hpath/src/Path.hs

314 lines
8.5 KiB
Haskell
Raw Normal View History

{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE EmptyDataDecls #-}
2015-05-07 18:14:23 +00:00
-- | A normalizing well-typed path type.
module Path
(-- * Types
Path
,Abs
,Rel
,File
,Dir
-- * Parsing
,parseAbsDir
,parseRelDir
,parseAbsFile
,parseRelFile
,PathParseException
-- * Constructors
,mkAbsDir
,mkRelDir
,mkAbsFile
,mkRelFile
2015-05-08 11:33:37 +00:00
-- * Operations
,(</>)
,stripDir
,isParentOf
2015-05-11 16:29:15 +00:00
,parent
2015-05-08 11:33:37 +00:00
,filename
2015-05-11 16:59:26 +00:00
,dirname
-- * Conversion
,toFilePath
)
where
import Control.Exception (Exception)
import Control.Monad.Catch (MonadThrow(..))
import Data.Data
import Data.List
2015-05-08 11:33:37 +00:00
import Data.Maybe
import Language.Haskell.TH
import Path.Internal
import qualified System.FilePath as FilePath
--------------------------------------------------------------------------------
-- Types
-- | An absolute path.
2015-05-11 06:47:17 +00:00
data Abs deriving (Typeable)
-- | A relative path; one without a root.
2015-05-11 06:47:17 +00:00
data Rel deriving (Typeable)
-- | A file path.
2015-05-11 06:47:17 +00:00
data File deriving (Typeable)
-- | A directory path.
2015-05-11 06:47:17 +00:00
data Dir deriving (Typeable)
-- | Exception when parsing a location.
data PathParseException
= InvalidAbsDir FilePath
| InvalidRelDir FilePath
| InvalidAbsFile FilePath
| InvalidRelFile FilePath
2015-05-22 09:32:41 +00:00
| Couldn'tStripPrefixDir FilePath FilePath
deriving (Show,Typeable)
instance Exception PathParseException
--------------------------------------------------------------------------------
-- Parsers
-- | Get a location for an absolute directory. Produces a normalized
-- path which always ends in a path separator.
--
-- Throws: 'PathParseException'
--
parseAbsDir :: MonadThrow m
=> FilePath -> m (Path Abs Dir)
parseAbsDir filepath =
if FilePath.isAbsolute filepath &&
not (null (normalizeDir filepath)) &&
2015-05-22 09:32:41 +00:00
not (isPrefixOf "~/" filepath) &&
not (hasParentDir filepath) &&
then return (Path (normalizeDir filepath))
else throwM (InvalidAbsDir filepath)
-- | Get a location for a relative directory. Produces a normalized
-- path which always ends in a path separator.
--
-- Throws: 'PathParseException'
--
parseRelDir :: MonadThrow m
=> FilePath -> m (Path Rel Dir)
parseRelDir filepath =
if not (FilePath.isAbsolute filepath) &&
not (null filepath) &&
not (isPrefixOf "~/" filepath) &&
not (hasParentDir filepath) &&
2015-05-22 09:32:41 +00:00
not (null (normalizeDir filepath)) &&
filepath /= ".."
then return (Path (normalizeDir filepath))
else throwM (InvalidRelDir filepath)
2015-05-08 13:57:03 +00:00
-- | Get a location for an absolute file.
--
-- Throws: 'PathParseException'
--
parseAbsFile :: MonadThrow m
=> FilePath -> m (Path Abs File)
parseAbsFile filepath =
if FilePath.isAbsolute filepath &&
not (FilePath.hasTrailingPathSeparator filepath) &&
not (isPrefixOf "~/" filepath) &&
not (hasParentDir filepath) &&
2015-05-22 09:32:41 +00:00
not (null (normalizeFile filepath)) &&
filepath /= ".."
then return (Path (normalizeFile filepath))
else throwM (InvalidAbsFile filepath)
2015-05-08 13:57:03 +00:00
-- | Get a location for a relative file.
--
-- Throws: 'PathParseException'
--
parseRelFile :: MonadThrow m
=> FilePath -> m (Path Rel File)
parseRelFile filepath =
2015-05-22 09:32:41 +00:00
if not (FilePath.isAbsolute filepath ||
FilePath.hasTrailingPathSeparator filepath) &&
not (null filepath) &&
not (isPrefixOf "~/" filepath) &&
not (hasParentDir filepath) &&
2015-05-22 09:32:41 +00:00
not (null (normalizeFile filepath)) &&
filepath /= ".."
then return (Path (normalizeFile filepath))
else throwM (InvalidRelFile filepath)
-- | Helper function: check if the filepath has any parent directories in it.
-- This handles the logic of checking for different path separators on Windows.
hasParentDir :: FilePath -> Bool
hasParentDir filepath' =
(isSuffixOf "/.." filepath) ||
(isInfixOf "/../" filepath) ||
(isPrefixOf "../" filepath)
where
filepath =
case FilePath.pathSeparator of
'/' -> filepath'
x -> map (\y -> if x == y then '/' else y) filepath'
--------------------------------------------------------------------------------
-- Constructors
-- | Make a 'Path Abs Dir'.
--
-- Remember: due to the nature of absolute paths this (e.g. @\/home\/foo@)
-- may compile on your platform, but it may not compile on another
-- platform (Windows).
mkAbsDir :: FilePath -> Q Exp
mkAbsDir s =
case parseAbsDir s of
Left err -> error (show err)
Right (Path str) ->
[|Path $(return (LitE (StringL str))) :: Path Abs Dir|]
-- | Make a 'Path Rel Dir'.
mkRelDir :: FilePath -> Q Exp
mkRelDir s =
case parseRelDir s of
Left err -> error (show err)
Right (Path str) ->
[|Path $(return (LitE (StringL str))) :: Path Rel Dir|]
-- | Make a 'Path Abs File'.
