Add command line parser

1 files changed, 44 insertions, 0 deletions

diff --git a/lib/Language/Elna/CommandLine.hs b/lib/Language/Elna/CommandLine.hs
new file mode 100644
index 0000000..b23be7d
--- /dev/null
+++ b/lib/Language/Elna/CommandLine.hs
@@ -0,0 +1,44 @@
+module Language.Elna.CommandLine
+    ( CommandLine(..)
+    , commandLine
+    , execParser
+    ) where
+
+import Options.Applicative
+    ( Parser
+    , ParserInfo(..)
+    , argument
+    , execParser
+    , fullDesc
+    , help
+    , helper
+    , info
+    , long
+    , metavar
+    , optional
+    , progDesc
+    , short
+    , str
+    , strOption
+    )
+import Control.Applicative ((<**>))
+
+data CommandLine = CommandLine
+    { input :: FilePath
+    , output :: Maybe FilePath
+    } deriving (Eq, Show)
+
+parser :: Parser CommandLine
+parser = CommandLine
+    <$> argument str inFile
+    <*> optional (strOption outFile)
+  where
+    inFile = metavar "INFILE" <> help "Input file."
+    outFile = long "output"
+        <> short 'o'
+        <> metavar "OUTFILE"
+        <> help "Output file."
+
+commandLine :: ParserInfo CommandLine
+commandLine = info (parser <**> helper)
+    $ fullDesc <> progDesc "Elna compiler."