-----------------------------------------------------------------------------
-- |
-- Module      :  Distribution.Simple.CCompiler
-- Copyright   :  2011, Dan Knapp
--
-- Maintainer  :  [email protected]
-- Portability :  portable
--
-- This simple package provides types and functions for interacting with
-- C compilers.  Currently it's just a type enumerating extant C-like
-- languages, which we call dialects.

{-
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    * Redistributions of source code must retain the above copyright
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    * Redistributions in binary form must reproduce the above
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      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.

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"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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module Distribution.Simple.CCompiler (
   CDialect(..),
   cSourceExtensions,
   cDialectFilenameExtension,
   filenameCDialect
  ) where

import Distribution.Compat.Semigroup as Semi

import System.FilePath
     ( takeExtension )


-- | Represents a dialect of C.  The Monoid instance expresses backward
--   compatibility, in the sense that 'mappend a b' is the least inclusive
--   dialect which both 'a' and 'b' can be correctly interpreted as.
data CDialect = C
              | ObjectiveC
              | CPlusPlus
              | ObjectiveCPlusPlus
              deriving (Eq, Show)

instance Monoid CDialect where
  mempty = C
  mappend = (Semi.<>)

instance Semigroup CDialect where
  C                  <> anything           = anything
  ObjectiveC         <> CPlusPlus          = ObjectiveCPlusPlus
  CPlusPlus          <> ObjectiveC         = ObjectiveCPlusPlus
  _                  <> ObjectiveCPlusPlus = ObjectiveCPlusPlus
  ObjectiveC         <> _                  = ObjectiveC
  CPlusPlus          <> _                  = CPlusPlus
  ObjectiveCPlusPlus <> _                  = ObjectiveCPlusPlus

-- | A list of all file extensions which are recognized as possibly containing
--   some dialect of C code.  Note that this list is only for source files,
--   not for header files.
cSourceExtensions :: [String]
cSourceExtensions = ["c", "i", "ii", "m", "mi", "mm", "M", "mii", "cc", "cp",
                     "cxx", "cpp", "CPP", "c++", "C"]


-- | Takes a dialect of C and whether code is intended to be passed through
--   the preprocessor, and returns a filename extension for containing that
--   code.
cDialectFilenameExtension :: CDialect -> Bool -> String
cDialectFilenameExtension C True  = "c"
cDialectFilenameExtension C False = "i"
cDialectFilenameExtension ObjectiveC True  = "m"
cDialectFilenameExtension ObjectiveC False = "mi"
cDialectFilenameExtension CPlusPlus True   = "cpp"
cDialectFilenameExtension CPlusPlus False  = "ii"
cDialectFilenameExtension ObjectiveCPlusPlus True  = "mm"
cDialectFilenameExtension ObjectiveCPlusPlus False = "mii"


-- | Infers from a filename's extension the dialect of C which it contains,
--   and whether it is intended to be passed through the preprocessor.
filenameCDialect :: String -> Maybe (CDialect, Bool)
filenameCDialect filename = do
  extension <- case takeExtension filename of
                 '.':ext -> Just ext
                 _       -> Nothing
  case extension of
    "c"   -> return (C, True)
    "i"   -> return (C, False)
    "ii"  -> return (CPlusPlus, False)
    "m"   -> return (ObjectiveC, True)
    "mi"  -> return (ObjectiveC, False)
    "mm"  -> return (ObjectiveCPlusPlus, True)
    "M"   -> return (ObjectiveCPlusPlus, True)
    "mii" -> return (ObjectiveCPlusPlus, False)
    "cc"  -> return (CPlusPlus, True)
    "cp"  -> return (CPlusPlus, True)
    "cxx" -> return (CPlusPlus, True)
    "cpp" -> return (CPlusPlus, True)
    "CPP" -> return (CPlusPlus, True)
    "c++" -> return (CPlusPlus, True)
    "C"   -> return (CPlusPlus, True)
    _     -> Nothing