Modules.hs

{- |
    Module      :  $Header$
    Description :  Compilation of a single module
    Copyright   :  (c) 1999 - 2004 Wolfgang Lux
                       2005        Martin Engelke
                       2007        Sebastian Fischer
                       2011 - 2014 Björn Peemöller
    License     :  OtherLicense

    Maintainer  :  bjp@informatik.uni-kiel.de
    Stability   :  experimental
    Portability :  portable

    This module controls the compilation of modules.
-}

module Modules
  ( compileModule, loadAndCheckModule, loadModule, checkModule
  , parseModule, checkModuleHeader
  ) where

import qualified Control.Exception as C   (catch, IOException)
import           Control.Monad            (liftM, unless, when)
import qualified Data.Map          as Map (elems)
import           Data.Maybe               (fromMaybe)
import           System.Directory         (getTemporaryDirectory, removeFile)
import           System.Exit              (ExitCode (..))
import           System.FilePath          (normalise)
import           System.IO
   (IOMode (ReadMode), Handle, hClose, hGetContents, hPutStr, openFile
  , openTempFile)
import           System.Process           (system)

import Curry.Base.Ident
import Curry.Base.Monad
import Curry.Base.Position
import Curry.Base.Pretty
import Curry.ExtendedFlat.InterfaceEquivalence (eqInterface)
import Curry.Files.Filenames
import Curry.Files.PathUtils
import Curry.Syntax.InterfaceEquivalence

import Base.Messages
import Env.Interface

-- source representations
import qualified Curry.AbstractCurry as AC
import qualified Curry.ExtendedFlat.Type as EF
import qualified Curry.Syntax as CS
import qualified IL as IL

import Checks
import CompilerEnv
import CompilerOpts
import Exports
import Generators
import Imports
import Interfaces
import ModuleSummary
import Transformations

-- The function 'compileModule' is the main entry-point of this
-- module for compiling a Curry source module. Depending on the command
-- line options, it will emit either FlatCurry code or AbstractCurry code
-- (typed, untyped or with type signatures) for the module.
-- Usually, the first step is to check the module.
-- Then the code is translated into the intermediate
-- language. If necessary, this phase will also update the module's
-- interface file. The resulting code then is written out
-- to the corresponding file.
-- The untyped  AbstractCurry representation is written
-- out directly after parsing and simple checking the source file.
-- The typed AbstractCurry code is written out after checking the module.
--
-- The compiler automatically loads the prelude when compiling any
-- module, except for the prelude itself, by adding an appropriate import
-- declaration to the module.
compileModule :: Options -> FilePath -> CYIO ()
compileModule opts fn = do
  (env, mdl) <- loadAndCheckModule opts fn
  liftIO $ writeOutput opts fn (env, mdl)

loadAndCheckModule :: Options -> FilePath -> CYIO (CompEnv CS.Module)
loadAndCheckModule opts fn = do
  (env, mdl) <- loadModule opts fn >>= checkModule opts
  warn (optWarnOpts opts) $ warnCheck opts env mdl
  return (env, mdl)

-- ---------------------------------------------------------------------------
-- Loading a module
-- ---------------------------------------------------------------------------

loadModule :: Options -> FilePath -> CYIO (CompEnv CS.Module)
loadModule opts fn = do
  parsed <- parseModule opts fn
  -- check module header
  mdl    <- checkModuleHeader opts fn parsed
  -- load the imported interfaces into an InterfaceEnv
  let paths = map (addCurrySubdir (optUseSubdir opts))
                  ("." : optImportPaths opts)
  iEnv   <- loadInterfaces paths mdl
  checkInterfaces opts iEnv
  -- add information of imported modules
  cEnv   <- importModules opts mdl iEnv
  return (cEnv, mdl)

parseModule :: Options -> FilePath -> CYIO CS.Module
parseModule opts fn = do
  mbSrc <- liftIO $ readModule fn
  case mbSrc of
    Nothing  -> failMessages [message $ text $ "Missing file: " ++ fn]
    Just src -> do
      ul    <- liftCYM $ CS.unlit fn src
      prepd <- preprocess (optPrepOpts opts) fn ul
      liftCYM $ CS.parseModule fn prepd

