content: {-# LANGUAGE DeriveDataTypeable #-}
  -----------------------------------------------------------------------------
  -- |
  -- Module      :  Distribution.PackageDescription
  -- Copyright   :  Isaac Jones 2003-2005
  --
  -- Maintainer  :  cabal-devel@haskell.org
  -- Portability :  portable
  --
  -- This defines the data structure for the @.cabal@ file format. There are
  -- several parts to this structure. It has top level info and then 'Library',
  -- 'Executable', 'TestSuite', and 'Benchmark' sections each of which have
  -- associated 'BuildInfo' data that's used to build the library, exe, test, or
  -- benchmark.  To further complicate things there is both a 'PackageDescription'
  -- and a 'GenericPackageDescription'. This distinction relates to cabal
  -- configurations. When we initially read a @.cabal@ file we get a
  -- 'GenericPackageDescription' which has all the conditional sections.
  -- Before actually building a package we have to decide
  -- on each conditional. Once we've done that we get a 'PackageDescription'.
  -- It was done this way initially to avoid breaking too much stuff when the
  -- feature was introduced. It could probably do with being rationalised at some
  -- point to make it simpler.
  
  {- 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
  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. -}
  
  module Distribution.PackageDescription (
          -- * Package descriptions
          PackageDescription(..),
          emptyPackageDescription,
          specVersion,
          descCabalVersion,
          BuildType(..),
          knownBuildTypes,
  
          -- ** Libraries
          Library(..),
          emptyLibrary,
          withLib,
          hasLibs,
          libModules,
  
          -- ** Executables
          Executable(..),
          emptyExecutable,
          withExe,
          hasExes,
          exeModules,
  
          -- * Tests
          TestSuite(..),
          TestSuiteInterface(..),
          TestType(..),
          testType,
          knownTestTypes,
          emptyTestSuite,
          hasTests,
          withTest,
          testModules,
          enabledTests,
  
          -- * Benchmarks
          Benchmark(..),
          BenchmarkInterface(..),
          BenchmarkType(..),
          benchmarkType,
          knownBenchmarkTypes,
          emptyBenchmark,
          hasBenchmarks,
          withBenchmark,
          benchmarkModules,
          enabledBenchmarks,
  
          -- * Build information
          BuildInfo(..),
          emptyBuildInfo,
          allBuildInfo,
          allLanguages,
          allExtensions,
          usedExtensions,
          hcOptions,
  
          -- ** Supplementary build information
          HookedBuildInfo,
          emptyHookedBuildInfo,
          updatePackageDescription,
  
          -- * package configuration
          GenericPackageDescription(..),
          Flag(..), FlagName(..), FlagAssignment,
          CondTree(..), ConfVar(..), Condition(..),
  
          -- * Source repositories
          SourceRepo(..),
          RepoKind(..),
          RepoType(..),
          knownRepoTypes,
    ) where
  
  import Data.Data   (Data)
  import Data.List   (nub, intercalate)
  import Data.Maybe  (fromMaybe, maybeToList)
  import Data.Monoid (Monoid(mempty, mappend))
  import Data.Typeable ( Typeable )
  import Control.Monad (MonadPlus(mplus))
  import Text.PrettyPrint as Disp
  import qualified Distribution.Compat.ReadP as Parse
  import qualified Data.Char as Char (isAlphaNum, isDigit, toLower)
  
  import Distribution.Package
           ( PackageName(PackageName), PackageIdentifier(PackageIdentifier)
           , Dependency, Package(..) )
  import Distribution.ModuleName ( ModuleName )
  import Distribution.Version
           ( Version(Version), VersionRange, anyVersion, orLaterVersion
           , asVersionIntervals, LowerBound(..) )
  import Distribution.License  (License(AllRightsReserved))
  import Distribution.Compiler (CompilerFlavor)
  import Distribution.System   (OS, Arch)
  import Distribution.Text
           ( Text(..), display )
  import Language.Haskell.Extension
           ( Language, Extension )
  
  -- -----------------------------------------------------------------------------
  -- The PackageDescription type
  
