InteractiveUI.hs

{-# OPTIONS -#include "Linker.h" #-}
-----------------------------------------------------------------------------
--
-- GHC Interactive User Interface
--
-- (c) The GHC Team 2005
--
-----------------------------------------------------------------------------
module InteractiveUI ( 
	interactiveUI,
	ghciWelcomeMsg
   ) where

#include "HsVersions.h"

-- The GHC interface
import qualified GHC
import GHC		( Session, verbosity, dopt, DynFlag(..),
			  mkModule, pprModule, Type, Module, SuccessFlag(..),
			  TyThing(..), Name, LoadHowMuch(..),
			  GhcException(..), showGhcException )
import Outputable

-- following all needed for :info... ToDo: remove
import IfaceSyn		( IfaceDecl(..), IfaceClassOp(..), IfaceConDecls(..),
			  IfaceConDecl(..), IfaceType,
		   	  pprIfaceDeclHead, pprParendIfaceType,
			  pprIfaceForAllPart, pprIfaceType )
import FunDeps		( pprFundeps )
import SrcLoc		( SrcLoc, isGoodSrcLoc )
import OccName		( OccName, parenSymOcc, occNameUserString )
import BasicTypes	( StrictnessMark(..), defaultFixity )

-- Other random utilities
import Panic 		( panic, installSignalHandlers )
import Config
import StaticFlags	( opt_IgnoreDotGhci )
import Linker		( showLinkerState )
import Util		( removeSpaces, handle, global, toArgs,
			  looksLikeModuleName, prefixMatch )

#ifndef mingw32_HOST_OS
import Util		( handle )
import System.Posix
#if __GLASGOW_HASKELL__ > 504
	hiding (getEnv)
#endif
#endif

#ifdef USE_READLINE
import Control.Concurrent	( yield )	-- Used in readline loop
import System.Console.Readline as Readline
#endif

--import SystemExts

import Control.Exception as Exception
import Data.Dynamic
-- import Control.Concurrent

import Numeric
import Data.List
import Data.Int		( Int64 )
import System.Cmd
import System.CPUTime
import System.Environment
import System.Exit	( exitWith, ExitCode(..) )
import System.Directory
import System.IO
import System.IO.Error as IO
import Data.Char
import Control.Monad as Monad
import Foreign.StablePtr	( newStablePtr )

import GHC.Exts		( unsafeCoerce# )
import GHC.IOBase	( IOErrorType(InvalidArgument) )

import Data.IORef	( IORef, newIORef, readIORef, writeIORef )

import System.Posix.Internals ( setNonBlockingFD )

-----------------------------------------------------------------------------

ghciWelcomeMsg =
 "   ___         ___ _\n"++
 "  / _ \\ /\\  /\\/ __(_)\n"++
 " / /_\\// /_/ / /  | |      GHC Interactive, version " ++ cProjectVersion ++ ", for Haskell 98.\n"++
 "/ /_\\\\/ __  / /___| |      http://www.haskell.org/ghc/\n"++
 "\\____/\\/ /_/\\____/|_|      Type :? for help.\n"

GLOBAL_VAR(commands, builtin_commands, [(String, String -> GHCi Bool)])

builtin_commands :: [(String, String -> GHCi Bool)]
builtin_commands = [
  ("add",	keepGoingPaths addModule),
  ("browse",    keepGoing browseCmd),
  ("cd",    	keepGoing changeDirectory),
  ("def",	keepGoing defineMacro),
  ("help",	keepGoing help),
  ("?",		keepGoing help),
  ("info",      keepGoing info),
  ("load",	keepGoingPaths loadModule),
  ("module",	keepGoing setContext),
  ("reload",	keepGoing reloadModule),
  ("set",	keepGoing setCmd),
  ("show",	keepGoing showCmd),
  ("type",	keepGoing typeOfExpr),
  ("kind",	keepGoing kindOfType),
  ("unset",	keepGoing unsetOptions),
  ("undef",     keepGoing undefineMacro),
  ("quit",	quit)
  ]

keepGoing :: (String -> GHCi ()) -> (String -> GHCi Bool)
keepGoing a str = a str >> return False

keepGoingPaths :: ([FilePath] -> GHCi ()) -> (String -> GHCi Bool)
keepGoingPaths a str = a (toArgs str) >> return False

shortHelpText = "use :? for help.\n"

