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{-
- Copyright 2015 Egor Tensin <Egor.Tensin@gmail.com>
- This file is licensed under the terms of the MIT License.
- See LICENSE.txt for details.
-}
module Main (main) where
import System.Console.GetOpt
import System.Directory (doesDirectoryExist)
import System.Environment (getArgs, getProgName)
import System.Exit (exitFailure, exitSuccess)
import System.IO (hPutStr, stderr)
import qualified Environment
main :: IO ()
main = do
rawArgs <- getArgs
case getOpt Permute optionDescription rawArgs of
(actions, args, []) -> do
options <- foldl (>>=) (return defaultOptions) actions
case args of
[] -> listPath options
_ -> invalidNumberOfArguments
(_, _, errorMessages) -> exitWithUsageErrors errorMessages
listPath :: Options -> IO ()
listPath options = do
val <- Environment.getEnv $ name options
mapM_ printPath $ Environment.splitPaths val
where
printPath p = do
exists <- doesDirectoryExist p
putStrLn $ (if exists then "+" else "-") ++ " " ++ p
data Options = Options { name :: String } deriving (Eq, Show)
defaultOptions :: Options
defaultOptions = Options { name = "PATH" }
buildHelpMessage :: IO String
buildHelpMessage = do
header <- buildHeader
return $ usageInfo header optionDescription
where
buildHeader :: IO String
buildHeader = do
progName <- getProgName
return $ "Usage: " ++ progName ++ " [OPTIONS...]\nOptions:"
exitWithHelpMessage :: a -> IO b
exitWithHelpMessage _ = do
helpMessage <- buildHelpMessage
putStr helpMessage
exitSuccess
exitWithUsageErrors :: [String] -> IO a
exitWithUsageErrors errorMessages = do
hPutStr stderr $ concatMap ("Usage error: " ++) errorMessages
helpMessage <- buildHelpMessage
hPutStr stderr helpMessage
exitFailure
invalidNumberOfArguments :: IO a
invalidNumberOfArguments = exitWithUsageErrors ["invalid number of arguments\n"]
optionDescription :: [OptDescr (Options -> IO Options)]
optionDescription =
[ Option "n" ["name"] (ReqArg (\s opts -> return opts { name = s }) "NAME") "set the variable name ('PATH' by default)"
, Option "h" ["help"] (NoArg exitWithHelpMessage) "show this message and exit"
]
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