  -- | This data type is the internal representation of the file @pkg.cabal@.
  -- It contains two kinds of information about the package: information
  -- which is needed for all packages, such as the package name and version, and
  -- information which is needed for the simple build system only, such as
  -- the compiler options and library name.
  --
  data PackageDescription
      =  PackageDescription {
          -- the following are required by all packages:
          package        :: PackageIdentifier,
          license        :: License,
          licenseFile    :: FilePath,
          copyright      :: String,
          maintainer     :: String,
          author         :: String,
          stability      :: String,
          testedWith     :: [(CompilerFlavor,VersionRange)],
          homepage       :: String,
          pkgUrl         :: String,
          bugReports     :: String,
          sourceRepos    :: [SourceRepo],
          synopsis       :: String, -- ^A one-line summary of this package
          description    :: String, -- ^A more verbose description of this package
          category       :: String,
          customFieldsPD :: [(String,String)], -- ^Custom fields starting
                                               -- with x-, stored in a
                                               -- simple assoc-list.
          buildDepends   :: [Dependency],
          -- | The version of the Cabal spec that this package description uses.
          -- For historical reasons this is specified with a version range but
          -- only ranges of the form @>= v@ make sense. We are in the process of
          -- transitioning to specifying just a single version, not a range.
          specVersionRaw :: Either Version VersionRange,
          buildType      :: Maybe BuildType,
          -- components
          library        :: Maybe Library,
          executables    :: [Executable],
          testSuites     :: [TestSuite],
          benchmarks     :: [Benchmark],
          dataFiles      :: [FilePath],
          dataDir        :: FilePath,
          extraSrcFiles  :: [FilePath],
          extraTmpFiles  :: [FilePath],
          extraDocFiles  :: [FilePath]
      }
      deriving (Show, Read, Eq, Typeable, Data)
  
  instance Package PackageDescription where
    packageId = package
  
  -- | The version of the Cabal spec that this package should be interpreted
  -- against.
  --
  -- Historically we used a version range but we are switching to using a single
  -- version. Currently we accept either. This function converts into a single
  -- version by ignoring upper bounds in the version range.
  --
  specVersion :: PackageDescription -> Version
  specVersion pkg = case specVersionRaw pkg of
    Left  version      -> version
    Right versionRange -> case asVersionIntervals versionRange of
                            []                            -> Version [0] []
                            ((LowerBound version _, _):_) -> version
  
  -- | The range of versions of the Cabal tools that this package is intended to
  -- work with.
  --
  -- This function is deprecated and should not be used for new purposes, only to
  -- support old packages that rely on the old interpretation.
  --
  descCabalVersion :: PackageDescription -> VersionRange
  descCabalVersion pkg = case specVersionRaw pkg of
    Left  version      -> orLaterVersion version
    Right versionRange -> versionRange
  {-# DEPRECATED descCabalVersion "Use specVersion instead" #-}
  
  emptyPackageDescription :: PackageDescription
  emptyPackageDescription
      =  PackageDescription {
                        package      = PackageIdentifier (PackageName "")
                                                         (Version [] []),
                        license      = AllRightsReserved,
                        licenseFile  = "",
                        specVersionRaw = Right anyVersion,
                        buildType    = Nothing,
                        copyright    = "",
                        maintainer   = "",
                        author       = "",
                        stability    = "",
                        testedWith   = [],
                        buildDepends = [],
                        homepage     = "",
                        pkgUrl       = "",
                        bugReports   = "",
                        sourceRepos  = [],
                        synopsis     = "",
                        description  = "",
                        category     = "",
                        customFieldsPD = [],
                        library      = Nothing,
                        executables  = [],
                        testSuites   = [],
                        benchmarks   = [],
                        dataFiles    = [],
                        dataDir      = "",
                        extraSrcFiles = [],
                        extraTmpFiles = [],
                        extraDocFiles = []
                       }
  
  -- | The type of build system used by this package.
  data BuildType
    = Simple      -- ^ calls @Distribution.Simple.defaultMain@
    | Configure   -- ^ calls @Distribution.Simple.defaultMainWithHooks defaultUserHooks@,
                  -- which invokes @configure@ to generate additional build
                  -- information used by later phases.
    | Make        -- ^ calls @Distribution.Make.defaultMain@
    | Custom      -- ^ uses user-supplied @Setup.hs@ or @Setup.lhs@ (default)
    | UnknownBuildType String
                  -- ^ a package that uses an unknown build type cannot actually
                  --   be built. Doing it this way rather than just giving a
                  --   parse error means we get better error messages and allows
                  --   you to inspect the rest of the package description.
                  deriving (Show, Read, Eq, Typeable, Data)
  
  knownBuildTypes :: [BuildType]
  knownBuildTypes = [Simple, Configure, Make, Custom]
  
  instance Text BuildType where
    disp (UnknownBuildType other) = Disp.text other
    disp other                    = Disp.text (show other)
  
    parse = do
      name <- Parse.munch1 Char.isAlphaNum
      return $ case name of
        "Simple"    -> Simple
        "Configure" -> Configure
        "Custom"    -> Custom
        "Make"      -> Make
        _           -> UnknownBuildType name
  
  -- ---------------------------------------------------------------------------
  -- The Library type
  
  data Library = Library {
          exposedModules    :: [ModuleName],
          libExposed        :: Bool, -- ^ Is the lib to be exposed by default?
          libBuildInfo      :: BuildInfo
      }
      deriving (Show, Eq, Read, Typeable, Data)
  
  instance Monoid Library where
    mempty = Library {
      exposedModules = mempty,
      libExposed     = True,
      libBuildInfo   = mempty
    }
    mappend a b = Library {
      exposedModules = combine exposedModules,
      libExposed     = libExposed a && libExposed b, -- so False propagates
      libBuildInfo   = combine libBuildInfo
    }
      where combine field = field a `mappend` field b
  
  emptyLibrary :: Library
  emptyLibrary = mempty
  
  -- |does this package have any libraries?
  hasLibs :: PackageDescription -> Bool
  hasLibs p = maybe False (buildable . libBuildInfo) (library p)
  
