{-# LANGUAGE RecordWildCards #-}
module System.Console.CmdArgs.Explicit.SplitJoin(splitArgs, joinArgs) where
import Data.Char
import Data.Maybe
-- | Given a sequence of arguments, join them together in a manner that could be used on
-- the command line, giving preference to the Windows @cmd@ shell quoting conventions.
--
-- For an alternative version, intended for actual running the result in a shell, see "System.Process.showCommandForUser"
joinArgs :: [String] -> String
joinArgs = unwords . map f
where
f x = q ++ g x ++ q
where
hasSpace = any isSpace x
q = ['\"' | hasSpace || null x]
g ('\\':'\"':xs) = '\\':'\\':'\\':'\"': g xs
g "\\" | hasSpace = "\\\\"
g ('\"':xs) = '\\':'\"': g xs
g (x:xs) = x : g xs
g [] = []
data State = Init -- either I just started, or just emitted something
| Norm -- I'm seeing characters
| Quot -- I've seen a quote
-- | Given a string, split into the available arguments. The inverse of 'joinArgs'.
splitArgs :: String -> [String]
splitArgs = join . f Init
where
-- Nothing is start a new string
-- Just x is accumulate onto the existing string
join :: [Maybe Char] -> [String]
join [] = []
join xs = map fromJust a : join (drop 1 b)
where (a,b) = break isNothing xs
f Init (x:xs) | isSpace x = f Init xs
f Init "\"\"" = [Nothing]
f Init "\"" = [Nothing]
f Init xs = f Norm xs
f m ('\"':'\"':'\"':xs) = Just '\"' : f m xs
f m ('\\':'\"':xs) = Just '\"' : f m xs
f m ('\\':'\\':'\"':xs) = Just '\\' : f m ('\"':xs)
f Norm ('\"':xs) = f Quot xs
f Quot ('\"':'\"':xs) = Just '\"' : f Norm xs
f Quot ('\"':xs) = f Norm xs
f Norm (x:xs) | isSpace x = Nothing : f Init xs
f m (x:xs) = Just x : f m xs
f m [] = []