-- NOTE: spaces at the end of each line to workaround CPP/string gap bug.
helpText =
 " Commands available from the prompt:\n" ++
 "\n" ++
 "   <stmt>                      evaluate/run <stmt>\n" ++
 "   :add <filename> ...         add module(s) to the current target set\n" ++
 "   :browse [*]<module>         display the names defined by <module>\n" ++
 "   :cd <dir>                   change directory to <dir>\n" ++
 "   :def <cmd> <expr>           define a command :<cmd>\n" ++
 "   :help, :?                   display this list of commands\n" ++
 "   :info [<name> ...]          display information about the given names\n" ++
 "   :load <filename> ...        load module(s) and their dependents\n" ++
 "   :module [+/-] [*]<mod> ...  set the context for expression evaluation\n" ++
 "   :reload                     reload the current module set\n" ++
 "\n" ++
 "   :set <option> ...           set options\n" ++
 "   :set args <arg> ...         set the arguments returned by System.getArgs\n" ++
 "   :set prog <progname>        set the value returned by System.getProgName\n" ++
 "\n" ++
 "   :show modules               show the currently loaded modules\n" ++
 "   :show bindings              show the current bindings made at the prompt\n" ++
 "\n" ++
 "   :type <expr>                show the type of <expr>\n" ++
 "   :kind <type>                show the kind of <type>\n" ++
 "   :undef <cmd>                undefine user-defined command :<cmd>\n" ++
 "   :unset <option> ...         unset options\n" ++
 "   :quit                       exit GHCi\n" ++
 "   :!<command>                 run the shell command <command>\n" ++
 "\n" ++
 " Options for ':set' and ':unset':\n" ++
 "\n" ++
 "    +r            revert top-level expressions after each evaluation\n" ++
 "    +s            print timing/memory stats after each evaluation\n" ++
 "    +t            print type after evaluation\n" ++
 "    -<flags>      most GHC command line flags can also be set here\n" ++
 "                         (eg. -v2, -fglasgow-exts, etc.)\n"


interactiveUI :: Session -> [FilePath] -> Maybe String -> IO ()
interactiveUI session srcs maybe_expr = do

   -- HACK! If we happen to get into an infinite loop (eg the user
   -- types 'let x=x in x' at the prompt), then the thread will block
   -- on a blackhole, and become unreachable during GC.  The GC will
   -- detect that it is unreachable and send it the NonTermination
   -- exception.  However, since the thread is unreachable, everything
   -- it refers to might be finalized, including the standard Handles.
   -- This sounds like a bug, but we don't have a good solution right
   -- now.
   newStablePtr stdin
   newStablePtr stdout
   newStablePtr stderr

   hFlush stdout
   hSetBuffering stdout NoBuffering

	-- Initialise buffering for the *interpreted* I/O system
   initInterpBuffering session

	-- We don't want the cmd line to buffer any input that might be
	-- intended for the program, so unbuffer stdin.
   hSetBuffering stdin NoBuffering

	-- initial context is just the Prelude
   GHC.setContext session [] [prelude_mod]

#ifdef USE_READLINE
   Readline.initialize
#endif

   startGHCi (runGHCi srcs maybe_expr)
	GHCiState{ progname = "<interactive>",
		   args = [],
		   session = session,
		   options = [] }

#ifdef USE_READLINE
   Readline.resetTerminal Nothing
#endif

   return ()

runGHCi :: [FilePath] -> Maybe String -> GHCi ()
runGHCi paths maybe_expr = do
  let read_dot_files = not opt_IgnoreDotGhci

  when (read_dot_files) $ do
    -- Read in ./.ghci.
    let file = "./.ghci"
    exists <- io (doesFileExist file)
    when exists $ do
       dir_ok  <- io (checkPerms ".")
       file_ok <- io (checkPerms file)
       when (dir_ok && file_ok) $ do
  	  either_hdl <- io (IO.try (openFile "./.ghci" ReadMode))
  	  case either_hdl of
  	     Left e    -> return ()
  	     Right hdl -> fileLoop hdl False
    
  when (read_dot_files) $ do
    -- Read in $HOME/.ghci
    either_dir <- io (IO.try (getEnv "HOME"))
    case either_dir of
       Left e -> return ()
       Right dir -> do
  	  cwd <- io (getCurrentDirectory)
  	  when (dir /= cwd) $ do
  	     let file = dir ++ "/.ghci"
  	     ok <- io (checkPerms file)
  	     when ok $ do
  	       either_hdl <- io (IO.try (openFile file ReadMode))
  	       case either_hdl of
  		  Left e    -> return ()
  		  Right hdl -> fileLoop hdl False

  -- Perform a :load for files given on the GHCi command line
  when (not (null paths)) $
     ghciHandle showException $
	loadModule paths

  -- if verbosity is greater than 0, or we are connected to a
  -- terminal, display the prompt in the interactive loop.
  is_tty <- io (hIsTerminalDevice stdin)
  dflags <- getDynFlags
  let show_prompt = verbosity dflags > 0 || is_tty

  case maybe_expr of
	Nothing -> 
	    -- enter the interactive loop
	    interactiveLoop is_tty show_prompt
	Just expr -> do
	    -- just evaluate the expression we were given
	    runCommandEval expr
	    return ()