preprocess :: PrepOpts -> FilePath -> String -> CYIO String
preprocess opts fn src
  | not (ppPreprocess opts) = return src
  | otherwise               = do
    res <- liftIO $ withTempFile $ \ inFn inHdl -> do
      hPutStr inHdl src
      hClose inHdl
      withTempFile $ \ outFn outHdl -> do
        hClose outHdl
        ec <- system $ unwords $
          [ppCmd opts, normalise fn, inFn, outFn] ++ ppOpts opts
        case ec of
          ExitFailure x -> return $ Left [message $ text $
              "Preprocessor exited with exit code " ++ show x]
          ExitSuccess   -> Right `liftM` readFile outFn
    either failMessages ok res

withTempFile :: (FilePath -> Handle -> IO a) -> IO a
withTempFile act = do
  tmp       <- getTemporaryDirectory
  (fn, hdl) <- openTempFile tmp "cymake.curry"
  res       <- act fn hdl
  hClose hdl
  removeFile fn
  return res

checkModuleHeader :: Monad m => Options -> FilePath -> CS.Module
                  -> CYT m CS.Module
checkModuleHeader opts fn = checkModuleId fn
                          . importPrelude opts fn
                          . CS.patchModuleId fn

-- |Check whether the 'ModuleIdent' and the 'FilePath' fit together
checkModuleId :: Monad m => FilePath -> CS.Module
              -> CYT m CS.Module
checkModuleId fn m@(CS.Module _ mid _ _ _)
  | last (midQualifiers mid) == takeBaseName fn
  = ok m
  | otherwise
  = failMessages [errModuleFileMismatch mid]

-- An implicit import of the prelude is added to the declarations of
-- every module, except for the prelude itself, or when the import is disabled
-- by a compiler option. If no explicit import for the prelude is present,
-- the prelude is imported unqualified, otherwise a qualified import is added.

importPrelude :: Options -> FilePath -> CS.Module -> CS.Module
importPrelude opts fn m@(CS.Module ps mid es is ds)
    -- the Prelude itself
  | mid == preludeMIdent          = m
    -- disabled by compiler option
  | noImpPrelude                  = m
    -- already imported
  | preludeMIdent `elem` imported = m
    -- let's add it!
  | otherwise                     = CS.Module ps mid es (preludeImp : is) ds
  where
  noImpPrelude = NoImplicitPrelude `elem` optExtensions opts
                 || m `CS.hasLanguageExtension` NoImplicitPrelude
  preludeImp   = CS.ImportDecl (first fn) preludeMIdent
                  False   -- qualified?
                  Nothing -- no alias
                  Nothing -- no selection of types, functions, etc.
  imported     = [imp | (CS.ImportDecl _ imp _ _ _) <- is]

checkInterfaces :: Monad m => Options -> InterfaceEnv -> CYT m ()
checkInterfaces opts iEnv = mapM_ checkInterface (Map.elems iEnv)
  where
  checkInterface intf
    = interfaceCheck opts (importInterfaces opts intf iEnv, intf) >> return ()

-- ---------------------------------------------------------------------------
-- Checking a module
-- ---------------------------------------------------------------------------

-- TODO: The order of the checks should be improved!
checkModule :: Options -> CompEnv CS.Module -> CYIO (CompEnv CS.Module)
checkModule opts mdl = do
  _  <- dumpCS DumpParsed mdl
   -- Should be separated into kind checking and type syntax checking (see MCC)
  kc <- kindCheck   opts mdl >>= dumpCS DumpKindChecked
  sc <- syntaxCheck opts kc  >>= dumpCS DumpSyntaxChecked
  pc <- precCheck   opts sc  >>= dumpCS DumpPrecChecked
  tc <- typeCheck   opts pc  >>= dumpCS DumpTypeChecked
  -- TODO: This is a workaround to avoid the expansion of the export
  -- specification for generating the HTML listing. If a module does not
  -- contain an export specification, the check generates one which leads
  -- to a mismatch between the identifiers from the lexer and those in the
  -- resulting module.
  -- Therefore, it would be better if checking and expansion are separated.
  if null (optTargetTypes opts)
    then return tc
    else exportCheck opts tc >>= dumpCS DumpExportChecked
  where dumpCS = dumpWith opts CS.ppModule

