1 A Haskell port of GNU's getopt library
3 Sven Panne <Sven.Panne@informatik.uni-muenchen.de> Oct. 1996; last change: Jul. 1998
5 Two rather obscure features are missing: The Bash 2.0 non-option hack (if you don't
6 already know it, you probably don't want to hear about it...) and the recognition of
7 long options with a single dash (e.g. '-help' is recognised as '--help', as long as
8 there is no short option 'h').
10 Other differences between GNU's getopt and this implementation:
11 * To enforce a coherent description of options and arguments, there are explanation
12 fields in the option/argument descriptor.
13 * Error messages are now more informative, but no longer POSIX compliant... :-(
15 And a final Haskell advertisement: The GNU C implementation uses well over 1100 lines,
16 we need only 199 here, including a 46 line example! :-)
20 ArgOrder(..), OptDescr(..), ArgDescr(..), usageInfo, getOpt
23 import List(isPrefixOf)
25 data ArgOrder a -- what to do with options following non-options:
26 = RequireOrder -- no option processing after first non-option
27 | Permute -- freely intersperse options and non-options
28 | ReturnInOrder (String -> a) -- wrap non-options into options
30 data OptDescr a = -- description of a single options:
31 Option [Char] -- list of short option characters
32 [String] -- list of long option strings (without "--")
33 (ArgDescr a) -- argument descriptor
34 String -- explanation of option for user
36 data ArgDescr a -- description of an argument option:
37 = NoArg a -- no argument expected
38 | ReqArg (String -> a) String -- option requires argument
39 | OptArg (Maybe String -> a) String -- optional argument
41 data OptKind a -- kind of cmd line arg (internal use only):
43 | NonOpt String -- a non-option
44 | EndOfOpts -- end-of-options marker (i.e. "--")
45 | OptErr String -- something went wrong...
47 usageInfo :: String -- header
48 -> [OptDescr a] -- option descriptors
49 -> String -- nicely formatted decription of options
50 usageInfo header optDescr = unlines (header:table)
51 where (ss,ls,ds) = (unzip3 . map fmtOpt) optDescr
52 table = zipWith3 paste (sameLen ss) (sameLen ls) (sameLen ds)
53 paste x y z = " " ++ x ++ " " ++ y ++ " " ++ z
54 sameLen xs = flushLeft ((maximum . map length) xs) xs
55 flushLeft n xs = [ take n (x ++ repeat ' ') | x <- xs ]
57 fmtOpt :: OptDescr a -> (String,String,String)
58 fmtOpt (Option sos los ad descr) = (sepBy ", " (map (fmtShort ad) sos),
59 sepBy ", " (map (fmtLong ad) los),
63 sepBy sep (x:xs) = x ++ sep ++ sepBy sep xs
65 fmtShort :: ArgDescr a -> Char -> String
66 fmtShort (NoArg _ ) so = "-" ++ [so]
67 fmtShort (ReqArg _ ad) so = "-" ++ [so] ++ " " ++ ad
68 fmtShort (OptArg _ ad) so = "-" ++ [so] ++ "[" ++ ad ++ "]"
70 fmtLong :: ArgDescr a -> String -> String
71 fmtLong (NoArg _ ) lo = "--" ++ lo
72 fmtLong (ReqArg _ ad) lo = "--" ++ lo ++ "=" ++ ad
73 fmtLong (OptArg _ ad) lo = "--" ++ lo ++ "[=" ++ ad ++ "]"
75 getOpt :: ArgOrder a -- non-option handling
76 -> [OptDescr a] -- option descriptors
77 -> [String] -- the commandline arguments
78 -> ([a],[String],[String]) -- (options,non-options,error messages)
79 getOpt _ _ [] = ([],[],[])
80 getOpt ordering optDescr args = procNextOpt opt ordering
81 where procNextOpt (Opt o) _ = (o:os,xs,es)
82 procNextOpt (NonOpt x) RequireOrder = ([],x:rest,[])
83 procNextOpt (NonOpt x) Permute = (os,x:xs,es)
84 procNextOpt (NonOpt x) (ReturnInOrder f) = (f x :os, xs,es)
85 procNextOpt EndOfOpts RequireOrder = ([],rest,[])
86 procNextOpt EndOfOpts Permute = ([],rest,[])
87 procNextOpt EndOfOpts (ReturnInOrder f) = (map f rest,[],[])
88 procNextOpt (OptErr e) _ = (os,xs,e:es)
90 (opt,rest) = getNext args optDescr
91 (os,xs,es) = getOpt ordering optDescr rest
93 -- take a look at the next cmd line arg and decide what to do with it
94 getNext :: [String] -> [OptDescr a] -> (OptKind a,[String])
95 getNext (('-':'-':[]):rest) _ = (EndOfOpts,rest)
96 getNext (('-':'-':xs):rest) optDescr = longOpt xs rest optDescr
97 getNext (('-':x:xs) :rest) optDescr = shortOpt x xs rest optDescr
98 getNext (a :rest) _ = (NonOpt a,rest)
99 getNext [] _ = error "getNext: impossible"
101 -- handle long option
102 longOpt :: String -> [String] -> [OptDescr a] -> (OptKind a,[String])
