Building a C/C++ library from Cabal

Setup.hs

--
-- Modified version of the wxcore Cabal setup.hs file which builds the C++ code in a buildhook
-- so that we have some control over how the linking works.
--
import Control.Monad                      (when)
import Data.List                          (foldl', intercalate, nub, lookup)
import Data.Maybe                         (fromJust)
import Distribution.PackageDescription
import Distribution.Simple
import Distribution.Simple.LocalBuildInfo (LocalBuildInfo, localPkgDescr, withPrograms, buildDir)
import Distribution.Simple.Program        (ConfiguredProgram (..), lookupProgram, runProgram, simpleProgram)
import Distribution.Simple.Setup          (ConfigFlags, BuildFlags)
import Distribution.System                (OS (..), Arch (..), buildOS, buildArch)
import Distribution.Verbosity             (normal, verbose)
import System.Cmd                         (system)
import System.Directory                   (createDirectoryIfMissing, doesFileExist, getCurrentDirectory, getModificationTime)
import System.Environment                 (getEnv)
import System.FilePath.Posix              ((</>), (<.>), replaceExtension, takeFileName, dropFileName, addExtension)
import System.IO.Unsafe                   (unsafePerformIO)
import System.Process                     (readProcess)

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

main :: IO ()
main = defaultMainWithHooks simpleUserHooks { confHook = myConfHook, buildHook = myBuildHook }

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

sourceDirectory  :: FilePath
eiffelDirectory  :: FilePath
includeDirectory :: FilePath
wxcoreDirectory  :: FilePath

sourceDirectory  = "src"
eiffelDirectory  = sourceDirectory </> "eiffel"
includeDirectory = sourceDirectory </> "include"
wxcoreDirectory  = sourceDirectory </> "haskell/Graphics/UI/WXCore"

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

wxcoreIncludeFile :: FilePath
wxcoreIncludeFile = includeDirectory </> "wxc.h"

eiffelFiles :: [FilePath]
eiffelFiles =
    map ((<.> "e") . (eiffelDirectory </>)) names
  where
    names = ["wxc_defs", "wx_defs", "stc"]

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

-- | Extend the default configuration hook so that wxdirect is executed over the files from which
--   certain wxCore Haskell source files are generated, and use wx-config to determine the compile
--   and link environment for wxWidgets.
--   Note that we have to add the wxc DLL here as it becomes part of our build dependencies, even
--   though we haven't built it yet.
myConfHook (pkg0, pbi) flags = do
    createDirectoryIfMissing True wxcoreDirectory
    system $ "wxdirect -t --wxc " ++ sourceDirectory ++ " -o " ++ wxcoreDirectory ++ " " ++ wxcoreIncludeFile
    system $ "wxdirect -i --wxc " ++ sourceDirectory ++ " -o " ++ wxcoreDirectory ++ " " ++ wxcoreIncludeFile
    system $ "wxdirect -c --wxc " ++ sourceDirectory ++ " -o " ++ wxcoreDirectory ++ " " ++ wxcoreIncludeFile
    system $ "wxdirect -d --wxc " ++ sourceDirectory ++ " -o " ++ wxcoreDirectory ++ " " ++ intercalate " " eiffelFiles

    wx <- fmap parseWxConfig (readProcess "wx-config" ["--libs", "--cppflags"] "")
    lbi <- confHook simpleUserHooks (pkg0, pbi) flags

    let lpd        = localPkgDescr lbi
    let lib        = fromJust (library lpd)
    let libbi      = libBuildInfo lib
    let custom_bi  = customFieldsBI libbi
    -- Lookup the DLLs we need to add to our extra-libs from x-dll-name and x-dll-extra-libs
    let all_dlls   = parseDLLs ["x-dll-name", "x-dll-extra-libraries"] custom_bi
    let libbi' = libbi
          { extraLibDirs = extraLibDirs libbi ++ extraLibDirs wx
          , extraLibs    = extraLibs    libbi ++ extraLibs all_dlls ++ extraLibs wx
          , ldOptions    = ldOptions    libbi ++ ldOptions    wx
          , frameworks   = frameworks   libbi ++ frameworks   wx
          , includeDirs  = includeDirs  libbi ++ includeDirs  wx
          , ccOptions    = ccOptions    libbi ++ ccOptions    wx ++ ["-DwxcREFUSE_MEDIACTRL"]
          }