  -- and finally, exit
  io $ do when (verbosity dflags > 0) $ putStrLn "Leaving GHCi."


interactiveLoop is_tty show_prompt = do
  -- Ignore ^C exceptions caught here
  ghciHandleDyn (\e -> case e of 
			Interrupted -> ghciUnblock (interactiveLoop is_tty show_prompt)
			_other      -> return ()) $ do

  -- read commands from stdin
#ifdef USE_READLINE
  if (is_tty) 
	then readlineLoop
	else fileLoop stdin show_prompt
#else
  fileLoop stdin show_prompt
#endif


-- NOTE: We only read .ghci files if they are owned by the current user,
-- and aren't world writable.  Otherwise, we could be accidentally 
-- running code planted by a malicious third party.

-- Furthermore, We only read ./.ghci if . is owned by the current user
-- and isn't writable by anyone else.  I think this is sufficient: we
-- don't need to check .. and ../.. etc. because "."  always refers to
-- the same directory while a process is running.

checkPerms :: String -> IO Bool
checkPerms name =
#ifdef mingw32_HOST_OS
  return True
#else
  Util.handle (\_ -> return False) $ do
     st <- getFileStatus name
     me <- getRealUserID
     if fileOwner st /= me then do
   	putStrLn $ "WARNING: " ++ name ++ " is owned by someone else, IGNORING!"
   	return False
      else do
   	let mode =  fileMode st
   	if (groupWriteMode == (mode `intersectFileModes` groupWriteMode))
   	   || (otherWriteMode == (mode `intersectFileModes` otherWriteMode)) 
   	   then do
   	       putStrLn $ "*** WARNING: " ++ name ++ 
   			  " is writable by someone else, IGNORING!"
   	       return False
   	  else return True
#endif

fileLoop :: Handle -> Bool -> GHCi ()
fileLoop hdl prompt = do
   session <- getSession
   (mod,imports) <- io (GHC.getContext session)
   when prompt (io (putStr (mkPrompt mod imports)))
   l <- io (IO.try (hGetLine hdl))
   case l of
	Left e | isEOFError e		   -> return ()
	       | InvalidArgument <- etype  -> return ()
	       | otherwise		   -> io (ioError e)
		where etype = ioeGetErrorType e
		-- treat InvalidArgument in the same way as EOF:
		-- this can happen if the user closed stdin, or
		-- perhaps did getContents which closes stdin at
		-- EOF.
	Right l -> 
	  case removeSpaces l of
	    "" -> fileLoop hdl prompt
	    l  -> do quit <- runCommand l
          	     if quit then return () else fileLoop hdl prompt

stringLoop :: [String] -> GHCi ()
stringLoop [] = return ()
stringLoop (s:ss) = do
   case removeSpaces s of
	"" -> stringLoop ss
	l  -> do quit <- runCommand l
                 if quit then return () else stringLoop ss

mkPrompt toplevs exports
  = showSDoc (hsep (map (\m -> char '*' <> pprModule m) toplevs)
	     <+> hsep (map pprModule exports)
	     <> text "> ")

#ifdef USE_READLINE
readlineLoop :: GHCi ()
readlineLoop = do
   session <- getSession
   (mod,imports) <- io (GHC.getContext session)
   io yield
   l <- io (readline (mkPrompt mod imports)
	  	`finally` setNonBlockingFD 0)
		-- readline sometimes puts stdin into blocking mode,
		-- so we need to put it back for the IO library
   case l of
	Nothing -> return ()
	Just l  ->
	  case removeSpaces l of
	    "" -> readlineLoop
	    l  -> do
        	  io (addHistory l)
  	  	  quit <- runCommand l
          	  if quit then return () else readlineLoop
#endif

runCommand :: String -> GHCi Bool
runCommand c = ghciHandle handler (doCommand c)

-- This version is for the GHC command-line option -e.  The only difference
-- from runCommand is that it catches the ExitException exception and
-- exits, rather than printing out the exception.
runCommandEval c = ghciHandle handleEval (doCommand c)
  where 
    handleEval (ExitException code) = io (exitWith code)
    handleEval e                    = do showException e
				         io (exitWith (ExitFailure 1))

