Compiler.hs

-----------------------------------------------------------------------------
-- |
-- Module      :  Distribution.Compiler
-- Copyright   :  Isaac Jones 2003-2004
--
-- Maintainer  :  cabal-devel@haskell.org
-- Portability :  portable
--
-- This has an enumeration of the various compilers that Cabal knows about. It
-- also specifies the default compiler. Sadly you'll often see code that does
-- case analysis on this compiler flavour enumeration like:
--
-- > case compilerFlavor comp of
-- >   GHC -> GHC.getInstalledPackages verbosity packageDb progconf
-- >   JHC -> JHC.getInstalledPackages verbosity packageDb progconf
--
-- Obviously it would be better to use the proper 'Compiler' abstraction
-- because that would keep all the compiler-specific code together.
-- Unfortunately we cannot make this change yet without breaking the
-- 'UserHooks' api, which would break all custom @Setup.hs@ files, so for the
-- moment we just have to live with this deficiency. If you're interested, see
-- ticket #50.

{- All rights reserved.

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module Distribution.Compiler (
  -- * Compiler flavor
  CompilerFlavor(..),
  buildCompilerFlavor,
  defaultCompilerFlavor,
  parseCompilerFlavorCompat,

  -- * Compiler id
  CompilerId(..),
  ) where

import Distribution.Version (Version(..))

import qualified System.Info (compilerName)
import Distribution.Text (Text(..), display)
import qualified Distribution.Compat.ReadP as Parse
import qualified Text.PrettyPrint as Disp
import Text.PrettyPrint ((<>))

import qualified Data.Char as Char (toLower, isDigit, isAlphaNum)
import Control.Monad (when)

data CompilerFlavor = GHC | NHC | YHC | Hugs | HBC | Helium | JHC | LHC | UHC
                    | OtherCompiler String
  deriving (Show, Read, Eq, Ord)

knownCompilerFlavors :: [CompilerFlavor]
knownCompilerFlavors = [GHC, NHC, YHC, Hugs, HBC, Helium, JHC, LHC, UHC]

instance Text CompilerFlavor where
  disp (OtherCompiler name) = Disp.text name
  disp NHC                  = Disp.text "nhc98"
  disp other                = Disp.text (lowercase (show other))

  parse = do
    comp <- Parse.munch1 Char.isAlphaNum
    when (all Char.isDigit comp) Parse.pfail
    return (classifyCompilerFlavor comp)

classifyCompilerFlavor :: String -> CompilerFlavor
classifyCompilerFlavor s =
  case lookup (lowercase s) compilerMap of
    Just compiler -> compiler
    Nothing       -> OtherCompiler s
  where
    compilerMap = [ (display compiler, compiler)
                  | compiler <- knownCompilerFlavors ]


--TODO: In some future release, remove 'parseCompilerFlavorCompat' and use
-- ordinary 'parse'. Also add ("nhc", NHC) to the above 'compilerMap'.

-- | Like 'classifyCompilerFlavor' but compatible with the old ReadS parser.
--
-- It is compatible in the sense that it accepts only the same strings,
-- eg "GHC" but not "ghc". However other strings get mapped to 'OtherCompiler'.
-- The point of this is that we do not allow extra valid values that would
-- upset older Cabal versions that had a stricter parser however we cope with
-- new values more gracefully so that we'll be able to introduce new value in
-- future without breaking things so much.
--
parseCompilerFlavorCompat :: Parse.ReadP r CompilerFlavor
parseCompilerFlavorCompat = do
  comp <- Parse.munch1 Char.isAlphaNum
  when (all Char.isDigit comp) Parse.pfail
  case lookup comp compilerMap of
    Just compiler -> return compiler
    Nothing       -> return (OtherCompiler comp)
  where
    compilerMap = [ (show compiler, compiler)
                  | compiler <- knownCompilerFlavors
                  , compiler /= YHC ]

buildCompilerFlavor :: CompilerFlavor
buildCompilerFlavor = classifyCompilerFlavor System.Info.compilerName

-- | The default compiler flavour to pick when compiling stuff. This defaults
-- to the compiler used to build the Cabal lib.
--
-- However if it's not a recognised compiler then it's 'Nothing' and the user
-- will have to specify which compiler they want.
--
defaultCompilerFlavor :: Maybe CompilerFlavor
defaultCompilerFlavor = case buildCompilerFlavor of
  OtherCompiler _ -> Nothing
  _               -> Just buildCompilerFlavor

-- ------------------------------------------------------------
-- * Compiler Id
-- ------------------------------------------------------------

data CompilerId = CompilerId CompilerFlavor Version
  deriving (Eq, Ord, Read, Show)

instance Text CompilerId where
  disp (CompilerId f (Version [] _)) = disp f
  disp (CompilerId f v) = disp f <> Disp.char '-' <> disp v

  parse = do
    flavour <- parse
    version <- (Parse.char '-' >> parse) Parse.<++ return (Version [] [])
    return (CompilerId flavour version)

lowercase :: String -> String
lowercase = map Char.toLower