => replaceBaseName x (takeBaseName x) == x
replaceBaseName :: FilePath -> String -> FilePath
replaceBaseName pth nam = combineAlways a (nam <.> ext)
where
(a,b) = splitFileName_ pth
ext = takeExtension b
-- | Is an item either a directory or the last character a path separator?
--
-- > hasTrailingPathSeparator "test" == False
-- > hasTrailingPathSeparator "test/" == True
hasTrailingPathSeparator :: FilePath -> Bool
hasTrailingPathSeparator "" = False
hasTrailingPathSeparator x = isPathSeparator (last x)
hasLeadingPathSeparator :: FilePath -> Bool
hasLeadingPathSeparator "" = False
hasLeadingPathSeparator x = isPathSeparator (head x)
-- | Add a trailing file path separator if one is not already present.
--
-- > hasTrailingPathSeparator (addTrailingPathSeparator x)
-- > hasTrailingPathSeparator x ==> addTrailingPathSeparator x == x
-- > Posix: addTrailingPathSeparator "test/rest" == "test/rest/"
addTrailingPathSeparator :: FilePath -> FilePath
addTrailingPathSeparator x = if hasTrailingPathSeparator x then x else x ++ [pathSeparator]
-- | Remove any trailing path separators
--
-- > dropTrailingPathSeparator "file/test/" == "file/test"
-- > dropTrailingPathSeparator "/" == "/"
-- > Windows: dropTrailingPathSeparator "\\" == "\\"
-- > Posix: not (hasTrailingPathSeparator (dropTrailingPathSeparator x)) || isDrive x
dropTrailingPathSeparator :: FilePath -> FilePath
dropTrailingPathSeparator x =
if hasTrailingPathSeparator x && not (isDrive x)
then let x' = dropWhileEnd isPathSeparator x
in if null x' then [last x] else x'
else x
-- | Get the directory name, move up one level.
--
-- > takeDirectory "/directory/other.ext" == "/directory"
-- > takeDirectory x `isPrefixOf` x || takeDirectory x == "."
-- > takeDirectory "foo" == "."
-- > takeDirectory "/" == "/"
-- > takeDirectory "/foo" == "/"
-- > takeDirectory "/foo/bar/baz" == "/foo/bar"
-- > takeDirectory "/foo/bar/baz/" == "/foo/bar/baz"
-- > takeDirectory "foo/bar/baz" == "foo/bar"
-- > Windows: takeDirectory "foo\\bar" == "foo"
-- > Windows: takeDirectory "foo\\bar\\\\" == "foo\\bar"
-- > Windows: takeDirectory "C:\\" == "C:\\"
takeDirectory :: FilePath -> FilePath
takeDirectory = dropTrailingPathSeparator . dropFileName
-- | Set the directory, keeping the filename the same.
--
-- > replaceDirectory "root/file.ext" "/directory/" == "/directory/file.ext"
-- > Valid x => replaceDirectory x (takeDirectory x) `equalFilePath` x
replaceDirectory :: FilePath -> String -> FilePath
replaceDirectory x dir = combineAlways dir (takeFileName x)
-- | An alias for '</>'.
combine :: FilePath -> FilePath -> FilePath
combine a b | hasLeadingPathSeparator b || hasDrive b = b
| otherwise = combineAlways a b
-- | Combine two paths, assuming rhs is NOT absolute.
combineAlways :: FilePath -> FilePath -> FilePath
combineAlways a b | null a = b
| null b = a
| hasTrailingPathSeparator a = a ++ b
| otherwise = case a of
[a1,':'] | isWindows && isLetter a1 -> a ++ b
_ -> a ++ [pathSeparator] ++ b
-- | Combine two paths with a path separator.
-- If the second path starts with a path separator or a drive letter, then it returns the second.
-- The intention is that @readFile (dir '</>' file)@ will access the same file as
-- @setCurrentDirectory dir; readFile file@.
