Remove Control.Parallel*, now in package parallel
[packages/random.git] / System / Console / GetOpt.hs
1 -----------------------------------------------------------------------------
2 -- |
3 -- Module : System.Console.GetOpt
4 -- Copyright : (c) Sven Panne 2002-2005
5 -- License : BSD-style (see the file libraries/base/LICENSE)
6 --
7 -- Maintainer : libraries@haskell.org
8 -- Stability : experimental
9 -- Portability : portable
10 --
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
13 -- @getopt@ library.
14 --
15 -----------------------------------------------------------------------------
16
17 {-
18 Sven Panne <Sven.Panne@informatik.uni-muenchen.de> Oct. 1996 (small
19 changes Dec. 1997)
20
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
25 option 'h').
26
27 Other differences between GNU's getopt and this implementation:
28
29 * To enforce a coherent description of options and arguments, there
30 are explanation fields in the option/argument descriptor.
31
32 * Error messages are now more informative, but no longer POSIX
33 compliant... :-(
34
35 And a final Haskell advertisement: The GNU C implementation uses well
36 over 1100 lines, we need only 195 here, including a 46 line example!
37 :-)
38 -}
39
40 module System.Console.GetOpt (
41 -- * GetOpt
42 getOpt, getOpt',
43 usageInfo,
44 ArgOrder(..),
45 OptDescr(..),
46 ArgDescr(..),
47
48 -- * Examples
49
50 -- |To hopefully illuminate the role of the different data structures,
51 -- here are the command-line options for a (very simple) compiler,
52 -- done in two different ways.
53 -- The difference arises because the type of 'getOpt' is
54 -- parameterized by the type of values derived from flags.
55
56 -- ** Interpreting flags as concrete values
57 -- $example1
58
59 -- ** Interpreting flags as transformations of an options record
60 -- $example2
61 ) where
62
63 import Prelude -- necessary to get dependencies right
64
65 import Data.List ( isPrefixOf )
66
67 -- |What to do with options following non-options
68 data ArgOrder a
69 = RequireOrder -- ^ no option processing after first non-option
70 | Permute -- ^ freely intersperse options and non-options
71 | ReturnInOrder (String -> a) -- ^ wrap non-options into options
72
73 {-|
74 Each 'OptDescr' describes a single option.
75
76 The arguments to 'Option' are:
77
78 * list of short option characters
79
80 * list of long option strings (without \"--\")
81
82 * argument descriptor
83
84 * explanation of option for user
85 -}
86 data OptDescr a = -- description of a single options:
87 Option [Char] -- list of short option characters
88 [String] -- list of long option strings (without "--")
89 (ArgDescr a) -- argument descriptor
90 String -- explanation of option for user
91
92 -- |Describes whether an option takes an argument or not, and if so
93 -- how the argument is injected into a value of type @a@.
94 data ArgDescr a
95 = NoArg a -- ^ no argument expected
96 | ReqArg (String -> a) String -- ^ option requires argument
97 | OptArg (Maybe String -> a) String -- ^ optional argument
98
99 data OptKind a -- kind of cmd line arg (internal use only):
100 = Opt a -- an option
101 | UnreqOpt String -- an un-recognized option
102 | NonOpt String -- a non-option
103 | EndOfOpts -- end-of-options marker (i.e. "--")
104 | OptErr String -- something went wrong...
105
106 -- | Return a string describing the usage of a command, derived from
107 -- the header (first argument) and the options described by the
108 -- second argument.