  -- |'Maybe' version of 'hasLibs'
  maybeHasLibs :: PackageDescription -> Maybe Library
  maybeHasLibs p =
     library p >>= \lib -> if buildable (libBuildInfo lib)
                             then Just lib
                             else Nothing
  
  -- |If the package description has a library section, call the given
  --  function with the library build info as argument.
  withLib :: PackageDescription -> (Library -> IO ()) -> IO ()
  withLib pkg_descr f =
     maybe (return ()) f (maybeHasLibs pkg_descr)
  
  -- | Get all the module names from the library (exposed and internal modules)
  libModules :: Library -> [ModuleName]
  libModules lib = exposedModules lib
                ++ otherModules (libBuildInfo lib)
  
  -- ---------------------------------------------------------------------------
  -- The Executable type
  
  data Executable = Executable {
          exeName    :: String,
          modulePath :: FilePath,
          buildInfo  :: BuildInfo
      }
      deriving (Show, Read, Eq, Typeable, Data)
  
  instance Monoid Executable where
    mempty = Executable {
      exeName    = mempty,
      modulePath = mempty,
      buildInfo  = mempty
    }
    mappend a b = Executable{
      exeName    = combine' exeName,
      modulePath = combine modulePath,
      buildInfo  = combine buildInfo
    }
      where combine field = field a `mappend` field b
            combine' field = case (field a, field b) of
                        ("","") -> ""
                        ("", x) -> x
                        (x, "") -> x
                        (x, y) -> error $ "Ambiguous values for executable field: '"
                                    ++ x ++ "' and '" ++ y ++ "'"
  
  emptyExecutable :: Executable
  emptyExecutable = mempty
  
  -- |does this package have any executables?
  hasExes :: PackageDescription -> Bool
  hasExes p = any (buildable . buildInfo) (executables p)
  
  -- | Perform the action on each buildable 'Executable' in the package
  -- description.
  withExe :: PackageDescription -> (Executable -> IO ()) -> IO ()
  withExe pkg_descr f =
    sequence_ [f exe | exe <- executables pkg_descr, buildable (buildInfo exe)]
  
  -- | Get all the module names from an exe
  exeModules :: Executable -> [ModuleName]
  exeModules exe = otherModules (buildInfo exe)
  
  -- ---------------------------------------------------------------------------
  -- The TestSuite type
  
  -- | A \"test-suite\" stanza in a cabal file.
  --
  data TestSuite = TestSuite {
          testName      :: String,
          testInterface :: TestSuiteInterface,
          testBuildInfo :: BuildInfo,
          testEnabled   :: Bool
          -- TODO: By having a 'testEnabled' field in the PackageDescription, we
          -- are mixing build status information (i.e., arguments to 'configure')
          -- with static package description information. This is undesirable, but
          -- a better solution is waiting on the next overhaul to the
          -- GenericPackageDescription -> PackageDescription resolution process.
      }
      deriving (Show, Read, Eq, Typeable, Data)
  
  -- | The test suite interfaces that are currently defined. Each test suite must
  -- specify which interface it supports.
  --
  -- More interfaces may be defined in future, either new revisions or totally
  -- new interfaces.
  --
  data TestSuiteInterface =
  
       -- | Test interface \"exitcode-stdio-1.0\". The test-suite takes the form
       -- of an executable. It returns a zero exit code for success, non-zero for
       -- failure. The stdout and stderr channels may be logged. It takes no
       -- command line parameters and nothing on stdin.
       --
       TestSuiteExeV10 Version FilePath
  
       -- | Test interface \"detailed-0.9\". The test-suite takes the form of a
       -- library containing a designated module that exports \"tests :: [Test]\".
       --
     | TestSuiteLibV09 Version ModuleName
  
       -- | A test suite that does not conform to one of the above interfaces for
       -- the given reason (e.g. unknown test type).
       --
     | TestSuiteUnsupported TestType
     deriving (Eq, Read, Show, Typeable, Data)
  
  instance Monoid TestSuite where
      mempty = TestSuite {
          testName      = mempty,
          testInterface = mempty,
          testBuildInfo = mempty,
          testEnabled   = False
      }
  
      mappend a b = TestSuite {
          testName      = combine' testName,
          testInterface = combine  testInterface,
          testBuildInfo = combine  testBuildInfo,
          testEnabled   = testEnabled a || testEnabled b
      }
          where combine   field = field a `mappend` field b
                combine' f = case (f a, f b) of
                          ("", x) -> x
                          (x, "") -> x
                          (x, y) -> error "Ambiguous values for test field: '"
                              ++ x ++ "' and '" ++ y ++ "'"
  
  instance Monoid TestSuiteInterface where
      mempty  =  TestSuiteUnsupported (TestTypeUnknown mempty (Version [] []))
      mappend a (TestSuiteUnsupported _) = a
      mappend _ b                        = b
  
  emptyTestSuite :: TestSuite
  emptyTestSuite = mempty
  
  -- | Does this package have any test suites?
  hasTests :: PackageDescription -> Bool
  hasTests = any (buildable . testBuildInfo) . testSuites
  
