main/CmdLineParser.hs

    -------------------------------------------------------------------------------
    --
    -- | Command-line parser
    --
    -- This is an abstract command-line parser used by both StaticFlags and
    -- DynFlags.
    --
    -- (c) The University of Glasgow 2005
    --
    -------------------------------------------------------------------------------

    module CmdLineParser
        (
          processArgs, OptKind(..),
          CmdLineP(..), getCmdLineState, putCmdLineState,
          Flag(..),
          errorsToGhcException,

          EwM, addErr, addWarn, getArg, getCurLoc, liftEwM, deprecate
        ) where

    #include "HsVersions.h"

    import Util
    import Outputable
    import Panic
    import Bag
    import SrcLoc

    import Data.Function
    import Data.List

    import Control.Monad (liftM, ap)
    import Control.Applicative (Applicative(..))

    --------------------------------------------------------
    --         The Flag and OptKind types
    --------------------------------------------------------

    data Flag m = Flag
        {   flagName    :: String,   -- Flag, without the leading "-"
            flagOptKind :: OptKind m -- What to do if we see it
        }

    data OptKind m                             -- Suppose the flag is -f
        = NoArg     (EwM m ())                 -- -f all by itself
        | HasArg    (String -> EwM m ())       -- -farg or -f arg
        | SepArg    (String -> EwM m ())       -- -f arg
        | Prefix    (String -> EwM m ())       -- -farg
        | OptPrefix (String -> EwM m ())       -- -f or -farg (i.e. the arg is optional)
        | OptIntSuffix (Maybe Int -> EwM m ()) -- -f or -f=n; pass n to fn
        | IntSuffix (Int -> EwM m ())          -- -f or -f=n; pass n to fn
        | FloatSuffix (Float -> EwM m ())      -- -f or -f=n; pass n to fn
        | PassFlag  (String -> EwM m ())       -- -f; pass "-f" fn
        | AnySuffix (String -> EwM m ())       -- -f or -farg; pass entire "-farg" to fn
        | PrefixPred    (String -> Bool) (String -> EwM m ())
        | AnySuffixPred (String -> Bool) (String -> EwM m ())
        | VersionSuffix (Int -> Int -> EwM m ())
          -- -f or -f=maj.min; pass major and minor version to fn

    --------------------------------------------------------
    --         The EwM monad
    --------------------------------------------------------

    type Err   = Located String
    type Warn  = Located String
    type Errs  = Bag Err
    type Warns = Bag Warn

    -- EwM ("errors and warnings monad") is a monad
    -- transformer for m that adds an (err, warn) state
    newtype EwM m a = EwM { unEwM :: Located String -- Current parse arg
                                  -> Errs -> Warns
                                  -> m (Errs, Warns, a) }

    instance Monad m => Functor (EwM m) where
        fmap = liftM

    instance Monad m => Applicative (EwM m) where
        pure = return
        (<*>) = ap

    instance Monad m => Monad (EwM m) where
        (EwM f) >>= k = EwM (\l e w -> do (e', w', r) <- f l e w
                                          unEwM (k r) l e' w')
        return v = EwM (\_ e w -> return (e, w, v))

    setArg :: Monad m => Located String -> EwM m () -> EwM m ()
    setArg l (EwM f) = EwM (\_ es ws -> f l es ws)

    addErr :: Monad m => String -> EwM m ()
    addErr e = EwM (\(L loc _) es ws -> return (es `snocBag` L loc e, ws, ()))

    addWarn :: Monad m => String -> EwM m ()
    addWarn msg = EwM (\(L loc _) es ws -> return (es, ws `snocBag` L loc msg, ()))

    deprecate :: Monad m => String -> EwM m ()
    deprecate s = do
        arg <- getArg
        addWarn (arg ++ " is deprecated: " ++ s)

    getArg :: Monad m => EwM m String
    getArg = EwM (\(L _ arg) es ws -> return (es, ws, arg))

    getCurLoc :: Monad m => EwM m SrcSpan
    getCurLoc = EwM (\(L loc _) es ws -> return (es, ws, loc))

    liftEwM :: Monad m => m a -> EwM m a
    liftEwM action = EwM (\_ es ws -> do { r <- action; return (es, ws, r) })

    --------------------------------------------------------
    -- A state monad for use in the command-line parser
    --------------------------------------------------------

    -- (CmdLineP s) typically instantiates the 'm' in (EwM m) and (OptKind m)
    newtype CmdLineP s a = CmdLineP { runCmdLine :: s -> (a, s) }

    instance Functor (CmdLineP s) where
        fmap = liftM

    instance Applicative (CmdLineP s) where
        pure = return
        (<*>) = ap

    instance Monad (CmdLineP s) where
        m >>= k = CmdLineP $ \s ->
                      let (a, s') = runCmdLine m s
                      in runCmdLine (k a) s'

        return a = CmdLineP $ \s -> (a, s)

    getCmdLineState :: CmdLineP s s
    getCmdLineState   = CmdLineP $ \s -> (s,s)
    putCmdLineState :: s -> CmdLineP s ()
    putCmdLineState s = CmdLineP $ \_ -> ((),s)

    --------------------------------------------------------
    --         Processing arguments
    --------------------------------------------------------

    processArgs :: Monad m
                => [Flag m]               -- cmdline parser spec
                -> [Located String]       -- args
                -> m ( [Located String],  -- spare args
                       [Located String],  -- errors
                       [Located String] ) -- warnings
    processArgs spec args = do
        (errs, warns, spare) <- unEwM action (panic "processArgs: no arg yet")
                                      emptyBag emptyBag
        return (spare, bagToList errs, bagToList warns)
      where
        action = process args []

