Copyright | (c) Neil Mitchell 2005-2014 |
---|---|
License | BSD3 |
Maintainer | ndmitchell@gmail.com |
Stability | stable |
Portability | portable |
Safe Haskell | Safe |
Language | Haskell98 |
A library for FilePath
manipulations, using Windows style paths on
all platforms. Importing System.FilePath is usually better.
Given the eample 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:
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] Naming Files, Paths and Namespaces (Microsoft MSDN)
- type FilePath = String
- pathSeparator :: Char
- pathSeparators :: [Char]
- isPathSeparator :: Char -> Bool
- searchPathSeparator :: Char
- isSearchPathSeparator :: Char -> Bool
- extSeparator :: Char
- isExtSeparator :: Char -> Bool
- splitSearchPath :: String -> [FilePath]
- getSearchPath :: IO [FilePath]
- splitExtension :: FilePath -> (String, String)
- takeExtension :: FilePath -> String
- replaceExtension :: FilePath -> String -> FilePath
- (-<.>) :: FilePath -> String -> FilePath
- dropExtension :: FilePath -> FilePath
- addExtension :: FilePath -> String -> FilePath
- hasExtension :: FilePath -> Bool
- (<.>) :: FilePath -> String -> FilePath
- splitExtensions :: FilePath -> (FilePath, String)
- dropExtensions :: FilePath -> FilePath
- takeExtensions :: FilePath -> String
- splitFileName :: FilePath -> (String, String)
- takeFileName :: FilePath -> FilePath
- replaceFileName :: FilePath -> String -> FilePath
- dropFileName :: FilePath -> FilePath
- takeBaseName :: FilePath -> String
- replaceBaseName :: FilePath -> String -> FilePath
- takeDirectory :: FilePath -> FilePath
- replaceDirectory :: FilePath -> String -> FilePath
- combine :: FilePath -> FilePath -> FilePath
- (</>) :: FilePath -> FilePath -> FilePath
- splitPath :: FilePath -> [FilePath]
- joinPath :: [FilePath] -> FilePath
- splitDirectories :: FilePath -> [FilePath]
- splitDrive :: FilePath -> (FilePath, FilePath)
- joinDrive :: FilePath -> FilePath -> FilePath
- takeDrive :: FilePath -> FilePath
- hasDrive :: FilePath -> Bool
- dropDrive :: FilePath -> FilePath
- isDrive :: FilePath -> Bool
- hasTrailingPathSeparator :: FilePath -> Bool
- addTrailingPathSeparator :: FilePath -> FilePath
- dropTrailingPathSeparator :: FilePath -> FilePath
- normalise :: FilePath -> FilePath
- equalFilePath :: FilePath -> FilePath -> Bool
- makeRelative :: FilePath -> FilePath -> FilePath
- isRelative :: FilePath -> Bool
- isAbsolute :: FilePath -> Bool
- isValid :: FilePath -> Bool
- makeValid :: FilePath -> FilePath
Separator predicates
File and directory names are values of type String
, whose precise
meaning is operating system dependent. Files can be opened, yielding a
handle which can then be used to operate on the contents of that file.
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
pathSeparators :: [Char]
The list of all possible separators.
Windows: pathSeparators == ['\\', '/'] Posix: pathSeparators == ['/'] pathSeparator `elem` pathSeparators
isPathSeparator :: Char -> Bool
Rather than using (==
, use this. Test if something
is a path separator.pathSeparator
)
isPathSeparator a == (a `elem` pathSeparators)
The character that is used to separate the entries in the $PATH environment variable.
Windows: searchPathSeparator == ';' Posix: searchPathSeparator == ':'
isSearchPathSeparator :: Char -> Bool
Is the character a file separator?
isSearchPathSeparator a == (a == searchPathSeparator)
extSeparator :: Char
File extension character
extSeparator == '.'
isExtSeparator :: Char -> Bool
Is the character an extension character?
isExtSeparator a == (a == extSeparator)
$PATH
methods
splitSearchPath :: String -> [FilePath]
Take a string, split it on the searchPathSeparator
character.
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"]
getSearchPath :: IO [FilePath]
Get a list of FilePath
s in the $PATH variable.