  -- | Get all the enabled test suites from a package.
  enabledTests :: PackageDescription -> [TestSuite]
  enabledTests = filter testEnabled . testSuites
  
  -- | Perform an action on each buildable 'TestSuite' in a package.
  withTest :: PackageDescription -> (TestSuite -> IO ()) -> IO ()
  withTest pkg_descr f =
      mapM_ f $ filter (buildable . testBuildInfo) $ enabledTests pkg_descr
  
  -- | Get all the module names from a test suite.
  testModules :: TestSuite -> [ModuleName]
  testModules test = (case testInterface test of
                       TestSuiteLibV09 _ m -> [m]
                       _                   -> [])
                  ++ otherModules (testBuildInfo test)
  
  -- | The \"test-type\" field in the test suite stanza.
  --
  data TestType = TestTypeExe Version     -- ^ \"type: exitcode-stdio-x.y\"
                | TestTypeLib Version     -- ^ \"type: detailed-x.y\"
                | TestTypeUnknown String Version -- ^ Some unknown test type e.g. \"type: foo\"
      deriving (Show, Read, Eq, Typeable, Data)
  
  knownTestTypes :: [TestType]
  knownTestTypes = [ TestTypeExe (Version [1,0] [])
                   , TestTypeLib (Version [0,9] []) ]
  
  stdParse :: Text ver => (ver -> String -> res) -> Parse.ReadP r res
  stdParse f = do
    cs   <- Parse.sepBy1 component (Parse.char '-')
    _    <- Parse.char '-'
    ver  <- parse
    let name = intercalate "-" cs
    return $! f ver (lowercase name)
    where
      component = do
        cs <- Parse.munch1 Char.isAlphaNum
        if all Char.isDigit cs then Parse.pfail else return cs
        -- each component must contain an alphabetic character, to avoid
        -- ambiguity in identifiers like foo-1 (the 1 is the version number).
  
  instance Text TestType where
    disp (TestTypeExe ver)          = text "exitcode-stdio-" <> disp ver
    disp (TestTypeLib ver)          = text "detailed-"       <> disp ver
    disp (TestTypeUnknown name ver) = text name <> char '-' <> disp ver
  
    parse = stdParse $ \ver name -> case name of
      "exitcode-stdio" -> TestTypeExe ver
      "detailed"       -> TestTypeLib ver
      _                -> TestTypeUnknown name ver
  
  
  testType :: TestSuite -> TestType
  testType test = case testInterface test of
    TestSuiteExeV10 ver _         -> TestTypeExe ver
    TestSuiteLibV09 ver _         -> TestTypeLib ver
    TestSuiteUnsupported testtype -> testtype
  
  -- ---------------------------------------------------------------------------
  -- The Benchmark type
  
  -- | A \"benchmark\" stanza in a cabal file.
  --
  data Benchmark = Benchmark {
          benchmarkName      :: String,
          benchmarkInterface :: BenchmarkInterface,
          benchmarkBuildInfo :: BuildInfo,
          benchmarkEnabled   :: Bool
          -- TODO: See TODO for 'testEnabled'.
      }
      deriving (Show, Read, Eq, Typeable, Data)
  
  -- | The benchmark interfaces that are currently defined. Each
  -- benchmark must specify which interface it supports.
  --
  -- More interfaces may be defined in future, either new revisions or
  -- totally new interfaces.
  --
  data BenchmarkInterface =
  
       -- | Benchmark interface \"exitcode-stdio-1.0\". The benchmark
       -- takes the form of an executable. It returns a zero exit code
       -- for success, non-zero for failure. The stdout and stderr
       -- channels may be logged. It takes no command line parameters
       -- and nothing on stdin.
       --
       BenchmarkExeV10 Version FilePath
  
       -- | A benchmark that does not conform to one of the above
       -- interfaces for the given reason (e.g. unknown benchmark type).
       --
     | BenchmarkUnsupported BenchmarkType
     deriving (Eq, Read, Show, Typeable, Data)
  
  instance Monoid Benchmark where
      mempty = Benchmark {
          benchmarkName      = mempty,
          benchmarkInterface = mempty,
          benchmarkBuildInfo = mempty,
          benchmarkEnabled   = False
      }
  
      mappend a b = Benchmark {
          benchmarkName      = combine' benchmarkName,
          benchmarkInterface = combine  benchmarkInterface,
          benchmarkBuildInfo = combine  benchmarkBuildInfo,
          benchmarkEnabled   = benchmarkEnabled a || benchmarkEnabled b
      }
          where combine   field = field a `mappend` field b
                combine' f = case (f a, f b) of
                          ("", x) -> x
                          (x, "") -> x
                          (x, y) -> error "Ambiguous values for benchmark field: '"
                              ++ x ++ "' and '" ++ y ++ "'"
  
