216 lines
6.9 KiB
Haskell
216 lines
6.9 KiB
Haskell
{- path manipulation
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-
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- Copyright 2010-2020 Joey Hess <id@joeyh.name>
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-
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- License: BSD-2-clause
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-}
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{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE CPP #-}
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{-# OPTIONS_GHC -fno-warn-tabs #-}
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module Utility.Path (
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simplifyPath,
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parentDir,
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upFrom,
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dirContains,
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segmentPaths,
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segmentPaths',
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runSegmentPaths,
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runSegmentPaths',
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inPath,
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searchPath,
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dotfile,
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splitShortExtensions,
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relPathDirToFileAbs,
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) where
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import System.FilePath.ByteString
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import qualified System.FilePath as P
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import qualified Data.ByteString as B
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import Data.List
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import Data.Maybe
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import Control.Applicative
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import Prelude
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import Utility.Monad
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import Utility.SystemDirectory
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#ifdef mingw32_HOST_OS
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import Data.Char
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import Utility.FileSystemEncoding
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#endif
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{- Simplifies a path, removing any "." component, collapsing "dir/..",
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- and removing the trailing path separator.
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-
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- On Windows, preserves whichever style of path separator might be used in
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- the input RawFilePaths. This is done because some programs in Windows
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- demand a particular path separator -- and which one actually varies!
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-
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- This does not guarantee that two paths that refer to the same location,
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- and are both relative to the same location (or both absolute) will
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- yeild the same result. Run both through normalise from System.RawFilePath
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- to ensure that.
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-}
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simplifyPath :: RawFilePath -> RawFilePath
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simplifyPath path = dropTrailingPathSeparator $
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joinDrive drive $ joinPath $ norm [] $ splitPath path'
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where
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(drive, path') = splitDrive path
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norm c [] = reverse c
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norm c (p:ps)
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| p' == ".." && not (null c) && dropTrailingPathSeparator (c !! 0) /= ".." =
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norm (drop 1 c) ps
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| p' == "." = norm c ps
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| otherwise = norm (p:c) ps
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where
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p' = dropTrailingPathSeparator p
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{- takeDirectory "foo/bar/" is "foo/bar". This instead yields "foo" -}
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parentDir :: RawFilePath -> RawFilePath
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parentDir = takeDirectory . dropTrailingPathSeparator
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{- Just the parent directory of a path, or Nothing if the path has no
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- parent (ie for "/" or "." or "foo") -}
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upFrom :: RawFilePath -> Maybe RawFilePath
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upFrom dir
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| length dirs < 2 = Nothing
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| otherwise = Just $ joinDrive drive $
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B.intercalate (B.singleton pathSeparator) $ init dirs
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where
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-- on Unix, the drive will be "/" when the dir is absolute,
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-- otherwise ""
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(drive, path) = splitDrive dir
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dirs = filter (not . B.null) $ B.splitWith isPathSeparator path
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{- Checks if the first RawFilePath is, or could be said to contain the second.
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- For example, "foo/" contains "foo/bar". Also, "foo", "./foo", "foo/" etc
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- are all equivilant.
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-}
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dirContains :: RawFilePath -> RawFilePath -> Bool
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dirContains a b = a == b
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|| a' == b'
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|| (addTrailingPathSeparator a') `B.isPrefixOf` b'
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|| a' == "." && normalise ("." </> b') == b'
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where
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a' = norm a
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b' = norm b
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norm = normalise . simplifyPath
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{- Given an original list of paths, and an expanded list derived from it,
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- which may be arbitrarily reordered, generates a list of lists, where
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- each sublist corresponds to one of the original paths.
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-
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- When the original path is a directory, any items in the expanded list
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- that are contained in that directory will appear in its segment.
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-
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- The order of the original list of paths is attempted to be preserved in
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- the order of the returned segments. However, doing so has a O^NM
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- growth factor. So, if the original list has more than 100 paths on it,
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- we stop preserving ordering at that point. Presumably a user passing
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- that many paths in doesn't care too much about order of the later ones.