--
-- > Posix: "/directory" </> "file.ext" == "/directory/file.ext"
-- > Windows: "/directory" </> "file.ext" == "/directory\\file.ext"
-- > "directory" </> "/file.ext" == "/file.ext"
-- > Valid x => (takeDirectory x </> takeFileName x) `equalFilePath` x
--
-- Combined:
--
-- > Posix: "/" </> "test" == "/test"
-- > Posix: "home" </> "bob" == "home/bob"
-- > Posix: "x:" </> "foo" == "x:/foo"
-- > Windows: "C:\\foo" </> "bar" == "C:\\foo\\bar"
-- > Windows: "home" </> "bob" == "home\\bob"
--
-- Not combined:
--
-- > Posix: "home" </> "/bob" == "/bob"
-- > Windows: "home" </> "C:\\bob" == "C:\\bob"
--
-- Not combined (tricky):
--
-- On Windows, if a filepath starts with a single slash, it is relative to the
-- root of the current drive. In [1], this is (confusingly) referred to as an
-- absolute path.
-- The current behavior of '</>' is to never combine these forms.
--
-- > Windows: "home" </> "/bob" == "/bob"
-- > Windows: "home" </> "\\bob" == "\\bob"
-- > Windows: "C:\\home" </> "\\bob" == "\\bob"
--
-- On Windows, from [1]: "If a file name begins with only a disk designator
-- but not the backslash after the colon, it is interpreted as a relative path
-- to the current directory on the drive with the specified letter."
-- The current behavior of '</>' is to never combine these forms.
--
-- > Windows: "D:\\foo" </> "C:bar" == "C:bar"
-- > Windows: "C:\\foo" </> "C:bar" == "C:bar"
(</>) :: FilePath -> FilePath -> FilePath
(</>) = combine
-- | Split a path by the directory separator.
--
-- > splitPath "/directory/file.ext" == ["/","directory/","file.ext"]
-- > concat (splitPath x) == x
-- > splitPath "test//item/" == ["test//","item/"]
-- > splitPath "test/item/file" == ["test/","item/","file"]
-- > splitPath "" == []
-- > Windows: splitPath "c:\\test\\path" == ["c:\\","test\\","path"]
-- > Posix: splitPath "/file/test" == ["/","file/","test"]
splitPath :: FilePath -> [FilePath]
splitPath x = [drive | drive /= ""] ++ f path
where
(drive,path) = splitDrive x
f "" = []
f y = (a++c) : f d
where
(a,b) = break isPathSeparator y
(c,d) = span isPathSeparator b
-- | Just as 'splitPath', but don't add the trailing slashes to each element.
--
-- > splitDirectories "/directory/file.ext" == ["/","directory","file.ext"]
-- > splitDirectories "test/file" == ["test","file"]
-- > splitDirectories "/test/file" == ["/","test","file"]
-- > Windows: splitDirectories "C:\\test\\file" == ["C:\\", "test", "file"]
-- > Valid x => joinPath (splitDirectories x) `equalFilePath` x
-- > splitDirectories "" == []
-- > Windows: splitDirectories "C:\\test\\\\\\file" == ["C:\\", "test", "file"]
-- > splitDirectories "/test///file" == ["/","test","file"]
splitDirectories :: FilePath -> [FilePath]
splitDirectories = map dropTrailingPathSeparator . splitPath
-- | Join path elements back together.
--
-- > joinPath ["/","directory/","file.ext"] == "/directory/file.ext"
-- > Valid x => joinPath (splitPath x) == x
-- > joinPath [] == ""
-- > Posix: joinPath ["test","file","path"] == "test/file/path"
joinPath :: [FilePath] -> FilePath
-- Note that this definition on c:\\c:\\, join then split will give c:\\.
joinPath = foldr combine ""
---------------------------------------------------------------------
-- File name manipulators
-- | Equality of two 'FilePath's.
-- If you call @System.Directory.canonicalizePath@
-- first this has a much better chance of working.
-- Note that this doesn't follow symlinks or DOSNAM~1s.
--
-- > x == y ==> equalFilePath x y
-- > normalise x == normalise y ==> equalFilePath x y
-- > equalFilePath "foo" "foo/"
-- > not (equalFilePath "foo" "/foo")
-- > Posix: not (equalFilePath "foo" "FOO")
-- > Windows: equalFilePath "foo" "FOO"
-- > Windows: not (equalFilePath "C:" "C:/")
equalFilePath :: FilePath -> FilePath -> Bool
equalFilePath a b = f a == f b
where
f x | isWindows = dropTrailingPathSeparator $ map toLower $ normalise x
| otherwise = dropTrailingPathSeparator $ normalise x
-- | Contract a filename, based on a relative path. Note that the resulting path
-- will never introduce @..@ paths, as the presence of symlinks means @..\/b@
-- may not reach @a\/b@ if it starts from @a\/c@. For a worked example see
-- <http://neilmitchell.blogspot.co.uk/2015/10/filepaths-are-subtle-symlinks-are-hard.html this blog post>.
