module Twee.Array where
#include "errors.h"
import qualified Data.Primitive as P
import Control.Monad.ST
import Data.List
data Array a =
Array {
arraySize :: !Int,
arrayContents :: !(P.Array a) }
class Default a where def :: a
toList :: Array a -> [(Int, a)]
toList arr =
[ (i, x)
| i <- [0..arraySize arr1],
let x = P.indexArray (arrayContents arr) i ]
instance Show a => Show (Array a) where
show arr =
"{" ++
intercalate ", "
[ show i ++ "->" ++ show x
| (i, x) <- toList arr ] ++
"}"
newArray :: Default a => Array a
newArray = runST $ do
marr <- P.newArray 0 def
arr <- P.unsafeFreezeArray marr
return (Array 0 arr)
(!) :: Default a => Array a -> Int -> a
arr ! n
| 0 <= n && n < arraySize arr =
P.indexArray (arrayContents arr) n
| otherwise = def
update :: Default a => Int -> a -> Array a -> Array a
update n x arr = runST $ do
let size = arraySize arr `max` (n+1)
marr <- P.newArray size def
P.copyArray marr 0 (arrayContents arr) 0 (arraySize arr)
P.writeArray marr n x
arr' <- P.unsafeFreezeArray marr
return (Array size arr')