  instance Monoid BenchmarkInterface where
      mempty  =  BenchmarkUnsupported (BenchmarkTypeUnknown mempty (Version [] []))
      mappend a (BenchmarkUnsupported _) = a
      mappend _ b                        = b
  
  emptyBenchmark :: Benchmark
  emptyBenchmark = mempty
  
  -- | Does this package have any benchmarks?
  hasBenchmarks :: PackageDescription -> Bool
  hasBenchmarks = any (buildable . benchmarkBuildInfo) . benchmarks
  
  -- | Get all the enabled benchmarks from a package.
  enabledBenchmarks :: PackageDescription -> [Benchmark]
  enabledBenchmarks = filter benchmarkEnabled . benchmarks
  
  -- | Perform an action on each buildable 'Benchmark' in a package.
  withBenchmark :: PackageDescription -> (Benchmark -> IO ()) -> IO ()
  withBenchmark pkg_descr f =
      mapM_ f $ filter (buildable . benchmarkBuildInfo) $ enabledBenchmarks pkg_descr
  
  -- | Get all the module names from a benchmark.
  benchmarkModules :: Benchmark -> [ModuleName]
  benchmarkModules benchmark = otherModules (benchmarkBuildInfo benchmark)
  
  -- | The \"benchmark-type\" field in the benchmark stanza.
  --
  data BenchmarkType = BenchmarkTypeExe Version
                       -- ^ \"type: exitcode-stdio-x.y\"
                     | BenchmarkTypeUnknown String Version
                       -- ^ Some unknown benchmark type e.g. \"type: foo\"
      deriving (Show, Read, Eq, Typeable, Data)
  
  knownBenchmarkTypes :: [BenchmarkType]
  knownBenchmarkTypes = [ BenchmarkTypeExe (Version [1,0] []) ]
  
  instance Text BenchmarkType where
    disp (BenchmarkTypeExe ver)          = text "exitcode-stdio-" <> disp ver
    disp (BenchmarkTypeUnknown name ver) = text name <> char '-' <> disp ver
  
    parse = stdParse $ \ver name -> case name of
      "exitcode-stdio" -> BenchmarkTypeExe ver
      _                -> BenchmarkTypeUnknown name ver
  
  
  benchmarkType :: Benchmark -> BenchmarkType
  benchmarkType benchmark = case benchmarkInterface benchmark of
    BenchmarkExeV10 ver _              -> BenchmarkTypeExe ver
    BenchmarkUnsupported benchmarktype -> benchmarktype
  
  -- ---------------------------------------------------------------------------
  -- The BuildInfo type
  
  -- Consider refactoring into executable and library versions.
  data BuildInfo = BuildInfo {
          buildable         :: Bool,      -- ^ component is buildable here
          buildTools        :: [Dependency], -- ^ tools needed to build this bit
          cppOptions        :: [String],  -- ^ options for pre-processing Haskell code
          ccOptions         :: [String],  -- ^ options for C compiler
          ldOptions         :: [String],  -- ^ options for linker
          pkgconfigDepends  :: [Dependency], -- ^ pkg-config packages that are used
          frameworks        :: [String], -- ^support frameworks for Mac OS X
          cSources          :: [FilePath],
          hsSourceDirs      :: [FilePath], -- ^ where to look for the haskell module hierarchy
          otherModules      :: [ModuleName], -- ^ non-exposed or non-main modules
  
          defaultLanguage   :: Maybe Language,-- ^ language used when not explicitly specified
          otherLanguages    :: [Language],    -- ^ other languages used within the package
          defaultExtensions :: [Extension],   -- ^ language extensions used by all modules
          otherExtensions   :: [Extension],   -- ^ other language extensions used within the package
          oldExtensions     :: [Extension],   -- ^ the old extensions field, treated same as 'defaultExtensions'
  
          extraLibs         :: [String], -- ^ what libraries to link with when compiling a program that uses your package
          extraLibDirs      :: [String],
          includeDirs       :: [FilePath], -- ^directories to find .h files
          includes          :: [FilePath], -- ^ The .h files to be found in includeDirs
          installIncludes   :: [FilePath], -- ^ .h files to install with the package
          options           :: [(CompilerFlavor,[String])],
          ghcProfOptions    :: [String],
          ghcSharedOptions  :: [String],
          customFieldsBI    :: [(String,String)], -- ^Custom fields starting
                                                  -- with x-, stored in a
                                                  -- simple assoc-list.
          targetBuildDepends :: [Dependency] -- ^ Dependencies specific to a library or executable target
      }
      deriving (Show,Read,Eq,Typeable,Data)
  
