1 -----------------------------------------------------------------------------
3 -- Module : System.Console.GetOpt
4 -- Copyright : (c) Sven Panne Oct. 1996 (small changes Dec. 1997)
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: * To
28 enforce a coherent description of options and arguments, there are
29 explanation fields in the option/argument descriptor. * Error
30 messages are now more informative, but no longer POSIX
31 compliant... :-( And a final Haskell advertisement: The GNU C
32 implementation uses well over 1100 lines, we need only 195 here,
33 including a 46 line example! :-)
36 module System.Console.GetOpt (
50 import Data.List ( isPrefixOf )
52 -- |What to do with options following non-options
54 = RequireOrder -- ^ no option processing after first non-option
55 | Permute -- ^ freely intersperse options and non-options
56 | ReturnInOrder (String -> a) -- ^ wrap non-options into options
59 Each 'OptDescr' describes a single option.
61 The arguments to 'Option' are:
63 * list of short option characters
65 * list of long option strings (without "--")
69 * explanation of option for user
71 data OptDescr a = -- description of a single options:
72 Option [Char] -- list of short option characters
73 [String] -- list of long option strings (without "--")
74 (ArgDescr a) -- argument descriptor
75 String -- explanation of option for user
77 -- |Describes whether an option takes an argument or not, and if so
78 -- how the argument is injected into a value of type @a@.
80 = NoArg a -- ^ no argument expected
81 | ReqArg (String -> a) String -- ^ option requires argument
82 | OptArg (Maybe String -> a) String -- ^ optional argument
84 data OptKind a -- kind of cmd line arg (internal use only):
86 | NonOpt String -- a non-option
87 | EndOfOpts -- end-of-options marker (i.e. "--")
88 | OptErr String -- something went wrong...
90 -- | Return a string describing the usage of a command, derived from
91 -- the header (first argument) and the options described by the
93 usageInfo :: String -- header
94 -> [OptDescr a] -- option descriptors
95 -> String -- nicely formatted decription of options
96 usageInfo header optDescr = unlines (header:table)
97 where (ss,ls,ds) = (unzip3 . map fmtOpt) optDescr
98 table = zipWith3 paste (sameLen ss) (sameLen ls) ds
99 paste x y z = " " ++ x ++ " " ++ y ++ " " ++ z
100 sameLen xs = flushLeft ((maximum . map length) xs) xs
101 flushLeft n xs = [ take n (x ++ repeat ' ') | x <- xs ]
103 fmtOpt :: OptDescr a -> (String,String,String)
104 fmtOpt (Option sos los ad descr) = (sepBy ',' (map (fmtShort ad) sos),
105 sepBy ',' (map (fmtLong ad) los),
107 where sepBy _ [] = ""
109 sepBy ch (x:xs) = x ++ ch:' ':sepBy ch xs
111 fmtShort :: ArgDescr a -> Char -> String
112 fmtShort (NoArg _ ) so = "-" ++ [so]
113 fmtShort (ReqArg _ ad) so = "-" ++ [so] ++ " " ++ ad
114 fmtShort (OptArg _ ad) so = "-" ++ [so] ++ "[" ++ ad ++ "]"
116 fmtLong :: ArgDescr a -> String -> String
117 fmtLong (NoArg _ ) lo = "--" ++ lo
118 fmtLong (ReqArg _ ad) lo = "--" ++ lo ++ "=" ++ ad
119 fmtLong (OptArg _ ad) lo = "--" ++ lo ++ "[=" ++ ad ++ "]"
122 Process the command-line, and return the list of values that matched
123 (and those that didn\'t). The arguments are:
125 * The order requirements (see 'ArgOrder')
127 * The option descriptions (see 'OptDescr')
129 * The actual command line arguments (presumably got from
130 'System.Console.Environment.getArgs').
132 'getOpt' returns a triple, consisting of the argument values, a list
133 of options that didn\'t match, and a list of error messages.
