/usr/lib/hugs/packages/base/System/IO/Error.hs is in libhugs-base-bundled 98.200609.21-5.4+b3.
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-----------------------------------------------------------------------------
-- |
-- Module : System.IO.Error
-- Copyright : (c) The University of Glasgow 2001
-- License : BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer : libraries@haskell.org
-- Stability : provisional
-- Portability : portable
--
-- Standard IO Errors.
--
-----------------------------------------------------------------------------
module System.IO.Error (
-- * I\/O errors
IOError, -- = IOException
userError, -- :: String -> IOError
mkIOError, -- :: IOErrorType -> String -> Maybe Handle
-- -> Maybe FilePath -> IOError
annotateIOError, -- :: IOError -> String -> Maybe Handle
-- -> Maybe FilePath -> IOError
-- ** Classifying I\/O errors
isAlreadyExistsError, -- :: IOError -> Bool
isDoesNotExistError,
isAlreadyInUseError,
isFullError,
isEOFError,
isIllegalOperation,
isPermissionError,
isUserError,
-- ** Attributes of I\/O errors
ioeGetErrorType, -- :: IOError -> IOErrorType
ioeGetErrorString, -- :: IOError -> String
ioeGetHandle, -- :: IOError -> Maybe Handle
ioeGetFileName, -- :: IOError -> Maybe FilePath
ioeSetErrorType, -- :: IOError -> IOErrorType -> IOError
ioeSetErrorString, -- :: IOError -> String -> IOError
ioeSetHandle, -- :: IOError -> Handle -> IOError
ioeSetFileName, -- :: IOError -> FilePath -> IOError
-- * Types of I\/O error
IOErrorType, -- abstract
alreadyExistsErrorType, -- :: IOErrorType
doesNotExistErrorType,
alreadyInUseErrorType,
fullErrorType,
eofErrorType,
illegalOperationErrorType,
permissionErrorType,
userErrorType,
-- ** 'IOErrorType' predicates
isAlreadyExistsErrorType, -- :: IOErrorType -> Bool
isDoesNotExistErrorType,
isAlreadyInUseErrorType,
isFullErrorType,
isEOFErrorType,
isIllegalOperationErrorType,
isPermissionErrorType,
isUserErrorType,
-- * Throwing and catching I\/O errors
ioError, -- :: IOError -> IO a
catch, -- :: IO a -> (IOError -> IO a) -> IO a
try, -- :: IO a -> IO (Either IOError a)
modifyIOError, -- :: (IOError -> IOError) -> IO a -> IO a
) where
import Data.Either
import Data.Maybe
import Hugs.Prelude(Handle, IOException(..), IOErrorType(..))
-- | The construct 'try' @comp@ exposes IO errors which occur within a
-- computation, and which are not fully handled.
--
-- Non-I\/O exceptions are not caught by this variant; to catch all
-- exceptions, use 'Control.Exception.try' from "Control.Exception".
try :: IO a -> IO (Either IOError a)
try f = catch (do r <- f
return (Right r))
(return . Left)
-- -----------------------------------------------------------------------------
-- Constructing an IOError
-- | Construct an 'IOError' of the given type where the second argument
-- describes the error location and the third and fourth argument
-- contain the file handle and file path of the file involved in the
-- error if applicable.
mkIOError :: IOErrorType -> String -> Maybe Handle -> Maybe FilePath -> IOError
mkIOError t location maybe_hdl maybe_filename =
IOError{ ioe_type = t,
ioe_location = location,
ioe_description = "",
ioe_handle = maybe_hdl,
ioe_filename = maybe_filename
}
-- -----------------------------------------------------------------------------
-- IOErrorType
-- | An error indicating that an 'IO' operation failed because
-- one of its arguments already exists.
isAlreadyExistsError :: IOError -> Bool
isAlreadyExistsError = isAlreadyExistsErrorType . ioeGetErrorType
-- | An error indicating that an 'IO' operation failed because
-- one of its arguments does not exist.
isDoesNotExistError :: IOError -> Bool
isDoesNotExistError = isDoesNotExistErrorType . ioeGetErrorType
-- | An error indicating that an 'IO' operation failed because
-- one of its arguments is a single-use resource, which is already
-- being used (for example, opening the same file twice for writing
-- might give this error).
isAlreadyInUseError :: IOError -> Bool
isAlreadyInUseError = isAlreadyInUseErrorType . ioeGetErrorType
-- | An error indicating that an 'IO' operation failed because
-- the device is full.
isFullError :: IOError -> Bool
isFullError = isFullErrorType . ioeGetErrorType
-- | An error indicating that an 'IO' operation failed because
-- the end of file has been reached.
isEOFError :: IOError -> Bool
isEOFError = isEOFErrorType . ioeGetErrorType
-- | An error indicating that an 'IO' operation failed because
-- the operation was not possible.
