304 lines
8.2 KiB
Haskell
304 lines
8.2 KiB
Haskell
{-# LANGUAGE TemplateHaskell #-}
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{-# LANGUAGE DeriveGeneric #-}
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{-# LANGUAGE DeriveDataTypeable #-}
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{-# LANGUAGE EmptyDataDecls #-}
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-- | A normalizing well-typed path type.
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module Path
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(-- * Types
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Path
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,Abs
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,Rel
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,File
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,Dir
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-- * Parsing
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,parseAbsDir
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,parseRelDir
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,parseAbsFile
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,parseRelFile
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,PathParseException
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-- * Constructors
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,mkAbsDir
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,mkRelDir
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,mkAbsFile
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,mkRelFile
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-- * Operations
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,(</>)
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,stripDir
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,isParentOf
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,parent
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,filename
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,dirname
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-- * Conversion
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,toFilePath
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)
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where
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import Control.Exception (Exception)
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import Control.Monad.Catch (MonadThrow(..))
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import Data.Data
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import Data.List
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import Data.Maybe
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import Language.Haskell.TH
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import Path.Internal
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import qualified System.FilePath as FilePath
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--------------------------------------------------------------------------------
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-- Types
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-- | An absolute path.
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data Abs deriving (Typeable)
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-- | A relative path; one without a root.
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data Rel deriving (Typeable)
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-- | A file path.
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data File deriving (Typeable)
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-- | A directory path.
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data Dir deriving (Typeable)
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-- | Exception when parsing a location.
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data PathParseException
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= InvalidAbsDir FilePath
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| InvalidRelDir FilePath
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| InvalidAbsFile FilePath
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| InvalidRelFile FilePath
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| Couldn'tStripPrefixDir FilePath FilePath
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deriving (Show,Typeable)
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instance Exception PathParseException
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--------------------------------------------------------------------------------
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-- Parsers
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-- | Get a location for an absolute directory. Produces a normalized
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-- path which always ends in a path separator.
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--
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-- Throws: 'PathParseException'
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--
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parseAbsDir :: MonadThrow m
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=> FilePath -> m (Path Abs Dir)
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parseAbsDir filepath =
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if FilePath.isAbsolute filepath &&
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not (null (normalizeDir filepath)) &&
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not (isPrefixOf "~/" filepath) &&
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not (isSuffixOf "/.." filepath) &&
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not (isInfixOf "/../" filepath) &&
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not (isPrefixOf "../" filepath)
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then return (Path (normalizeDir filepath))
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else throwM (InvalidAbsDir filepath)
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-- | Get a location for a relative directory. Produces a normalized
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-- path which always ends in a path separator.
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--
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-- Throws: 'PathParseException'
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--
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parseRelDir :: MonadThrow m
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=> FilePath -> m (Path Rel Dir)
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parseRelDir filepath =
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if not (FilePath.isAbsolute filepath) &&
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not (null filepath) &&
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not (isPrefixOf "~/" filepath) &&
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not (isPrefixOf "../" filepath) &&
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not (isSuffixOf "/.." filepath) &&
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not (isInfixOf "/../" filepath) &&
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not (null (normalizeDir filepath)) &&
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filepath /= ".."
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then return (Path (normalizeDir filepath))
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else throwM (InvalidRelDir filepath)
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-- | Get a location for an absolute file.
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--
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-- Throws: 'PathParseException'
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--
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parseAbsFile :: MonadThrow m
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=> FilePath -> m (Path Abs File)
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parseAbsFile filepath =
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if FilePath.isAbsolute filepath &&
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not (FilePath.hasTrailingPathSeparator filepath) &&
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not (isPrefixOf "~/" filepath) &&
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not (isPrefixOf "../" filepath) &&
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not (isSuffixOf "/.." filepath) &&
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not (isInfixOf "/../" filepath) &&
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not (null (normalizeFile filepath)) &&
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filepath /= ".."
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then return (Path (normalizeFile filepath))
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else throwM (InvalidAbsFile filepath)
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-- | Get a location for a relative file.
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--
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-- Throws: 'PathParseException'
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--
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parseRelFile :: MonadThrow m
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=> FilePath -> m (Path Rel File)
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parseRelFile filepath =
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if not (FilePath.isAbsolute filepath ||
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FilePath.hasTrailingPathSeparator filepath) &&
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not (null filepath) &&
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not (isPrefixOf "~/" filepath) &&
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not (isPrefixOf "../" filepath) &&
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not (isInfixOf "/../" filepath) &&
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not (isSuffixOf "/.." filepath) &&
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not (isInfixOf "/../" filepath) &&
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not (null (normalizeFile filepath)) &&
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filepath /= ".."
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then return (Path (normalizeFile filepath))
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else throwM (InvalidRelFile filepath)
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--------------------------------------------------------------------------------
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-- Constructors
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-- | Make a 'Path Abs Dir'.
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--
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-- Remember: due to the nature of absolute paths this (e.g. @\/home\/foo@)
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-- may compile on your platform, but it may not compile on another
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-- platform (Windows).
