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{-# LANGUAGE TypeSynonymInstances, FlexibleInstances, UndecidableInstances, OverlappingInstances, TypeOperators #-}
module ReadArgs where
import Control.Arrow (first)
import Data.Maybe
import Data.List
import Data.Typeable
import Data.Text (Text, pack)
import Filesystem.Path (FilePath)
import Filesystem.Path.CurrentOS (fromText)
import Prelude hiding (FilePath)
import System.Environment
import System.Exit
import System.IO hiding (FilePath)
-- |parse the desired argument tuple from the command line or
-- print a simple usage statment and quit
readArgs :: ArgumentTuple a => IO a
readArgs = getArgs >>= readArgsFrom
-- |read args from the given strings or
-- print a simple usage statment and quit
-- (so you can do option parsing first)
readArgsFrom :: ArgumentTuple a => [String] -> IO a
readArgsFrom ss =
let ma@(~(Just a)) = parseArgsFrom ss
in case ma of
Nothing -> do
progName <- getProgName
hPutStrLn stderr $ "usage: " ++ progName ++ usageFor a
exitFailure
_ -> return a
-- |a class for types that can be parsed from exactly one command line argument
class Arguable a where
parse :: String -> Maybe a
-- |name's argument will usually be undefined, so when defining instances of
-- Arguable, it should be lazy in its argument
name :: a -> String
-- |all types that are typeable and readable can be used as simple arguments
instance (Typeable t, Read t) => Arguable t where
parse s = case reads s of
[(i,"")] -> Just i
_ -> Nothing
name t = showsTypeRep (typeOf t) ""
-- |string is a special case, so that we don't force the user to double-quote
-- their input
instance Arguable String where
parse = Just
name _ = "String"
-- |Text is a special case, so that we don't force the user to double-quote
-- their input
instance Arguable Text where
parse = Just . pack
name _ = "Text"
-- |FilePath is a special case, so that we don't force the user to double-quote
-- their input
instance Arguable FilePath where
parse = Just . fromText . pack
name _ = "FilePath"
-- |char is a special case, so that we don't force the user to single-quote
-- their input
instance Arguable Char where
parse [x] = Just x
parse _ = Nothing
name _ = "Char"
-- |a class for types that can be parsed from some number of command line
-- arguments
class Argument a where
parseArg :: [String] -> [(a, [String])]
-- |argName's argument will usually be undefined, so when defining instances of
-- Arguable, it should be lazy in its argument
argName :: a -> String
-- |use the arguable tyep to just parse a single argument
instance Arguable a => Argument a where
parseArg [] = []
parseArg (s:ss) = do
a <- maybeToList $ parse s
return (a, ss)
argName = name
-- |use Maybe when it should be parsed from one or zero (greedily)
instance Arguable a => Argument (Maybe a) where
argName ~(Just x) = "["++name x++"]"
parseArg [] = [(Nothing, [])]
parseArg ss'@(s:ss) = case parse s of
Nothing -> [(Nothing, ss')]
justA -> [(justA, ss),(Nothing,ss')]
-- |use a list when it should be parsed from zero or more (greedily)
instance Arguable a => Argument [a] where
argName ~(x:_) = "["++name x ++"...]"
parseArg ss = reverse $ inits ss' `zip` tails ss
where ss' = map fromJust . takeWhile isJust $ map parse ss
-- |a wrapper type to indicate a non-greedy list or maybe
newtype NonGreedy m a = NonGreedy { unNonGreedy :: m a } deriving (Show, Eq)
-- |use NonGreedy when it should be parsed non-greedily
-- (e.g. @(NonGreedy xs :: NonGreedy [] Int, x :: Maybe Float) <- readArgs@)
instance Argument (m a) => Argument (NonGreedy m a) where
argName ~(NonGreedy m) = argName m
parseArg = map (first NonGreedy) . reverse . parseArg
-- |make sure strings are handled as a separate type, not a list of chars
instance Argument String where
parseArg [] = []
parseArg (s:ss) = do
a <- maybeToList $ parse s
return (a, ss)
argName = name
-- |a class for tuples of types that can be parsed from the entire list
-- of arguments
class ArgumentTuple a where
parseArgsFrom :: [String] -> Maybe a
-- |usageFor's argument will usually be undefined, so when defining instances of
-- Arguable, it should be lazy in its argument
usageFor :: a -> String
-- |use () for no arguments
instance ArgumentTuple () where
parseArgsFrom [] = Just ()
parseArgsFrom _ = Nothing
usageFor = const ""
-- |use :& to construct arbitrary length tuples of any parsable arguments
data a :& b = a :& b deriving (Show, Eq)
infixr 5 :&
instance (Argument a, ArgumentTuple y) => ArgumentTuple (a :& y) where
parseArgsFrom ss = listToMaybe $ do
(a, ss') <- parseArg ss
y <- maybeToList $ parseArgsFrom ss'
return $ a :& y
usageFor ~(a :& y) = " " ++ argName a ++ usageFor y
-- Use :& to derive an instance for single arguments
