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--- The Glasgow Haskell Compiler License
---
--- Copyright 2004, The University Court of the University of Glasgow.
--- All rights reserved.
---
--- Redistribution and use in source and binary forms, with or without
--- modification, are permitted provided that the following conditions are met:
---
--- - Redistributions of source code must retain the above copyright notice,
--- this list of conditions and the following disclaimer.
---
--- - Redistributions in binary form must reproduce the above copyright notice,
--- this list of conditions and the following disclaimer in the documentation
--- and/or other materials provided with the distribution.
---
--- - Neither name of the University nor the names of its contributors may be
--- used to endorse or promote products derived from this software without
--- specific prior written permission.
---
--- THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY COURT OF THE UNIVERSITY OF
--- GLASGOW AND THE CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
--- INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
--- FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
--- UNIVERSITY COURT OF THE UNIVERSITY OF GLASGOW OR THE CONTRIBUTORS BE LIABLE
--- FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
--- DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
--- SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
--- CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
--- LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
--- OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
--- DAMAGE.
---
--- ---------------------------------------------------------------------------
{-
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... :-(
-}
module System.Console.GetOpt
-- * GetOpt
( getOpt, 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
) where
import Prelude -- necessary to get dependencies right
import Data.List (isPrefixOf, find)
--- A type to describe what to do with options following non-options.
data ArgOrder 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
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
-- |Describes whether an option takes an argument or not, and if so
-- how the argument is injected into a value of type @a@.
data ArgDescr a
= 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
| 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 decription of options
usageInfo 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 ]
maximum :: Ord a => [a] -> a
maximum [] = error "maximum with empty list"
maximum xs@(_:_) = foldl1 max xs
fmtOpt :: OptDescr a -> [(String,String,String)]
fmtOpt (Option sos los ad descr) =
case lines descr of
[] -> [(sosFmt,losFmt,"")]
(d:ds) -> (sosFmt,losFmt,d) : [ ("","",d') | d' <- ds ]
where sepBy _ [] = ""
sepBy _ [x] = x
sepBy ch (x:y:xs) = x ++ ch : ' ' : sepBy ch (y: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 did not match). 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 where
procNextOpt (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)
procNextOpt EndOfOpts RequireOrder = ([],rest,[],[])
procNextOpt EndOfOpts Permute = ([],rest,[],[])
procNextOpt EndOfOpts (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 it
getNext :: String -> [String] -> [OptDescr a] -> (OptKind a,[String])
getNext s rest optDescr = case s of
'-':'-':[] -> (EndOfOpts, rest)
'-':'-':xs -> longOpt xs rest optDescr
'-': x :xs -> shortOpt x xs rest optDescr
_ -> (NonOpt s,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
getWith p = [ o | o@(Option _ xs _ _) <- optDescr
, find (p opt) xs /= Nothing ]
exact = getWith (==)
options = if null exact then getWith isPrefixOf else exact
ads = [ ad | Option _ _ ad _ <- options ]
optStr = ("--"++opt)
long ads0 arg0 rs0 = case (ads0, arg0, rs0) of
((_:_:_) , _ , rest ) -> (errAmbig options optStr,rest)
([NoArg a ], [] , rest ) -> (Opt a ,rest)
([NoArg _ ], ('=':_) , rest ) -> (errNoArg optStr ,rest)
([ReqArg _ d], [] , [] ) -> (errReq d optStr ,[] )
([ReqArg f _], [] , (r:rest)) -> (Opt (f r) ,rest)
([ReqArg f _], ('=':xs), rest ) -> (Opt (f xs) ,rest)
([OptArg f _], [] , rest ) -> (Opt (f Nothing) ,rest)
([OptArg f _], ('=':xs), rest ) -> (Opt (f (Just xs)) ,rest)
(_ , _ , rest ) -> (UnreqOpt ("--" ++ ls) ,rest)
-- handle short option
shortOpt :: Char -> String -> [String] -> [OptDescr a] -> (OptKind a,[String])
shortOpt y ys rs optDescr = short ads ys rs where
options = [ o | o@(Option ss _ _ _) <- optDescr, s <- ss, y == s ]
ads = [ ad | Option _ _ ad _ <- options ]
optStr = '-':[y]
short [] [] rest = (UnreqOpt optStr,rest)
short [] xs@(_:_) rest = (UnreqOpt optStr,('-':xs):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 = (errAmbig options optStr,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 -> 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.
-}
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