----------------------------------------------------------------------------------------- -- A Haskell port of GNU's getopt library -- -- Sven Panne Oct. 1996; last change: Jul. 1998 -- -- Two rather obscure features are missing: The Bash 2.0 non-option hack (if you don't -- already know it, you probably don't want to hear about it...) and the recognition of -- long options with a single dash (e.g. '-help' is recognised as '--help', as long as -- there is no short option 'h'). -- -- Other differences between GNU's getopt and this implementation: -- * To enforce a coherent description of options and arguments, there are explanation -- fields in the option/argument descriptor. -- * Error messages are now more informative, but no longer POSIX compliant... :-( -- -- And a final Haskell advertisement: The GNU C implementation uses well over 1100 lines, -- we need only 199 here, including a 46 line example! :-) ----------------------------------------------------------------------------------------- module GetOpt ( ArgOrder(..), OptDescr(..), ArgDescr(..), usageInfo, getOpt ) where import Data.List(isPrefixOf) data ArgOrder a -- what to do with options following non-options: = RequireOrder -- no option processing after first non-option | Permute -- freely intersperse options and non-options | ReturnInOrder (String -> a) -- wrap non-options into options data OptDescr a = -- description of a single options: Option [Char] -- list of short option characters [String] -- list of long option strings (without "--") (ArgDescr a) -- argument descriptor String -- explanation of option for user data ArgDescr a -- description of an argument option: = NoArg a -- no argument expected | ReqArg (String -> a) String -- option requires argument | OptArg (Maybe String -> a) String -- optional argument data OptKind a -- kind of cmd line arg (internal use only): = Opt a -- an option | NonOpt String -- a non-option | EndOfOpts -- end-of-options marker (i.e. "--") | OptErr String -- something went wrong... usageInfo :: String -- header -> [OptDescr a] -- option descriptors -> String -- nicely formatted decription of options usageInfo header optDescr = unlines (header:table) where (ss,ls,ds) = (unzip3 . map fmtOpt) optDescr table = zipWith3 paste (sameLen ss) (sameLen ls) (sameLen ds) paste x y z = " " ++ x ++ " " ++ y ++ " " ++ z sameLen xs = flushLeft ((maximum . map length) xs) xs flushLeft n xs = [ take n (x ++ repeat ' ') | x <- xs ] fmtOpt :: OptDescr a -> (String,String,String) fmtOpt (Option sos los ad descr) = (sepBy ", " (map (fmtShort ad) sos), sepBy ", " (map (fmtLong ad) los), descr) where sepBy _ [] = "" sepBy _ [x] = x sepBy sep (x:xs) = x ++ sep ++ sepBy sep xs fmtShort :: ArgDescr a -> Char -> String fmtShort (NoArg _ ) so = "-" ++ [so] fmtShort (ReqArg _ ad) so = "-" ++ [so] ++ " " ++ ad fmtShort (OptArg _ ad) so = "-" ++ [so] ++ "[" ++ ad ++ "]" fmtLong :: ArgDescr a -> String -> String fmtLong (NoArg _ ) lo = "--" ++ lo fmtLong (ReqArg _ ad) lo = "--" ++ lo ++ "=" ++ ad fmtLong (OptArg _ ad) lo = "--" ++ lo ++ "[=" ++ ad ++ "]" getOpt :: ArgOrder a -- non-option handling -> [OptDescr a] -- option descriptors -> [String] -- the commandline arguments -> ([a],[String],[String]) -- (options,non-options,error messages) getOpt _ _ [] = ([],[],[]) getOpt ordering optDescr args = procNextOpt opt ordering where procNextOpt (Opt o) _ = (o:os,xs,es) procNextOpt (NonOpt x) RequireOrder = ([],x:rest,[]) procNextOpt (NonOpt x) Permute = (os,x:xs,es) procNextOpt (NonOpt x) (ReturnInOrder f) = (f x :os, xs,es) procNextOpt EndOfOpts RequireOrder = ([],rest,[]) procNextOpt EndOfOpts Permute = ([],rest,[]) procNextOpt EndOfOpts (ReturnInOrder f) = (map f rest,[],[]) procNextOpt (OptErr e) _ = (os,xs,e:es) (opt,rest) = getNext args optDescr (os,xs,es) = getOpt ordering optDescr rest -- take a look at the next cmd line arg and decide what to do with it getNext :: [String] -> [OptDescr a] -> (OptKind a,[String]) getNext (('-':'-':[]):rest) _ = (EndOfOpts,rest) getNext (('-':'-':xs):rest) optDescr = longOpt xs rest optDescr getNext (('-':x:xs) :rest) optDescr = shortOpt x xs rest optDescr