1 -----------------------------------------------------------------------------
3 -- Module : System.Console.GetOpt
4 -- Copyright : (c) Sven Panne 2002-2004
5 -- License : BSD-style (see the file libraries/base/LICENSE)
7 -- Maintainer : libraries@haskell.org
8 -- Stability : experimental
9 -- Portability : portable
11 -- This library provides facilities for parsing the command-line options
12 -- in a standalone program. It is essentially a Haskell port of the GNU
15 -----------------------------------------------------------------------------
18 Sven Panne <Sven.Panne@informatik.uni-muenchen.de> Oct. 1996 (small
21 Two rather obscure features are missing: The Bash 2.0 non-option hack
22 (if you don't already know it, you probably don't want to hear about
23 it...) and the recognition of long options with a single dash
24 (e.g. '-help' is recognised as '--help', as long as there is no short
27 Other differences between GNU's getopt and this implementation:
29 * To enforce a coherent description of options and arguments, there
30 are explanation fields in the option/argument descriptor.
32 * Error messages are now more informative, but no longer POSIX
35 And a final Haskell advertisement: The GNU C implementation uses well
36 over 1100 lines, we need only 195 here, including a 46 line example!
40 module System.Console.GetOpt (
53 import Data.List ( isPrefixOf )
55 -- |What to do with options following non-options
57 = RequireOrder -- ^ no option processing after first non-option
58 | Permute -- ^ freely intersperse options and non-options
59 | ReturnInOrder (String -> a) -- ^ wrap non-options into options
62 Each 'OptDescr' describes a single option.
64 The arguments to 'Option' are:
66 * list of short option characters
68 * list of long option strings (without \"--\")
72 * explanation of option for user
74 data OptDescr a = -- description of a single options:
75 Option [Char] -- list of short option characters
76 [String] -- list of long option strings (without "--")
77 (ArgDescr a) -- argument descriptor
78 String -- explanation of option for user
80 -- |Describes whether an option takes an argument or not, and if so
81 -- how the argument is injected into a value of type @a@.
83 = NoArg a -- ^ no argument expected
84 | ReqArg (String -> a) String -- ^ option requires argument
85 | OptArg (Maybe String -> a) String -- ^ optional argument
87 data OptKind a -- kind of cmd line arg (internal use only):
89 | NonOpt String -- a non-option
90 | EndOfOpts -- end-of-options marker (i.e. "--")
91 | OptErr String -- something went wrong...
93 -- | Return a string describing the usage of a command, derived from
94 -- the header (first argument) and the options described by the
96 usageInfo :: String -- header
97 -> [OptDescr a] -- option descriptors
98 -> String -- nicely formatted decription of options
99 usageInfo header optDescr = unlines (header:table)
100 where (ss,ls,ds) = (unzip3 . concatMap fmtOpt) optDescr
101 table = zipWith3 paste (sameLen ss) (sameLen ls) ds
102 paste x y z = " " ++ x ++ " " ++ y ++ " " ++ z
103 sameLen xs = flushLeft ((maximum . map length) xs) xs
104 flushLeft n xs = [ take n (x ++ repeat ' ') | x <- xs ]
106 fmtOpt :: OptDescr a -> [(String,String,String)]
107 fmtOpt (Option sos los ad descr) =
109 [] -> [(sosFmt,losFmt,"")]
110 (d:ds) -> (sosFmt,losFmt,d) : [ ("","",d') | d' <- ds ]
111 where sepBy _ [] = ""
113 sepBy ch (x:xs) = x ++ ch:' ':sepBy ch xs
114 sosFmt = sepBy ',' (map (fmtShort ad) sos)
115 losFmt = sepBy ',' (map (fmtLong ad) los)
117 fmtShort :: ArgDescr a -> Char -> String
118 fmtShort (NoArg _ ) so = "-" ++ [so]
119 fmtShort (ReqArg _ ad) so = "-" ++ [so] ++ " " ++ ad
120 fmtShort (OptArg _ ad) so = "-" ++ [so] ++ "[" ++ ad ++ "]"
122 fmtLong :: ArgDescr a -> String -> String
123 fmtLong (NoArg _ ) lo = "--" ++ lo
124 fmtLong (ReqArg _ ad) lo = "--" ++ lo ++ "=" ++ ad
125 fmtLong (OptArg _ ad) lo = "--" ++ lo ++ "[=" ++ ad ++ "]"
128 Process the command-line, and return the list of values that matched
129 (and those that didn\'t). The arguments are:
131 * The order requirements (see 'ArgOrder')
133 * The option descriptions (see 'OptDescr')
135 * The actual command line arguments (presumably got from
136 'System.Environment.getArgs').
