Add stage options

lib/Language/Elna/Driver.hs

@@ -0,0 +1,37 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+module Language.Elna.Driver
+    ( Driver(..)
+    , IntermediateStage(..)
+    , drive
+    , execParser
+    ) where
+
+import Data.Maybe (fromMaybe)
+import Language.Elna.Driver.CommandLine
+    ( CommandLine(..)
+    , IntermediateStage(..)
+    , commandLine
+    )
+import Options.Applicative (execParser)
+import System.FilePath (replaceExtension, takeFileName)
+
+data Driver = Driver
+    { input :: FilePath
+    , output :: FilePath
+    , intermediateStage :: Maybe IntermediateStage
+    } deriving (Eq, Show)
+
+drive :: IO Driver
+drive = rewrite <$> execParser commandLine
+  where
+    rewrite CommandLine{..} =
+        let defaultOutputName = replaceExtension (takeFileName input) "o"
+            outputName = fromMaybe defaultOutputName output
+         in Driver
+            { input = input
+            , output = outputName
+            , intermediateStage = intermediateStage
+            }