----------------------------------------------------------------------------- -- | -- Module : System.Console.GetOpt -- Copyright : (c) Sven Panne 2002-2005 -- License : BSD-style (see the file libraries/base/LICENSE) -- -- Maintainer : libraries@haskell.org -- Stability : experimental -- Portability : portable -- -- This library provides facilities for parsing the command-line options -- in a standalone program. It is essentially a Haskell port of the GNU -- @getopt@ library. -- ----------------------------------------------------------------------------- {- Sven Panne <Sven.Panne@informatik.uni-muenchen.de> Oct. 1996 (small changes Dec. 1997) 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 195 here, including a 46 line example! :-) -} module System.Console.GetOpt ( -- * GetOpt getOpt, getOpt', usageInfo, ArgOrder(..), OptDescr(..), ArgDescr(..), -- * Examples -- |To hopefully illuminate the role of the different data structures, -- here are the command-line options for a (very simple) compiler, -- done in two different ways. -- The difference arises because the type of 'getOpt' is -- parameterized by the type of values derived from flags. -- ** Interpreting flags as concrete values -- $example1 -- ** Interpreting flags as transformations of an options record -- $example2 ) where import Prelude -- necessary to get dependencies right import Data.List ( isPrefixOf ) -- |What to do with options following non-options data ArgOrder a = RequireOrder -- ^ no option processing after first non-option | Permute -- ^ freely intersperse options and non-options | ReturnInOrder (String -> a) -- ^ wrap non-options into options {-| Each 'OptDescr' describes a single option. The arguments to 'Option' are: * list of short option characters * list of long option strings (without \"--\") * argument descriptor * explanation of option for user -} 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 -- |Describes whether an option takes an argument or not, and if so -- how the argument is injected into a value of type @a@. data ArgDescr a = 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 | UnreqOpt String -- an un-recognized option | NonOpt String -- a non-option | EndOfOpts -- end-of-options marker (i.e. "--") | OptErr String -- something went wrong... -- | Return a string describing the usage of a command, derived from -- the header (first argument) and the options described by the -- second argument. usageInfo :: String -- header -> [OptDescr a] -- option descriptors -> String -- nicely formatted decription of options usageInfo header optDescr = unlines (header:table) where (ss,ls,ds) = (unzip3 . concatMap fmtOpt) optDescr table = zipWith3 paste (sameLen ss) (sameLen ls) 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) = case lines descr of [] -> [(sosFmt,losFmt,"")] (d:ds) -> (sosFmt,losFmt,d) : [ ("","",d') | d' <- ds ] where sepBy _ [] = "" sepBy _ [x] = x sepBy ch (x:xs) = x ++ ch:' ':sepBy ch xs sosFmt = sepBy ',' (map (fmtShort ad) sos) losFmt = sepBy ',' (map (fmtLong ad) los) 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 ++ "]" {-| Process the command-line, and return the list of values that matched (and those that didn\'t). The arguments are: * The order requirements (see 'ArgOrder') * The option descriptions (see 'OptDescr') * The actual command line arguments (presumably got from 'System.Environment.getArgs'). 'getOpt' returns a triple consisting of the option arguments, a list of non-options, and a list of error messages. -} getOpt :: ArgOrder a -- non-option handling -> [OptDescr a] -- option descriptors -> [String] -- the command-line arguments -> ([a],[String],[String]) -- (options,non-options,error messages) getOpt ordering optDescr args = (os,xs,es ++ map errUnrec us) where (os,xs,us,es) = getOpt' ordering optDescr args {-| This is almost the same as 'getOpt', but returns a quadruple consisting of the option arguments, a list of non-options, a list of unrecognized options, and a list of error messages. -} getOpt' :: ArgOrder a -- non-option handling -> [OptDescr a] -- option descriptors -> [String] -- the command-line arguments -> ([a],[String], [String] ,[String]) -- (options,non-options,unrecognized,error messages) getOpt' _ _ [] = ([],[],[],[]) getOpt' ordering optDescr (arg:args) = procNextOpt opt ordering where procNextOpt (Opt o) _ = (o:os,xs,us,es) procNextOpt (UnreqOpt u) _ = (os,xs,u:us,es) procNextOpt (NonOpt x) RequireOrder = ([],x:rest,[],[]) procNextOpt (NonOpt x) Permute = (os,x:xs,us,es) procNextOpt (NonOpt x) (ReturnInOrder f) = (f x :os, xs,us,es) procNextOpt EndOfOpts RequireOrder = ([],rest,[],[]) procNextOpt EndOfOpts Permute = ([],rest,[],[]) procNextOpt EndOfOpts (ReturnInOrder f) = (map f rest,[],[],[]) procNextOpt (OptErr e) _ = (os,xs,us,e:es) (opt,rest) = getNext arg args optDescr (os,xs,us,es) = getOpt' ordering optDescr rest -- take a look at the next cmd line arg and decide what to do with it getNext :: String -> [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) -- handle long option longOpt :: String -> [String] -> [OptDescr a] -> (OptKind a,[String]) longOpt ls rs optDescr = long ads arg rs where (opt,arg) = break (=='=') ls getWith p = [ o | o@(Option _ xs _ _) <- optDescr, x <- xs, opt `p` x ] exact = getWith (==) options = if null exact then getWith isPrefixOf else exact ads = [ ad | Option _ _ ad _ <- options ] optStr = ("--"++opt) long (_:_:_) _ rest = (errAmbig options optStr,rest) long [NoArg a ] [] rest = (Opt a,rest) long [NoArg _ ] ('=':_) rest = (errNoArg optStr,rest) long [ReqArg _ d] [] [] = (errReq d optStr,[]) long [ReqArg f _] [] (r:rest) = (Opt (f r),rest) long [ReqArg f _] ('=':xs) rest = (Opt (f xs),rest) long [OptArg f _] [] rest = (Opt (f Nothing),rest) long [OptArg f _] ('=':xs) rest = (Opt (f (Just xs)),rest) long _ _ rest = (UnreqOpt ("--"++ls),rest) -- handle short option shortOpt :: Char -> String -> [String] -> [OptDescr a] -> (OptKind a,[String]) shortOpt y ys rs optDescr = short ads ys rs where options = [ o | o@(Option ss _ _ _) <- optDescr, s <- ss, y == s ] ads = [ ad | Option _ _ ad _ <- options ] optStr = '-':[y] short (_:_:_) _ rest = (errAmbig options optStr,rest) short (NoArg a :_) [] rest = (Opt a,rest) short (NoArg a :_) xs rest = (Opt a,('-':xs):rest) short (ReqArg _ d:_) [] [] = (errReq d optStr,[]) short (ReqArg f _:_) [] (r:rest) = (Opt (f r),rest) short (ReqArg f _:_) xs rest = (Opt (f xs),rest) short (OptArg f _:_) [] rest = (Opt (f Nothing),rest) short (OptArg f _:_) xs rest = (Opt (f (Just xs)),rest) short [] [] rest = (UnreqOpt optStr,rest) short [] xs rest = (UnreqOpt optStr,('-':xs):rest) -- 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 -> String errUnrec optStr = "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 ----------------------------------------------------------------------------------------- -} {- $example1 A simple choice for the type associated with flags is to define a type @Flag@ as an algebraic type representing the possible flags and their arguments: > module Opts1 where > > import System.Console.GetOpt > import Data.Maybe ( fromMaybe ) > > data Flag > = Verbose | Version > | Input String | Output String | LibDir String > deriving Show > > options :: [OptDescr Flag] > options = > [ Option ['v'] ["verbose"] (NoArg Verbose) "chatty output on stderr" > , Option ['V','?'] ["version"] (NoArg Version) "show version number" > , Option ['o'] ["output"] (OptArg outp "FILE") "output FILE" > , Option ['c'] [] (OptArg inp "FILE") "input FILE" > , Option ['L'] ["libdir"] (ReqArg LibDir "DIR") "library directory" > ] > > inp,outp :: Maybe String -> Flag > outp = Output . fromMaybe "stdout" > inp = Input . fromMaybe "stdin" > > compilerOpts :: [String] -> IO ([Flag], [String]) > compilerOpts argv = > case getOpt Permute options argv of > (o,n,[] ) -> return (o,n) > (_,_,errs) -> ioError (userError (concat errs ++ usageInfo header options)) > where header = "Usage: ic [OPTION...] files..." Then the rest of the program will use the constructed list of flags to determine it\'s behaviour. -} {- $example2 A different approach is to group the option values in a record of type @Options@, and have each flag yield a function of type @Options -> Options@ transforming this record. > module Opts2 where > > import System.Console.GetOpt > import Data.Maybe ( fromMaybe ) > > data Options = Options > { optVerbose :: Bool > , optShowVersion :: Bool > , optOutput :: Maybe FilePath > , optInput :: Maybe FilePath > , optLibDirs :: [FilePath] > } deriving Show > > defaultOptions = Options > { optVerbose = False > , optShowVersion = False > , optOutput = Nothing > , optInput = Nothing > , optLibDirs = [] > } > > options :: [OptDescr (Options -> Options)] > options = > [ Option ['v'] ["verbose"] > (NoArg (\ opts -> opts { optVerbose = True })) > "chatty output on stderr" > , Option ['V','?'] ["version"] > (NoArg (\ opts -> opts { optShowVersion = True })) > "show version number" > , Option ['o'] ["output"] > (OptArg ((\ f opts -> opts { optOutput = Just f }) . fromMaybe "output") > "FILE") > "output FILE" > , Option ['c'] [] > (OptArg ((\ f opts -> opts { optInput = Just f }) . fromMaybe "input") > "FILE") > "input FILE" > , Option ['L'] ["libdir"] > (ReqArg (\ d opts -> opts { optLibDirs = optLibDirs opts ++ [d] }) "DIR") > "library directory" > ] > > compilerOpts :: [String] -> IO (Options, [String]) > compilerOpts argv = > case getOpt Permute options argv of > (o,n,[] ) -> return (foldl (flip id) defaultOptions o, n) > (_,_,errs) -> ioError (userError (concat errs ++ usageInfo header options)) > where header = "Usage: ic [OPTION...] files..." Similarly, each flag could yield a monadic function transforming a record, of type @Options -> IO Options@ (or any other monad), allowing option processing to perform actions of the chosen monad, e.g. printing help or version messages, checking that file arguments exist, etc. -}