module GraphRewrite.Main.CmdLineOpts
where
import System.Console.GetOpt
import System.Environment
data Options = Options
{ showVersion :: Bool -- ^ just show the version and exit
, inputFile :: Maybe String -- ^ Nothing: stdin
, outputFile :: Maybe String -- ^ Nothing: stdout
, isVerbose :: Bool
}
defaultOptions :: Options
defaultOptions = Options
{ showVersion = False
, inputFile = Nothing
, outputFile = Nothing
, isVerbose = False
}
----------------------------------- possible options
options :: [OptDescr (Options -> Options)]
options =
[ Option ['v'] ["verbose"] (NoArg (\r -> r {isVerbose = True})) "verbose output on stderr"
, Option ['V','?'] ["version"] (NoArg (\r -> r {showVersion = True})) "show version number"
, Option ['o'] ["output"] (ReqArg (\f r -> r {outputFile = Just f}) "FILE") "output FILE"
, Option ['i'] ["input"] (ReqArg (\f r -> r {inputFile = Just f}) "FILE") "input FILE"
]
----------------------------------- parse options
addInput :: String -> Options -> Options
addInput f r = r {inputFile = Just f}
parseOptions :: [String] -> IO Options
parseOptions argv = do
progName <- getProgName
let header = "Usage: " ++ progName ++ " [OPTION...] files..."
case getOpt Permute options argv of
(o,n,[] ) -> let
o' = foldl (flip id) defaultOptions o
o'' = foldl (flip addInput) o' n
in return o''
(_,_,errs) -> error (concat errs ++ usageInfo header options)
{-
id :: (a -> b) -> a -> b
flip id :: a -> (a -> b) -> b
foldl (flip id) :: b -> [b -> b] -> b
foldl (flip id) 3 [(+1),(*2)] == 8
-}
-----------------------------------