CoreFoundation.hs

-- |Partial binding to CoreFoundation. 
-- At the moment only CFString is supported.

{-# LANGUAGE ForeignFunctionInterface, EmptyDataDecls #-}
module System.MacOSX.CoreFoundation 
  ( -- * types
    UInt8  
  , UInt16  
  , UInt32 
  , UInt64
  , SInt8  
  , SInt16  
  , SInt32 
  , SInt64
  , OSErr
  , OSStatus
  , UniChar
  , CFIndex
  , ItemCount
  , ByteCount
--  , CFString
  , CFDataRef
  , CFStringRef
  , CFAllocatorRef
  , Boolean
  , Float32
  , Float64
    -- * CFString
  , newCFString
  , releaseCFString
  , peekCFString
  , withCFString
    -- * OSStatus
  , osStatusString
  , osStatusError
  , osStatusReport
  
  ) where

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import Data.Bits
import Data.Char
import Data.Word
import Data.Int

import Control.Monad

import Foreign
import Foreign.C
import Foreign.Marshal

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type UInt8    = Word8
type UInt16   = Word16
type UInt32   = Word32
type UInt64   = Word64

type SInt8    = Int8
type SInt16   = Int16
type SInt32   = Int32
type SInt64   = Int64

type OSErr    = SInt16
type OSStatus = SInt32

type Boolean  = Bool
type Float32  = Float
type Float64  = Double

type UniChar   = UInt16      -- utf16 char, not utf32 !!!
type CFIndex   = SInt32
type ItemCount = UInt32
type ByteCount = UInt32

data CFData
data CFString
data CFAllocator

type CFDataRef      = Ptr CFData    
type CFStringRef    = Ptr CFString
type CFAllocatorRef = Ptr CFAllocator

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kCFAllocatorDefault :: CFAllocatorRef
kCFAllocatorDefault = nullPtr

----- error "handling" :) -----

osStatusString :: OSStatus -> String
osStatusString osstatus = "OSStatus = " ++ show osstatus

osStatusError :: OSStatus -> IO a
osStatusError osstatus = fail $ osStatusString osstatus

osStatusReport :: OSStatus -> IO ()
osStatusReport osstatus = when (osstatus/=0) $ putStrLn $ osStatusString osstatus

----- Base -----

-- CFDataRef CFDataCreate ( CFAllocatorRef allocator, const UInt8 *bytes, CFIndex length ); 
foreign import ccall unsafe "CFBase.h CFDataCreate"
  c_CFDataCreate :: CFAllocatorRef -> Ptr UInt8 -> CFIndex -> IO CFDataRef
  
foreign import ccall unsafe "CFBase.h CFRelease" 
  c_CFRelease :: Ptr a -> IO ()

----- CFStrings -----

foreign import ccall unsafe "CFString.h CFStringGetLength" 
  c_CFStringGetLength :: CFStringRef -> IO CFIndex

foreign import ccall unsafe "CFString.h CFStringGetCharactersPtr"
  c_CFStringGetCharactersPtr :: CFStringRef -> IO (Ptr UniChar)  

foreign import ccall unsafe "CFString.h CFStringGetCharacterAtIndex"
  c_CFStringGetCharacterAtIndex :: CFStringRef -> CFIndex -> IO UniChar 

foreign import ccall unsafe "CFString.h CFStringCreateWithCharacters"
  c_CFStringCreateWithCharacters :: CFAllocatorRef -> Ptr UniChar -> CFIndex -> IO CFStringRef

-- | Manually releasing a CFString.
releaseCFString :: CFStringRef -> IO ()
releaseCFString = c_CFRelease

-- | Peeks a CFString.
peekCFString :: CFStringRef -> IO String
peekCFString cfstring = do
  n <- c_CFStringGetLength        cfstring
  p <- c_CFStringGetCharactersPtr cfstring
  -- print (n,p)
  if p /= nullPtr 
    then forM [0..n-1] $ \i -> liftM (chr . fromIntegral) $ peekElemOff p (fromIntegral i)
    else forM [0..n-1] $ \i -> liftM (chr . fromIntegral) $ c_CFStringGetCharacterAtIndex cfstring i
 
-- | Creates a new CFString. You have to release it manually.
newCFString :: String -> IO CFStringRef
newCFString string = do
  let n = length string 
  allocaArray n $ \p -> do
    pokeArray p [ fromIntegral (ord c) | c <- string ]
    c_CFStringCreateWithCharacters kCFAllocatorDefault p (fromIntegral n)
 
-- | Safe passing of a CFString to the OS (releases it afterwards).
withCFString :: String -> (CFStringRef -> IO a) -> IO a
withCFString string action = do
  cfstring <- newCFString string
  x <- action cfstring
  releaseCFString cfstring
  return x

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