-- This is the exception handler for exceptions generated by the
-- user's code; it normally just prints out the exception.  The
-- handler must be recursive, in case showing the exception causes
-- more exceptions to be raised.
--
-- Bugfix: if the user closed stdout or stderr, the flushing will fail,
-- raising another exception.  We therefore don't put the recursive
-- handler arond the flushing operation, so if stderr is closed
-- GHCi will just die gracefully rather than going into an infinite loop.
handler :: Exception -> GHCi Bool
handler exception = do
  flushInterpBuffers
  io installSignalHandlers
  ghciHandle handler (showException exception >> return False)

showException (DynException dyn) =
  case fromDynamic dyn of
    Nothing               -> io (putStrLn ("*** Exception: (unknown)"))
    Just Interrupted      -> io (putStrLn "Interrupted.")
    Just (CmdLineError s) -> io (putStrLn s)	 -- omit the location for CmdLineError
    Just ph@PhaseFailed{} -> io (putStrLn (showGhcException ph "")) -- ditto
    Just other_ghc_ex     -> io (print other_ghc_ex)

showException other_exception
  = io (putStrLn ("*** Exception: " ++ show other_exception))

doCommand (':' : command) = specialCommand command
doCommand stmt
   = do timeIt (do nms <- runStmt stmt; finishEvalExpr nms)
        return False

runStmt :: String -> GHCi [Name]
runStmt stmt
 | null (filter (not.isSpace) stmt) = return []
 | otherwise
 = do st <- getGHCiState
      session <- getSession
      result <- io $ withProgName (progname st) $ withArgs (args st) $
	     	     GHC.runStmt session stmt
      case result of
	GHC.RunFailed      -> return []
	GHC.RunException e -> throw e  -- this is caught by runCommand(Eval)
	GHC.RunOk names    -> return names

-- possibly print the type and revert CAFs after evaluating an expression
finishEvalExpr names
 = do b <- isOptionSet ShowType
      session <- getSession
      when b (mapM_ (showTypeOfName session) names)

      flushInterpBuffers
      io installSignalHandlers
      b <- isOptionSet RevertCAFs
      io (when b revertCAFs)
      return True

showTypeOfName :: Session -> Name -> GHCi ()
showTypeOfName session n
   = do maybe_tything <- io (GHC.lookupName session n)
	case maybe_tything of
	  Nothing    -> return ()
	  Just thing -> showTyThing thing

showForUser :: SDoc -> GHCi String
showForUser doc = do
  session <- getSession
  unqual <- io (GHC.getPrintUnqual session)
  return $! showSDocForUser unqual doc

specialCommand :: String -> GHCi Bool
specialCommand ('!':str) = shellEscape (dropWhile isSpace str)
specialCommand str = do
  let (cmd,rest) = break isSpace str
  cmds <- io (readIORef commands)
  case [ (s,f) | (s,f) <- cmds, prefixMatch cmd s ] of
     []      -> io (hPutStr stdout ("unknown command ':" ++ cmd ++ "'\n" 
		                    ++ shortHelpText) >> return False)
     [(_,f)] -> f (dropWhile isSpace rest)
     cs      -> io (hPutStrLn stdout ("prefix " ++ cmd ++ 
			    	      " matches multiple commands (" ++ 
	         	     	       foldr1 (\a b -> a ++ ',':b) (map fst cs)
					 ++ ")") >> return False)

noArgs c = throwDyn (CmdLineError ("command '" ++ c ++ "' takes no arguments"))


-----------------------------------------------------------------------------
-- To flush buffers for the *interpreted* computation we need
-- to refer to *its* stdout/stderr handles

GLOBAL_VAR(flush_interp,       error "no flush_interp", IO ())
GLOBAL_VAR(turn_off_buffering, error "no flush_stdout", IO ())

no_buf_cmd = "System.IO.hSetBuffering System.IO.stdout System.IO.NoBuffering" ++
	     " Prelude.>> System.IO.hSetBuffering System.IO.stderr System.IO.NoBuffering"
flush_cmd  = "System.IO.hFlush System.IO.stdout Prelude.>> System.IO.hFlush IO.stderr"

initInterpBuffering :: Session -> IO ()
initInterpBuffering session
 = do maybe_hval <- GHC.compileExpr session no_buf_cmd
	
      case maybe_hval of
	Just hval -> writeIORef turn_off_buffering (unsafeCoerce# hval :: IO ())
	other	  -> panic "interactiveUI:setBuffering"
	
      maybe_hval <- GHC.compileExpr session flush_cmd
      case maybe_hval of
	Just hval -> writeIORef flush_interp (unsafeCoerce# hval :: IO ())
	_         -> panic "interactiveUI:flush"

      turnOffBuffering	-- Turn it off right now

      return ()


flushInterpBuffers :: GHCi ()
flushInterpBuffers
 = io $ do Monad.join (readIORef flush_interp)
           return ()

turnOffBuffering :: IO ()
turnOffBuffering
 = do Monad.join (readIORef turn_off_buffering)
      return ()