--
-- The corresponding @makeAbsolute@ function can be found in
-- @System.Directory@.
--
-- > makeRelative "/directory" "/directory/file.ext" == "file.ext"
-- > Valid x => makeRelative (takeDirectory x) x `equalFilePath` takeFileName x
-- > makeRelative x x == "."
-- > Valid x y => equalFilePath x y || (isRelative x && makeRelative y x == x) || equalFilePath (y </> makeRelative y x) x
-- > Windows: makeRelative "C:\\Home" "c:\\home\\bob" == "bob"
-- > Windows: makeRelative "C:\\Home" "c:/home/bob" == "bob"
-- > Windows: makeRelative "C:\\Home" "D:\\Home\\Bob" == "D:\\Home\\Bob"
-- > Windows: makeRelative "C:\\Home" "C:Home\\Bob" == "C:Home\\Bob"
-- > Windows: makeRelative "/Home" "/home/bob" == "bob"
-- > Windows: makeRelative "/" "//" == "//"
-- > Posix: makeRelative "/Home" "/home/bob" == "/home/bob"
-- > Posix: makeRelative "/home/" "/home/bob/foo/bar" == "bob/foo/bar"
-- > Posix: makeRelative "/fred" "bob" == "bob"
-- > Posix: makeRelative "/file/test" "/file/test/fred" == "fred"
-- > Posix: makeRelative "/file/test" "/file/test/fred/" == "fred/"
-- > Posix: makeRelative "some/path" "some/path/a/b/c" == "a/b/c"
makeRelative :: FilePath -> FilePath -> FilePath
makeRelative root path
| equalFilePath root path = "."
| takeAbs root /= takeAbs path = path
| otherwise = f (dropAbs root) (dropAbs path)
where
f "" y = dropWhile isPathSeparator y
f x y = let (x1,x2) = g x
(y1,y2) = g y
in if equalFilePath x1 y1 then f x2 y2 else path
g x = (dropWhile isPathSeparator a, dropWhile isPathSeparator b)
where (a,b) = break isPathSeparator $ dropWhile isPathSeparator x
-- on windows, need to drop '/' which is kind of absolute, but not a drive
dropAbs x | hasLeadingPathSeparator x && not (hasDrive x) = tail x
dropAbs x = dropDrive x
takeAbs x | hasLeadingPathSeparator x && not (hasDrive x) = [pathSeparator]
takeAbs x = map (\y -> if isPathSeparator y then pathSeparator else toLower y) $ takeDrive x
-- | Normalise a file
--
-- * \/\/ outside of the drive can be made blank
--
-- * \/ -> 'pathSeparator'
--
-- * .\/ -> \"\"
--
-- > Posix: normalise "/file/\\test////" == "/file/\\test/"
-- > Posix: normalise "/file/./test" == "/file/test"
-- > Posix: normalise "/test/file/../bob/fred/" == "/test/file/../bob/fred/"
-- > Posix: normalise "../bob/fred/" == "../bob/fred/"
-- > Posix: normalise "./bob/fred/" == "bob/fred/"
-- > Windows: normalise "c:\\file/bob\\" == "C:\\file\\bob\\"
-- > Windows: normalise "c:\\" == "C:\\"
-- > Windows: normalise "C:.\\" == "C:"
-- > Windows: normalise "\\\\server\\test" == "\\\\server\\test"
-- > Windows: normalise "//server/test" == "\\\\server\\test"
-- > Windows: normalise "c:/file" == "C:\\file"
-- > Windows: normalise "/file" == "\\file"
-- > Windows: normalise "\\" == "\\"
-- > Windows: normalise "/./" == "\\"
-- > normalise "." == "."
