{-# LANGUAGE MagicHash, CPP, UnboxedTuples, BangPatterns #-}
-----------------------------------------------------------------------------
-- |
-- Module      :  Data.Packed.Internal.Vector
-- Copyright   :  (c) Alberto Ruiz 2007
-- License     :  GPL-style
--
-- Maintainer  :  Alberto Ruiz <aruiz@um.es>
-- Stability   :  provisional
-- Portability :  portable (uses FFI)
--
-- Vector implementation
--
-----------------------------------------------------------------------------
-- #hide

module Data.Packed.Internal.Vector where

import Data.Packed.Internal.Common
import Foreign
import Complex
import Control.Monad(when)

#if __GLASGOW_HASKELL__ >= 605
import GHC.ForeignPtr           (mallocPlainForeignPtrBytes)
#else
import Foreign.ForeignPtr       (mallocForeignPtrBytes)
#endif

import GHC.Base
import GHC.IOBase

-- | A one-dimensional array of objects stored in a contiguous memory block.
data Vector t =
    V { dim  :: {-# UNPACK #-} !Int               -- ^ number of elements
      , fptr :: {-# UNPACK #-} !(ForeignPtr t)    -- ^ foreign pointer to the memory block
      }

vec = withVector

withVector (V n fp) f = withForeignPtr fp $ \p -> do
    let v g = do
        g (fi n) p
    f v

-- | allocates memory for a new vector
createVector :: Storable a => Int -> IO (Vector a)
createVector n = do
    when (n <= 0) $ error ("trying to createVector of dim "++show n)
    fp <- doMalloc undefined
    return $ V n fp
  where
    --
    -- Use the much cheaper Haskell heap allocated storage
    -- for foreign pointer space we control
    --
    doMalloc :: Storable b => b -> IO (ForeignPtr b)
    doMalloc dummy = do
#if __GLASGOW_HASKELL__ >= 605
        mallocPlainForeignPtrBytes (n * sizeOf dummy)
#else
        mallocForeignPtrBytes      (n * sizeOf dummy)
#endif

{- | creates a Vector from a list:

@> fromList [2,3,5,7]
4 |> [2.0,3.0,5.0,7.0]@

-}
fromList :: Storable a => [a] -> Vector a
fromList l = unsafePerformIO $ do
    v <- createVector (length l)
    let f _ p = pokeArray p l >> return 0
    app1 f vec v "fromList"
    return v

safeRead v = inlinePerformIO . withForeignPtr (fptr v)
{-# INLINE safeRead #-}

inlinePerformIO :: IO a -> a
inlinePerformIO (IO m) = case m realWorld# of (# _, r #) -> r
{-# INLINE inlinePerformIO #-}

{- | extracts the Vector elements to a list

@> toList (linspace 5 (1,10))
[1.0,3.25,5.5,7.75,10.0]@

-}
toList :: Storable a => Vector a -> [a]
toList v = safeRead v $ peekArray (dim v)

{- | An alternative to 'fromList' with explicit dimension. The input
     list is explicitly truncated if it is too long, so it may safely
     be used, for instance, with infinite lists.

     This is the format used in the instances for Show (Vector a).
-}
(|>) :: (Storable a) => Int -> [a] -> Vector a
infixl 9 |>
n |> l = if length l' == n
            then fromList l'
            else error "list too short for |>"
  where l' = take n l


-- | access to Vector elements without range checking
at' :: Storable a => Vector a -> Int -> a
at' v n = safeRead v $ flip peekElemOff n
{-# INLINE at' #-}

--
-- turn off bounds checking with -funsafe at configure time.
-- ghc will optimise away the salways true case at compile time.
--
#if defined(UNSAFE)
safe :: Bool
safe = False
#else
safe = True
#endif

-- | access to Vector elements with range checking.
at :: Storable a => Vector a -> Int -> a
at v n
    | safe      = if n >= 0 && n < dim v
                    then at' v n
                    else error "vector index out of range"
    | otherwise = at' v n
{-# INLINE at #-}