-----------------------------------------------------------------------------
-- Commands

help :: String -> GHCi ()
help _ = io (putStr helpText)

info :: String -> GHCi ()
info "" = throwDyn (CmdLineError "syntax: ':i <thing-you-want-info-about>'")
info s  = do { let names = words s
	     ; session <- getSession
	     ; dflags <- getDynFlags
	     ; let exts = dopt Opt_GlasgowExts dflags
	     ; mapM_ (infoThing exts session) names }
  where
    infoThing exts session name
	= do { stuff <- io (GHC.getInfo session name)
	     ; unqual <- io (GHC.getPrintUnqual session)
	     ; io (putStrLn (showSDocForUser unqual $
     		   vcat (intersperse (text "") (map (showThing exts) stuff)))) }

showThing :: Bool -> GHC.GetInfoResult -> SDoc
showThing exts (wanted_str, thing, fixity, src_loc, insts) 
    = vcat [ showWithLoc src_loc (showDecl exts want_name thing),
	     show_fixity fixity,
	     vcat (map show_inst insts)]
  where
    want_name occ = wanted_str == occNameUserString occ

    show_fixity fix 
	| fix == defaultFixity = empty
	| otherwise            = ppr fix <+> text wanted_str

    show_inst (inst_ty, loc)
	= showWithLoc loc (ptext SLIT("instance") <+> ppr inst_ty)

showWithLoc :: SrcLoc -> SDoc -> SDoc
showWithLoc loc doc 
    = hang doc 2 (char '\t' <> show_loc loc)
		-- The tab tries to make them line up a bit
  where
    show_loc loc	-- The ppr function for SrcLocs is a bit wonky
	| isGoodSrcLoc loc = comment <+> ptext SLIT("Defined at") <+> ppr loc
	| otherwise	   = comment <+> ppr loc
    comment = ptext SLIT("--")


-- Now there is rather a lot of goop just to print declarations in a
-- civilised way with "..." for the parts we are less interested in.

showDecl :: Bool -> (OccName -> Bool) -> IfaceDecl -> SDoc
showDecl exts want_name (IfaceForeign {ifName = tc})
  = ppr tc <+> ptext SLIT("is a foreign type")

showDecl exts want_name (IfaceId {ifName = var, ifType = ty})
  = ppr var <+> dcolon <+> showIfaceType exts ty 

showDecl exts want_name (IfaceSyn {ifName = tycon, ifTyVars = tyvars, ifSynRhs = mono_ty})
  = hang (ptext SLIT("type") <+> pprIfaceDeclHead [] tycon tyvars)
       2 (equals <+> ppr mono_ty)

showDecl exts want_name (IfaceData {ifName = tycon, 
		     ifTyVars = tyvars, ifCons = condecls})
  = hang (pp_nd <+> pprIfaceDeclHead context tycon tyvars)
       2 (add_bars (ppr_trim show_con cs))
  where
    show_con (IfVanillaCon { ifConOcc = con_name, ifConInfix = is_infix, ifConArgTys = tys, 
			     ifConStricts = strs, ifConFields = flds})
	| want_name tycon || want_name con_name || any want_name flds
	= Just (show_guts con_name is_infix tys_w_strs flds)
	| otherwise = Nothing
	where
	  tys_w_strs = tys `zip` (strs ++ repeat NotMarkedStrict)
    show_con (IfGadtCon { ifConOcc = con_name, ifConTyVars = tvs, ifConCtxt = theta, 
			  ifConArgTys = arg_tys, ifConResTys = res_tys, ifConStricts = strs })
	| want_name tycon || want_name con_name
	= Just (ppr_bndr con_name <+> colon <+> pprIfaceForAllPart tvs theta pp_tau)
	| otherwise = Nothing
	where
	  tys_w_strs = arg_tys `zip` (strs ++ repeat NotMarkedStrict)
	  pp_tau = foldr add pp_res_ty tys_w_strs
	  pp_res_ty = ppr_bndr tycon <+> hsep (map pprParendIfaceType res_tys)
	  add bty pp_ty = ppr_bangty bty <+> arrow <+> pp_ty

    show_guts con True [ty1, ty2] flds = sep [ppr_bangty ty1, ppr con, ppr_bangty ty2]
    show_guts con _ tys []   = ppr_bndr con <+> sep (map ppr_bangty tys)
    show_guts con _ tys flds 
	= ppr_bndr con <+> braces (sep (punctuate comma (ppr_trim show_fld (tys `zip` flds))))
	where
	  show_fld (bty, fld) | want_name tycon || want_name con || want_name fld
			      = Just (ppr_bndr fld <+> dcolon <+> ppr_bangty bty)
			      | otherwise = Nothing

