{-# LANGUAGE Safe #-}------------------------------------------------------------------------------- |-- Module : System.Console.GetOpt-- Copyright : (c) Sven Panne 2002-2005-- License : BSD-style (see the file libraries/base/LICENSE)-- -- Maintainer : libraries@haskell.org-- Stability : experimental-- Portability : portable---- This library provides facilities for parsing the command-line options-- in a standalone program. It is essentially a Haskell port of the GNU -- @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! 
:-)
-}moduleSystem.Console.GetOpt(-- * GetOptgetOpt ,getOpt' ,usageInfo ,ArgOrder (..),OptDescr (..),ArgDescr (..),-- * Examples-- |To hopefully illuminate the role of the different data structures,-- here are the command-line options for a (very simple) compiler,-- done in two different ways.-- The difference arises because the type of 'getOpt' is-- parameterized by the type of values derived from flags.-- ** Interpreting flags as concrete values-- $example1-- ** Interpreting flags as transformations of an options record-- $example2)whereimportData.List (isPrefixOf ,find )-- |What to do with options following non-optionsdataArgOrder a =RequireOrder -- ^ no option processing after first non-option|Permute -- ^ freely intersperse options and non-options|ReturnInOrder (String ->a )-- ^ wrap non-options into options{-|
Each 'OptDescr' describes a single option.
The arguments to 'Option' are:
* list of short option characters
* list of long option strings (without \"--\")
* argument descriptor
* explanation of option for user
-}dataOptDescr a =-- description of a single options:Option [Char]-- list of short option characters[String ]-- list of long option strings (without "--")(ArgDescr a )-- argument descriptorString -- explanation of option for user-- |Describes whether an option takes an argument or not, and if so-- how the argument is injected into a value of type @a@.dataArgDescr a =NoArg a -- ^ no argument expected|ReqArg (String ->a )String -- ^ option requires argument|OptArg (Maybe String ->a )String -- ^ optional argument-- | @since 4.6.0.0instanceFunctor ArgOrder wherefmap _RequireOrder =RequireOrder fmap_Permute =Permute fmapf (ReturnInOrder g )=ReturnInOrder (f . g )-- | @since 4.6.0.0instanceFunctor OptDescr wherefmap f (Option a b argDescr c )=Option a b (fmap f argDescr )c -- | @since 4.6.0.0instanceFunctor ArgDescr wherefmap f (NoArg a )=NoArg (f a )fmapf (ReqArg g s )=ReqArg (f . g )s fmapf (OptArg g s )=OptArg (f . g )s dataOptKind a -- kind of cmd line arg (internal use only):=Opt a -- an option|UnreqOpt String -- an un-recognized option|NonOpt String -- a non-option|EndOfOpts -- end-of-options marker (i.e. "--")|OptErr String -- something went wrong...-- | Return a string describing the usage of a command, derived from-- the header (first argument) and the options described by the -- second argument.usageInfo::String -- header->[OptDescr a ]-- option descriptors->String -- nicely formatted description of optionsusageInfo header optDescr =unlines (header :table )where(ss ,ls ,ds )=(unzip3 . concatMap 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 )=caselines descr of[]->[(sosFmt ,losFmt ,"")](d :ds )->(sosFmt ,losFmt ,d ):[("","",d' )|d' <-ds ]wheresepBy _[]=""sepBy_[x ]=x sepBych (x :xs )=x ++ ch :' ':sepBy ch xs sosFmt =sepBy ','(map (fmtShort ad )sos )losFmt =sepBy ','(map (fmtLong ad )los )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 ++ "]"{-|
Process the command-line, and return the list of values that matched
(and those that didn\'t). The arguments are:
* The order requirements (see 'ArgOrder')
* The option descriptions (see 'OptDescr')
* The actual command line arguments (presumably got from 
 'System.Environment.getArgs').
'getOpt' returns a triple consisting of the option arguments, a list
of non-options, and a list of error messages.
-}getOpt::ArgOrder a -- non-option handling->[OptDescr a ]-- option descriptors->[String ]-- the command-line arguments->([a ],[String ],[String ])-- (options,non-options,error messages)getOpt ordering optDescr args =(os ,xs ,es ++ map errUnrec us )where(os ,xs ,us ,es )=getOpt' ordering optDescr args {-|
This is almost the same as 'getOpt', but returns a quadruple
consisting of the option arguments, a list of non-options, a list of
unrecognized options, and a list of error messages.