{- | takes a number of consecutive elements from a Vector

@> subVector 2 3 (fromList [1..10])
3 |> [3.0,4.0,5.0]@

-}
subVector :: Storable t => Int       -- ^ index of the starting element
                        -> Int       -- ^ number of elements to extract
                        -> Vector t  -- ^ source
                        -> Vector t  -- ^ result
subVector k l (v@V {dim=n})
    | k<0 || k >= n || k+l > n || l < 0 = error "subVector out of range"
    | otherwise = unsafePerformIO $ do
        r <- createVector l
        let f _ s _ d = copyArray d (advancePtr s k) l >> return 0
        app2 f vec v vec r "subVector"
        return r

{- | Reads a vector position:

@> fromList [0..9] \@\> 7
7.0@

-}
(@>) :: Storable t => Vector t -> Int -> t
infixl 9 @>
(@>) = at


{- | creates a new Vector by joining a list of Vectors

@> join [fromList [1..5], constant 1 3]
8 |> [1.0,2.0,3.0,4.0,5.0,1.0,1.0,1.0]@

-}
join :: Storable t => [Vector t] -> Vector t
join [] = error "joining zero vectors"
join as = unsafePerformIO $ do
    let tot = sum (map dim as)
    r@V {fptr = p} <- createVector tot
    withForeignPtr p $ \ptr ->
        joiner as tot ptr
    return r
  where joiner [] _ _ = return ()
        joiner (V {dim = n, fptr = b} : cs) _ p = do
            withForeignPtr b $ \pb -> copyArray p pb n
            joiner cs 0 (advancePtr p n)


-- | transforms a complex vector into a real vector with alternating real and imaginary parts 
asReal :: Vector (Complex Double) -> Vector Double
asReal v = V { dim = 2*dim v, fptr =  castForeignPtr (fptr v) }

-- | transforms a real vector into a complex vector with alternating real and imaginary parts
asComplex :: Vector Double -> Vector (Complex Double)
asComplex v = V { dim = dim v `div` 2, fptr =  castForeignPtr (fptr v) }

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

liftVector f x = mapVector f x

liftVector2 f u v = zipVector f u v

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

cloneVector :: Storable t => Vector t -> IO (Vector t)
cloneVector (v@V {dim=n}) = do
        r <- createVector n
        let f _ s _ d =  copyArray d s n >> return 0
        app2 f vec v vec r "cloneVector"
        return r

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

-- | map on Vectors
mapVector :: (Storable a, Storable b) => (a-> b) -> Vector a -> Vector b
mapVector f v = unsafePerformIO $ do
    w <- createVector (dim v)
    withForeignPtr (fptr v) $ \p ->
        withForeignPtr (fptr w) $ \q -> do
            let go (-1) = return ()
                go !k = do x <- peekElemOff p k
                           pokeElemOff      q k (f x)
                           go (k-1)
            go (dim v -1)
    return w
{-# INLINE mapVector #-}

-- | zipWith for Vectors
zipVector :: (Storable a, Storable b, Storable c) => (a-> b -> c) -> Vector a -> Vector b -> Vector c
zipVector f u v = unsafePerformIO $ do
    let n = min (dim u) (dim v)
    w <- createVector n
    withForeignPtr (fptr u) $ \pu ->
        withForeignPtr (fptr v) $ \pv ->
            withForeignPtr (fptr w) $ \pw -> do
                let go (-1) = return ()
                    go !k = do x <- peekElemOff pu k
                               y <- peekElemOff pv k
                               pokeElemOff      pw k (f x y)
                               go (k-1)
                go (n -1)
    return w
{-# INLINE zipVector #-}

foldVector f x v = unsafePerformIO $
    withForeignPtr (fptr (v::Vector Double)) $ \p -> do
        let go (-1) s = return s
            go !k !s = do y <- peekElemOff p k
                          go (k-1::Int) (f y s)
        go (dim v -1) x
{-# INLINE foldVector #-}

foldLoop f s0 d = go (d - 1) s0
     where
       go 0 s = f (0::Int) s
       go !j !s = go (j - 1) (f j s)

foldVectorG f s0 v = foldLoop g s0 (dim v)
    where g !k !s = f k (at' v) s
          {-# INLINE g #-} -- Thanks to Ryan Ingram (http://permalink.gmane.org/gmane.comp.lang.haskell.cafe/46479)
{-# INLINE foldVectorG #-}