Extension functions
splitExtension :: FilePath -> (String, String)
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/","")
takeExtension :: FilePath -> String
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"
replaceExtension :: FilePath -> String -> FilePath
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
(-<.>) :: FilePath -> String -> FilePath infixr 7
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"
dropExtension :: FilePath -> FilePath
Remove last extension, and the "." preceding it.
dropExtension "/directory/path.ext" == "/directory/path" dropExtension x == fst (splitExtension x)
addExtension :: FilePath -> String -> FilePath
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" Valid x => takeFileName (addExtension (addTrailingPathSeparator x) "ext") == ".ext" Windows: addExtension "\\\\share" ".txt" == "\\\\share\\.txt"
hasExtension :: FilePath -> Bool
Does the given filename have an extension?
hasExtension "/directory/path.ext" == True hasExtension "/directory/path" == False null (takeExtension x) == not (hasExtension x)
(<.>) :: FilePath -> String -> FilePath infixr 7
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"
splitExtensions :: FilePath -> (FilePath, String)
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")
dropExtensions :: FilePath -> FilePath
Drop all extensions.
dropExtensions "/directory/path.ext" == "/directory/path" dropExtensions "file.tar.gz" == "file" not $ hasExtension $ dropExtensions x not $ any isExtSeparator $ takeFileName $ dropExtensions x
takeExtensions :: FilePath -> String
Get all extensions.
takeExtensions "/directory/path.ext" == ".ext" takeExtensions "file.tar.gz" == ".tar.gz"
Filename/directory functions
splitFileName :: FilePath -> (String, String)
Split a filename into directory and file. combine
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:","")
takeFileName :: FilePath -> FilePath
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)
replaceFileName :: FilePath -> String -> FilePath
Set the filename.
replaceFileName "/directory/other.txt" "file.ext" == "/directory/file.ext" Valid x => replaceFileName x (takeFileName x) == x
dropFileName :: FilePath -> FilePath
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)
takeBaseName :: FilePath -> String
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"
replaceBaseName :: FilePath -> String -> FilePath
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
takeDirectory :: FilePath -> FilePath
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:\\"
replaceDirectory :: FilePath -> String -> FilePath
Set the directory, keeping the filename the same.
replaceDirectory "root/file.ext" "/directory/" == "/directory/file.ext" Valid x => replaceDirectory x (takeDirectory x) `equalFilePath` x
combine :: FilePath -> FilePath -> FilePath
Combine two paths, if the second path starts with a path separator or a drive letter, then it returns the second.
Valid x => combine (takeDirectory x) (takeFileName x) `equalFilePath` x
Combined: > Posix: combine "" "test" == "test" > Posix: combine "home" "bob" == "home/bob" > Posix: combine "x:" "foo" == "x:/foo" > Windows: combine C:\\foo "bar" == C:\\foo\\bar > Windows: combine "home" "bob" == "home\bob"
Not combined: > Posix: combine "home" "bob" == "bob" > Windows: combine "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 combine
is to never combine these forms.
Windows: combine "home" "/bob" == "/bob" Windows: combine "home" "\\bob" == "\\bob" Windows: combine "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 combine
is to never combine these forms.
Windows: combine "D:\\foo" "C:bar" == "C:bar" Windows: combine "C:\\foo" "C:bar" == "C:bar"
(</>) :: FilePath -> FilePath -> FilePath infixr 5
Join two values with a path separator. For examples and caveats see the equivalent function combine
.
Posix: "/directory" </> "file.ext" == "/directory/file.ext" Windows: "/directory" </> "file.ext" == "/directory\\file.ext"
splitPath :: FilePath -> [FilePath]
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"]
joinPath :: [FilePath] -> FilePath
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"
splitDirectories :: FilePath -> [FilePath]
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"]
Drive functions
splitDrive :: FilePath -> (FilePath, FilePath)
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")
joinDrive :: FilePath -> FilePath -> FilePath
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"
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
Is an element a drive
Posix: isDrive "/" == True Posix: isDrive "/foo" == False Windows: isDrive "C:\\" == True Windows: isDrive "C:\\foo" == False isDrive "" == False
Trailing slash functions
hasTrailingPathSeparator :: FilePath -> Bool
Is an item either a directory or the last character a path separator?
hasTrailingPathSeparator "test" == False hasTrailingPathSeparator "test/" == True
addTrailingPathSeparator :: FilePath -> FilePath
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/"
dropTrailingPathSeparator :: FilePath -> FilePath
Remove any trailing path separators
dropTrailingPathSeparator "file/test/" == "file/test" dropTrailingPathSeparator "/" == "/" Windows: dropTrailingPathSeparator "\\" == "\\" Posix: not (hasTrailingPathSeparator (dropTrailingPathSeparator x)) || isDrive x
File name manipulations
normalise :: FilePath -> FilePath
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"
equalFilePath :: FilePath -> FilePath -> Bool
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:/")
makeRelative :: FilePath -> FilePath -> FilePath
Contract a filename, based on a relative path.
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"
isRelative :: FilePath -> Bool
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."
isAbsolute :: FilePath -> Bool
not . isRelative
isAbsolute x == not (isRelative x)
Is a FilePath valid, i.e. could you create a file like it?
isValid "" == 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
makeValid :: FilePath -> FilePath
Take a FilePath and make it valid; does not change already valid FilePaths.
isValid (makeValid x) isValid x ==> makeValid x == x makeValid "" == "_" 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"