content: -----------------------------------------------------------------------------
  -- |
  -- 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.
  
  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are
  met:
  
      * Redistributions of source code must retain the above copyright
        notice, this list of conditions and the following disclaimer.
  
      * Redistributions in binary form must reproduce the above
        copyright notice, this list of conditions and the following
        disclaimer in the documentation and/or other materials provided
        with the distribution.
  
      * Neither the name of Isaac Jones nor the names of other
        contributors may be used to endorse or promote products derived
        from this software without specific prior written permission.
  
  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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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
  