138 'getOpt' returns a triple, consisting of the argument values, a list
139 of options that didn\'t match, and a list of error messages.
141 getOpt :: ArgOrder a -- non-option handling
142 -> [OptDescr a] -- option descriptors
143 -> [String] -- the commandline arguments
144 -> ([a],[String],[String]) -- (options,non-options,error messages)
145 getOpt _ _ [] = ([],[],[])
146 getOpt ordering optDescr (arg:args) = procNextOpt opt ordering
147 where procNextOpt (Opt o) _ = (o:os,xs,es)
148 procNextOpt (NonOpt x) RequireOrder = ([],x:rest,[])
149 procNextOpt (NonOpt x) Permute = (os,x:xs,es)
150 procNextOpt (NonOpt x) (ReturnInOrder f) = (f x :os, xs,es)
151 procNextOpt EndOfOpts RequireOrder = ([],rest,[])
152 procNextOpt EndOfOpts Permute = ([],rest,[])
153 procNextOpt EndOfOpts (ReturnInOrder f) = (map f rest,[],[])
154 procNextOpt (OptErr e) _ = (os,xs,e:es)
156 (opt,rest) = getNext arg args optDescr
157 (os,xs,es) = getOpt ordering optDescr rest
159 -- take a look at the next cmd line arg and decide what to do with it
160 getNext :: String -> [String] -> [OptDescr a] -> (OptKind a,[String])
161 getNext ('-':'-':[]) rest _ = (EndOfOpts,rest)
162 getNext ('-':'-':xs) rest optDescr = longOpt xs rest optDescr
163 getNext ('-': x :xs) rest optDescr = shortOpt x xs rest optDescr
164 getNext a rest _ = (NonOpt a,rest)
166 -- handle long option
167 longOpt :: String -> [String] -> [OptDescr a] -> (OptKind a,[String])
168 longOpt ls rs optDescr = long ads arg rs
169 where (opt,arg) = break (=='=') ls
170 getWith p = [ o | o@(Option _ ls _ _) <- optDescr, l <- ls, opt `p` l ]
172 options = if null exact then getWith isPrefixOf else exact
173 ads = [ ad | Option _ _ ad _ <- options ]
176 long (_:_:_) _ rest = (errAmbig options optStr,rest)
177 long [NoArg a ] [] rest = (Opt a,rest)
178 long [NoArg _ ] ('=':_) rest = (errNoArg optStr,rest)
179 long [ReqArg _ d] [] [] = (errReq d optStr,[])
180 long [ReqArg f _] [] (r:rest) = (Opt (f r),rest)
181 long [ReqArg f _] ('=':xs) rest = (Opt (f xs),rest)
182 long [OptArg f _] [] rest = (Opt (f Nothing),rest)
183 long [OptArg f _] ('=':xs) rest = (Opt (f (Just xs)),rest)
184 long _ _ rest = (errUnrec optStr,rest)
186 -- handle short option
187 shortOpt :: Char -> String -> [String] -> [OptDescr a] -> (OptKind a,[String])
188 shortOpt x xs rest optDescr = short ads xs rest
189 where options = [ o | o@(Option ss _ _ _) <- optDescr, s <- ss, x == s ]
190 ads = [ ad | Option _ _ ad _ <- options ]
193 short (_:_:_) _ rest = (errAmbig options optStr,rest)
194 short (NoArg a :_) [] rest = (Opt a,rest)
195 short (NoArg a :_) xs rest = (Opt a,('-':xs):rest)
196 short (ReqArg _ d:_) [] [] = (errReq d optStr,[])
197 short (ReqArg f _:_) [] (r:rest) = (Opt (f r),rest)
198 short (ReqArg f _:_) xs rest = (Opt (f xs),rest)
199 short (OptArg f _:_) [] rest = (Opt (f Nothing),rest)
200 short (OptArg f _:_) xs rest = (Opt (f (Just xs)),rest)
201 short [] [] rest = (errUnrec optStr,rest)
202 short [] xs rest = (errUnrec optStr,('-':xs):rest)
204 -- miscellaneous error formatting
206 errAmbig :: [OptDescr a] -> String -> OptKind a
207 errAmbig ods optStr = OptErr (usageInfo header ods)
208 where header = "option `" ++ optStr ++ "' is ambiguous; could be one of:"
210 errReq :: String -> String -> OptKind a
211 errReq d optStr = OptErr ("option `" ++ optStr ++ "' requires an argument " ++ d ++ "\n")
