1 {-# OPTIONS_GHC -fno-implicit-prelude #-}
3 -----------------------------------------------------------------------------
5 -- Module : System.FilePath
6 -- Copyright : (c) The University of Glasgow 2004
7 -- License : BSD-style (see the file libraries/base/LICENSE)
9 -- Maintainer : libraries@haskell.org
11 -- Portability : portable
13 -- System-independent pathname manipulations.
15 -----------------------------------------------------------------------------
17 module System.FilePath
43 -- * Filename extensions
49 #ifdef __GLASGOW_HASKELL__
51 import GHC.IOBase(FilePath)
54 import Prelude -- necessary to get dependencies right
59 --------------------------------------------------------------
61 --------------------------------------------------------------
63 -- | Split the path into directory and file name
69 -- > splitFileName "/" == ("/", "")
70 -- > splitFileName "/foo/bar.ext" == ("/foo", "bar.ext")
71 -- > splitFileName "bar.ext" == (".", "bar.ext")
72 -- > splitFileName "/foo/." == ("/foo", ".")
73 -- > splitFileName "/foo/.." == ("/foo", "..")
77 -- > splitFileName "\\" == ("\\", "")
78 -- > splitFileName "c:\\foo\\bar.ext" == ("c:\\foo", "bar.ext")
79 -- > splitFileName "bar.ext" == (".", "bar.ext")
80 -- > splitFileName "c:\\foo\\." == ("c:\\foo", ".")
81 -- > splitFileName "c:\\foo\\.." == ("c:\\foo", "..")
83 -- The first case in the above examples returns an empty file name.
84 -- This is a special case because the \"\/\" (\"\\\\\" on Windows)
85 -- path doesn\'t refer to an object (file or directory) which resides
86 -- within a directory.
87 splitFileName :: FilePath -> (String, String)
88 splitFileName p = (reverse (path2++drive), reverse fname)
90 #ifdef mingw32_TARGET_OS
91 (path,drive) = break (== ':') (reverse p)
93 (path,drive) = (reverse p,"")
95 (fname,path1) = break isPathSeparator path
98 [_] -> path1 -- don't remove the trailing slash if
99 -- there is only one character
100 (c:path) | isPathSeparator c -> path
103 -- | Split the path into file name and extension. If the file doesn\'t have extension,
104 -- the function will return empty string. The extension doesn\'t include a leading period.
108 -- > splitFileExt "foo.ext" == ("foo", "ext")
109 -- > splitFileExt "foo" == ("foo", "")
110 -- > splitFileExt "." == (".", "")
111 -- > splitFileExt ".." == ("..", "")
112 splitFileExt :: FilePath -> (String, String)
116 (_:pre) -> (reverse (pre++path), reverse suf)
118 (fname,path) = break isPathSeparator (reverse p)
119 (suf,pre) | fname == "." || fname == ".." = (fname,"")
120 | otherwise = break (== '.') fname
122 -- | Split the path into directory, file name and extension.
123 -- The function is an optimized version of the following equation:
125 -- > splitFilePath path = (dir,name,ext)
127 -- > (dir,basename) = splitFileName path
128 -- > (name,ext) = splitFileExt basename
129 splitFilePath :: FilePath -> (String, String, String)
132 [] -> (reverse real_dir, reverse suf, [])
133 (_:pre) -> (reverse real_dir, reverse pre, reverse suf)
135 #ifdef mingw32_TARGET_OS
136 (path,drive) = break (== ':') (reverse p)
138 (path,drive) = (reverse p,"")
140 (file,dir) = break isPathSeparator path
141 (suf,pre) = case file of
143 _ -> break (== '.') file
145 real_dir = case dir of
147 [_] -> pathSeparator:drive
148 (_:dir) -> dir++drive
150 -- | The 'joinFileName' function is the opposite of 'splitFileName'.
151 -- It joins directory and file names to form a complete file path.
153 -- The general rule is:
155 -- > dir `joinFileName` basename == path
157 -- > (dir,basename) = splitFileName path
159 -- There might be an exceptions to the rule but in any case the
160 -- reconstructed path will refer to the same object (file or directory).
161 -- An example exception is that on Windows some slashes might be converted
163 joinFileName :: String -> String -> FilePath
164 joinFileName "" fname = fname
165 joinFileName "." fname = fname
166 joinFileName dir "" = dir
167 joinFileName dir fname
168 | isPathSeparator (last dir) = dir++fname
169 | otherwise = dir++pathSeparator:fname
171 -- | The 'joinFileExt' function is the opposite of 'splitFileExt'.
172 -- It joins a file name and an extension to form a complete file path.