--
-- Remember: due to the nature of absolute paths this (e.g. @\/home\/foo@)
-- may compile on your platform, but it may not compile on another
-- platform (Windows).
mkAbsFile :: FilePath -> Q Exp
mkAbsFile s =
case parseAbsFile s of
Left err -> error (show err)
Right (Path str) ->
[|Path $(return (LitE (StringL str))) :: Path Abs File|]
-- | Make a 'Path Rel File'.
mkRelFile :: FilePath -> Q Exp
mkRelFile s =
case parseRelFile s of
Left err -> error (show err)
Right (Path str) ->
[|Path $(return (LitE (StringL str))) :: Path Rel File|]
--------------------------------------------------------------------------------
-- Conversion
-- | Convert to a 'FilePath' type.
toFilePath :: Path b t -> FilePath
toFilePath (Path l) = l
2015-05-08 11:33:37 +00:00
--------------------------------------------------------------------------------
-- Operations
-- | Append two paths.
--
-- The following cases are valid and the equalities hold:
--
-- @$(mkAbsDir x) \<\/> $(mkRelDir y) = $(mkAbsDir (x ++ \"/\" ++ y))@
--
-- @$(mkAbsDir x) \<\/> $(mkRelFile y) = $(mkAbsFile (x ++ \"/\" ++ y))@
--
-- @$(mkRelDir x) \<\/> $(mkRelDir y) = $(mkRelDir (x ++ \"/\" ++ y))@
--
-- @$(mkRelDir x) \<\/> $(mkRelFile y) = $(mkRelFile (x ++ \"/\" ++ y))@
--
-- The following are proven not possible to express:
--
-- @$(mkAbsFile …) \<\/> x@
--
-- @$(mkRelFile …) \<\/> x@
--
-- @x \<\/> $(mkAbsFile …)@
--
-- @x \<\/> $(mkAbsDir …)@
--
(</>) :: Path b Dir -> Path Rel t -> Path b t
(</>) (Path a) (Path b) = Path (a ++ b)
-- | Strip directory from path, making it relative to that directory.
-- Returns 'Nothing' if directory is not a parent of the path.
--
-- The following properties hold:
--
2015-05-11 06:47:17 +00:00
-- @stripDir parent (parent \<\/> child) = child@
2015-05-08 11:33:37 +00:00
--
-- Cases which are proven not possible:
--
-- @stripDir (a :: Path Abs …) (b :: Path Rel …)@
--
2015-05-14 15:44:41 +00:00
-- @stripDir (a :: Path Rel …) (b :: Path Abs …)@
2015-05-08 11:33:37 +00:00
--
-- In other words the bases must match.
--
2015-05-22 09:32:57 +00:00
-- Throws: 'Couldn'tStripPrefixDir'
--
stripDir :: MonadThrow m
=> Path b Dir -> Path b t -> m (Path Rel t)
2015-05-08 11:33:37 +00:00
stripDir (Path p) (Path l) =
2015-05-27 15:08:03 +00:00
case stripPrefix p l of
2015-05-22 09:32:57 +00:00
Nothing -> throwM (Couldn'tStripPrefixDir p l)
2015-05-27 15:08:03 +00:00
Just "" -> throwM (Couldn'tStripPrefixDir p l)
Just ok -> return (Path ok)
2015-05-08 11:33:37 +00:00
-- | Is p a parent of the given location? Implemented in terms of
-- 'stripDir'. The bases must match.
isParentOf :: Path b Dir -> Path b t -> Bool
isParentOf p l =
isJust (stripDir p l)
-- | Take the absolute parent directory from the absolute path.
--
-- The following properties hold:
--
2015-05-11 16:29:15 +00:00
-- @parent (parent \<\/> child) == parent@
2015-05-08 11:33:37 +00:00
--
-- On the root, getting the parent is idempotent:
--
2015-05-11 16:29:15 +00:00
-- @parent (parent \"\/\") = \"\/\"@
2015-05-08 11:33:37 +00:00
--
2015-05-11 16:29:15 +00:00
parent :: Path Abs t -> Path Abs Dir
parent (Path fp) =
2015-05-08 11:33:37 +00:00
Path (normalizeDir (FilePath.takeDirectory (FilePath.dropTrailingPathSeparator fp)))
2015-05-11 16:29:15 +00:00
-- | Extract the file part of a path.
2015-05-08 11:33:37 +00:00
--
-- The following properties hold:
--
-- @filename (parent \<\/> filename a) == a@
--
filename :: Path b File -> Path Rel File
2015-05-11 16:59:26 +00:00
filename (Path l) =
Path (normalizeFile (FilePath.takeFileName l))
-- | Extract the last directory name of a path.
--
-- The following properties hold:
--
-- @dirname (parent \<\/> dirname a) == a@
--
dirname :: Path b Dir -> Path Rel Dir
dirname (Path l) =
Path (last (FilePath.splitPath l))
2015-05-08 11:33:37 +00:00
--------------------------------------------------------------------------------
-- Internal functions
-- | Internal use for normalizing a directory.
normalizeDir :: FilePath -> FilePath
normalizeDir =
clean . FilePath.addTrailingPathSeparator . FilePath.normalise
where clean "./" = ""
clean ('/':'/':xs) = clean ('/':xs)
clean x = x
-- | Internal use for normalizing a fileectory.
normalizeFile :: FilePath -> FilePath
normalizeFile =
clean . FilePath.normalise
where clean "./" = ""
clean ('/':'/':xs) = clean ('/':xs)
clean x = x