84 lines
2 KiB
Haskell
84 lines
2 KiB
Haskell
{- portable environment variables
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-
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- Copyright 2013 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 CPP #-}
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{-# OPTIONS_GHC -fno-warn-tabs #-}
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module Utility.Env where
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#ifdef mingw32_HOST_OS
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import Utility.Exception
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import Control.Applicative
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import Data.Maybe
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import Prelude
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import qualified System.Environment as E
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import qualified System.SetEnv
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#else
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import qualified System.Posix.Env as PE
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#endif
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getEnv :: String -> IO (Maybe String)
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#ifndef mingw32_HOST_OS
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getEnv = PE.getEnv
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#else
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getEnv = catchMaybeIO . E.getEnv
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#endif
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getEnvDefault :: String -> String -> IO String
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#ifndef mingw32_HOST_OS
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getEnvDefault = PE.getEnvDefault
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#else
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getEnvDefault var fallback = fromMaybe fallback <$> getEnv var
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#endif
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getEnvironment :: IO [(String, String)]
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#ifndef mingw32_HOST_OS
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getEnvironment = PE.getEnvironment
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#else
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getEnvironment = E.getEnvironment
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#endif
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{- Sets an environment variable. To overwrite an existing variable,
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- overwrite must be True.
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-
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- On Windows, setting a variable to "" unsets it. -}
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setEnv :: String -> String -> Bool -> IO ()
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#ifndef mingw32_HOST_OS
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setEnv var val overwrite = PE.setEnv var val overwrite
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#else
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setEnv var val True = System.SetEnv.setEnv var val
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setEnv var val False = do
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r <- getEnv var
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case r of
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Nothing -> setEnv var val True
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Just _ -> return ()
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#endif
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unsetEnv :: String -> IO ()
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#ifndef mingw32_HOST_OS
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unsetEnv = PE.unsetEnv
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#else
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unsetEnv = System.SetEnv.unsetEnv
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#endif
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{- Adds the environment variable to the input environment. If already
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- present in the list, removes the old value.
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-
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- This does not really belong here, but Data.AssocList is for some reason
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- buried inside hxt.
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-}
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addEntry :: Eq k => k -> v -> [(k, v)] -> [(k, v)]
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addEntry k v l = ( (k,v) : ) $! delEntry k l
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addEntries :: Eq k => [(k, v)] -> [(k, v)] -> [(k, v)]
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addEntries = foldr (.) id . map (uncurry addEntry) . reverse
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delEntry :: Eq k => k -> [(k, v)] -> [(k, v)]
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delEntry _ [] = []
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delEntry k (x@(k1,_) : rest)
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| k == k1 = rest
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| otherwise = ( x : ) $! delEntry k rest
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