135 getOpt :: ArgOrder a -- non-option handling
136 -> [OptDescr a] -- option descriptors
137 -> [String] -- the commandline arguments
138 -> ([a],[String],[String]) -- (options,non-options,error messages)
139 getOpt _ _ [] = ([],[],[])
140 getOpt ordering optDescr (arg:args) = procNextOpt opt ordering
141 where procNextOpt (Opt o) _ = (o:os,xs,es)
142 procNextOpt (NonOpt x) RequireOrder = ([],x:rest,[])
143 procNextOpt (NonOpt x) Permute = (os,x:xs,es)
144 procNextOpt (NonOpt x) (ReturnInOrder f) = (f x :os, xs,es)
145 procNextOpt EndOfOpts RequireOrder = ([],rest,[])
146 procNextOpt EndOfOpts Permute = ([],rest,[])
147 procNextOpt EndOfOpts (ReturnInOrder f) = (map f rest,[],[])
148 procNextOpt (OptErr e) _ = (os,xs,e:es)
150 (opt,rest) = getNext arg args optDescr
151 (os,xs,es) = getOpt ordering optDescr rest
153 -- take a look at the next cmd line arg and decide what to do with it
154 getNext :: String -> [String] -> [OptDescr a] -> (OptKind a,[String])
155 getNext ('-':'-':[]) rest _ = (EndOfOpts,rest)
156 getNext ('-':'-':xs) rest optDescr = longOpt xs rest optDescr
157 getNext ('-': x :xs) rest optDescr = shortOpt x xs rest optDescr
158 getNext a rest _ = (NonOpt a,rest)
160 -- handle long option
161 longOpt :: String -> [String] -> [OptDescr a] -> (OptKind a,[String])
162 longOpt ls rs optDescr = long ads arg rs
163 where (opt,arg) = break (=='=') ls
164 options = [ o | o@(Option _ ls _ _) <- optDescr, l <- ls, opt `isPrefixOf` l ]
165 ads = [ ad | Option _ _ ad _ <- options ]
168 long (_:_:_) _ rest = (errAmbig options optStr,rest)
169 long [NoArg a ] [] rest = (Opt a,rest)
170 long [NoArg _ ] ('=':_) rest = (errNoArg optStr,rest)
171 long [ReqArg _ d] [] [] = (errReq d optStr,[])
172 long [ReqArg f _] [] (r:rest) = (Opt (f r),rest)
173 long [ReqArg f _] ('=':xs) rest = (Opt (f xs),rest)
174 long [OptArg f _] [] rest = (Opt (f Nothing),rest)
175 long [OptArg f _] ('=':xs) rest = (Opt (f (Just xs)),rest)
176 long _ _ rest = (errUnrec optStr,rest)
178 -- handle short option
179 shortOpt :: Char -> String -> [String] -> [OptDescr a] -> (OptKind a,[String])
180 shortOpt x xs rest optDescr = short ads xs rest
181 where options = [ o | o@(Option ss _ _ _) <- optDescr, s <- ss, x == s ]
182 ads = [ ad | Option _ _ ad _ <- options ]
185 short (_:_:_) _ rest = (errAmbig options optStr,rest)
186 short (NoArg a :_) [] rest = (Opt a,rest)
187 short (NoArg a :_) xs rest = (Opt a,('-':xs):rest)
188 short (ReqArg _ d:_) [] [] = (errReq d optStr,[])
189 short (ReqArg f _:_) [] (r:rest) = (Opt (f r),rest)
190 short (ReqArg f _:_) xs rest = (Opt (f xs),rest)
191 short (OptArg f _:_) [] rest = (Opt (f Nothing),rest)
192 short (OptArg f _:_) xs rest = (Opt (f (Just xs)),rest)
193 short [] [] rest = (errUnrec optStr,rest)
194 short [] xs rest = (errUnrec optStr,('-':xs):rest)
196 -- miscellaneous error formatting
198 errAmbig :: [OptDescr a] -> String -> OptKind a
199 errAmbig ods optStr = OptErr (usageInfo header ods)
200 where header = "option `" ++ optStr ++ "' is ambiguous; could be one of:"
202 errReq :: String -> String -> OptKind a
203 errReq d optStr = OptErr ("option `" ++ optStr ++ "' requires an argument " ++ d ++ "\n")
205 errUnrec :: String -> OptKind a