-- ---------------------------------------------------------------------------
-- Translating a module
-- ---------------------------------------------------------------------------

transModule :: Options -> CompEnv CS.Module -> IO (CompEnv IL.Module)
transModule opts mdl = do
  desugared   <- dumpCS DumpDesugared     $ desugar False mdl
  simplified  <- dumpCS DumpSimplified    $ simplify      desugared
  lifted      <- dumpCS DumpLifted        $ lift          simplified
  desugared2  <- dumpCS DumpDesugared     $ desugar True  lifted
  simplified2 <- dumpCS DumpSimplified    $ simplify      desugared2
  lifted2     <- dumpCS DumpLifted        $ lift          simplified2
  il          <- dumpIL DumpTranslated    $ ilTrans       lifted2
  ilCaseComp  <- dumpIL DumpCaseCompleted $ completeCase  il
  return ilCaseComp
  where
  dumpCS = dumpWith opts CS.ppModule
  dumpIL = dumpWith opts IL.ppModule

-- ---------------------------------------------------------------------------
-- Writing output
-- ---------------------------------------------------------------------------

writeOutput :: Options -> FilePath -> CompEnv CS.Module -> IO ()
writeOutput opts fn mdl@(_, modul) = do
  writeParsed opts fn modul
  (env1, qlfd) <- dumpWith opts CS.ppModule DumpQualified $ qual opts mdl
  writeAbstractCurry opts fn env1 qlfd
  when withFlat $ do
    (env2, il) <- transModule opts (env1, qlfd)
    -- generate interface file
    let intf = exportInterface env2 qlfd
    writeInterface opts fn intf
    -- generate target code
    let modSum = summarizeModule (tyConsEnv env2) intf qlfd
    writeFlat opts fn env2 modSum il
  where
  withFlat = any (`elem` optTargetTypes opts) [FlatCurry, ExtendedFlatCurry]

-- The functions \texttt{genFlat} and \texttt{genAbstract} generate
-- flat and abstract curry representations depending on the specified option.
-- If the interface of a modified Curry module did not change, the
-- corresponding file name will be returned within the result of 'genFlat'
-- (depending on the compiler flag "force") and other modules importing this
-- module won't be dependent on it any longer.

-- |Output the parsed 'Module' on request
writeParsed :: Options -> FilePath -> CS.Module -> IO ()
writeParsed opts fn modul@(CS.Module _ m _ _ _) = when srcTarget $
  writeModule (useSubDir $ sourceRepName fn) source
  where
  srcTarget  = Parsed `elem` optTargetTypes opts
  useSubDir  = addCurrySubdirModule (optUseSubdir opts) m
  source     = CS.showModule modul

writeInterface :: Options -> FilePath -> CS.Interface -> IO ()
writeInterface opts fn intf@(CS.Interface m _ _)
  | optForce opts = outputInterface
  | otherwise     = do
      equal <- C.catch (matchInterface interfaceFile intf) ignoreIOException
      unless equal outputInterface
  where
  ignoreIOException :: C.IOException -> IO Bool
  ignoreIOException _ = return False

  interfaceFile   = interfName fn
  outputInterface = writeModule
                    (addCurrySubdirModule (optUseSubdir opts) m interfaceFile)
                    (show $ CS.ppInterface intf)

matchInterface :: FilePath -> CS.Interface -> IO Bool
matchInterface ifn i = do
  hdl <- openFile ifn ReadMode
  src <- hGetContents hdl
  case runCYM (CS.parseInterface ifn src) of
    Left  _  -> hClose hdl >> return False
    Right i' -> return (i `intfEquiv` fixInterface i')

writeFlat :: Options -> FilePath -> CompilerEnv -> ModuleSummary -> IL.Module
          -> IO ()
writeFlat opts fn env modSum il = do
  when (extTarget || fcyTarget) $ do
    writeFlatCurry opts fn env modSum il
    writeFlatIntf  opts fn env modSum il
  where
  extTarget = ExtendedFlatCurry `elem` optTargetTypes opts
  fcyTarget = FlatCurry         `elem` optTargetTypes opts