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mkAbsDir :: FilePath -> Q Exp
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mkAbsDir s =
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case parseAbsDir s of
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Left err -> error (show err)
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Right (Path str) ->
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[|Path $(return (LitE (StringL str))) :: Path Abs Dir|]
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-- | Make a 'Path Rel Dir'.
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mkRelDir :: FilePath -> Q Exp
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mkRelDir s =
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case parseRelDir s of
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Left err -> error (show err)
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Right (Path str) ->
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[|Path $(return (LitE (StringL str))) :: Path Rel Dir|]
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-- | Make a 'Path Abs File'.
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--
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-- Remember: due to the nature of absolute paths this (e.g. @\/home\/foo@)
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-- may compile on your platform, but it may not compile on another
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-- platform (Windows).
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mkAbsFile :: FilePath -> Q Exp
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mkAbsFile s =
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case parseAbsFile s of
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Left err -> error (show err)
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Right (Path str) ->
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[|Path $(return (LitE (StringL str))) :: Path Abs File|]
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-- | Make a 'Path Rel File'.
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mkRelFile :: FilePath -> Q Exp
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mkRelFile s =
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case parseRelFile s of
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Left err -> error (show err)
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Right (Path str) ->
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[|Path $(return (LitE (StringL str))) :: Path Rel File|]
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--------------------------------------------------------------------------------
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-- Conversion
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-- | Convert to a 'FilePath' type.
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toFilePath :: Path b t -> FilePath
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toFilePath (Path l) = l
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--------------------------------------------------------------------------------
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-- Operations
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-- | Append two paths.
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--
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-- The following cases are valid and the equalities hold:
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--
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-- @$(mkAbsDir x) \<\/> $(mkRelDir y) = $(mkAbsDir (x ++ \"/\" ++ y))@
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--
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-- @$(mkAbsDir x) \<\/> $(mkRelFile y) = $(mkAbsFile (x ++ \"/\" ++ y))@
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--
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-- @$(mkRelDir x) \<\/> $(mkRelDir y) = $(mkRelDir (x ++ \"/\" ++ y))@
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--
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-- @$(mkRelDir x) \<\/> $(mkRelFile y) = $(mkRelFile (x ++ \"/\" ++ y))@
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--
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-- The following are proven not possible to express:
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--
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-- @$(mkAbsFile …) \<\/> x@
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--
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-- @$(mkRelFile …) \<\/> x@
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--
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-- @x \<\/> $(mkAbsFile …)@
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--
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-- @x \<\/> $(mkAbsDir …)@
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--
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(</>) :: Path b Dir -> Path Rel t -> Path b t
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(</>) (Path a) (Path b) = Path (a ++ b)
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-- | Strip directory from path, making it relative to that directory.
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-- Returns 'Nothing' if directory is not a parent of the path.
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--
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-- The following properties hold:
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--
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-- @stripDir parent (parent \<\/> child) = child@
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--
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-- Cases which are proven not possible:
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--
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-- @stripDir (a :: Path Abs …) (b :: Path Rel …)@
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--
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-- @stripDir (a :: Path Rel …) (b :: Path Abs …)@
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--
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-- In other words the bases must match.
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--
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stripDir :: Path b Dir -> Path b t -> Maybe (Path Rel t)
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stripDir (Path p) (Path l) =
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fmap Path (stripPrefix p l)
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-- | Is p a parent of the given location? Implemented in terms of
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-- 'stripDir'. The bases must match.
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isParentOf :: Path b Dir -> Path b t -> Bool
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isParentOf p l =
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isJust (stripDir p l)
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-- | Take the absolute parent directory from the absolute path.
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--
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-- The following properties hold:
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--
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-- @parent (parent \<\/> child) == parent@
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--
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-- On the root, getting the parent is idempotent:
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--
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-- @parent (parent \"\/\") = \"\/\"@
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--
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parent :: Path Abs t -> Path Abs Dir
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parent (Path fp) =
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Path (normalizeDir (FilePath.takeDirectory (FilePath.dropTrailingPathSeparator fp)))
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-- | Extract the file part of a path.
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--
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-- The following properties hold:
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--
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-- @filename (parent \<\/> filename a) == a@
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--
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filename :: Path b File -> Path Rel File
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filename (Path l) =
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Path (normalizeFile (FilePath.takeFileName l))
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-- | Extract the last directory name of a path.
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--
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-- The following properties hold:
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--
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-- @dirname (parent \<\/> dirname a) == a@
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--
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dirname :: Path b Dir -> Path Rel Dir
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dirname (Path l) =
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Path (last (FilePath.splitPath l))
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--------------------------------------------------------------------------------
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-- Internal functions
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-- | Internal use for normalizing a directory.
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normalizeDir :: FilePath -> FilePath
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normalizeDir =
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clean . FilePath.addTrailingPathSeparator . FilePath.normalise
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where clean "./" = ""
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clean ('/':'/':xs) = clean ('/':xs)
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clean x = x
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-- | Internal use for normalizing a fileectory.
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normalizeFile :: FilePath -> FilePath
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normalizeFile =
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clean . FilePath.normalise
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where clean "./" = ""
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clean ('/':'/':xs) = clean ('/':xs)
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clean x = x
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