MutableArray.hs

{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE ScopedTypeVariables #-}

--
-- Copyright (c) 2009-2011, ERICSSON AB
-- All rights reserved.
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-- Redistribution and use in source and binary forms, with or without
-- modification, are permitted provided that the following conditions are met:
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--     * Redistributions in binary form must reproduce the above copyright
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--

module Feldspar.Core.Frontend.MutableArray
where

import Language.Syntactic

import Data.List (genericLength)
import Control.Monad (zipWithM_)

import Feldspar.Core.Types
import Feldspar.Core.Constructs
import Feldspar.Core.Constructs.Loop
import Feldspar.Core.Constructs.MutableArray
import Feldspar.Core.Frontend.Mutable
import Feldspar.Core.Frontend.Literal (value)

-- | Create a new 'Mutable' Array and intialize all elements
newArr :: Type a => Data Length -> Data a -> M (Data (MArr a))
newArr = sugarSymC NewArr

-- | Create a new 'Mutable' Array but leave the elements un-initialized
newArr_ :: Type a => Data Length -> M (Data (MArr a))
newArr_ = sugarSymC NewArr_

-- | Create a new 'Mutable' Array and initialize with elements from the
-- list
newListArr :: forall a. Type a => [Data a] -> M (Data (MArr a))
newListArr xs = do arr <- newArr_ (value $ genericLength xs)
                   zipWithM_ (setArr arr . value) [0..] xs
                   return arr

-- | Extract the element at index
getArr :: Type a => Data (MArr a) -> Data Index -> M (Data a)
getArr = sugarSymC GetArr

-- | Replace the value at index
setArr :: Type a => Data (MArr a) -> Data Index -> Data a -> M ()
setArr = sugarSymC SetArr

-- | Modify the element at index
modifyArr :: Type a
          => Data (MArr a) -> Data Index -> (Data a -> Data a) -> M ()
modifyArr arr i f = getArr arr i >>= setArr arr i . f

-- | Query the length of the array
arrLength :: Type a => Data (MArr a) -> M (Data Length)
arrLength = sugarSymC ArrLength

-- | Modify all elements
mapArray :: Type a => (Data a -> Data a) -> Data (MArr a) -> M (Data (MArr a))
mapArray f arr = do
    len <- arrLength arr
    forArr len (flip (modifyArr arr) f)
    return arr

forArr :: Syntax a => Data Length -> (Data Index -> M a) -> M ()
forArr = sugarSymC For

-- | Swap two elements
swap :: Type a
     => Data (MArr a) -> Data Index -> Data Index -> M ()
swap a i1 i2 = do
    tmp <- getArr a i1
    getArr a i2 >>= setArr a i1
    setArr a i2 tmp