109 usageInfo :: String -- header
110 -> [OptDescr a] -- option descriptors
111 -> String -- nicely formatted decription of options
112 usageInfo header optDescr = unlines (header:table)
113 where (ss,ls,ds) = (unzip3 . concatMap fmtOpt) optDescr
114 table = zipWith3 paste (sameLen ss) (sameLen ls) ds
115 paste x y z = " " ++ x ++ " " ++ y ++ " " ++ z
116 sameLen xs = flushLeft ((maximum . map length) xs) xs
117 flushLeft n xs = [ take n (x ++ repeat ' ') | x <- xs ]
118
119 fmtOpt :: OptDescr a -> [(String,String,String)]
120 fmtOpt (Option sos los ad descr) =
121 case lines descr of
122 [] -> [(sosFmt,losFmt,"")]
123 (d:ds) -> (sosFmt,losFmt,d) : [ ("","",d') | d' <- ds ]
124 where sepBy _ [] = ""
125 sepBy _ [x] = x
126 sepBy ch (x:xs) = x ++ ch:' ':sepBy ch xs
127 sosFmt = sepBy ',' (map (fmtShort ad) sos)
128 losFmt = sepBy ',' (map (fmtLong ad) los)
129
130 fmtShort :: ArgDescr a -> Char -> String
131 fmtShort (NoArg _ ) so = "-" ++ [so]
132 fmtShort (ReqArg _ ad) so = "-" ++ [so] ++ " " ++ ad
133 fmtShort (OptArg _ ad) so = "-" ++ [so] ++ "[" ++ ad ++ "]"
134
135 fmtLong :: ArgDescr a -> String -> String
136 fmtLong (NoArg _ ) lo = "--" ++ lo
137 fmtLong (ReqArg _ ad) lo = "--" ++ lo ++ "=" ++ ad
138 fmtLong (OptArg _ ad) lo = "--" ++ lo ++ "[=" ++ ad ++ "]"
139
140 {-|
141 Process the command-line, and return the list of values that matched
142 (and those that didn\'t). The arguments are:
143
144 * The order requirements (see 'ArgOrder')
145
146 * The option descriptions (see 'OptDescr')
147
148 * The actual command line arguments (presumably got from
149 'System.Environment.getArgs').
150
151 'getOpt' returns a triple consisting of the option arguments, a list
152 of non-options, and a list of error messages.
153 -}
154 getOpt :: ArgOrder a -- non-option handling
155 -> [OptDescr a] -- option descriptors
156 -> [String] -- the command-line arguments
157 -> ([a],[String],[String]) -- (options,non-options,error messages)
158 getOpt ordering optDescr args = (os,xs,es ++ map errUnrec us)
159 where (os,xs,us,es) = getOpt' ordering optDescr args
160
161 {-|
162 This is almost the same as 'getOpt', but returns a quadruple
163 consisting of the option arguments, a list of non-options, a list of
164 unrecognized options, and a list of error messages.
165 -}
166 getOpt' :: ArgOrder a -- non-option handling
167 -> [OptDescr a] -- option descriptors
168 -> [String] -- the command-line arguments
169 -> ([a],[String], [String] ,[String]) -- (options,non-options,unrecognized,error messages)
170 getOpt' _ _ [] = ([],[],[],[])
171 getOpt' ordering optDescr (arg:args) = procNextOpt opt ordering
172 where procNextOpt (Opt o) _ = (o:os,xs,us,es)
173 procNextOpt (UnreqOpt u) _ = (os,xs,u:us,es)
174 procNextOpt (NonOpt x) RequireOrder = ([],x:rest,[],[])
175 procNextOpt (NonOpt x) Permute = (os,x:xs,us,es)
176 procNextOpt (NonOpt x) (ReturnInOrder f) = (f x :os, xs,us,es)
177 procNextOpt EndOfOpts RequireOrder = ([],rest,[],[])
178 procNextOpt EndOfOpts Permute = ([],rest,[],[])
179 procNextOpt EndOfOpts (ReturnInOrder f) = (map f rest,[],[],[])
180 procNextOpt (OptErr e) _ = (os,xs,us,e:es)
181
182 (opt,rest) = getNext arg args optDescr
183 (os,xs,us,es) = getOpt' ordering optDescr rest
184
185 -- take a look at the next cmd line arg and decide what to do with it
186 getNext :: String -> [String] -> [OptDescr a] -> (OptKind a,[String])
187 getNext ('-':'-':[]) rest _ = (EndOfOpts,rest)
188 getNext ('-':'-':xs) rest optDescr = longOpt xs rest optDescr
189 getNext ('-': x :xs) rest optDescr = shortOpt x xs rest optDescr
190 getNext a rest _ = (NonOpt a,rest)
191
192 -- handle long option
193 longOpt :: String -> [String] -> [OptDescr a] -> (OptKind a,[String])
194 longOpt ls rs optDescr = long ads arg rs
195 where (opt,arg) = break (=='=') ls
196 getWith p = [ o | o@(Option _ xs _ _) <- optDescr, x <- xs, opt `p` x ]