  instance Monoid BuildInfo where
    mempty = BuildInfo {
      buildable         = True,
      buildTools        = [],
      cppOptions        = [],
      ccOptions         = [],
      ldOptions         = [],
      pkgconfigDepends  = [],
      frameworks        = [],
      cSources          = [],
      hsSourceDirs      = [],
      otherModules      = [],
      defaultLanguage   = Nothing,
      otherLanguages    = [],
      defaultExtensions = [],
      otherExtensions   = [],
      oldExtensions     = [],
      extraLibs         = [],
      extraLibDirs      = [],
      includeDirs       = [],
      includes          = [],
      installIncludes   = [],
      options           = [],
      ghcProfOptions    = [],
      ghcSharedOptions  = [],
      customFieldsBI    = [],
      targetBuildDepends = []
    }
    mappend a b = BuildInfo {
      buildable         = buildable a && buildable b,
      buildTools        = combine    buildTools,
      cppOptions        = combine    cppOptions,
      ccOptions         = combine    ccOptions,
      ldOptions         = combine    ldOptions,
      pkgconfigDepends  = combine    pkgconfigDepends,
      frameworks        = combineNub frameworks,
      cSources          = combineNub cSources,
      hsSourceDirs      = combineNub hsSourceDirs,
      otherModules      = combineNub otherModules,
      defaultLanguage   = combineMby defaultLanguage,
      otherLanguages    = combineNub otherLanguages,
      defaultExtensions = combineNub defaultExtensions,
      otherExtensions   = combineNub otherExtensions,
      oldExtensions     = combineNub oldExtensions,
      extraLibs         = combine    extraLibs,
      extraLibDirs      = combineNub extraLibDirs,
      includeDirs       = combineNub includeDirs,
      includes          = combineNub includes,
      installIncludes   = combineNub installIncludes,
      options           = combine    options,
      ghcProfOptions    = combine    ghcProfOptions,
      ghcSharedOptions  = combine    ghcSharedOptions,
      customFieldsBI    = combine    customFieldsBI,
      targetBuildDepends = combineNub targetBuildDepends
    }
      where
        combine    field = field a `mappend` field b
        combineNub field = nub (combine field)
        combineMby field = field b `mplus` field a
  
  emptyBuildInfo :: BuildInfo
  emptyBuildInfo = mempty
  
  -- | The 'BuildInfo' for the library (if there is one and it's buildable), and
  -- all buildable executables, test suites and benchmarks.  Useful for gathering
  -- dependencies.
  allBuildInfo :: PackageDescription -> [BuildInfo]
  allBuildInfo pkg_descr = [ bi | Just lib <- [library pkg_descr]
                                , let bi = libBuildInfo lib
                                , buildable bi ]
                        ++ [ bi | exe <- executables pkg_descr
                                , let bi = buildInfo exe
                                , buildable bi ]
                        ++ [ bi | tst <- testSuites pkg_descr
                                , let bi = testBuildInfo tst
                                , buildable bi
                                , testEnabled tst ]
                        ++ [ bi | tst <- benchmarks pkg_descr
                                , let bi = benchmarkBuildInfo tst
                                , buildable bi
                                , benchmarkEnabled tst ]
    --FIXME: many of the places where this is used, we actually want to look at
    --       unbuildable bits too, probably need separate functions
  
  -- | The 'Language's used by this component
  --
  allLanguages :: BuildInfo -> [Language]
  allLanguages bi = maybeToList (defaultLanguage bi)
                 ++ otherLanguages bi
  
  -- | The 'Extension's that are used somewhere by this component
  --
  allExtensions :: BuildInfo -> [Extension]
  allExtensions bi = usedExtensions bi
                  ++ otherExtensions bi
  
  -- | The 'Extensions' that are used by all modules in this component
  --
  usedExtensions :: BuildInfo -> [Extension]
  usedExtensions bi = oldExtensions bi
                   ++ defaultExtensions bi
  
  type HookedBuildInfo = (Maybe BuildInfo, [(String, BuildInfo)])
  
  emptyHookedBuildInfo :: HookedBuildInfo
  emptyHookedBuildInfo = (Nothing, [])
  
  -- |Select options for a particular Haskell compiler.
  hcOptions :: CompilerFlavor -> BuildInfo -> [String]
  hcOptions hc bi = [ opt | (hc',opts) <- options bi
                          , hc' == hc
                          , opt <- opts ]
  
  -- ------------------------------------------------------------
  -- * Source repos
  -- ------------------------------------------------------------
  
  -- | Information about the source revision control system for a package.
  --
  -- When specifying a repo it is useful to know the meaning or intention of the
  -- information as doing so enables automation. There are two obvious common
  -- purposes: one is to find the repo for the latest development version, the
  -- other is to find the repo for this specific release. The 'ReopKind'
  -- specifies which one we mean (or another custom one).
  --
  -- A package can specify one or the other kind or both. Most will specify just
  -- a head repo but some may want to specify a repo to reconstruct the sources
  -- for this package release.
  --
  -- The required information is the 'RepoType' which tells us if it's using
  -- 'Darcs', 'Git' for example. The 'repoLocation' and other details are
  -- interpreted according to the repo type.
  --
  data SourceRepo = SourceRepo {
    -- | The kind of repo. This field is required.
    repoKind     :: RepoKind,
  
