1 A Haskell port of GNU's getopt library
3 Sven Panne <Sven.Panne@informatik.uni-muenchen.de> Oct. 1996 (small
6 Two rather obscure features are missing: The Bash 2.0 non-option hack
7 (if you don't already know it, you probably don't want to hear about
8 it...) and the recognition of long options with a single dash
9 (e.g. '-help' is recognised as '--help', as long as there is no short
12 Other differences between GNU's getopt and this implementation: * To
13 enforce a coherent description of options and arguments, there are
14 explanation fields in the option/argument descriptor. * Error
15 messages are now more informative, but no longer POSIX
16 compliant... :-( And a final Haskell advertisement: The GNU C
17 implementation uses well over 1100 lines, we need only 195 here,
18 including a 46 line example! :-)
21 module GetOpt (ArgOrder(..), OptDescr(..), ArgDescr(..), usageInfo, getOpt) where
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),
61 where sepBy sep [] = ""
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 (arg: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 arg 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 -> [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)
100 -- handle long option
101 longOpt :: String -> [String] -> [OptDescr a] -> (OptKind a,[String])
102 longOpt xs rest optDescr = long ads arg rest
103 where (opt,arg) = break (=='=') xs
104 options = [ o | o@(Option _ ls _ _) <- optDescr, l <- ls, opt `isPrefixOf` l ]
105 ads = [ ad | Option _ _ ad _ <- options ]
108 long (_:_:_) _ rest = (errAmbig options optStr,rest)
109 long [NoArg a ] [] rest = (Opt a,rest)
110 long [NoArg a ] ('=':xs) rest = (errNoArg optStr,rest)
111 long [ReqArg f d] [] [] = (errReq d optStr,[])
112 long [ReqArg f _] [] (r:rest) = (Opt (f r),rest)
113 long [ReqArg f _] ('=':xs) rest = (Opt (f xs),rest)
114 long [OptArg f _] [] rest = (Opt (f Nothing),rest)
115 long [OptArg f _] ('=':xs) rest = (Opt (f (Just xs)),rest)
116 long _ _ rest = (errUnrec optStr,rest)
118 -- handle short option
119 shortOpt :: Char -> String -> [String] -> [OptDescr a] -> (OptKind a,[String])
120 shortOpt x xs rest optDescr = short ads xs rest
121 where options = [ o | o@(Option ss _ _ _) <- optDescr, s <- ss, x == s ]
122 ads = [ ad | Option _ _ ad _ <- options ]
125 short (_:_:_) _ rest = (errAmbig options optStr,rest)
126 short (NoArg a :_) [] rest = (Opt a,rest)
127 short (NoArg a :_) xs rest = (Opt a,('-':xs):rest)
128 short (ReqArg f d:_) [] [] = (errReq d optStr,[])
129 short (ReqArg f _:_) [] (r:rest) = (Opt (f r),rest)
130 short (ReqArg f _:_) xs rest = (Opt (f xs),rest)
131 short (OptArg f _:_) [] rest = (Opt (f Nothing),rest)
132 short (OptArg f _:_) xs rest = (Opt (f (Just xs)),rest)
133 short [] [] rest = (errUnrec optStr,rest)
134 short [] xs rest = (errUnrec optStr,('-':xs):rest)
136 -- miscellaneous error formatting
138 errAmbig :: [OptDescr a] -> String -> OptKind a
139 errAmbig ods optStr = OptErr (usageInfo header ods)
140 where header = "option `" ++ optStr ++ "' is ambiguous; could be one of:"
142 errReq :: String -> String -> OptKind a
143 errReq d optStr = OptErr ("option `" ++ optStr ++ "' requires an argument " ++ d ++ "\n")
145 errUnrec :: String -> OptKind a
146 errUnrec optStr = OptErr ("unrecognized option `" ++ optStr ++ "'\n")
148 errNoArg :: String -> OptKind a
149 errNoArg optStr = OptErr ("option `" ++ optStr ++ "' doesn't allow an argument\n")
152 -----------------------------------------------------------------------------------------
153 -- and here a small and hopefully enlightening example:
155 data Flag = Verbose | Version | Name String | Output String | Arg String deriving Show
157 options :: [OptDescr Flag]
159 [Option ['v'] ["verbose"] (NoArg Verbose) "verbosely list files",
160 Option ['V','?'] ["version","release"] (NoArg Version) "show version info",
161 Option ['o'] ["output"] (OptArg out "FILE") "use FILE for dump",
162 Option ['n'] ["name"] (ReqArg Name "USER") "only dump USER's files"]
164 out :: Maybe String -> Flag
165 out Nothing = Output "stdout"
166 out (Just o) = Output o
168 test :: ArgOrder Flag -> [String] -> String
169 test order cmdline = case getOpt order options cmdline of
170 (o,n,[] ) -> "options=" ++ show o ++ " args=" ++ show n ++ "\n"
171 (_,_,errs) -> concat errs ++ usageInfo header options
172 where header = "Usage: foobar [OPTION...] files..."
175 -- putStr (test RequireOrder ["foo","-v"])
176 -- ==> options=[] args=["foo", "-v"]
177 -- putStr (test Permute ["foo","-v"])
178 -- ==> options=[Verbose] args=["foo"]
179 -- putStr (test (ReturnInOrder Arg) ["foo","-v"])
180 -- ==> options=[Arg "foo", Verbose] args=[]
181 -- putStr (test Permute ["foo","--","-v"])
182 -- ==> options=[] args=["foo", "-v"]
183 -- putStr (test Permute ["-?o","--name","bar","--na=baz"])
184 -- ==> options=[Version, Output "stdout", Name "bar", Name "baz"] args=[]
185 -- putStr (test Permute ["--ver","foo"])
186 -- ==> option `--ver' is ambiguous; could be one of:
187 -- -v --verbose verbosely list files
188 -- -V, -? --version, --release show version info
189 -- Usage: foobar [OPTION...] files...
190 -- -v --verbose verbosely list files
191 -- -V, -? --version, --release show version info
192 -- -o[FILE] --output[=FILE] use FILE for dump
193 -- -n USER --name=USER only dump USER's files
194 -----------------------------------------------------------------------------------------