197 exact = getWith (==)
198 options = if null exact then getWith isPrefixOf else exact
199 ads = [ ad | Option _ _ ad _ <- options ]
200 optStr = ("--"++opt)
201
202 long (_:_:_) _ rest = (errAmbig options optStr,rest)
203 long [NoArg a ] [] rest = (Opt a,rest)
204 long [NoArg _ ] ('=':_) rest = (errNoArg optStr,rest)
205 long [ReqArg _ d] [] [] = (errReq d optStr,[])
206 long [ReqArg f _] [] (r:rest) = (Opt (f r),rest)
207 long [ReqArg f _] ('=':xs) rest = (Opt (f xs),rest)
208 long [OptArg f _] [] rest = (Opt (f Nothing),rest)
209 long [OptArg f _] ('=':xs) rest = (Opt (f (Just xs)),rest)
210 long _ _ rest = (UnreqOpt ("--"++ls),rest)
211
212 -- handle short option
213 shortOpt :: Char -> String -> [String] -> [OptDescr a] -> (OptKind a,[String])
214 shortOpt y ys rs optDescr = short ads ys rs
215 where options = [ o | o@(Option ss _ _ _) <- optDescr, s <- ss, y == s ]
216 ads = [ ad | Option _ _ ad _ <- options ]
217 optStr = '-':[y]
218
219 short (_:_:_) _ rest = (errAmbig options optStr,rest)
220 short (NoArg a :_) [] rest = (Opt a,rest)
221 short (NoArg a :_) xs rest = (Opt a,('-':xs):rest)
222 short (ReqArg _ d:_) [] [] = (errReq d optStr,[])
223 short (ReqArg f _:_) [] (r:rest) = (Opt (f r),rest)
224 short (ReqArg f _:_) xs rest = (Opt (f xs),rest)
225 short (OptArg f _:_) [] rest = (Opt (f Nothing),rest)
226 short (OptArg f _:_) xs rest = (Opt (f (Just xs)),rest)
227 short [] [] rest = (UnreqOpt optStr,rest)
228 short [] xs rest = (UnreqOpt optStr,('-':xs):rest)
229
230 -- miscellaneous error formatting
231
232 errAmbig :: [OptDescr a] -> String -> OptKind a
233 errAmbig ods optStr = OptErr (usageInfo header ods)
234 where header = "option `" ++ optStr ++ "' is ambiguous; could be one of:"
235
236 errReq :: String -> String -> OptKind a
237 errReq d optStr = OptErr ("option `" ++ optStr ++ "' requires an argument " ++ d ++ "\n")
238
239 errUnrec :: String -> String
240 errUnrec optStr = "unrecognized option `" ++ optStr ++ "'\n"
241
242 errNoArg :: String -> OptKind a
243 errNoArg optStr = OptErr ("option `" ++ optStr ++ "' doesn't allow an argument\n")
244
245 {-
246 -----------------------------------------------------------------------------------------
247 -- and here a small and hopefully enlightening example:
248
249 data Flag = Verbose | Version | Name String | Output String | Arg String deriving Show
250
251 options :: [OptDescr Flag]
252 options =
253 [Option ['v'] ["verbose"] (NoArg Verbose) "verbosely list files",
254 Option ['V','?'] ["version","release"] (NoArg Version) "show version info",
255 Option ['o'] ["output"] (OptArg out "FILE") "use FILE for dump",
256 Option ['n'] ["name"] (ReqArg Name "USER") "only dump USER's files"]
257
258 out :: Maybe String -> Flag
259 out Nothing = Output "stdout"
260 out (Just o) = Output o
261
262 test :: ArgOrder Flag -> [String] -> String
263 test order cmdline = case getOpt order options cmdline of
264 (o,n,[] ) -> "options=" ++ show o ++ " args=" ++ show n ++ "\n"
265 (_,_,errs) -> concat errs ++ usageInfo header options
266 where header = "Usage: foobar [OPTION...] files..."
267
268 -- example runs:
269 -- putStr (test RequireOrder ["foo","-v"])
270 -- ==> options=[] args=["foo", "-v"]
271 -- putStr (test Permute ["foo","-v"])
272 -- ==> options=[Verbose] args=["foo"]
273 -- putStr (test (ReturnInOrder Arg) ["foo","-v"])
274 -- ==> options=[Arg "foo", Verbose] args=[]
275 -- putStr (test Permute ["foo","--","-v"])
276 -- ==> options=[] args=["foo", "-v"]
277 -- putStr (test Permute ["-?o","--name","bar","--na=baz"])
278 -- ==> options=[Version, Output "stdout", Name "bar", Name "baz"] args=[]
279 -- putStr (test Permute ["--ver","foo"])
280 -- ==> option `--ver' is ambiguous; could be one of:
281 -- -v --verbose verbosely list files
282 -- -V, -? --version, --release show version info
283 -- Usage: foobar [OPTION...] files...