    let lib' = lib { libBuildInfo = libbi' }
    let lpd' = lpd { library = Just lib' }

    return $ lbi { localPkgDescr = lpd' }

-- | Determine the name(s) of DLLs used when linking to wxcore. These are added to
--   the extraLibs stanza of the build information.
parseDLLs :: [String] -> [(String, String)] -> BuildInfo
parseDLLs x_stanzas bi =
    buildBI emptyBuildInfo dlls
        where
          dlls = concat $ map (\e -> (lines . fromJust) (lookup e bi)) x_stanzas
          buildBI bi (w:ws) = buildBI (bi { extraLibs = w : extraLibs bi }) ws
          buildBI bi []     = bi

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

-- | Parse the output of wx-config. Note that, like wx-config itself, this
--   function only works for gcc or other UNix-like compilers.
parseWxConfig :: String -> BuildInfo
parseWxConfig s =
    helper emptyBuildInfo (words s)
  where
    helper b ("-framework":w:ws) = helper (b { frameworks = w : frameworks b }) ws
    helper b (w:ws)              = helper (f b w) ws
    helper b []                  = b
    f b w =
        case w of
          ('-':'L':v) -> b { extraLibDirs = v : extraLibDirs b }
          ('-':'l':v) -> b { extraLibs    = v : extraLibs b }
          ('-':'I':v) -> b { includeDirs  = v : includeDirs b }
          ('-':'D':_) -> b { ccOptions    = w : ccOptions b }
          _           -> b

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

-- | Extend the standard build hook to build a shared library for wxc - this will statically link
--   any libraries which are unavailable as shared variants. This is mainly a work-around for the
--   fact that GHCi needs to load shared libraries at run-time, and that the Windows MinGW environment
--   is shipped with only a static version of libstdc++.
--   TODO: Does not currently create the build output directory.
myBuildHook pkg_descr local_bld_info user_hooks bld_flags =
    do
    -- Extract the custom fields customFieldsPD where field name is x-cpp-dll-sources
    let lib       = fromJust (library pkg_descr)
        lib_bi    = libBuildInfo lib
        custom_bi = customFieldsBI lib_bi
        dll_name  = fromJust (lookup "x-dll-name" custom_bi)
        dll_srcs  = (lines . fromJust) (lookup "x-dll-sources" custom_bi)
        dll_libs  = (lines . fromJust) (lookup "x-dll-extra-libraries" custom_bi)
        cc_opts   = ccOptions lib_bi
        ld_opts   = ldOptions lib_bi
        inc_dirs  = includeDirs lib_bi
        lib_dirs  = extraLibDirs lib_bi
        libs      = extraLibs lib_bi
        bld_dir   = buildDir local_bld_info
        progs     = withPrograms local_bld_info
        gcc       = fromJust (lookupProgram (simpleProgram "gcc") progs)
        ver       = (pkgVersion . package) pkg_descr
    -- Compile C/C++ sources - output directory is dist/build/src/cpp
    putStrLn "Building wxc"
    objs <- mapM (compileCxx gcc cc_opts inc_dirs bld_dir) dll_srcs
    -- Link C/C++ sources as a DLL - output directory is dist/build
    putStrLn "Linking wxc"
    linkSharedLib gcc ld_opts lib_dirs (libs ++ dll_libs) objs ver bld_dir dll_name
    -- Remove C/C++ source code from the hooked build (don't change libs)
    putStrLn "Invoke default build hook"
    buildHook simpleUserHooks pkg_descr local_bld_info user_hooks bld_flags

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

-- | Return any compiler options required to support shared library creation
osCompileOpts :: [String] -- ^ Platform-specific compile options
osCompileOpts =
    case buildOS of
      Windows -> ["-DBUILD_DLL"]
      OSX     -> ["-fPIC"]
      _       -> ["-fPIC"]