103 longOpt xs rest optDescr = long ads arg rest
104 where (opt,arg) = break (=='=') xs
105 options = [ o | o@(Option _ ls _ _) <- optDescr, l <- ls, opt `isPrefixOf` l ]
106 ads = [ ad | Option _ _ ad _ <- options ]
109 long (_:_:_) _ rest1 = (errAmbig options optStr,rest1)
110 long [NoArg a ] [] rest1 = (Opt a,rest1)
111 long [NoArg _ ] ('=':_) rest1 = (errNoArg optStr,rest1)
112 long [ReqArg _ d] [] [] = (errReq d optStr,[])
113 long [ReqArg f _] [] (r:rest1) = (Opt (f r),rest1)
114 long [ReqArg f _] ('=':ys) rest1 = (Opt (f ys),rest1)
115 long [OptArg f _] [] rest1 = (Opt (f Nothing),rest1)
116 long [OptArg f _] ('=':ys) rest1 = (Opt (f (Just ys)),rest1)
117 long [_] (_ :_) _ = error "long: impossible"
118 long [] _ rest1 = (errUnrec optStr,rest1)
120 -- handle short option
121 shortOpt :: Char -> String -> [String] -> [OptDescr a] -> (OptKind a,[String])
122 shortOpt x xs rest optDescr = short ads xs rest
123 where options = [ o | o@(Option ss _ _ _) <- optDescr, s <- ss, x == s ]
124 ads = [ ad | Option _ _ ad _ <- options ]
127 short (_:_:_) _ rest1 = (errAmbig options optStr,rest1)
128 short (NoArg a :_) [] rest1 = (Opt a,rest1)
129 short (NoArg a :_) ys rest1 = (Opt a,('-':ys):rest1)
130 short (ReqArg _ d:_) [] [] = (errReq d optStr,[])
131 short (ReqArg f _:_) [] (r:rest1) = (Opt (f r),rest1)
132 short (ReqArg f _:_) ys rest1 = (Opt (f ys),rest1)
133 short (OptArg f _:_) [] rest1 = (Opt (f Nothing),rest1)
134 short (OptArg f _:_) ys rest1 = (Opt (f (Just ys)),rest1)
135 short [] [] rest1 = (errUnrec optStr,rest1)
136 short [] ys rest1 = (errUnrec optStr,('-':ys):rest1)
138 -- miscellaneous error formatting
140 errAmbig :: [OptDescr a] -> String -> OptKind a
141 errAmbig ods optStr = OptErr (usageInfo header ods)
142 where header = "option `" ++ optStr ++ "' is ambiguous; could be one of:"
144 errReq :: String -> String -> OptKind a
145 errReq d optStr = OptErr ("option `" ++ optStr ++ "' requires an argument " ++ d ++ "\n")
147 errUnrec :: String -> OptKind a
148 errUnrec optStr = OptErr ("unrecognized option `" ++ optStr ++ "'\n")
150 errNoArg :: String -> OptKind a
151 errNoArg optStr = OptErr ("option `" ++ optStr ++ "' doesn't allow an argument\n")
155 -----------------------------------------------------------------------------------------
156 -- and here a small and hopefully enlightening example:
158 data Flag = Verbose | Version | Name String | Output String | Arg String deriving Show
160 options :: [OptDescr Flag]
162 [Option ['v'] ["verbose"] (NoArg Verbose) "verbosely list files",
163 Option ['V','?'] ["version","release"] (NoArg Version) "show version info",
164 Option ['o'] ["output"] (OptArg out "FILE") "use FILE for dump",
165 Option ['n'] ["name"] (ReqArg Name "USER") "only dump USER's files"]
167 out :: Maybe String -> Flag
168 out Nothing = Output "stdout"
169 out (Just o) = Output o
171 test :: ArgOrder Flag -> [String] -> String
172 test order cmdline = case getOpt order options cmdline of
173 (o,n,[] ) -> "options=" ++ show o ++ " args=" ++ show n ++ "\n"
174 (_,_,errs) -> concat errs ++ usageInfo header options
175 where header = "Usage: foobar [OPTION...] files..."
178 -- putStr (test RequireOrder ["foo","-v"])
179 -- ==> options=[] args=["foo", "-v"]
180 -- putStr (test Permute ["foo","-v"])
181 -- ==> options=[Verbose] args=["foo"]
182 -- putStr (test (ReturnInOrder Arg) ["foo","-v"])
183 -- ==> options=[Arg "foo", Verbose] args=[]
184 -- putStr (test Permute ["foo","--","-v"])
185 -- ==> options=[] args=["foo", "-v"]
186 -- putStr (test Permute ["-?o","--name","bar","--na=baz"])
187 -- ==> options=[Version, Output "stdout", Name "bar", Name "baz"] args=[]
188 -- putStr (test Permute ["--ver","foo"])
189 -- ==> option `--ver' is ambiguous; could be one of:
190 -- -v --verbose verbosely list files
191 -- -V, -? --version, --release show version info
192 -- Usage: foobar [OPTION...] files...
193 -- -v --verbose verbosely list files
194 -- -V, -? --version, --release show version info
195 -- -o[FILE] --output[=FILE] use FILE for dump
196 -- -n USER --name=USER only dump USER's files
197 -----------------------------------------------------------------------------------------