    -- | The type of the source repository system for this repo, eg 'Darcs' or
    -- 'Git'. This field is required.
    repoType     :: Maybe RepoType,
  
    -- | The location of the repository. For most 'RepoType's this is a URL.
    -- This field is required.
    repoLocation :: Maybe String,
  
    -- | 'CVS' can put multiple \"modules\" on one server and requires a
    -- module name in addition to the location to identify a particular repo.
    -- Logically this is part of the location but unfortunately has to be
    -- specified separately. This field is required for the 'CVS' 'RepoType' and
    -- should not be given otherwise.
    repoModule   :: Maybe String,
  
    -- | The name or identifier of the branch, if any. Many source control
    -- systems have the notion of multiple branches in a repo that exist in the
    -- same location. For example 'Git' and 'CVS' use this while systems like
    -- 'Darcs' use different locations for different branches. This field is
    -- optional but should be used if necessary to identify the sources,
    -- especially for the 'RepoThis' repo kind.
    repoBranch   :: Maybe String,
  
    -- | The tag identify a particular state of the repository. This should be
    -- given for the 'RepoThis' repo kind and not for 'RepoHead' kind.
    --
    repoTag      :: Maybe String,
  
    -- | Some repositories contain multiple projects in different subdirectories
    -- This field specifies the subdirectory where this packages sources can be
    -- found, eg the subdirectory containing the @.cabal@ file. It is interpreted
    -- relative to the root of the repository. This field is optional. If not
    -- given the default is \".\" ie no subdirectory.
    repoSubdir   :: Maybe FilePath
  }
    deriving (Eq, Read, Show, Typeable, Data)
  
  -- | What this repo info is for, what it represents.
  --
  data RepoKind =
      -- | The repository for the \"head\" or development version of the project.
      -- This repo is where we should track the latest development activity or
      -- the usual repo people should get to contribute patches.
      RepoHead
  
      -- | The repository containing the sources for this exact package version
      -- or release. For this kind of repo a tag should be given to give enough
      -- information to re-create the exact sources.
    | RepoThis
  
    | RepoKindUnknown String
    deriving (Eq, Ord, Read, Show, Typeable, Data)
  
  -- | An enumeration of common source control systems. The fields used in the
  -- 'SourceRepo' depend on the type of repo. The tools and methods used to
  -- obtain and track the repo depend on the repo type.
  --
  data RepoType = Darcs | Git | SVN | CVS
                | Mercurial | GnuArch | Bazaar | Monotone
                | OtherRepoType String
    deriving (Eq, Ord, Read, Show, Typeable, Data)
  
  knownRepoTypes :: [RepoType]
  knownRepoTypes = [Darcs, Git, SVN, CVS
                   ,Mercurial, GnuArch, Bazaar, Monotone]
  
  repoTypeAliases :: RepoType -> [String]
  repoTypeAliases Bazaar    = ["bzr"]
  repoTypeAliases Mercurial = ["hg"]
  repoTypeAliases GnuArch   = ["arch"]
  repoTypeAliases _         = []
  
  instance Text RepoKind where
    disp RepoHead                = Disp.text "head"
    disp RepoThis                = Disp.text "this"
    disp (RepoKindUnknown other) = Disp.text other
  
    parse = do
      name <- ident
      return $ case lowercase name of
        "head" -> RepoHead
        "this" -> RepoThis
        _      -> RepoKindUnknown name
  
  instance Text RepoType where
    disp (OtherRepoType other) = Disp.text other
    disp other                 = Disp.text (lowercase (show other))
    parse = fmap classifyRepoType ident
  
  classifyRepoType :: String -> RepoType
  classifyRepoType s =
    fromMaybe (OtherRepoType s) $ lookup (lowercase s) repoTypeMap
    where
      repoTypeMap = [ (name, repoType')
                    | repoType' <- knownRepoTypes
                    , name <- display repoType' : repoTypeAliases repoType' ]
  
  ident :: Parse.ReadP r String
  ident = Parse.munch1 (\c -> Char.isAlphaNum c || c == '_' || c == '-')
  
  lowercase :: String -> String
  lowercase = map Char.toLower
  
  -- ------------------------------------------------------------
  -- * Utils
  -- ------------------------------------------------------------
  
  updatePackageDescription :: HookedBuildInfo -> PackageDescription -> PackageDescription
  updatePackageDescription (mb_lib_bi, exe_bi) p
      = p{ executables = updateExecutables exe_bi    (executables p)
         , library     = updateLibrary     mb_lib_bi (library     p)
         }
      where
        updateLibrary :: Maybe BuildInfo -> Maybe Library -> Maybe Library
        updateLibrary (Just bi) (Just lib) = Just (lib{libBuildInfo = bi `mappend` libBuildInfo lib})
        updateLibrary Nothing   mb_lib     = mb_lib
        updateLibrary (Just _)  Nothing    = Nothing
  
