import Panic ( assertPanic )
#endif
-data OptKind m
- = NoArg (m ()) -- flag with no argument
- | HasArg (String -> m ()) -- flag has an argument (maybe prefix)
- | SepArg (String -> m ()) -- flag has a separate argument
- | Prefix (String -> m ()) -- flag is a prefix only
- | OptPrefix (String -> m ()) -- flag may be a prefix
- | AnySuffix (String -> m ()) -- flag is a prefix, pass whole arg to fn
- | PassFlag (String -> m ()) -- flag with no arg, pass flag to fn
+data OptKind m -- Suppose the flag is -f
+ = NoArg (m ()) -- -f all by itself
+ | HasArg (String -> m ()) -- -farg or -f arg
+ | SepArg (String -> m ()) -- -f arg
+ | Prefix (String -> m ()) -- -farg
+ | OptPrefix (String -> m ()) -- -f or -farg (i.e. the arg is optional)
+ | OptIntSuffix (Maybe Int -> m ()) -- -f or -f=n; pass n to fn
+ | IntSuffix (Int -> m ()) -- -f or -f=n; pass n to fn
+ | PassFlag (String -> m ()) -- -f; pass "-f" fn
+ | AnySuffix (String -> m ()) -- -f or -farg; pass entire "-farg" to fn
| PrefixPred (String -> Bool) (String -> m ())
| AnySuffixPred (String -> Bool) (String -> m ())
-
+
processArgs :: Monad m
=> [(String, OptKind m)] -- cmdline parser spec
-> [String] -- args
process _spec [] spare errs =
return (reverse spare, reverse errs)
- process spec args@(('-':arg):args') spare errs =
+ process spec (dash_arg@('-':arg):args) spare errs =
case findArg spec arg of
Just (rest,action) ->
- case processOneArg action rest args of
- Left err -> process spec args' spare (err:errs)
- Right (action,rest) -> do
- action >> process spec rest spare errs
- Nothing ->
- process spec args' (('-':arg):spare) errs
+ case processOneArg action rest arg args of
+ Left err -> process spec args spare (err:errs)
+ Right (action,rest) -> action >> process spec rest spare errs
+ Nothing -> process spec args (dash_arg:spare) errs
process spec (arg:args) spare errs =
process spec args (arg:spare) errs
-processOneArg :: OptKind m -> String -> [String]
- -> Either String (m (), [String])
-processOneArg action rest (dash_arg@('-':arg):args) =
- case action of
+processOneArg :: OptKind m -> String -> String -> [String]
+ -> Either String (m (), [String])
+processOneArg action rest arg args
+ = let dash_arg = '-' : arg
+ rest_no_eq = dropEq rest
+ in case action of
NoArg a -> ASSERT(null rest) Right (a, args)
- HasArg f ->
- if rest /= ""
- then Right (f rest, args)
- else case args of
- [] -> missingArgErr dash_arg
- (arg1:args1) -> Right (f arg1, args1)
+ HasArg f | notNull rest_no_eq -> Right (f rest_no_eq, args)
+ | otherwise -> case args of
+ [] -> missingArgErr dash_arg
+ (arg1:args1) -> Right (f arg1, args1)
- SepArg f ->
- case args of
+ SepArg f -> case args of
[] -> unknownFlagErr dash_arg
(arg1:args1) -> Right (f arg1, args1)
- Prefix f ->
- if rest /= ""
- then Right (f rest, args)
- else unknownFlagErr dash_arg
+ Prefix f | notNull rest_no_eq -> Right (f rest_no_eq, args)
+ | otherwise -> unknownFlagErr dash_arg
- PrefixPred p f ->
- if rest /= ""
- then Right (f rest, args)
- else unknownFlagErr dash_arg
+ PrefixPred p f | notNull rest_no_eq -> Right (f rest_no_eq, args)
+ | otherwise -> unknownFlagErr dash_arg
- OptPrefix f -> Right (f rest, args)
+ PassFlag f | notNull rest -> unknownFlagErr dash_arg
+ | otherwise -> Right (f dash_arg, args)
- AnySuffix f -> Right (f dash_arg, args)
+ OptIntSuffix f | null rest -> Right (f Nothing, args)
+ | Just n <- parseInt rest_no_eq -> Right (f (Just n), args)
+ | otherwise -> Left ("malformed integer argument in " ++ dash_arg)
- AnySuffixPred p f -> Right (f dash_arg, args)
+ IntSuffix f | Just n <- parseInt rest_no_eq -> Right (f n, args)
+ | otherwise -> Left ("malformed integer argument in " ++ dash_arg)
- PassFlag f ->
- if rest /= ""
- then unknownFlagErr dash_arg
- else Right (f dash_arg, args)
+ OptPrefix f -> Right (f rest_no_eq, args)
+ AnySuffix f -> Right (f dash_arg, args)
+ AnySuffixPred p f -> Right (f dash_arg, args)
findArg :: [(String,OptKind a)] -> String -> Maybe (String,OptKind a)
arg_ok (HasArg _) rest arg = True
arg_ok (SepArg _) rest arg = null rest
arg_ok (Prefix _) rest arg = notNull rest
-arg_ok (PrefixPred p _) rest arg = notNull rest && p rest
+arg_ok (PrefixPred p _) rest arg = notNull rest && p (dropEq rest)
+arg_ok (OptIntSuffix _) rest arg = True
+arg_ok (IntSuffix _) rest arg = True
arg_ok (OptPrefix _) rest arg = True
arg_ok (PassFlag _) rest arg = null rest
arg_ok (AnySuffix _) rest arg = True
arg_ok (AnySuffixPred p _) rest arg = p arg
+parseInt :: String -> Maybe Int
+-- Looks for "433" or "=342", with no trailing gubbins
+-- n or =n => Just n
+-- gibberish => Nothing
+parseInt s = case reads s of
+ ((n,""):_) -> Just n
+ other -> Nothing
+
+dropEq :: String -> String
+-- Discards a leading equals sign
+dropEq ('=' : s) = s
+dropEq s = s
+
unknownFlagErr :: String -> Either String a
unknownFlagErr f = Left ("unrecognised flag: " ++ f)