-- | Return any linker options required to support shared library creation
linkCxxOpts :: Version     -- ^ Version information to be used for Unix shared libraries 
            -> FilePath    -- ^ Directory in which library will be built
            -> String      -- ^ Name of the shared library
            -> [String]    -- ^ List of options which can be applied to 'runProgram'
linkCxxOpts ver out_dir basename =
    let dll_pathname    = normalisePath (out_dir </> addExtension basename ".dll")
        implib_pathname = normalisePath (out_dir </> "lib" ++ addExtension basename ".a") in
    case buildOS of
      Windows -> ["--dll", "-shared", "-o " ++ addExtension basename ".dll", 
                  "-Wl,--out-implib," ++ "lib" ++ addExtension basename ".a",
                  "-Wl,--export-all-symbols"]
      OSX     -> ["-dynamiclib", 
                  "-o " ++ out_dir </> addExtension basename ".so", 
                  "-Wl,undefined,dynamic_lookup"]
      _       -> ["-shared", 
                  "-Wl,-soname,lib" ++ basename ++ ".so." ++ maj_ver, 
                  "-o " ++ out_dir </> "lib" ++ basename ++ ".so." ++ full_ver]
        where
          maj_ver     = (show . head . versionBranch) ver
          (a:b:c:d:_) = versionBranch ver
          full_ver    = (show a) ++ "." ++ (show b) ++ "." ++ (show c) ++ "." ++ (show d)

-- | Compile a single source file using the configured gcc, if the object file does not yet
--   exist, or is older than the source file.
--   TODO: Does not do dependency resolution properly
compileCxx :: ConfiguredProgram  -- ^ Program used to perform C/C++ compilation (gcc)
           -> [String]           -- ^ Compile options provided by Cabal and wxConfig
           -> [String]           -- ^ Include paths provided by Cabal and wxConfig
           -> FilePath           -- ^ Base output directory
           -> FilePath           -- ^ Path to source file
           -> IO FilePath        -- ^ Path to generated object code
compileCxx gcc opts incls out_path cxx_src =
    do
    let includes  = map ("-I" ++) incls
        out_path' = normalisePath out_path
        cxx_src'  = normalisePath cxx_src
        out_file  = out_path' </> dropFileName cxx_src </> replaceExtension (takeFileName cxx_src) ".o"
        out       = ["-c", cxx_src', "-o", out_file]
        opts'     = opts ++ osCompileOpts
    do_it <- needsCompiling cxx_src out_file
    when do_it $ createDirectoryIfMissing True (dropFileName out_file) >> 
                 runProgram verbose gcc (includes ++ opts' ++ out)
    return out_file

-- | Return True if obj does not exist or is older than src.
--   Real dependency checking would be nice here...
needsCompiling :: FilePath        -- ^ Path to source file
               -> FilePath        -- ^ Path to object file
               -> IO Bool         -- ^ True if compilation required
needsCompiling src obj =
    do
    has_obj <- doesFileExist obj
    if has_obj
        then do
          mtime_src <- getModificationTime src
          mtime_obj <- getModificationTime obj
          if mtime_obj < mtime_src then return True else return False
        else
          return True

-- | Create a dynamically linked library using the configured ld.
linkSharedLib :: ConfiguredProgram -- ^ Program used to perform linking
              -> [String]          -- ^ Linker options supplied by Cabal
              -> [FilePath]        -- ^ Library directories
              -> [String]          -- ^ Libraries
              -> [String]          -- ^ Objects
              -> Version           -- ^ wxCore version (wxC has same version number)
              -> FilePath          -- ^ Directory in which library will begenerated
              -> String            -- ^ Name of the shared library
              -> IO ()
linkSharedLib gcc opts lib_dirs libs objs ver out_dir dll_name =
    do
    cwd <- getCurrentDirectory
    let lib_dirs' = map (\d -> "-L" ++ normalisePath d) lib_dirs
        out_dir'  = normalisePath out_dir
        opts'     = opts ++ linkCxxOpts ver (cwd </> out_dir') dll_name
        objs'     = map normalisePath objs
        libs'     = ["-lstdc++"] ++ map ("-l" ++) libs
    runProgram verbose gcc (opts' ++ objs' ++ lib_dirs' ++ libs')

-- | The 'normalise' implementation in System.FilePath does not meet the requirements of 
--   calling and/or running external programs on Windows particularly well as it does not
--   normalise the '/' character to '\\'. The problem is that some MinGW programs do not
--   like to see paths with a mixture of '/' and '\\'. Sine we are calling out to these,
--   we require a stricter normalisation.
normalisePath :: FilePath -> FilePath
normalisePath = case buildOS of
                  Windows -> dosifyFilePath
                  _       -> unixifyFilePath

