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https://github.com/idris-lang/Idris2.git
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85 lines
2.6 KiB
Idris
85 lines
2.6 KiB
Idris
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module Data.IOArray
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import Data.List
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-- Implemented externally
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data ArrayData : Type -> Type where
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-- 'unsafe' primitive access, backend dependent
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-- get and set assume that the bounds have been checked. Behavious is undefined
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-- otherwise.
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%extern prim__newArray : forall a . Int -> a -> PrimIO (ArrayData a)
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%extern prim__arrayGet : forall a . ArrayData a -> Int -> PrimIO a
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%extern prim__arraySet : forall a . ArrayData a -> Int -> a -> PrimIO ()
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export
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record IOArray elem where
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constructor MkIOArray
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max : Int
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content : ArrayData (Maybe elem)
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export
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newArray : Int -> IO (IOArray elem)
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newArray size
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= pure (MkIOArray size !(primIO (prim__newArray size Nothing)))
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export
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writeArray : IOArray elem -> Int -> elem -> IO ()
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writeArray arr pos el
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= if pos < 0 || pos >= max arr
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then pure ()
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else primIO (prim__arraySet (content arr) pos (Just el))
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export
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readArray : IOArray elem -> Int -> IO (Maybe elem)
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readArray arr pos
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= if pos < 0 || pos >= max arr
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then pure Nothing
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else primIO (prim__arrayGet (content arr) pos)
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-- Make a new array of the given size with the elements copied from the
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-- other array
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export
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newArrayCopy : (newsize : Int) -> IOArray elem -> IO (IOArray elem)
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newArrayCopy newsize arr
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= do let newsize' = if newsize < max arr then max arr else newsize
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arr' <- newArray newsize'
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copyFrom (content arr) (content arr') (max arr - 1)
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pure arr'
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where
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copyFrom : ArrayData (Maybe elem) ->
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ArrayData (Maybe elem) ->
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Int -> IO ()
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copyFrom old new pos
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= if pos < 0
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then pure ()
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else do el <- primIO $ prim__arrayGet old pos
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primIO $ prim__arraySet new pos el
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assert_total (copyFrom old new (pos - 1))
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export
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toList : IOArray elem -> IO (List (Maybe elem))
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toList arr = iter 0 (max arr) []
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where
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iter : Int -> Int -> List (Maybe elem) -> IO (List (Maybe elem))
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iter pos end acc
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= if pos >= end
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then pure (reverse acc)
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else do el <- readArray arr pos
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assert_total (iter (pos + 1) end (el :: acc))
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export
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fromList : List (Maybe elem) -> IO (IOArray elem)
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fromList ns
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= do arr <- newArray (cast (length ns))
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addToArray 0 ns arr
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pure arr
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where
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addToArray : Int -> List (Maybe elem) -> IOArray elem -> IO ()
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addToArray loc [] arr = pure ()
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addToArray loc (Nothing :: ns) arr
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= assert_total (addToArray (loc + 1) ns arr)
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addToArray loc (Just el :: ns) arr
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= do primIO $ prim__arraySet (content arr) loc (Just el)
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assert_total (addToArray (loc + 1) ns arr)
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