-- |Export an 'IL.Module' into a FlatCurry file
writeFlatCurry :: Options -> FilePath -> CompilerEnv -> ModuleSummary
               -> IL.Module -> IO ()
writeFlatCurry opts fn env modSum il = do
  when extTarget $ EF.writeExtendedFlat (useSubDir $ extFlatName fn) prog
  when fcyTarget $ EF.writeFlatCurry    (useSubDir $ flatName    fn) prog
  where
  extTarget = ExtendedFlatCurry `elem` optTargetTypes opts
  fcyTarget = FlatCurry         `elem` optTargetTypes opts
  useSubDir = addCurrySubdirModule (optUseSubdir opts) (moduleIdent env)
  prog      = genFlatCurry modSum env il

writeFlatIntf :: Options -> FilePath -> CompilerEnv -> ModuleSummary
              -> IL.Module -> IO ()
writeFlatIntf opts fn env modSum il
  | not (optInterface opts) = return ()
  | optForce opts           = outputInterface
  | otherwise               = do
      mfint <- EF.readFlatInterface targetFile
      let oldInterface = fromMaybe emptyIntf mfint
      when (mfint == mfint) $ return () -- necessary to close file -- TODO
      unless (oldInterface `eqInterface` intf) $ outputInterface
  where
  targetFile      = flatIntName fn
  emptyIntf       = EF.Prog "" [] [] [] []
  intf            = genFlatInterface modSum env il
  useSubDir       = addCurrySubdirModule (optUseSubdir opts) (moduleIdent env)
  outputInterface = EF.writeFlatCurry (useSubDir targetFile) intf

writeAbstractCurry :: Options -> FilePath -> CompilerEnv -> CS.Module -> IO ()
writeAbstractCurry opts fname env modul = do
  when  acyTarget $ AC.writeCurry (useSubDir $  acyName fname)
                  $ genAbstractCurry env modul
  when uacyTarget $ AC.writeCurry (useSubDir $ uacyName fname)
                  $ genAbstractCurry env modul
  where
  acyTarget  = AbstractCurry        `elem` optTargetTypes opts
  uacyTarget = UntypedAbstractCurry `elem` optTargetTypes opts
  useSubDir  = addCurrySubdirModule (optUseSubdir opts) (moduleIdent env)

type Dump = (DumpLevel, CompilerEnv, String)

dumpWith :: (MonadIO m, Show a)
         => Options -> (a -> Doc) -> DumpLevel -> CompEnv a -> m (CompEnv a)
dumpWith opts view lvl res@(env, mdl) = do
  let str = if dbDumpRaw (optDebugOpts opts) then show mdl else show (view mdl)
  doDump (optDebugOpts opts) (lvl, env, str)
  return res

-- |Translate FlatCurry into the intermediate language 'IL'
-- |The 'dump' function writes the selected information to standard output.
doDump :: MonadIO m => DebugOpts -> Dump -> m ()
doDump opts (level, env, dump) = when (level `elem` dbDumpLevels opts) $ do
  when (dbDumpEnv opts) $ liftIO $ putStrLn $ showCompilerEnv env
  liftIO $ putStrLn $ unlines [header, replicate (length header) '=', dump]
  where
  header = lookupHeader dumpLevel
  lookupHeader []            = "Unknown dump level " ++ show level
  lookupHeader ((l,_,h):lhs)
    | level == l = h
    | otherwise  = lookupHeader lhs

errModuleFileMismatch :: ModuleIdent -> Message
errModuleFileMismatch mid = posMessage mid $ hsep $ map text
  [ "Module", moduleName mid, "must be in a file"
  , moduleName mid ++ ".(l)curry" ]