213 errUnrec :: String -> OptKind a
214 errUnrec optStr = OptErr ("unrecognized option `" ++ optStr ++ "'\n")
216 errNoArg :: String -> OptKind a
217 errNoArg optStr = OptErr ("option `" ++ optStr ++ "' doesn't allow an argument\n")
220 -----------------------------------------------------------------------------------------
221 -- and here a small and hopefully enlightening example:
223 data Flag = Verbose | Version | Name String | Output String | Arg String deriving Show
225 options :: [OptDescr Flag]
227 [Option ['v'] ["verbose"] (NoArg Verbose) "verbosely list files",
228 Option ['V','?'] ["version","release"] (NoArg Version) "show version info",
229 Option ['o'] ["output"] (OptArg out "FILE") "use FILE for dump",
230 Option ['n'] ["name"] (ReqArg Name "USER") "only dump USER's files"]
232 out :: Maybe String -> Flag
233 out Nothing = Output "stdout"
234 out (Just o) = Output o
236 test :: ArgOrder Flag -> [String] -> String
237 test order cmdline = case getOpt order options cmdline of
238 (o,n,[] ) -> "options=" ++ show o ++ " args=" ++ show n ++ "\n"
239 (_,_,errs) -> concat errs ++ usageInfo header options
240 where header = "Usage: foobar [OPTION...] files..."
243 -- putStr (test RequireOrder ["foo","-v"])
244 -- ==> options=[] args=["foo", "-v"]
245 -- putStr (test Permute ["foo","-v"])
246 -- ==> options=[Verbose] args=["foo"]
247 -- putStr (test (ReturnInOrder Arg) ["foo","-v"])
248 -- ==> options=[Arg "foo", Verbose] args=[]
249 -- putStr (test Permute ["foo","--","-v"])
250 -- ==> options=[] args=["foo", "-v"]
251 -- putStr (test Permute ["-?o","--name","bar","--na=baz"])
252 -- ==> options=[Version, Output "stdout", Name "bar", Name "baz"] args=[]
253 -- putStr (test Permute ["--ver","foo"])
254 -- ==> option `--ver' is ambiguous; could be one of:
255 -- -v --verbose verbosely list files
256 -- -V, -? --version, --release show version info
257 -- Usage: foobar [OPTION...] files...
258 -- -v --verbose verbosely list files
259 -- -V, -? --version, --release show version info
260 -- -o[FILE] --output[=FILE] use FILE for dump
261 -- -n USER --name=USER only dump USER's files
262 -----------------------------------------------------------------------------------------
267 To hopefully illuminate the role of the different data
268 structures, here\'s the command-line options for a (very simple)
273 > import System.Console.GetOpt
274 > import Data.Maybe ( fromMaybe )
277 > = Verbose | Version
278 > | Input String | Output String | LibDir String
281 > options :: [OptDescr Flag]
283 > [ Option ['v'] ["verbose"] (NoArg Verbose) "chatty output on stderr"
284 > , Option ['V','?'] ["version"] (NoArg Version) "show version number"
285 > , Option ['o'] ["output"] (OptArg outp "FILE") "output FILE"
286 > , Option ['c'] [] (OptArg inp "FILE") "input FILE"
287 > , Option ['L'] ["libdir"] (ReqArg LibDir "DIR") "library directory"
290 > inp,outp :: Maybe String -> Flag
291 > outp = Output . fromMaybe "stdout"
292 > inp = Input . fromMaybe "stdout"
294 > compilerOpts :: [String] -> IO ([Flag], [String])
295 > compilerOpts argv =
296 > case (getOpt Permute options argv) of
297 > (o,n,[] ) -> return (o,n)
298 > (_,_,errs) -> ioError (userError (concat errs ++ usageInfo header options))
299 > where header = "Usage: ic [OPTION...] files..."