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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) 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 _ [] = ""
sepBy _ [x] = x
sepBy ch (x:xs) = x ++ ch:' ':sepBy ch 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 ls rs optDescr = long ads arg rs
where (opt,arg) = break (=='=') ls
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 _ ] ('=':_) rest = (errNoArg optStr,rest)
long [ReqArg _ 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 _ 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}
|
