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-rw-r--r--ListPath.hs72
1 files changed, 72 insertions, 0 deletions
diff --git a/ListPath.hs b/ListPath.hs
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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 EnvUtils
+
+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 <- EnvUtils.getEnv $ name options
+ mapM_ printPath $ EnvUtils.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"
+ ]