        updateExecutables :: [(String, BuildInfo)] -- ^[(exeName, new buildinfo)]
                          -> [Executable]          -- ^list of executables to update
                          -> [Executable]          -- ^list with exeNames updated
        updateExecutables exe_bi' executables' = foldr updateExecutable executables' exe_bi'
  
        updateExecutable :: (String, BuildInfo) -- ^(exeName, new buildinfo)
                         -> [Executable]        -- ^list of executables to update
                         -> [Executable]        -- ^libst with exeName updated
        updateExecutable _                 []         = []
        updateExecutable exe_bi'@(name,bi) (exe:exes)
          | exeName exe == name = exe{buildInfo = bi `mappend` buildInfo exe} : exes
          | otherwise           = exe : updateExecutable exe_bi' exes
  
  -- ---------------------------------------------------------------------------
  -- The GenericPackageDescription type
  
  data GenericPackageDescription =
      GenericPackageDescription {
          packageDescription :: PackageDescription,
          genPackageFlags       :: [Flag],
          condLibrary        :: Maybe (CondTree ConfVar [Dependency] Library),
          condExecutables    :: [(String, CondTree ConfVar [Dependency] Executable)],
          condTestSuites     :: [(String, CondTree ConfVar [Dependency] TestSuite)],
          condBenchmarks     :: [(String, CondTree ConfVar [Dependency] Benchmark)]
        }
      deriving (Show, Eq, Typeable, Data)
  
  instance Package GenericPackageDescription where
    packageId = packageId . packageDescription
  
  --TODO: make PackageDescription an instance of Text.
  
  -- | A flag can represent a feature to be included, or a way of linking
  --   a target against its dependencies, or in fact whatever you can think of.
  data Flag = MkFlag
      { flagName        :: FlagName
      , flagDescription :: String
      , flagDefault     :: Bool
      , flagManual      :: Bool
      }
      deriving (Show, Eq, Typeable, Data)
  
  -- | A 'FlagName' is the name of a user-defined configuration flag
  newtype FlagName = FlagName String
      deriving (Eq, Ord, Show, Read, Typeable, Data)
  
  -- | A 'FlagAssignment' is a total or partial mapping of 'FlagName's to
  -- 'Bool' flag values. It represents the flags chosen by the user or
  -- discovered during configuration. For example @--flags=foo --flags=-bar@
  -- becomes @[("foo", True), ("bar", False)]@
  --
  type FlagAssignment = [(FlagName, Bool)]
  
  -- | A @ConfVar@ represents the variable type used.
  data ConfVar = OS OS
               | Arch Arch
               | Flag FlagName
               | Impl CompilerFlavor VersionRange
      deriving (Eq, Show, Typeable, Data)
  
  --instance Text ConfVar where
  --    disp (OS os) = "os(" ++ display os ++ ")"
  --    disp (Arch arch) = "arch(" ++ display arch ++ ")"
  --    disp (Flag (ConfFlag f)) = "flag(" ++ f ++ ")"
  --    disp (Impl c v) = "impl(" ++ display c
  --                       ++ " " ++ display v ++ ")"
  
  -- | A boolean expression parameterized over the variable type used.
  data Condition c = Var c
                   | Lit Bool
                   | CNot (Condition c)
                   | COr (Condition c) (Condition c)
                   | CAnd (Condition c) (Condition c)
      deriving (Show, Eq, Typeable, Data)
  
  --instance Text c => Text (Condition c) where
  --  disp (Var x) = text (show x)
  --  disp (Lit b) = text (show b)
  --  disp (CNot c) = char '!' <> parens (ppCond c)
  --  disp (COr c1 c2) = parens $ sep [ppCond c1, text "||" <+> ppCond c2]
  --  disp (CAnd c1 c2) = parens $ sep [ppCond c1, text "&&" <+> ppCond c2]
  
  data CondTree v c a = CondNode
      { condTreeData        :: a
      , condTreeConstraints :: c
      , condTreeComponents  :: [( Condition v
                                , CondTree v c a
                                , Maybe (CondTree v c a))]
      }
      deriving (Show, Eq, Typeable, Data)
  
  --instance (Text v, Text c) => Text (CondTree v c a) where
  --  disp (CondNode _dat cs ifs) =
  --    (text "build-depends: " <+>
  --      disp cs)
  --    $+$
  --    (vcat $ map ppIf ifs)
  --  where
  --    ppIf (c,thenTree,mElseTree) =
  --        ((text "if" <+> ppCond c <> colon) $$
  --          nest 2 (ppCondTree thenTree disp))
  --        $+$ (maybe empty (\t -> text "else: " $$ nest 2 (ppCondTree t disp))
  --                   mElseTree)
  