284 -- -v --verbose verbosely list files
285 -- -V, -? --version, --release show version info
286 -- -o[FILE] --output[=FILE] use FILE for dump
287 -- -n USER --name=USER only dump USER's files
288 -----------------------------------------------------------------------------------------
289 -}
290
291 {- $example1
292
293 A simple choice for the type associated with flags is to define a type
294 @Flag@ as an algebraic type representing the possible flags and their
295 arguments:
296
297 > module Opts1 where
298 >
299 > import System.Console.GetOpt
300 > import Data.Maybe ( fromMaybe )
301 >
302 > data Flag
303 > = Verbose | Version
304 > | Input String | Output String | LibDir String
305 > deriving Show
306 >
307 > options :: [OptDescr Flag]
308 > options =
309 > [ Option ['v'] ["verbose"] (NoArg Verbose) "chatty output on stderr"
310 > , Option ['V','?'] ["version"] (NoArg Version) "show version number"
311 > , Option ['o'] ["output"] (OptArg outp "FILE") "output FILE"
312 > , Option ['c'] [] (OptArg inp "FILE") "input FILE"
313 > , Option ['L'] ["libdir"] (ReqArg LibDir "DIR") "library directory"
314 > ]
315 >
316 > inp,outp :: Maybe String -> Flag
317 > outp = Output . fromMaybe "stdout"
318 > inp = Input . fromMaybe "stdin"
319 >
320 > compilerOpts :: [String] -> IO ([Flag], [String])
321 > compilerOpts argv =
322 > case getOpt Permute options argv of
323 > (o,n,[] ) -> return (o,n)
324 > (_,_,errs) -> ioError (userError (concat errs ++ usageInfo header options))
325 > where header = "Usage: ic [OPTION...] files..."
326
327 Then the rest of the program will use the constructed list of flags
328 to determine it\'s behaviour.
329
330 -}
331
332 {- $example2
333
334 A different approach is to group the option values in a record of type
335 @Options@, and have each flag yield a function of type
336 @Options -> Options@ transforming this record.
337
338 > module Opts2 where
339 >
340 > import System.Console.GetOpt
341 > import Data.Maybe ( fromMaybe )
342 >
343 > data Options = Options
344 > { optVerbose :: Bool
345 > , optShowVersion :: Bool
346 > , optOutput :: Maybe FilePath
347 > , optInput :: Maybe FilePath
348 > , optLibDirs :: [FilePath]
349 > } deriving Show
350 >
351 > defaultOptions = Options
352 > { optVerbose = False
353 > , optShowVersion = False
354 > , optOutput = Nothing
355 > , optInput = Nothing
356 > , optLibDirs = []
357 > }
358 >
359 > options :: [OptDescr (Options -> Options)]
360 > options =
361 > [ Option ['v'] ["verbose"]
362 > (NoArg (\ opts -> opts { optVerbose = True }))
363 > "chatty output on stderr"
364 > , Option ['V','?'] ["version"]
365 > (NoArg (\ opts -> opts { optShowVersion = True }))
366 > "show version number"
367 > , Option ['o'] ["output"]
368 > (OptArg ((\ f opts -> opts { optOutput = Just f }) . fromMaybe "output")
369 > "FILE")
370 > "output FILE"
371 > , Option ['c'] []
372 > (OptArg ((\ f opts -> opts { optInput = Just f }) . fromMaybe "input")
373 > "FILE")
374 > "input FILE"
375 > , Option ['L'] ["libdir"]
376 > (ReqArg (\ d opts -> opts { optLibDirs = optLibDirs opts ++ [d] }) "DIR")
377 > "library directory"
378 > ]
379 >
380 > compilerOpts :: [String] -> IO (Options, [String])
381 > compilerOpts argv =
382 > case getOpt Permute options argv of
383 > (o,n,[] ) -> return (foldl (flip id) defaultOptions o, n)
384 > (_,_,errs) -> ioError (userError (concat errs ++ usageInfo header options))
385 > where header = "Usage: ic [OPTION...] files..."
386
387 Similarly, each flag could yield a monadic function transforming a record,
388 of type @Options -> IO Options@ (or any other monad), allowing option
389 processing to perform actions of the chosen monad, e.g. printing help or
390 version messages, checking that file arguments exist, etc.
391
392 -}