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{-# 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]
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