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-}
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segmentPaths :: (a -> RawFilePath) -> [RawFilePath] -> [a] -> [[a]]
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segmentPaths = segmentPaths' (\_ r -> r)
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segmentPaths' :: (Maybe RawFilePath -> a -> r) -> (a -> RawFilePath) -> [RawFilePath] -> [a] -> [[r]]
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segmentPaths' f _ [] new = [map (f Nothing) new]
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segmentPaths' f _ [i] new = [map (f (Just i)) new] -- optimisation
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segmentPaths' f c (i:is) new =
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map (f (Just i)) found : segmentPaths' f c is rest
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where
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(found, rest) = if length is < 100
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then partition ini new
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else break (not . ini) new
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ini p = i `dirContains` c p
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{- This assumes that it's cheaper to call segmentPaths on the result,
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- than it would be to run the action separately with each path. In
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- the case of git file list commands, that assumption tends to hold.
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-}
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runSegmentPaths :: (a -> RawFilePath) -> ([RawFilePath] -> IO [a]) -> [RawFilePath] -> IO [[a]]
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runSegmentPaths c a paths = segmentPaths c paths <$> a paths
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runSegmentPaths' :: (Maybe RawFilePath -> a -> r) -> (a -> RawFilePath) -> ([RawFilePath] -> IO [a]) -> [RawFilePath] -> IO [[r]]
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runSegmentPaths' si c a paths = segmentPaths' si c paths <$> a paths
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{- Checks if a command is available in PATH.
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-
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- The command may be fully-qualified, in which case, this succeeds as
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- long as it exists. -}
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inPath :: String -> IO Bool
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inPath command = isJust <$> searchPath command
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{- Finds a command in PATH and returns the full path to it.
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-
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- The command may be fully qualified already, in which case it will
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- be returned if it exists.
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-
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- Note that this will find commands in PATH that are not executable.
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-}
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searchPath :: String -> IO (Maybe FilePath)
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searchPath command
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| P.isAbsolute command = check command
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| otherwise = P.getSearchPath >>= getM indir
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where
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indir d = check $ d P.</> command
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check f = firstM doesFileExist
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#ifdef mingw32_HOST_OS
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[f, f ++ ".exe"]
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#else
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[f]
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#endif
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{- Checks if a filename is a unix dotfile. All files inside dotdirs
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- count as dotfiles. -}
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dotfile :: RawFilePath -> Bool
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dotfile file
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| f == "." = False
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| f == ".." = False
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| f == "" = False
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| otherwise = "." `B.isPrefixOf` f || dotfile (takeDirectory file)
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where
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f = takeFileName file
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{- Similar to splitExtensions, but knows that some things in RawFilePaths
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- after a dot are too long to be extensions. -}
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splitShortExtensions :: RawFilePath -> (RawFilePath, [B.ByteString])
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splitShortExtensions = splitShortExtensions' 5 -- enough for ".jpeg"
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splitShortExtensions' :: Int -> RawFilePath -> (RawFilePath, [B.ByteString])
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splitShortExtensions' maxextension = go []
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where
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go c f
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| len > 0 && len <= maxextension && not (B.null base) =
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go (ext:c) base
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| otherwise = (f, c)
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where
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(base, ext) = splitExtension f
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len = B.length ext
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{- This requires the first path to be absolute, and the
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- second path cannot contain ../ or ./
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-
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- On Windows, if the paths are on different drives,
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- a relative path is not possible and the path is simply
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- returned as-is.
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-}
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relPathDirToFileAbs :: RawFilePath -> RawFilePath -> RawFilePath
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relPathDirToFileAbs from to
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#ifdef mingw32_HOST_OS
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| normdrive from /= normdrive to = to
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#endif
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| otherwise = joinPath $ dotdots ++ uncommon
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where
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pfrom = sp from
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pto = sp to
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sp = map dropTrailingPathSeparator . splitPath . dropDrive
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common = map fst $ takeWhile same $ zip pfrom pto
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same (c,d) = c == d
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uncommon = drop numcommon pto
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dotdots = replicate (length pfrom - numcommon) ".."
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numcommon = length common
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#ifdef mingw32_HOST_OS
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normdrive = map toLower . takeWhile (/= ':') . fromRawFilePath . takeDrive
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#endif
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