-- > Posix: normalise "./" == "./"
-- > Posix: normalise "./." == "./"
-- > Posix: normalise "/./" == "/"
-- > Posix: normalise "/" == "/"
-- > Posix: normalise "bob/fred/." == "bob/fred/"
-- > Posix: normalise "//home" == "/home"
normalise :: FilePath -> FilePath
normalise path = result ++ [pathSeparator | addPathSeparator]
where
(drv,pth) = splitDrive path
result = joinDrive' (normaliseDrive drv) (f pth)
joinDrive' "" "" = "."
joinDrive' d p = joinDrive d p
addPathSeparator = isDirPath pth
&& not (hasTrailingPathSeparator result)
&& not (isRelativeDrive drv)
isDirPath xs = hasTrailingPathSeparator xs
|| not (null xs) && last xs == '.' && hasTrailingPathSeparator (init xs)
f = joinPath . dropDots . propSep . splitDirectories
propSep (x:xs) | all isPathSeparator x = [pathSeparator] : xs
| otherwise = x : xs
propSep [] = []
dropDots = filter ("." /=)
normaliseDrive :: FilePath -> FilePath
normaliseDrive "" = ""
normaliseDrive _ | isPosix = [pathSeparator]
normaliseDrive drive = if isJust $ readDriveLetter x2
then map toUpper x2
else x2
where
x2 = map repSlash drive
repSlash x = if isPathSeparator x then pathSeparator else x
-- Information for validity functions on Windows. See [1].
isBadCharacter :: Char -> Bool
isBadCharacter x = x >= '\0' && x <= '\31' || x `elem` ":*?><|\""
badElements :: [FilePath]
badElements =
["CON","PRN","AUX","NUL","CLOCK$"
,"COM1","COM2","COM3","COM4","COM5","COM6","COM7","COM8","COM9"
,"LPT1","LPT2","LPT3","LPT4","LPT5","LPT6","LPT7","LPT8","LPT9"]
-- | Is a FilePath valid, i.e. could you create a file like it? This function checks for invalid names,
-- and invalid characters, but does not check if length limits are exceeded, as these are typically
-- filesystem dependent.
--
-- > isValid "" == False
-- > isValid "\0" == False
-- > Posix: isValid "/random_ path:*" == True
-- > Posix: isValid x == not (null x)
-- > Windows: isValid "c:\\test" == True
-- > Windows: isValid "c:\\test:of_test" == False
-- > Windows: isValid "test*" == False
-- > Windows: isValid "c:\\test\\nul" == False
-- > Windows: isValid "c:\\test\\prn.txt" == False
-- > Windows: isValid "c:\\nul\\file" == False
-- > Windows: isValid "\\\\" == False
-- > Windows: isValid "\\\\\\foo" == False
-- > Windows: isValid "\\\\?\\D:file" == False
-- > Windows: isValid "foo\tbar" == False
-- > Windows: isValid "nul .txt" == False
-- > Windows: isValid " nul.txt" == True
isValid :: FilePath -> Bool
isValid "" = False
isValid x | '\0' `elem` x = False
isValid _ | isPosix = True
isValid path =
not (any isBadCharacter x2) &&
not (any f $ splitDirectories x2) &&
not (isJust (readDriveShare x1) && all isPathSeparator x1) &&
not (isJust (readDriveUNC x1) && not (hasTrailingPathSeparator x1))
where
(x1,x2) = splitDrive path
f x = map toUpper (dropWhileEnd (== ' ') $ dropExtensions x) `elem` badElements
-- | Take a FilePath and make it valid; does not change already valid FilePaths.