174 -- The general rule is:
176 -- > filename `joinFileExt` ext == path
178 -- > (filename,ext) = splitFileExt path
179 joinFileExt :: String -> String -> FilePath
180 joinFileExt path "" = path
181 joinFileExt path ext = path ++ '.':ext
183 -- | Given a directory path \"dir\" and a file\/directory path \"rel\",
184 -- returns a merged path \"full\" with the property that
185 -- (cd dir; do_something_with rel) is equivalent to
186 -- (do_something_with full). If the \"rel\" path is an absolute path
187 -- then the returned path is equal to \"rel\"
188 joinPaths :: FilePath -> FilePath -> FilePath
189 joinPaths path1 path2
190 | isRootedPath path2 = path2
192 #ifdef mingw32_TARGET_OS
194 d:':':path2' | take 2 path1 == [d,':'] -> path1 `joinFileName` path2'
196 _ -> path1 `joinFileName` path2
198 path1 `joinFileName` path2
201 -- | Changes the extension of a file path.
202 changeFileExt :: FilePath -- ^ The path information to modify.
203 -> String -- ^ The new extension (without a leading period).
204 -- Specify an empty string to remove an existing
205 -- extension from path.
206 -> FilePath -- ^ A string containing the modified path information.
207 changeFileExt path ext = joinFileExt name ext
209 (name,_) = splitFileExt path
211 -- | On Unix and Macintosh the 'isRootedPath' function is a synonym to 'isAbsolutePath'.
212 -- The difference is important only on Windows. The rooted path must start from the root
213 -- directory but may not include the drive letter while the absolute path always includes
214 -- the drive letter and the full file path.
215 isRootedPath :: FilePath -> Bool
216 isRootedPath (c:_) | isPathSeparator c = True
217 #ifdef mingw32_TARGET_OS
218 isRootedPath (_:':':c:_) | isPathSeparator c = True -- path with drive letter
220 isRootedPath _ = False
222 -- | Returns 'True' if this path\'s meaning is independent of any OS
223 -- \"working directory\", or 'False' if it isn\'t.
224 isAbsolutePath :: FilePath -> Bool
225 #ifdef mingw32_TARGET_OS
226 isAbsolutePath (_:':':c:_) | isPathSeparator c = True
228 isAbsolutePath (c:_) | isPathSeparator c = True
230 isAbsolutePath _ = False
232 -- | If the function is applied to an absolute path then it returns a
233 -- local path obtained by dropping the absolute prefix from the path.
234 -- Under Windows the prefix is @\"\\\"@, @\"c:\"@ or @\"c:\\\"@.
235 -- Under Unix the prefix is always @\"\/\"@.
236 dropAbsolutePrefix :: FilePath -> FilePath
237 dropAbsolutePrefix (c:cs) | isPathSeparator c = cs
238 #ifdef mingw32_TARGET_OS
239 dropAbsolutePrefix (_:':':c:cs) | isPathSeparator c = cs -- path with drive letter
240 dropAbsolutePrefix (_:':':cs) = cs
242 dropAbsolutePrefix cs = cs
244 -- | Gets this path and all its parents.
245 -- The function is useful in case if you want to create
246 -- some file but you aren\'t sure whether all directories
247 -- in the path exist or if you want to search upward for some file.
253 -- > pathParents "/" == ["/"]
254 -- > pathParents "/dir1" == ["/", "/dir1"]
255 -- > pathParents "/dir1/dir2" == ["/", "/dir1", "/dir1/dir2"]
256 -- > pathParents "dir1" == [".", "dir1"]
257 -- > pathParents "dir1/dir2" == [".", "dir1", "dir1/dir2"]
261 -- > pathParents "c:" == ["c:."]
262 -- > pathParents "c:\\" == ["c:\\"]
263 -- > pathParents "c:\\dir1" == ["c:\\", "c:\\dir1"]
264 -- > pathParents "c:\\dir1\\dir2" == ["c:\\", "c:\\dir1", "c:\\dir1\\dir2"]
265 -- > pathParents "c:dir1" == ["c:.","c:dir1"]
266 -- > pathParents "dir1\\dir2" == [".", "dir1", "dir1\\dir2"]
268 -- Note that if the file is relative then the current directory (\".\")
269 -- will be explicitly listed.
270 pathParents :: FilePath -> [FilePath]
272 root'' : map ((++) root') (dropEmptyPath $ inits path')
274 #ifdef mingw32_TARGET_OS
275 (root,path) = case break (== ':') p of
276 (path, "") -> ("",path)
277 (root,_:path) -> (root++":",path)
281 (root',root'',path') = case path of
282 (c:path) | isPathSeparator c -> (root++[pathSeparator],root++[pathSeparator],path)
283 _ -> (root ,root++"." ,path)
285 dropEmptyPath ("":paths) = paths
286 dropEmptyPath paths = paths
288 inits :: String -> [String]
293 ".." -> map (joinFileName pre) (dropEmptyPath $ inits suf)
294 _ -> "" : map (joinFileName pre) (inits suf)
296 (pre,suf) = case break isPathSeparator cs of
297 (pre,"") -> (pre, "")
298 (pre,_:suf) -> (pre,suf)
300 -- | Given a list of file paths, returns the longest common parent.