206 errUnrec optStr = OptErr ("unrecognized option `" ++ optStr ++ "'\n")
208 errNoArg :: String -> OptKind a
209 errNoArg optStr = OptErr ("option `" ++ optStr ++ "' doesn't allow an argument\n")
212 -----------------------------------------------------------------------------------------
213 -- and here a small and hopefully enlightening example:
215 data Flag = Verbose | Version | Name String | Output String | Arg String deriving Show
217 options :: [OptDescr Flag]
219 [Option ['v'] ["verbose"] (NoArg Verbose) "verbosely list files",
220 Option ['V','?'] ["version","release"] (NoArg Version) "show version info",
221 Option ['o'] ["output"] (OptArg out "FILE") "use FILE for dump",
222 Option ['n'] ["name"] (ReqArg Name "USER") "only dump USER's files"]
224 out :: Maybe String -> Flag
225 out Nothing = Output "stdout"
226 out (Just o) = Output o
228 test :: ArgOrder Flag -> [String] -> String
229 test order cmdline = case getOpt order options cmdline of
230 (o,n,[] ) -> "options=" ++ show o ++ " args=" ++ show n ++ "\n"
231 (_,_,errs) -> concat errs ++ usageInfo header options
232 where header = "Usage: foobar [OPTION...] files..."
235 -- putStr (test RequireOrder ["foo","-v"])
236 -- ==> options=[] args=["foo", "-v"]
237 -- putStr (test Permute ["foo","-v"])
238 -- ==> options=[Verbose] args=["foo"]
239 -- putStr (test (ReturnInOrder Arg) ["foo","-v"])
240 -- ==> options=[Arg "foo", Verbose] args=[]
241 -- putStr (test Permute ["foo","--","-v"])
242 -- ==> options=[] args=["foo", "-v"]
243 -- putStr (test Permute ["-?o","--name","bar","--na=baz"])
244 -- ==> options=[Version, Output "stdout", Name "bar", Name "baz"] args=[]
245 -- putStr (test Permute ["--ver","foo"])
246 -- ==> option `--ver' is ambiguous; could be one of:
247 -- -v --verbose verbosely list files
248 -- -V, -? --version, --release show version info
249 -- Usage: foobar [OPTION...] files...
250 -- -v --verbose verbosely list files
251 -- -V, -? --version, --release show version info
252 -- -o[FILE] --output[=FILE] use FILE for dump
253 -- -n USER --name=USER only dump USER's files
254 -----------------------------------------------------------------------------------------
259 To hopefully illuminate the role of the different "GetOpt" data
260 structures, here\'s the command-line options for a (very simple)
266 > import Maybe ( fromMaybe )
269 > = Verbose | Version
270 > | Input String | Output String | LibDir String
273 > options :: [OptDescr Flag]
275 > [ Option ['v'] ["verbose"] (NoArg Verbose) "chatty output on stderr"
276 > , Option ['V','?'] ["version"] (NoArg Version) "show version number"
277 > , Option ['o'] ["output"] (OptArg outp "FILE") "output FILE"
278 > , Option ['c'] [] (OptArg inp "FILE") "input FILE"
279 > , Option ['L'] ["libdir"] (ReqArg LibDir "DIR") "library directory"
282 > inp,outp :: Maybe String -> Flag
283 > outp = Output . fromMaybe "stdout"
284 > inp = Input . fromMaybe "stdout"
286 > compilerOpts :: [String] -> IO ([Flag], [String])
287 > compilerOpts argv =
288 > case (getOpt Permute options argv) of
289 > (o,n,[] ) -> return (o,n)
290 > (_,_,errs) -> failIO (concat errs ++ usageInfo header options)
291 > where header = "Usage: ic [OPTION...] files..."