instance (Argument a) => ArgumentTuple a where
parseArgsFrom ss = do
a :& () <- parseArgsFrom ss
return a
usageFor a = usageFor (a :& ())
-- Use :& to derive instances for all the normal tuple types
instance (Argument b, Argument a) => ArgumentTuple (b,a) where
parseArgsFrom ss = do
b :& a :& () <- parseArgsFrom ss
return (b,a)
usageFor ~(b,a) = usageFor (b :& a :& ())
instance (Argument c, Argument b, Argument a) => ArgumentTuple (c,b,a) where
parseArgsFrom ss = do
c :& b :& a :& () <- parseArgsFrom ss
return (c,b,a)
usageFor ~(c,b,a) = usageFor (c :& b :& a :& ())
instance (Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (d,c,b,a) where
parseArgsFrom ss = do
d :& c :& b :& a :& () <- parseArgsFrom ss
return (d,c,b,a)
usageFor ~(d,c,b,a) = usageFor (d :& c :& b :& a :& ())
instance (Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (e,d,c,b,a) where
parseArgsFrom ss = do
e :& d :& c :& b :& a :& () <- parseArgsFrom ss
return (e,d,c,b,a)
usageFor ~(e,d,c,b,a) = usageFor (e :& d :& c :& b :& a :& ())
instance (Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (f,e,d,c,b,a) where
parseArgsFrom ss = do
f :& e :& d :& c :& b :& a :& () <- parseArgsFrom ss
return (f,e,d,c,b,a)
usageFor ~(f,e,d,c,b,a) = usageFor (f :& e :& d :& c :& b :& a :& ())
instance (Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (g,f,e,d,c,b,a) where
parseArgsFrom ss = do
g :& f :& e :& d :& c :& b :& a :& () <- parseArgsFrom ss
return (g,f,e,d,c,b,a)
usageFor ~(g,f,e,d,c,b,a) = usageFor (g :& f :& e :& d :& c :& b :& a :& ())
instance (Argument h, Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (h,g,f,e,d,c,b,a) where
parseArgsFrom ss = do
h :& g :& f :& e :& d :& c :& b :& a :& () <- parseArgsFrom ss
return (h,g,f,e,d,c,b,a)
usageFor ~(h,g,f,e,d,c,b,a) = usageFor (h :& g :& f :& e :& d :& c :& b :& a :& ())
instance (Argument i, Argument h, Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (i,h,g,f,e,d,c,b,a) where
parseArgsFrom ss = do
i :& h :& g :& f :& e :& d :& c :& b :& a :& () <- parseArgsFrom ss
return (i,h,g,f,e,d,c,b,a)
usageFor ~(i,h,g,f,e,d,c,b,a) = usageFor (i :& h :& g :& f :& e :& d :& c :& b :& a :& ())
instance (Argument j, Argument i, Argument h, Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (j,i,h,g,f,e,d,c,b,a) where
parseArgsFrom ss = do
j :& i :& h :& g :& f :& e :& d :& c :& b :& a :& () <- parseArgsFrom ss
return (j,i,h,g,f,e,d,c,b,a)
usageFor ~(j,i,h,g,f,e,d,c,b,a) = usageFor (j :& i :& h :& g :& f :& e :& d :& c :& b :& a :& ())
instance (Argument k, Argument j, Argument i, Argument h, Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (k,j,i,h,g,f,e,d,c,b,a) where
parseArgsFrom ss = do
k :& j :& i :& h :& g :& f :& e :& d :& c :& b :& a :& () <- parseArgsFrom ss
return (k,j,i,h,g,f,e,d,c,b,a)
usageFor ~(k,j,i,h,g,f,e,d,c,b,a) = usageFor (k :& j :& i :& h :& g :& f :& e :& d :& c :& b :& a :& ())
instance (Argument l, Argument k, Argument j, Argument i, Argument h, Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (l,k,j,i,h,g,f,e,d,c,b,a) where
parseArgsFrom ss = do
l :& k :& j :& i :& h :& g :& f :& e :& d :& c :& b :& a :& () <- parseArgsFrom ss
return (l,k,j,i,h,g,f,e,d,c,b,a)
usageFor ~(l,k,j,i,h,g,f,e,d,c,b,a) = usageFor (l :& k :& j :& i :& h :& g :& f :& e :& d :& c :& b :& a :& ())
instance (Argument m, Argument l, Argument k, Argument j, Argument i, Argument h, Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (m,l,k,j,i,h,g,f,e,d,c,b,a) where
parseArgsFrom ss = do
m :& l :& k :& j :& i :& h :& g :& f :& e :& d :& c :& b :& a :& () <- parseArgsFrom ss
return (m,l,k,j,i,h,g,f,e,d,c,b,a)
usageFor ~(m,l,k,j,i,h,g,f,e,d,c,b,a) = usageFor (m :& l :& k :& j :& i :& h :& g :& f :& e :& d :& c :& b :& a :& ())
instance (Argument n, Argument m, Argument l, Argument k, Argument j, Argument i, Argument h, Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (n,m,l,k,j,i,h,g,f,e,d,c,b,a) where
parseArgsFrom ss = do
n :& m :& l :& k :& j :& i :& h :& g :& f :& e :& d :& c :& b :& a :& () <- parseArgsFrom ss
return (n,m,l,k,j,i,h,g,f,e,d,c,b,a)
usageFor ~(n,m,l,k,j,i,h,g,f,e,d,c,b,a) = usageFor (n :& m :& l :& k :& j :& i :& h :& g :& f :& e :& d :& c :& b :& a :& ())
instance (Argument o, Argument n, Argument m, Argument l, Argument k, Argument j, Argument i, Argument h, Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (o,n,m,l,k,j,i,h,g,f,e,d,c,b,a) where
parseArgsFrom ss = do
o :& n :& m :& l :& k :& j :& i :& h :& g :& f :& e :& d :& c :& b :& a :& () <- parseArgsFrom ss
return (o,n,m,l,k,j,i,h,g,f,e,d,c,b,a)
usageFor ~(o,n,m,l,k,j,i,h,g,f,e,d,c,b,a) = usageFor (o :& n :& m :& l :& k :& j :& i :& h :& g :& f :& e :& d :& c :& b :& a :& ())
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