content: -----------------------------------------------------------------------------
  -- |
  -- Module      :  Distribution.ModuleName
  -- Copyright   :  Duncan Coutts 2008
  --
  -- Maintainer  :  cabal-devel@haskell.org
  -- Portability :  portable
  --
  -- Data type for Haskell module names.
  
  {- All rights reserved.
  
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  met:
  
      * Redistributions of source code must retain the above copyright
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      * 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
  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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  module Distribution.ModuleName (
          ModuleName,
          fromString,
          components,
          toFilePath,
          main,
          simple,
    ) where
  
  import Distribution.Text
           ( Text(..) )
  
  import qualified Distribution.Compat.ReadP as Parse
  import qualified Text.PrettyPrint as Disp
  import qualified Data.Char as Char
           ( isAlphaNum, isUpper )
  import System.FilePath
           ( pathSeparator )
  import Data.List
           ( intersperse )
  
  -- | A valid Haskell module name.
  --
  newtype ModuleName = ModuleName [String]
    deriving (Eq, Ord, Read, Show)
  
  instance Text ModuleName where
    disp (ModuleName ms) =
      Disp.hcat (intersperse (Disp.char '.') (map Disp.text ms))
  
    parse = do
      ms <- Parse.sepBy1 component (Parse.char '.')
      return (ModuleName ms)
  
      where
        component = do
          c  <- Parse.satisfy Char.isUpper
          cs <- Parse.munch validModuleChar
          return (c:cs)
  
  validModuleChar :: Char -> Bool
  validModuleChar c = Char.isAlphaNum c || c == '_' || c == '\''
  
  validModuleComponent :: String -> Bool
  validModuleComponent []     = False
  validModuleComponent (c:cs) = Char.isUpper c
                             && all validModuleChar cs
  
  {-# DEPRECATED simple "use ModuleName.fromString instead" #-}
  simple :: String -> ModuleName
  simple str = ModuleName [str]
  
  -- | Construct a 'ModuleName' from a valid module name 'String'.
  --
  -- This is just a convenience function intended for valid module strings. It is
  -- an error if it is used with a string that is not a valid module name. If you
  -- are parsing user input then use 'Distribution.Text.simpleParse' instead.
  --
  fromString :: String -> ModuleName
  fromString string
    | all validModuleComponent components' = ModuleName components'
    | otherwise                            = error badName
  
    where
      components' = split string
      badName     = "ModuleName.fromString: invalid module name " ++ show string
  
      split cs = case break (=='.') cs of
        (chunk,[])     -> chunk : []
        (chunk,_:rest) -> chunk : split rest
  
  -- | The module name @Main@.
  --
  main :: ModuleName
  main = ModuleName ["Main"]
  
  -- | The individual components of a hierarchical module name. For example
  --
  -- > components (fromString "A.B.C") = ["A", "B", "C"]
  --
  components :: ModuleName -> [String]
  components (ModuleName ms) = ms
  
  -- | Convert a module name to a file path, but without any file extension.
  -- For example:
  --
  -- > toFilePath (fromString "A.B.C") = "A/B/C"
  --
  toFilePath :: ModuleName -> FilePath
  toFilePath = concat . intersperse [pathSeparator] . components
  