{-# LANGUAGE RecordWildCards #-} module System.Console.CmdArgs.Explicit.ExpandArgsAt(expandArgsAt) where import System.FilePath -- | Expand @\@@ directives in a list of arguments, usually obtained from 'getArgs'. -- As an example, given the file @test.txt@ with the lines @hello@ and @world@: -- -- > expandArgsAt ["@test.txt","!"] == ["hello","world","!"] -- -- Any @\@@ directives in the files will be recursively expanded (raising an error -- if there is infinite recursion). -- -- To supress @\@@ expansion, pass any @\@@ arguments after @--@. expandArgsAt :: [String] -> IO [String] expandArgsAt args = do ebefore <- mapM (f [] ".") before return $ concat ebefore ++ after where (before,after) = break (== "--") args f seen dir ('@':x) | x `elem` seen = error $ unlines $ "System.Console.CmdArgs.Explicit.expandArgsAt, recursion in @ directives:" : map (" "++) (reverse $ x:seen) | length seen > 15 = error $ unlines $ "System.Console.CmdArgs.Explicit.expandArgsAt, over 15 @ directives deep:" : map (" "++) (reverse seen) | otherwise = do src <- readFile $ dir </> x fmap concat $ mapM (f (x:seen) (takeDirectory x)) $ lines src f _ _ x = return [x]