--- /dev/null
+A Haskell port of GNU's 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! :-)
+
+\begin{code}
+module GetOpt (ArgOrder(..), OptDescr(..), ArgDescr(..), usageInfo, getOpt) where
+
+import List(isPrefixOf)
+
+data ArgOrder a -- what to do with options following non-options:
+ = RequireOrder -- no option processing after first non-option
+ | Permute -- freely intersperse options and non-options
+ | ReturnInOrder (String -> a) -- wrap non-options into options
+
+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
+
+data ArgDescr a -- description of an argument option:
+ = 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
+ | NonOpt String -- a non-option
+ | EndOfOpts -- end-of-options marker (i.e. "--")
+ | OptErr String -- something went wrong...
+
+usageInfo :: String -- header
+ -> [OptDescr a] -- option descriptors
+ -> String -- nicely formatted decription of options
+usageInfo header optDescr = unlines (header:table)
+ where (ss,ls,ds) = (unzip3 . map fmtOpt) optDescr
+ table = zipWith3 paste (sameLen ss) (sameLen ls) (sameLen 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) = (sepBy ", " (map (fmtShort ad) sos),
+ sepBy ", " (map (fmtLong ad) los),
+ descr)
+ where sepBy sep [] = ""
+ sepBy sep [x] = x
+ sepBy sep (x:xs) = x ++ sep ++ sepBy sep xs
+
+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 ++ "]"
+
+getOpt :: ArgOrder a -- non-option handling
+ -> [OptDescr a] -- option descriptors
+ -> [String] -- the commandline arguments
+ -> ([a],[String],[String]) -- (options,non-options,error messages)
+getOpt _ _ [] = ([],[],[])
+getOpt ordering optDescr (arg:args) = procNextOpt opt ordering
+ where procNextOpt (Opt o) _ = (o:os,xs,es)
+ procNextOpt (NonOpt x) RequireOrder = ([],x:rest,[])
+ procNextOpt (NonOpt x) Permute = (os,x:xs,es)
+ procNextOpt (NonOpt x) (ReturnInOrder f) = (f x :os, xs,es)
+ procNextOpt EndOfOpts RequireOrder = ([],rest,[])
+ procNextOpt EndOfOpts Permute = ([],rest,[])
+ procNextOpt EndOfOpts (ReturnInOrder f) = (map f rest,[],[])
+ procNextOpt (OptErr e) _ = (os,xs,e:es)
+
+ (opt,rest) = getNext arg args optDescr
+ (os,xs,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 xs rest optDescr = long ads arg rest
+ where (opt,arg) = break (=='=') xs
+ options = [ o | o@(Option _ ls _ _) <- optDescr, l <- ls, opt `isPrefixOf` l ]
+ ads = [ ad | Option _ _ ad _ <- options ]
+ optStr = ("--"++opt)
+
+ long (_:_:_) _ rest = (errAmbig options optStr,rest)
+ long [NoArg a ] [] rest = (Opt a,rest)
+ long [NoArg a ] ('=':xs) rest = (errNoArg optStr,rest)
+ long [ReqArg f 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 = (errUnrec optStr,rest)
+
+-- handle short option
+shortOpt :: Char -> String -> [String] -> [OptDescr a] -> (OptKind a,[String])
+shortOpt x xs rest optDescr = short ads xs rest
+ where options = [ o | o@(Option ss _ _ _) <- optDescr, s <- ss, x == s ]
+ ads = [ ad | Option _ _ ad _ <- options ]
+ optStr = '-':[x]
+
+ short (_:_:_) _ rest = (errAmbig options optStr,rest)
+ short (NoArg a :_) [] rest = (Opt a,rest)
+ short (NoArg a :_) xs rest = (Opt a,('-':xs):rest)
+ short (ReqArg f 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 = (errUnrec optStr,rest)
+ short [] xs rest = (errUnrec 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 -> OptKind a
+errUnrec optStr = OptErr ("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
+-----------------------------------------------------------------------------------------
+-}
+\end{code}
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