301 commonParent :: [FilePath] -> Maybe FilePath
302 commonParent [] = Nothing
303 commonParent paths@(p:ps) =
304 case common Nothing "" p ps of
305 #ifdef mingw32_TARGET_OS
306 Nothing | all (not . isAbsolutePath) paths ->
307 case foldr getDrive [] paths of
312 Nothing | all (not . isAbsolutePath) paths -> Just "."
316 #ifdef mingw32_TARGET_OS
317 getDrive (d:':':_) ds
318 | not (d `elem` ds) = d:ds
322 common i acc [] ps = checkSep i acc ps
323 common i acc (c:cs) ps
324 | isPathSeparator c = removeSep i acc cs [] ps
325 | otherwise = removeChar i acc c cs [] ps
327 checkSep i acc [] = Just (reverse acc)
328 checkSep i acc ([]:ps) = Just (reverse acc)
329 checkSep i acc ((c1:p):ps)
330 | isPathSeparator c1 = checkSep i acc ps
331 checkSep i acc ps = i
333 removeSep i acc cs pacc [] =
334 common (Just (reverse (pathSeparator:acc))) (pathSeparator:acc) cs pacc
335 removeSep i acc cs pacc ([] :ps) = Just (reverse acc)
336 removeSep i acc cs pacc ((c1:p):ps)
337 | isPathSeparator c1 = removeSep i acc cs (p:pacc) ps
338 removeSep i acc cs pacc ps = i
340 removeChar i acc c cs pacc [] = common i (c:acc) cs pacc
341 removeChar i acc c cs pacc ([] :ps) = i
342 removeChar i acc c cs pacc ((c1:p):ps)
343 | c == c1 = removeChar i acc c cs (p:pacc) ps
344 removeChar i acc c cs pacc ps = i
346 --------------------------------------------------------------
348 --------------------------------------------------------------
350 -- | The function splits the given string to substrings
351 -- using the 'searchPathSeparator'.
352 parseSearchPath :: String -> [FilePath]
353 parseSearchPath path = split searchPathSeparator path
355 split :: Char -> String -> [String]
359 _:rest' -> chunk : split c rest'
361 (chunk, rest) = break (==c) s
363 -- | The function concatenates the given paths to form a
364 -- single string where the paths are separated with 'searchPathSeparator'.
365 mkSearchPath :: [FilePath] -> String
366 mkSearchPath paths = concat (intersperse [searchPathSeparator] paths)
369 --------------------------------------------------------------
371 --------------------------------------------------------------
373 -- | Checks whether the character is a valid path separator for the host
374 -- platform. The valid character is a 'pathSeparator' but since the Windows
375 -- operating system also accepts a slash (\"\/\") since DOS 2, the function
376 -- checks for it on this platform, too.
377 isPathSeparator :: Char -> Bool
378 isPathSeparator ch = ch == pathSeparator || ch == '/'
380 -- | Provides a platform-specific character used to separate directory levels in
381 -- a path string that reflects a hierarchical file system organization. The
382 -- separator is a slash (@\"\/\"@) on Unix and Macintosh, and a backslash
383 -- (@\"\\\"@) on the Windows operating system.
384 pathSeparator :: Char
385 #ifdef mingw32_TARGET_OS
391 -- ToDo: This should be determined via autoconf (PATH_SEPARATOR)
392 -- | A platform-specific character used to separate search path strings in
393 -- environment variables. The separator is a colon (@\":\"@) on Unix and
394 -- Macintosh, and a semicolon (@\";\"@) on the Windows operating system.
395 searchPathSeparator :: Char
396 #ifdef mingw32_TARGET_OS
397 searchPathSeparator = ';'
399 searchPathSeparator = ':'
402 -- ToDo: This should be determined via autoconf (AC_EXEEXT)
403 -- | Extension for executable files
404 -- (typically @\"\"@ on Unix and @\"exe\"@ on Windows or OS\/2)
405 exeExtension :: String
406 #ifdef mingw32_TARGET_OS
412 -- ToDo: This should be determined via autoconf (AC_OBJEXT)
413 -- | Extension for object files. For GHC and NHC the extension is @\"o\"@.
414 -- Hugs uses either @\"o\"@ or @\"obj\"@ depending on the used C compiler.
415 objExtension :: String
418 -- | Extension for dynamically linked (or shared) libraries
419 -- (typically @\"so\"@ on Unix and @\"dll\"@ on Windows)
420 dllExtension :: String
421 #ifdef mingw32_TARGET_OS