From 7c12f0ac9224246dac308e837bccb5b2157062ee Mon Sep 17 00:00:00 2001
From: Joey Hess <id@joeyh.name>
Date: Tue, 15 Dec 2015 17:47:59 -0700
Subject: Import git-repair_1.20151215.orig.tar.xz

[dgit import orig git-repair_1.20151215.orig.tar.xz]
---
 Utility/Exception.hs | 99 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 99 insertions(+)
 create mode 100644 Utility/Exception.hs

(limited to 'Utility/Exception.hs')

diff --git a/Utility/Exception.hs b/Utility/Exception.hs
new file mode 100644
index 0000000..8b110ae
--- /dev/null
+++ b/Utility/Exception.hs
@@ -0,0 +1,99 @@
+{- Simple IO exception handling (and some more)
+ -
+ - Copyright 2011-2015 Joey Hess <id@joeyh.name>
+ -
+ - License: BSD-2-clause
+ -}
+
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# OPTIONS_GHC -fno-warn-tabs #-}
+
+module Utility.Exception (
+	module X,
+	catchBoolIO,
+	catchMaybeIO,
+	catchDefaultIO,
+	catchMsgIO,
+	catchIO,
+	tryIO,
+	bracketIO,
+	catchNonAsync,
+	tryNonAsync,
+	tryWhenExists,
+	catchIOErrorType,
+	IOErrorType(..)
+) where
+
+import Control.Monad.Catch as X hiding (Handler)
+import qualified Control.Monad.Catch as M
+import Control.Exception (IOException, AsyncException)
+import Control.Monad
+import Control.Monad.IO.Class (liftIO, MonadIO)
+import System.IO.Error (isDoesNotExistError, ioeGetErrorType)
+import GHC.IO.Exception (IOErrorType(..))
+
+import Utility.Data
+
+{- Catches IO errors and returns a Bool -}
+catchBoolIO :: MonadCatch m => m Bool -> m Bool
+catchBoolIO = catchDefaultIO False
+
+{- Catches IO errors and returns a Maybe -}
+catchMaybeIO :: MonadCatch m => m a -> m (Maybe a)
+catchMaybeIO a = catchDefaultIO Nothing $ a >>= (return . Just)
+
+{- Catches IO errors and returns a default value. -}
+catchDefaultIO :: MonadCatch m => a -> m a -> m a
+catchDefaultIO def a = catchIO a (const $ return def)
+
+{- Catches IO errors and returns the error message. -}
+catchMsgIO :: MonadCatch m => m a -> m (Either String a)
+catchMsgIO a = do
+	v <- tryIO a
+	return $ either (Left . show) Right v
+
+{- catch specialized for IO errors only -}
+catchIO :: MonadCatch m => m a -> (IOException -> m a) -> m a
+catchIO = M.catch
+
+{- try specialized for IO errors only -}
+tryIO :: MonadCatch m => m a -> m (Either IOException a)
+tryIO = M.try
+
+{- bracket with setup and cleanup actions lifted to IO.
+ -
+ - Note that unlike catchIO and tryIO, this catches all exceptions. -}
+bracketIO :: (MonadMask m, MonadIO m) => IO v -> (v -> IO b) -> (v -> m a) -> m a
+bracketIO setup cleanup = bracket (liftIO setup) (liftIO . cleanup)
+
+{- Catches all exceptions except for async exceptions.
+ - This is often better to use than catching them all, so that
+ - ThreadKilled and UserInterrupt get through.
+ -}
+catchNonAsync :: MonadCatch m => m a -> (SomeException -> m a) -> m a
+catchNonAsync a onerr = a `catches`
+	[ M.Handler (\ (e :: AsyncException) -> throwM e)
+	, M.Handler (\ (e :: SomeException) -> onerr e)
+	]
+
+tryNonAsync :: MonadCatch m => m a -> m (Either SomeException a)
+tryNonAsync a = go `catchNonAsync` (return . Left)
+  where
+	go = do
+		v <- a
+		return (Right v)
+
+{- Catches only DoesNotExist exceptions, and lets all others through. -}
+tryWhenExists :: MonadCatch m => m a -> m (Maybe a)
+tryWhenExists a = do
+	v <- tryJust (guard . isDoesNotExistError) a
+	return (eitherToMaybe v)
+
+{- Catches only IO exceptions of a particular type.
+ - Ie, use HardwareFault to catch disk IO errors. -}
+catchIOErrorType :: MonadCatch m => IOErrorType -> (IOException -> m a) -> m a -> m a
+catchIOErrorType errtype onmatchingerr a = catchIO a onlymatching
+  where
+	onlymatching e
+		| ioeGetErrorType e == errtype = onmatchingerr e
+		| otherwise = throwM e
-- 
cgit v1.2.3