-}getOpt'::ArgOrder a -- non-option handling->[OptDescr a ]-- option descriptors->[String ]-- the command-line arguments->([a ],[String ],[String ],[String ])-- (options,non-options,unrecognized,error messages)getOpt' __[]=([],[],[],[])getOpt'ordering optDescr (arg :args )=procNextOpt opt ordering whereprocNextOpt (Opt o )_=(o :os ,xs ,us ,es )procNextOpt(UnreqOpt u )_=(os ,xs ,u :us ,es )procNextOpt(NonOpt x )RequireOrder =([],x :rest ,[],[])procNextOpt(NonOpt x )Permute =(os ,x :xs ,us ,es )procNextOpt(NonOpt x )(ReturnInOrder f )=(f x :os ,xs ,us ,es )procNextOptEndOfOpts RequireOrder =([],rest ,[],[])procNextOptEndOfOpts Permute =([],rest ,[],[])procNextOptEndOfOpts (ReturnInOrder f )=(map f rest ,[],[],[])procNextOpt(OptErr e )_=(os ,xs ,us ,e :es )(opt ,rest )=getNext arg args optDescr (os ,xs ,us ,es )=getOpt' ordering optDescr rest -- take a look at the next cmd line arg and decide what to do with itgetNext::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 getNexta rest _=(NonOpt a ,rest )-- handle long optionlongOpt::String ->[String ]->[OptDescr a ]->(OptKind a ,[String ])longOpt ls rs optDescr =long ads arg rs where(opt ,arg )=break (=='=')ls getWith p =[o |o @(Option _xs __)<-optDescr ,find (p opt )xs /=Nothing ]exact =getWith (==)options =ifnull exact thengetWith isPrefixOf elseexact 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 =(UnreqOpt ("--"++ ls ),rest )-- handle short optionshortOpt::Char->String ->[String ]->[OptDescr a ]->(OptKind a ,[String ])shortOpt y ys rs optDescr =short ads ys rs whereoptions =[o |o @(Option ss ___)<-optDescr ,s <-ss ,y ==s ]ads =[ad |Option __ad _<-options ]optStr ='-':[y ]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 =(UnreqOpt optStr ,rest )short[]xs rest =(UnreqOpt optStr ,('-':xs ):rest )-- miscellaneous error formattingerrAmbig::[OptDescr a ]->String ->OptKind a errAmbig ods optStr =OptErr (usageInfo header ods )whereheader ="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 ->String errUnrec optStr ="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
-----------------------------------------------------------------------------------------
-}{- $example1
A simple choice for the type associated with flags is to define a type
@Flag@ as an algebraic type representing the possible flags and their
arguments:
> module Opts1 where
> 
> import System.Console.GetOpt
> import Data.Maybe ( fromMaybe )
> 
> data Flag 
> = Verbose | Version 
> | Input String | Output String | LibDir String
> deriving Show
> 
> options :: [OptDescr Flag]
> options =
> [ Option ['v'] ["verbose"] (NoArg Verbose) "chatty output on stderr"
> , Option ['V','?'] ["version"] (NoArg Version) "show version number"
> , Option ['o'] ["output"] (OptArg outp "FILE") "output FILE"
> , Option ['c'] [] (OptArg inp "FILE") "input FILE"
> , Option ['L'] ["libdir"] (ReqArg LibDir "DIR") "library directory"
> ]
> 
> inp,outp :: Maybe String -> Flag
> outp = Output . fromMaybe "stdout"
> inp = Input . fromMaybe "stdin"
> 
> compilerOpts :: [String] -> IO ([Flag], [String])
> compilerOpts argv = 
> case getOpt Permute options argv of
> (o,n,[] ) -> return (o,n)
> (_,_,errs) -> ioError (userError (concat errs ++ usageInfo header options))
> where header = "Usage: ic [OPTION...] files..."
Then the rest of the program will use the constructed list of flags
to determine it\'s behaviour.
-}{- $example2
A different approach is to group the option values in a record of type
@Options@, and have each flag yield a function of type
@Options -> Options@ transforming this record.
> module Opts2 where
>
> import System.Console.GetOpt
> import Data.Maybe ( fromMaybe )
>
> data Options = Options
> { optVerbose :: Bool
> , optShowVersion :: Bool
> , optOutput :: Maybe FilePath
> , optInput :: Maybe FilePath
> , optLibDirs :: [FilePath]
> } deriving Show
>
> defaultOptions = Options
> { optVerbose = False
> , optShowVersion = False
> , optOutput = Nothing
> , optInput = Nothing
> , optLibDirs = []
> }
>
> options :: [OptDescr (Options -> Options)]
> options =
> [ Option ['v'] ["verbose"]
> (NoArg (\ opts -> opts { optVerbose = True }))
> "chatty output on stderr"
> , Option ['V','?'] ["version"]
> (NoArg (\ opts -> opts { optShowVersion = True }))
> "show version number"
> , Option ['o'] ["output"]
> (OptArg ((\ f opts -> opts { optOutput = Just f }) . fromMaybe "output")
> "FILE")
> "output FILE"
> , Option ['c'] []
> (OptArg ((\ f opts -> opts { optInput = Just f }) . fromMaybe "input")
> "FILE")
> "input FILE"
> , Option ['L'] ["libdir"]
> (ReqArg (\ d opts -> opts { optLibDirs = optLibDirs opts ++ [d] }) "DIR")
> "library directory"
> ]
>
> compilerOpts :: [String] -> IO (Options, [String])
> compilerOpts argv =
> case getOpt Permute options argv of
> (o,n,[] ) -> return (foldl (flip id) defaultOptions o, n)
> (_,_,errs) -> ioError (userError (concat errs ++ usageInfo header options))
> where header = "Usage: ic [OPTION...] files..."
Similarly, each flag could yield a monadic function transforming a record,
of type @Options -> IO Options@ (or any other monad), allowing option
processing to perform actions of the chosen monad, e.g. printing help or
version messages, checking that file arguments exist, etc.
-}