use parser combinators to parse the shell commands. simplified CommandLine type

src-3.0/GF/Command/Parse.hs

@@ -0,0 +1,35 @@
+module GF.Command.Parse(readCommandLine) where
+
+import PGF.ExprSyntax
+import GF.Command.Abstract
+
+import Data.Char
+import qualified Text.ParserCombinators.ReadP as RP
+
+readCommandLine :: String -> Maybe CommandLine
+readCommandLine s = case [x | (x,cs) <- RP.readP_to_S pCommandLine s, all isSpace cs] of
+                      [x] -> Just x
+                      _   -> Nothing
+
+test s = RP.readP_to_S pCommandLine s 
+
+pCommandLine = RP.sepBy (RP.skipSpaces >> pPipe) (RP.skipSpaces >> RP.char ';')
+
+pPipe = RP.sepBy (RP.skipSpaces >> pCommand) (RP.skipSpaces >> RP.char '|')
+
+pCommand = do
+  cmd  <- pIdent
+  RP.skipSpaces
+  opts <- RP.many pOption
+  arg  <- RP.option ANoArg (fmap AExp (pExp False))
+  return (Command cmd opts arg)
+
+pOption = do
+  RP.char '-'
+  flg <- pIdent
+  RP.option (OOpt flg) (fmap (OFlag flg) (RP.char '=' >> pValue))
+
+pValue = do
+  fmap VId  pIdent
+  RP.<++
+  fmap (VInt . read) (RP.munch1 isDigit)