    (pp_nd, context, cs) = case condecls of
		    IfAbstractTyCon 	      -> (ptext SLIT("data"), [],   [])
		    IfDataTyCon (Just cxt) cs -> (ptext SLIT("data"), cxt, cs)
		    IfDataTyCon Nothing cs    -> (ptext SLIT("data"), [],  cs)
		    IfNewTyCon c    	      -> (ptext SLIT("newtype"), [], [c])

    add_bars []      = empty
    add_bars [c]     = equals <+> c
    add_bars (c:cs)  = equals <+> sep (c : map (char '|' <+>) cs)

    ppr_bangty (ty, str) = ppr_str str <> pprParendIfaceType ty
    ppr_str MarkedStrict    = char '!'
    ppr_str MarkedUnboxed   = ptext SLIT("!!")
    ppr_str NotMarkedStrict = empty

showDecl exts want_name (IfaceClass {ifCtxt = context, ifName = clas, ifTyVars = tyvars, 
		      ifFDs = fds, ifSigs = sigs})
  = hang (ptext SLIT("class") <+> pprIfaceDeclHead context clas tyvars
		<+> pprFundeps fds <+> opt_where)
       2 (vcat (ppr_trim show_op sigs))
  where
    opt_where | null sigs = empty
	      | otherwise = ptext SLIT("where")
    show_op (IfaceClassOp op dm ty) 
	| want_name clas || want_name op 
	= Just (ppr_bndr op <+> dcolon <+> showIfaceType exts ty)
	| otherwise
	= Nothing

showIfaceType :: Bool -> IfaceType -> SDoc
showIfaceType True  ty = pprIfaceType ty -- -fglasgow-exts: print with the foralls
showIfaceType False ty = ppr ty	    -- otherwise, print without the foralls

ppr_trim :: (a -> Maybe SDoc) -> [a] -> [SDoc]
ppr_trim show xs
  = snd (foldr go (False, []) xs)
  where
    go x (eliding, so_far)
	| Just doc <- show x = (False, doc : so_far)
	| otherwise = if eliding then (True, so_far)
		                 else (True, ptext SLIT("...") : so_far)

ppr_bndr :: OccName -> SDoc
-- Wrap operators in ()
ppr_bndr occ = parenSymOcc occ (ppr occ)


-----------------------------------------------------------------------------
-- Commands

addModule :: [FilePath] -> GHCi ()
addModule files = do
  io (revertCAFs)			-- always revert CAFs on load/add.
  files <- mapM expandPath files
  targets <- mapM (io . GHC.guessTarget) files
  session <- getSession
  io (mapM_ (GHC.addTarget session) targets)
  ok <- io (GHC.load session LoadAllTargets)
  afterLoad ok session

changeDirectory :: String -> GHCi ()
changeDirectory dir = do
  session <- getSession
  graph <- io (GHC.getModuleGraph session)
  when (not (null graph)) $
	io $ putStr "Warning: changing directory causes all loaded modules to be unloaded,\nbecause the search path has changed.\n"
  io (GHC.setTargets session [])
  io (GHC.load session LoadAllTargets)
  setContextAfterLoad []
  io (GHC.workingDirectoryChanged session)
  dir <- expandPath dir
  io (setCurrentDirectory dir)

defineMacro :: String -> GHCi ()
defineMacro s = do
  let (macro_name, definition) = break isSpace s
  cmds <- io (readIORef commands)
  if (null macro_name) 
	then throwDyn (CmdLineError "invalid macro name") 
	else do
  if (macro_name `elem` map fst cmds) 
	then throwDyn (CmdLineError 
		("command '" ++ macro_name ++ "' is already defined"))
	else do

  -- give the expression a type signature, so we can be sure we're getting
  -- something of the right type.
  let new_expr = '(' : definition ++ ") :: String -> IO String"

  -- compile the expression
  cms <- getSession
  maybe_hv <- io (GHC.compileExpr cms new_expr)
  case maybe_hv of
     Nothing -> return ()
     Just hv -> io (writeIORef commands --
		    ((macro_name, keepGoing (runMacro hv)) : cmds))

runMacro :: GHC.HValue{-String -> IO String-} -> String -> GHCi ()
runMacro fun s = do
  str <- io ((unsafeCoerce# fun :: String -> IO String) s)
  stringLoop (lines str)

undefineMacro :: String -> GHCi ()
undefineMacro macro_name = do
  cmds <- io (readIORef commands)
  if (macro_name `elem` map fst builtin_commands) 
	then throwDyn (CmdLineError
		("command '" ++ macro_name ++ "' cannot be undefined"))
	else do
  if (macro_name `notElem` map fst cmds) 
	then throwDyn (CmdLineError 
		("command '" ++ macro_name ++ "' not defined"))
	else do
  io (writeIORef commands (filter ((/= macro_name) . fst) cmds))


loadModule :: [FilePath] -> GHCi ()
loadModule fs = timeIt (loadModule' fs)

loadModule' :: [FilePath] -> GHCi ()
loadModule' files = do
  session <- getSession

  -- unload first
  io (GHC.setTargets session [])
  io (GHC.load session LoadAllTargets)

  -- expand tildes
  files <- mapM expandPath files
  targets <- io (mapM GHC.guessTarget files)