getNext (a :rest) _ = (NonOpt a,rest) getNext [] _ = error "getNext: impossible" -- handle long option longOpt :: String -> [String] -> [OptDescr a] -> (OptKind a,[String]) longOpt xs rest optDescr = long ads arg rest where (opt,arg) = break (=='=') xs options = [ o | o@(Option _ ls _ _) <- optDescr, l <- ls, opt `isPrefixOf` l ] ads = [ ad | Option _ _ ad _ <- options ] optStr = ("--"++opt) long (_:_:_) _ rest1 = (errAmbig options optStr,rest1) long [NoArg a ] [] rest1 = (Opt a,rest1) long [NoArg _ ] ('=':_) rest1 = (errNoArg optStr,rest1) long [ReqArg _ d] [] [] = (errReq d optStr,[]) long [ReqArg f _] [] (r:rest1) = (Opt (f r),rest1) long [ReqArg f _] ('=':ys) rest1 = (Opt (f ys),rest1) long [OptArg f _] [] rest1 = (Opt (f Nothing),rest1) long [OptArg f _] ('=':ys) rest1 = (Opt (f (Just ys)),rest1) long [_] (_ :_) _ = error "long: impossible" long [] _ rest1 = (errUnrec optStr,rest1) -- handle short option shortOpt :: Char -> String -> [String] -> [OptDescr a] -> (OptKind a,[String]) shortOpt x xs rest optDescr = short ads xs rest where options = [ o | o@(Option ss _ _ _) <- optDescr, s <- ss, x == s ] ads = [ ad | Option _ _ ad _ <- options ] optStr = '-':[x] short (_:_:_) _ rest1 = (errAmbig options optStr,rest1) short (NoArg a :_) [] rest1 = (Opt a,rest1) short (NoArg a :_) ys rest1 = (Opt a,('-':ys):rest1) short (ReqArg _ d:_) [] [] = (errReq d optStr,[]) short (ReqArg f _:_) [] (r:rest1) = (Opt (f r),rest1) short (ReqArg f _:_) ys rest1 = (Opt (f ys),rest1) short (OptArg f _:_) [] rest1 = (Opt (f Nothing),rest1) short (OptArg f _:_) ys rest1 = (Opt (f (Just ys)),rest1) short [] [] rest1 = (errUnrec optStr,rest1) short [] ys rest1 = (errUnrec optStr,('-':ys):rest1) -- miscellaneous error formatting errAmbig :: [OptDescr a] -> String -> OptKind a errAmbig ods optStr = OptErr (usageInfo header ods) where header = "option `" ++ optStr ++ "' is ambiguous; could be one of:" errReq :: String -> String -> OptKind a errReq d optStr = OptErr ("option `" ++ optStr ++ "' requires an argument " ++ d ++ "\n") errUnrec :: String -> OptKind a errUnrec optStr = OptErr ("unrecognized option `" ++ optStr ++ "'\n") errNoArg :: String -> OptKind a errNoArg optStr = OptErr ("option `" ++ optStr ++ "' doesn't allow an argument\n") {- ----------------------------------------------------------------------------------------- -- and here a small and hopefully enlightening example: data Flag = Verbose | Version | Name String | Output String | Arg String deriving Show options :: [OptDescr Flag] options = [Option ['v'] ["verbose"] (NoArg Verbose) "verbosely list files", Option ['V','?'] ["version","release"] (NoArg Version) "show version info", Option ['o'] ["output"] (OptArg out "FILE") "use FILE for dump", Option ['n'] ["name"] (ReqArg Name "USER") "only dump USER's files"] out :: Maybe String -> Flag out Nothing = Output "stdout" out (Just o) = Output o test :: ArgOrder Flag -> [String] -> String test order cmdline = case getOpt order options cmdline of (o,n,[] ) -> "options=" ++ show o ++ " args=" ++ show n ++ "\n" (_,_,errs) -> concat errs ++ usageInfo header options where header = "Usage: foobar [OPTION...] files..." -- example runs: -- putStr (test RequireOrder ["foo","-v"]) -- ==> options=[] args=["foo", "-v"] -- putStr (test Permute ["foo","-v"]) -- ==> options=[Verbose] args=["foo"] -- putStr (test (ReturnInOrder Arg) ["foo","-v"]) -- ==> options=[Arg "foo", Verbose] args=[] -- putStr (test Permute ["foo","--","-v"]) -- ==> options=[] args=["foo", "-v"] -- putStr (test Permute ["-?o","--name","bar","--na=baz"]) -- ==> options=[Version, Output "stdout", Name "bar", Name "baz"] args=[] -- putStr (test Permute ["--ver","foo"]) -- ==> option `--ver' is ambiguous; could be one of: -- -v --verbose verbosely list files -- -V, -? --version, --release show version info -- Usage: foobar [OPTION...] files... -- -v --verbose verbosely list files -- -V, -? --version, --release show version info -- -o[FILE] --output[=FILE] use FILE for dump -- -n USER --name=USER only dump USER's files ----------------------------------------------------------------------------------------- -}