--
-- > isValid (makeValid x)
-- > isValid x ==> makeValid x == x
-- > makeValid "" == "_"
-- > makeValid "file\0name" == "file_name"
-- > Windows: makeValid "c:\\already\\/valid" == "c:\\already\\/valid"
-- > Windows: makeValid "c:\\test:of_test" == "c:\\test_of_test"
-- > Windows: makeValid "test*" == "test_"
-- > Windows: makeValid "c:\\test\\nul" == "c:\\test\\nul_"
-- > Windows: makeValid "c:\\test\\prn.txt" == "c:\\test\\prn_.txt"
-- > Windows: makeValid "c:\\test/prn.txt" == "c:\\test/prn_.txt"
-- > Windows: makeValid "c:\\nul\\file" == "c:\\nul_\\file"
-- > Windows: makeValid "\\\\\\foo" == "\\\\drive"
-- > Windows: makeValid "\\\\?\\D:file" == "\\\\?\\D:\\file"
-- > Windows: makeValid "nul .txt" == "nul _.txt"
makeValid :: FilePath -> FilePath
makeValid "" = "_"
makeValid path
| isPosix = map (\x -> if x == '\0' then '_' else x) path
| isJust (readDriveShare drv) && all isPathSeparator drv = take 2 drv ++ "drive"
| isJust (readDriveUNC drv) && not (hasTrailingPathSeparator drv) =
makeValid (drv ++ [pathSeparator] ++ pth)
| otherwise = joinDrive drv $ validElements $ validChars pth
where
(drv,pth) = splitDrive path
validChars = map f
f x = if isBadCharacter x then '_' else x
validElements x = joinPath $ map g $ splitPath x
g x = h a ++ b
where (a,b) = break isPathSeparator x
h x = if map toUpper (dropWhileEnd (== ' ') a) `elem` badElements then a ++ "_" <.> b else x
where (a,b) = splitExtensions x
-- | Is a path relative, or is it fixed to the root?
--
-- > Windows: isRelative "path\\test" == True
-- > Windows: isRelative "c:\\test" == False
-- > Windows: isRelative "c:test" == True
-- > Windows: isRelative "c:\\" == False
-- > Windows: isRelative "c:/" == False
-- > Windows: isRelative "c:" == True
-- > Windows: isRelative "\\\\foo" == False
-- > Windows: isRelative "\\\\?\\foo" == False
-- > Windows: isRelative "\\\\?\\UNC\\foo" == False
-- > Windows: isRelative "/foo" == True
-- > Windows: isRelative "\\foo" == True
-- > Posix: isRelative "test/path" == True
-- > Posix: isRelative "/test" == False
-- > Posix: isRelative "/" == False
--
-- According to [1]:
--
-- * "A UNC name of any format [is never relative]."
--
-- * "You cannot use the "\\?\" prefix with a relative path."
isRelative :: FilePath -> Bool
isRelative x = null drive || isRelativeDrive drive
where drive = takeDrive x
{- c:foo -}
-- From [1]: "If a file name begins with only a disk designator but not the
-- backslash after the colon, it is interpreted as a relative path to the
-- current directory on the drive with the specified letter."
isRelativeDrive :: String -> Bool
isRelativeDrive x =
maybe False (not . hasTrailingPathSeparator . fst) (readDriveLetter x)
-- | @not . 'isRelative'@
--
-- > isAbsolute x == not (isRelative x)
isAbsolute :: FilePath -> Bool
isAbsolute = not . isRelative
-----------------------------------------------------------------------------
-- dropWhileEnd (>2) [1,2,3,4,1,2,3,4] == [1,2,3,4,1,2])
-- Note that Data.List.dropWhileEnd is only available in base >= 4.5.
dropWhileEnd :: (a -> Bool) -> [a] -> [a]
dropWhileEnd p = reverse . dropWhile p . reverse
-- takeWhileEnd (>2) [1,2,3,4,1,2,3,4] == [3,4])
takeWhileEnd :: (a -> Bool) -> [a] -> [a]
takeWhileEnd p = reverse . takeWhile p . reverse
-- spanEnd (>2) [1,2,3,4,1,2,3,4] = ([1,2,3,4,1,2], [3,4])
spanEnd :: (a -> Bool) -> [a] -> ([a], [a])
spanEnd p xs = (dropWhileEnd p xs, takeWhileEnd p xs)
-- breakEnd (< 2) [1,2,3,4,1,2,3,4] == ([1,2,3,4,1],[2,3,4])
breakEnd :: (a -> Bool) -> [a] -> ([a], [a])
breakEnd p = spanEnd (not . p)
-- | The stripSuffix function drops the given suffix from a list. It returns
-- Nothing if the list did not end with the suffix given, or Just the list
-- before the suffix, if it does.
stripSuffix :: Eq a => [a] -> [a] -> Maybe [a]
stripSuffix xs ys = fmap reverse $ stripPrefix (reverse xs) (reverse ys)