  -- NOTE: we used to do the dependency anal first, so that if it
  -- fails we didn't throw away the current set of modules.  This would
  -- require some re-working of the GHC interface, so we'll leave it
  -- as a ToDo for now.

  io (GHC.setTargets session targets)
  ok <- io (GHC.load session LoadAllTargets)
  afterLoad ok session


reloadModule :: String -> GHCi ()
reloadModule "" = do
  io (revertCAFs)		-- always revert CAFs on reload.
  session <- getSession
  ok <- io (GHC.load session LoadAllTargets)
  afterLoad ok session
reloadModule m = do
  io (revertCAFs)		-- always revert CAFs on reload.
  session <- getSession
  ok <- io (GHC.load session (LoadUpTo (mkModule m)))
  afterLoad ok session

afterLoad ok session = do
  io (revertCAFs)  -- always revert CAFs on load.
  graph <- io (GHC.getModuleGraph session)
  let mods = map GHC.ms_mod graph
  mods' <- filterM (io . GHC.isLoaded session) mods
  setContextAfterLoad mods'
  modulesLoadedMsg ok mods'

setContextAfterLoad [] = do
  session <- getSession
  io (GHC.setContext session [] [prelude_mod])
setContextAfterLoad (m:_) = do
  session <- getSession
  b <- io (GHC.moduleIsInterpreted session m)
  if b then io (GHC.setContext session [m] []) 
       else io (GHC.setContext session []  [m])

modulesLoadedMsg :: SuccessFlag -> [Module] -> GHCi ()
modulesLoadedMsg ok mods = do
  dflags <- getDynFlags
  when (verbosity dflags > 0) $ do
   let mod_commas 
	| null mods = text "none."
	| otherwise = hsep (
	    punctuate comma (map pprModule mods)) <> text "."
   case ok of
    Failed ->
       io (putStrLn (showSDoc (text "Failed, modules loaded: " <> mod_commas)))
    Succeeded  ->
       io (putStrLn (showSDoc (text "Ok, modules loaded: " <> mod_commas)))


typeOfExpr :: String -> GHCi ()
typeOfExpr str 
  = do cms <- getSession
       maybe_ty <- io (GHC.exprType cms str)
       case maybe_ty of
	  Nothing -> return ()
	  Just ty -> do ty' <- cleanType ty
			tystr <- showForUser (ppr ty')
		        io (putStrLn (str ++ " :: " ++ tystr))

kindOfType :: String -> GHCi ()
kindOfType str 
  = do cms <- getSession
       maybe_ty <- io (GHC.typeKind cms str)
       case maybe_ty of
	  Nothing    -> return ()
	  Just ty    -> do tystr <- showForUser (ppr ty)
		           io (putStrLn (str ++ " :: " ++ tystr))

quit :: String -> GHCi Bool
quit _ = return True

shellEscape :: String -> GHCi Bool
shellEscape str = io (system str >> return False)

-----------------------------------------------------------------------------
-- Browsing a module's contents

browseCmd :: String -> GHCi ()
browseCmd m = 
  case words m of
    ['*':m] | looksLikeModuleName m -> browseModule m False
    [m]     | looksLikeModuleName m -> browseModule m True
    _ -> throwDyn (CmdLineError "syntax:  :browse <module>")

browseModule m exports_only = do
  s <- getSession

  let modl = mkModule m
  is_interpreted <- io (GHC.moduleIsInterpreted s modl)
  when (not is_interpreted && not exports_only) $
	throwDyn (CmdLineError ("module '" ++ m ++ "' is not interpreted"))

  -- Temporarily set the context to the module we're interested in,
  -- just so we can get an appropriate PrintUnqualified
  (as,bs) <- io (GHC.getContext s)
  io (if exports_only then GHC.setContext s [] [prelude_mod,modl]
		      else GHC.setContext s [modl] [])
  io (GHC.setContext s as bs)

  things <- io (GHC.browseModule s modl exports_only)
  unqual <- io (GHC.getPrintUnqual s)

  dflags <- getDynFlags
  let exts = dopt Opt_GlasgowExts dflags
  io (putStrLn (showSDocForUser unqual (
   	 vcat (map (showDecl exts (const True)) things)
      )))

-----------------------------------------------------------------------------
-- Setting the module context

setContext str
  | all sensible mods = fn mods
  | otherwise = throwDyn (CmdLineError "syntax:  :module [+/-] [*]M1 ... [*]Mn")
  where
    (fn, mods) = case str of 
			'+':stuff -> (addToContext,      words stuff)
			'-':stuff -> (removeFromContext, words stuff)
			stuff     -> (newContext,        words stuff) 

    sensible ('*':m) = looksLikeModuleName m
    sensible m       = looksLikeModuleName m

newContext mods = do
  session <- getSession
  (as,bs) <- separate session mods [] []
  let bs' = if null as && prelude_mod `notElem` bs then prelude_mod:bs else bs
  io (GHC.setContext session as bs')

separate :: Session -> [String] -> [Module] -> [Module]
  -> GHCi ([Module],[Module])
separate session []           as bs = return (as,bs)
separate session (('*':m):ms) as bs = do
   let modl = mkModule m
   b <- io (GHC.moduleIsInterpreted session modl)
   if b then separate session ms (modl:as) bs
   	else throwDyn (CmdLineError ("module '" ++ m ++ "' is not interpreted"))
separate session (m:ms)       as bs = separate session ms as (mkModule m:bs)

prelude_mod = mkModule "Prelude"


addToContext mods = do
  cms <- getSession
  (as,bs) <- io (GHC.getContext cms)