        -- process :: [Located String] -> [Located String] -> EwM m [Located String]
        process [] spare = return (reverse spare)

        process (locArg@(L _ ('-' : arg)) : args) spare =
            case findArg spec arg of
                Just (rest, opt_kind) ->
                    case processOneArg opt_kind rest arg args of
                        Left err ->
                            let b = process args spare
                            in (setArg locArg $ addErr err) >> b

                        Right (action,rest) ->
                            let b = process rest spare
                            in (setArg locArg $ action) >> b

                Nothing -> process args (locArg : spare)

        process (arg : args) spare = process args (arg : spare)

    processOneArg :: OptKind m -> String -> String -> [Located String]
                  -> Either String (EwM m (), [Located String])
    processOneArg opt_kind rest arg args
      = let dash_arg = '-' : arg
            rest_no_eq = dropEq rest
        in case opt_kind of
            NoArg  a -> ASSERT(null rest) Right (a, args)

            HasArg f | notNull rest_no_eq -> Right (f rest_no_eq, args)
                     | otherwise -> case args of
                                        []               -> missingArgErr dash_arg
                                        (L _ arg1:args1) -> Right (f arg1, args1)

            SepArg f -> case args of
                            []               -> unknownFlagErr dash_arg
                            (L _ arg1:args1) -> Right (f arg1, args1)

            Prefix f | notNull rest_no_eq -> Right (f rest_no_eq, args)
                     | otherwise          -> unknownFlagErr dash_arg

            PrefixPred _ f | notNull rest_no_eq -> Right (f rest_no_eq, args)
                           | otherwise          -> unknownFlagErr dash_arg

            PassFlag f  | notNull rest -> unknownFlagErr dash_arg
                        | otherwise    -> Right (f dash_arg, args)

            OptIntSuffix f | null rest                     -> Right (f Nothing,  args)
                           | Just n <- parseInt rest_no_eq -> Right (f (Just n), args)
                           | otherwise -> Left ("malformed integer argument in " ++ dash_arg)

            IntSuffix f | Just n <- parseInt rest_no_eq -> Right (f n, args)
                        | otherwise -> Left ("malformed integer argument in " ++ dash_arg)

            FloatSuffix f | Just n <- parseFloat rest_no_eq -> Right (f n, args)
                          | otherwise -> Left ("malformed float argument in " ++ dash_arg)

            OptPrefix f       -> Right (f rest_no_eq, args)
            AnySuffix f       -> Right (f dash_arg, args)
            AnySuffixPred _ f -> Right (f dash_arg, args)

            VersionSuffix f | [maj_s, min_s] <- split '.' rest_no_eq,
                              Just maj <- parseInt maj_s,
                              Just min <- parseInt min_s -> Right (f maj min, args)
                            | [maj_s] <- split '.' rest_no_eq,
                              Just maj <- parseInt maj_s -> Right (f maj 0, args)
                            | null rest_no_eq -> Right (f 1 0, args)
                            | otherwise -> Left ("malformed version argument in " ++ dash_arg)

    findArg :: [Flag m] -> String -> Maybe (String, OptKind m)
    findArg spec arg =
        case sortBy (compare `on` (length . fst)) -- prefer longest matching flag
               [ (removeSpaces rest, optKind)
               | flag <- spec,
                 let optKind  = flagOptKind flag,
                 Just rest <- [stripPrefix (flagName flag) arg],
                 arg_ok optKind rest arg ]
        of
            []      -> Nothing
            (one:_) -> Just one

    arg_ok :: OptKind t -> [Char] -> String -> Bool
    arg_ok (NoArg           _)  rest _   = null rest
    arg_ok (HasArg          _)  _    _   = True
    arg_ok (SepArg          _)  rest _   = null rest
    arg_ok (Prefix          _)  rest _   = notNull rest
    arg_ok (PrefixPred p    _)  rest _   = notNull rest && p (dropEq rest)
    arg_ok (OptIntSuffix    _)  _    _   = True
    arg_ok (IntSuffix       _)  _    _   = True
    arg_ok (FloatSuffix     _)  _    _   = True
    arg_ok (OptPrefix       _)  _    _   = True
    arg_ok (PassFlag        _)  rest _   = null rest
    arg_ok (AnySuffix       _)  _    _   = True
    arg_ok (AnySuffixPred p _)  _    arg = p arg
    arg_ok (VersionSuffix   _)  _    _   = True

    -- | Parse an Int
    --
    -- Looks for "433" or "=342", with no trailing gubbins
    --   * n or =n      => Just n
    --   * gibberish    => Nothing
    parseInt :: String -> Maybe Int
    parseInt s = case reads s of
                     ((n,""):_) -> Just n
                     _          -> Nothing

    parseFloat :: String -> Maybe Float
    parseFloat s = case reads s of
                       ((n,""):_) -> Just n
                       _          -> Nothing

    -- | Discards a leading equals sign
    dropEq :: String -> String
    dropEq ('=' : s) = s
    dropEq s         = s

    unknownFlagErr :: String -> Either String a
    unknownFlagErr f = Left ("unrecognised flag: " ++ f)

    missingArgErr :: String -> Either String a
    missingArgErr f = Left ("missing argument for flag: " ++ f)

    --------------------------------------------------------
    -- Utils
    --------------------------------------------------------

    errorsToGhcException :: [Located String] -> GhcException
    errorsToGhcException errs =
        UsageError $
            intercalate "\n" [ showUserSpan True l ++ ": " ++ e | L l e <- errs ]