-- | Replace a character in a String with some other character
replace :: Char            -- ^ Character to replace
        -> Char            -- ^ Character with which to replace
        -> String          -- ^ String in which to replace
        -> String          -- ^ Transformed string
replace old new = map replace' 
    where
      replace' elem = if elem == old then new else elem

unixifyFilePath = replace '\\' '/'
dosifyFilePath  = replace '/' '\\'

wxcore.cabal

name:         wxcore
version:      0.12.1.7
license:      LGPL
license-file: LICENSE
author:       Daan Leijen
maintainer:   wxhaskell-devel@lists.sourceforge.net
category:     GUI, User interfaces
synopsis:     wxHaskell core
description:
  wxHaskell is a portable and native GUI library for Haskell. It is
  built on top of wxWidgets, a comprehensive C++ library that is
  portable across all major GUI platforms, including GTK, Windows,
  X11, and MacOS X. This version works with wxWidgets 2.8 only.
homepage:     http://haskell.org/haskellwiki/WxHaskell

cabal-version: >= 1.2
build-type:    Custom

extra-tmp-files:
  src/haskell/Graphics/UI/WXCore/WxcClassInfo.hs
  src/haskell/Graphics/UI/WXCore/WxcClassTypes.hs
  src/haskell/Graphics/UI/WXCore/WxcClasses.hs
  src/haskell/Graphics/UI/WXCore/WxcClassesAL.hs
  src/haskell/Graphics/UI/WXCore/WxcClassesMZ.hs
  src/haskell/Graphics/UI/WXCore/WxcDefs.hs

extra-source-files:
  src/cpp/stc_gen.cpp
  src/eiffel/wx_defs.e
  src/eiffel/wxc_defs.e
  src/eiffel/stc.e
  src/include/db.h
  src/include/dragimage.h
  src/include/eljgrid.h
  src/include/ewxw_def.h
  src/include/graphicscontext.h
  src/include/managed.h
  src/include/mediactrl.h
  src/include/previewframe.h
  src/include/printout.h
  src/include/sound.h
  src/include/stc.h
  src/include/stc_gen.h
  src/include/textstream.h
  src/include/wrapper.h
  src/include/wxc.h
  src/include/wxc_glue.h
  src/include/wxc_types.h