  (as',bs') <- separate cms mods [] []

  let as_to_add = as' \\ (as ++ bs)
      bs_to_add = bs' \\ (as ++ bs)

  io (GHC.setContext cms (as ++ as_to_add) (bs ++ bs_to_add))


removeFromContext mods = do
  cms <- getSession
  (as,bs) <- io (GHC.getContext cms)

  (as_to_remove,bs_to_remove) <- separate cms mods [] []

  let as' = as \\ (as_to_remove ++ bs_to_remove)
      bs' = bs \\ (as_to_remove ++ bs_to_remove)

  io (GHC.setContext cms as' bs')

----------------------------------------------------------------------------
-- Code for `:set'

-- set options in the interpreter.  Syntax is exactly the same as the
-- ghc command line, except that certain options aren't available (-C,
-- -E etc.)
--
-- This is pretty fragile: most options won't work as expected.  ToDo:
-- figure out which ones & disallow them.

setCmd :: String -> GHCi ()
setCmd ""
  = do st <- getGHCiState
       let opts = options st
       io $ putStrLn (showSDoc (
   	      text "options currently set: " <> 
   	      if null opts
   		   then text "none."
   		   else hsep (map (\o -> char '+' <> text (optToStr o)) opts)
   	   ))
setCmd str
  = case words str of
	("args":args) -> setArgs args
	("prog":prog) -> setProg prog
	wds -> setOptions wds

setArgs args = do
  st <- getGHCiState
  setGHCiState st{ args = args }

setProg [prog] = do
  st <- getGHCiState
  setGHCiState st{ progname = prog }
setProg _ = do
  io (hPutStrLn stderr "syntax: :set prog <progname>")

setOptions wds =
   do -- first, deal with the GHCi opts (+s, +t, etc.)
      let (plus_opts, minus_opts)  = partition isPlus wds
      mapM_ setOpt plus_opts

      -- then, dynamic flags
      dflags <- getDynFlags
      (dflags',leftovers) <- io $ GHC.parseDynamicFlags dflags minus_opts
      setDynFlags dflags'

        -- update things if the users wants more packages
{- TODO:
        let new_packages = pkgs_after \\ pkgs_before
        when (not (null new_packages)) $
  	   newPackages new_packages
-}

      if (not (null leftovers))
		then throwDyn (CmdLineError ("unrecognised flags: " ++ 
						unwords leftovers))
		else return ()


unsetOptions :: String -> GHCi ()
unsetOptions str
  = do -- first, deal with the GHCi opts (+s, +t, etc.)
       let opts = words str
	   (minus_opts, rest1) = partition isMinus opts
	   (plus_opts, rest2)  = partition isPlus rest1

       if (not (null rest2)) 
	  then io (putStrLn ("unknown option: '" ++ head rest2 ++ "'"))
	  else do

       mapM_ unsetOpt plus_opts
 
       -- can't do GHC flags for now
       if (not (null minus_opts))
	  then throwDyn (CmdLineError "can't unset GHC command-line flags")
	  else return ()

isMinus ('-':s) = True
isMinus _ = False

isPlus ('+':s) = True
isPlus _ = False

setOpt ('+':str)
  = case strToGHCiOpt str of
	Nothing -> io (putStrLn ("unknown option: '" ++ str ++ "'"))
	Just o  -> setOption o

unsetOpt ('+':str)
  = case strToGHCiOpt str of
	Nothing -> io (putStrLn ("unknown option: '" ++ str ++ "'"))
	Just o  -> unsetOption o

strToGHCiOpt :: String -> (Maybe GHCiOption)
strToGHCiOpt "s" = Just ShowTiming
strToGHCiOpt "t" = Just ShowType
strToGHCiOpt "r" = Just RevertCAFs
strToGHCiOpt _   = Nothing

optToStr :: GHCiOption -> String
optToStr ShowTiming = "s"
optToStr ShowType   = "t"
optToStr RevertCAFs = "r"

{- ToDo
newPackages new_pkgs = do	-- The new packages are already in v_Packages
  session <- getSession
  io (GHC.setTargets session [])
  io (GHC.load session Nothing)