-- Any computation which returns an 'IO' result may fail with
-- 'isIllegalOperation'. In some cases, an implementation will not be
-- able to distinguish between the possible error causes. In this case
-- it should fail with 'isIllegalOperation'.
isIllegalOperation :: IOError -> Bool
isIllegalOperation = isIllegalOperationErrorType . ioeGetErrorType
-- | An error indicating that an 'IO' operation failed because
-- the user does not have sufficient operating system privilege
-- to perform that operation.
isPermissionError :: IOError -> Bool
isPermissionError = isPermissionErrorType . ioeGetErrorType
-- | A programmer-defined error value constructed using 'userError'.
isUserError :: IOError -> Bool
isUserError = isUserErrorType . ioeGetErrorType
-- -----------------------------------------------------------------------------
-- IOErrorTypes
-- | I\/O error where the operation failed because one of its arguments
-- already exists.
alreadyExistsErrorType :: IOErrorType
alreadyExistsErrorType = AlreadyExists
-- | I\/O error where the operation failed because one of its arguments
-- does not exist.
doesNotExistErrorType :: IOErrorType
doesNotExistErrorType = NoSuchThing
-- | I\/O error where the operation failed because one of its arguments
-- is a single-use resource, which is already being used.
alreadyInUseErrorType :: IOErrorType
alreadyInUseErrorType = ResourceBusy
-- | I\/O error where the operation failed because the device is full.
fullErrorType :: IOErrorType
fullErrorType = ResourceExhausted
-- | I\/O error where the operation failed because the end of file has
-- been reached.
eofErrorType :: IOErrorType
eofErrorType = EOF
-- | I\/O error where the operation is not possible.
illegalOperationErrorType :: IOErrorType
illegalOperationErrorType = IllegalOperation
-- | I\/O error where the operation failed because the user does not
-- have sufficient operating system privilege to perform that operation.
permissionErrorType :: IOErrorType
permissionErrorType = PermissionDenied
-- | I\/O error that is programmer-defined.
userErrorType :: IOErrorType
userErrorType = UserError
-- -----------------------------------------------------------------------------
-- IOErrorType predicates
-- | I\/O error where the operation failed because one of its arguments
-- already exists.
isAlreadyExistsErrorType :: IOErrorType -> Bool
isAlreadyExistsErrorType AlreadyExists = True
isAlreadyExistsErrorType _ = False
-- | I\/O error where the operation failed because one of its arguments
-- does not exist.
isDoesNotExistErrorType :: IOErrorType -> Bool
isDoesNotExistErrorType NoSuchThing = True
isDoesNotExistErrorType _ = False
-- | I\/O error where the operation failed because one of its arguments
-- is a single-use resource, which is already being used.
isAlreadyInUseErrorType :: IOErrorType -> Bool
isAlreadyInUseErrorType ResourceBusy = True
isAlreadyInUseErrorType _ = False
-- | I\/O error where the operation failed because the device is full.
isFullErrorType :: IOErrorType -> Bool
isFullErrorType ResourceExhausted = True
isFullErrorType _ = False
-- | I\/O error where the operation failed because the end of file has
-- been reached.
isEOFErrorType :: IOErrorType -> Bool
isEOFErrorType EOF = True
isEOFErrorType _ = False
-- | I\/O error where the operation is not possible.
isIllegalOperationErrorType :: IOErrorType -> Bool
isIllegalOperationErrorType IllegalOperation = True
isIllegalOperationErrorType _ = False
-- | I\/O error where the operation failed because the user does not
-- have sufficient operating system privilege to perform that operation.
isPermissionErrorType :: IOErrorType -> Bool
isPermissionErrorType PermissionDenied = True
isPermissionErrorType _ = False
-- | I\/O error that is programmer-defined.
isUserErrorType :: IOErrorType -> Bool
isUserErrorType UserError = True
isUserErrorType _ = False
-- -----------------------------------------------------------------------------
-- Miscellaneous
ioeGetErrorType :: IOError -> IOErrorType
ioeGetErrorString :: IOError -> String
ioeGetHandle :: IOError -> Maybe Handle
ioeGetFileName :: IOError -> Maybe FilePath
ioeGetErrorType ioe = ioe_type ioe
ioeGetErrorString ioe
| isUserErrorType (ioe_type ioe) = ioe_description ioe
| otherwise = show (ioe_type ioe)
ioeGetHandle ioe = ioe_handle ioe
ioeGetFileName ioe = ioe_filename ioe
ioeSetErrorType :: IOError -> IOErrorType -> IOError
ioeSetErrorString :: IOError -> String -> IOError
ioeSetHandle :: IOError -> Handle -> IOError
ioeSetFileName :: IOError -> FilePath -> IOError
ioeSetErrorType ioe errtype = ioe{ ioe_type = errtype }
ioeSetErrorString ioe str = ioe{ ioe_description = str }
ioeSetHandle ioe hdl = ioe{ ioe_handle = Just hdl }
ioeSetFileName ioe filename = ioe{ ioe_filename = Just filename }
-- | Catch any 'IOError' that occurs in the computation and throw a
-- modified version.
modifyIOError :: (IOError -> IOError) -> IO a -> IO a
modifyIOError f io = catch io (\e -> ioError (f e))
-- -----------------------------------------------------------------------------
-- annotating an IOError
-- | Adds a location description and maybe a file path and file handle
-- to an 'IOError'. If any of the file handle or file path is not given
-- the corresponding value in the 'IOError' remains unaltered.
annotateIOError :: IOError
-> String
-> Maybe Handle
-> Maybe FilePath
-> IOError
annotateIOError (IOError ohdl errTy _ str opath) loc hdl path =
IOError (hdl `mplus` ohdl) errTy loc str (path `mplus` opath)
where
Nothing `mplus` ys = ys
xs `mplus` _ = xs
|