flag splitBase
  description:  use new split base
  default:      True

library
  hs-source-dirs:
    src/haskell

  include-dirs:
    src/include
  
  x-dll-sources:
    src/cpp/apppath.cpp
    src/cpp/db.cpp
    src/cpp/dragimage.cpp
    src/cpp/eljaccelerator.cpp
    src/cpp/eljartprov.cpp
    src/cpp/eljbitmap.cpp
    src/cpp/eljbrush.cpp
    src/cpp/eljbusyinfo.cpp
    src/cpp/eljbutton.cpp
    src/cpp/eljcalendarctrl.cpp
    src/cpp/eljcaret.cpp
    src/cpp/eljcheckbox.cpp
    src/cpp/eljchecklistbox.cpp
    src/cpp/eljchoice.cpp
    src/cpp/eljclipboard.cpp
    src/cpp/eljcoldata.cpp
    src/cpp/eljcolour.cpp
    src/cpp/eljcolourdlg.cpp
    src/cpp/eljcombobox.cpp
    src/cpp/eljconfigbase.cpp
    src/cpp/eljcontrol.cpp
    src/cpp/eljctxhelp.cpp
    src/cpp/eljcursor.cpp
    src/cpp/eljdataformat.cpp
    src/cpp/eljdatetime.cpp
    src/cpp/eljdc.cpp
    src/cpp/eljdcsvg.cpp
    src/cpp/eljdialog.cpp
    src/cpp/eljdirdlg.cpp
    src/cpp/eljdnd.cpp
    src/cpp/eljdrawing.cpp
    src/cpp/eljevent.cpp
    src/cpp/eljfiledialog.cpp
    src/cpp/eljfilehist.cpp
    src/cpp/eljfindrepldlg.cpp
    src/cpp/eljfont.cpp
    src/cpp/eljfontdata.cpp
    src/cpp/eljfontdlg.cpp
    src/cpp/eljframe.cpp
    src/cpp/eljgauge.cpp
    src/cpp/eljgrid.cpp
    src/cpp/eljhelpcontroller.cpp
    src/cpp/eljicnbndl.cpp
    src/cpp/eljicon.cpp
    src/cpp/eljimage.cpp
    src/cpp/eljimagelist.cpp
    src/cpp/eljlayoutconstraints.cpp
    src/cpp/eljlistbox.cpp
    src/cpp/eljlistctrl.cpp
    src/cpp/eljlocale.cpp
    src/cpp/eljlog.cpp
    src/cpp/eljmask.cpp
    src/cpp/eljmdi.cpp
    src/cpp/eljmenu.cpp
    src/cpp/eljmenubar.cpp
    src/cpp/eljmessagedialog.cpp
    src/cpp/eljmime.cpp
    src/cpp/eljminiframe.cpp
    src/cpp/eljnotebook.cpp
    src/cpp/eljpalette.cpp
    src/cpp/eljpanel.cpp
    src/cpp/eljpen.cpp
    src/cpp/eljprintdlg.cpp
    src/cpp/eljprinting.cpp
    src/cpp/eljprocess.cpp
    src/cpp/eljradiobox.cpp
    src/cpp/eljradiobutton.cpp
    src/cpp/eljrc.cpp
    src/cpp/eljregion.cpp
    src/cpp/eljregioniter.cpp
    src/cpp/eljsash.cpp
    src/cpp/eljscrollbar.cpp
    src/cpp/eljscrolledwindow.cpp
    src/cpp/eljsingleinst.cpp
    src/cpp/eljsizer.cpp
    src/cpp/eljslider.cpp
    src/cpp/eljspinctrl.cpp
    src/cpp/eljsplitterwindow.cpp
    src/cpp/eljstaticbox.cpp
    src/cpp/eljstaticline.cpp
    src/cpp/eljstatictext.cpp
    src/cpp/eljstatusbar.cpp
    src/cpp/eljsystemsettings.cpp
    src/cpp/eljtextctrl.cpp
    src/cpp/eljtimer.cpp
    src/cpp/eljtipwnd.cpp
    src/cpp/eljtoolbar.cpp
    src/cpp/eljvalidator.cpp
    src/cpp/eljwindow.cpp
    src/cpp/eljwizard.cpp
    src/cpp/ewxw_main.cpp
    src/cpp/extra.cpp
    src/cpp/graphicscontext.cpp
    src/cpp/image.cpp
    src/cpp/managed.cpp
    src/cpp/mediactrl.cpp
    src/cpp/previewframe.cpp
    src/cpp/printout.cpp
    src/cpp/sckaddr.cpp
    src/cpp/socket.cpp
    src/cpp/sound.cpp
    src/cpp/stc.cpp
    src/cpp/std.cpp
    src/cpp/taskbaricon.cpp
    src/cpp/textstream.cpp
    src/cpp/treectrl.cpp
    src/cpp/wrapper.cpp

  x-dll-name: wxc

  x-dll-extra-libraries:

  exposed-modules:
    Graphics.UI.WXCore
    Graphics.UI.WXCore.Controls
    Graphics.UI.WXCore.Db
    Graphics.UI.WXCore.Defines
    Graphics.UI.WXCore.Dialogs
    Graphics.UI.WXCore.DragAndDrop
    Graphics.UI.WXCore.Draw
    Graphics.UI.WXCore.Events
    Graphics.UI.WXCore.Frame
    Graphics.UI.WXCore.Image
    Graphics.UI.WXCore.Layout
    Graphics.UI.WXCore.Print
    Graphics.UI.WXCore.Process
    Graphics.UI.WXCore.Types
    Graphics.UI.WXCore.WxcClassInfo
    Graphics.UI.WXCore.WxcClassTypes
    Graphics.UI.WXCore.WxcClasses
    Graphics.UI.WXCore.WxcClassesAL
    Graphics.UI.WXCore.WxcClassesMZ
    Graphics.UI.WXCore.WxcDefs
    Graphics.UI.WXCore.WxcObject
    Graphics.UI.WXCore.WxcTypes

  build-depends:
    bytestring,
    filepath,
    parsec,
    stm,
    wxdirect >= 0.12.1.3,
    directory,
    old-time,
    time

  if flag(splitBase)
    build-depends:
      array >= 0.2 && < 0.4,
      base >= 4 && < 5,
      containers >= 0.2 && < 0.4
  else
    build-depends:
      array >= 0.1 && < 0.3,
      base >= 3 && < 4,
      containers >= 0.1 && < 0.3