\begin{code}
-{-# OPTIONS_GHC -fno-implicit-prelude #-}
+{-# LANGUAGE NoImplicitPrelude, NoBangPatterns, MagicHash, UnboxedTuples #-}
+{-# OPTIONS_GHC -funbox-strict-fields #-}
+{-# OPTIONS_HADDOCK hide #-}
+
-----------------------------------------------------------------------------
-- |
-- Module : GHC.Arr
-- #hide
module GHC.Arr where
-import {-# SOURCE #-} GHC.Err ( error )
import GHC.Enum
import GHC.Num
import GHC.ST
%*********************************************************
-%* *
+%* *
\subsection{The @Ix@ class}
-%* *
+%* *
%*********************************************************
\begin{code}
-- | The 'Ix' class is used to map a contiguous subrange of values in
-- a type onto integers. It is used primarily for array indexing
--- (see "Data.Array", "Data.Array.IArray" and "Data.Array.MArray").
+-- (see the array package).
--
-- The first argument @(l,u)@ of each of these operations is a pair
-- specifying the lower and upper bounds of a contiguous subrange of values.
-- An implementation is entitled to assume the following laws about these
-- operations:
--
--- * @'inRange' (l,u) i == 'elem' i ('range' (l,u))@
+-- * @'inRange' (l,u) i == 'elem' i ('range' (l,u))@ @ @
--
-- * @'range' (l,u) '!!' 'index' (l,u) i == i@, when @'inRange' (l,u) i@
--
--- * @'map' ('index' (l,u)) ('range' (l,u))) == [0..'rangeSize' (l,u)-1]@
+-- * @'map' ('index' (l,u)) ('range' (l,u))) == [0..'rangeSize' (l,u)-1]@ @ @
--
--- * @'rangeSize' (l,u) == 'length' ('range' (l,u))@
+-- * @'rangeSize' (l,u) == 'length' ('range' (l,u))@ @ @
--
-- Minimal complete instance: 'range', 'index' and 'inRange'.
--
class (Ord a) => Ix a where
-- | The list of values in the subrange defined by a bounding pair.
- range :: (a,a) -> [a]
+ range :: (a,a) -> [a]
-- | The position of a subscript in the subrange.
- index :: (a,a) -> a -> Int
+ index :: (a,a) -> a -> Int
-- | Like 'index', but without checking that the value is in range.
- unsafeIndex :: (a,a) -> a -> Int
+ unsafeIndex :: (a,a) -> a -> Int
-- | Returns 'True' the given subscript lies in the range defined
-- the bounding pair.
- inRange :: (a,a) -> a -> Bool
+ inRange :: (a,a) -> a -> Bool
-- | The size of the subrange defined by a bounding pair.
- rangeSize :: (a,a) -> Int
+ rangeSize :: (a,a) -> Int
-- | like 'rangeSize', but without checking that the upper bound is
-- in range.
unsafeRangeSize :: (a,a) -> Int
- -- Must specify one of index, unsafeIndex
- index b i | inRange b i = unsafeIndex b i
- | otherwise = error "Error in array index"
+ -- Must specify one of index, unsafeIndex
+
+ -- 'index' is typically over-ridden in instances, with essentially
+ -- the same code, but using indexError instead of hopelessIndexError
+ -- Reason: we have 'Show' at the instances
+ {-# INLINE index #-} -- See Note [Inlining index]
+ index b i | inRange b i = unsafeIndex b i
+ | otherwise = hopelessIndexError
+
unsafeIndex b i = index b i
rangeSize b@(_l,h) | inRange b h = unsafeIndex b h + 1
- | otherwise = 0
+ | otherwise = 0 -- This case is only here to
+ -- check for an empty range
+ -- NB: replacing (inRange b h) by (l <= h) fails for
+ -- tuples. E.g. (1,2) <= (2,1) but the range is empty
+
unsafeRangeSize b@(_l,h) = unsafeIndex b h + 1
\end{code}
Note that the following is NOT right
- rangeSize (l,h) | l <= h = index b h + 1
- | otherwise = 0
+ rangeSize (l,h) | l <= h = index b h + 1
+ | otherwise = 0
Because it might be the case that l<h, but the range
is nevertheless empty. Consider
- ((1,2),(2,1))
+ ((1,2),(2,1))
Here l<h, but the second index ranges from 2..1 and
hence is empty
%*********************************************************
-%* *
+%* *
\subsection{Instances of @Ix@}
-%* *
+%* *
%*********************************************************
+Note [Inlining index]
+~~~~~~~~~~~~~~~~~~~~~
+We inline the 'index' operation,
+
+ * Partly because it generates much faster code
+ (although bigger); see Trac #1216
+
+ * Partly because it exposes the bounds checks to the simplifier which
+ might help a big.
+
+If you make a per-instance index method, you may consider inlining it.
+
+Note [Double bounds-checking of index values]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+When you index an array, a!x, there are two possible bounds checks we might make:
+
+ (A) Check that (inRange (bounds a) x) holds.
+
+ (A) is checked in the method for 'index'
+
+ (B) Check that (index (bounds a) x) lies in the range 0..n,
+ where n is the size of the underlying array
+
+ (B) is checked in the top-level function (!), in safeIndex.
+
+Of course it *should* be the case that (A) holds iff (B) holds, but that
+is a property of the particular instances of index, bounds, and inRange,
+so GHC cannot guarantee it.
+
+ * If you do (A) and not (B), then you might get a seg-fault,
+ by indexing at some bizarre location. Trac #1610
+
+ * If you do (B) but not (A), you may get no complaint when you index
+ an array out of its semantic bounds. Trac #2120
+
+At various times we have had (A) and not (B), or (B) and not (A); both
+led to complaints. So now we implement *both* checks (Trac #2669).
+
+For 1-d, 2-d, and 3-d arrays of Int we have specialised instances to avoid this.
+
+Note [Out-of-bounds error messages]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The default method for 'index' generates hoplelessIndexError, because
+Ix doesn't have Show as a superclass. For particular base types we
+can do better, so we override the default method for index.
+
\begin{code}
--- abstract these errors from the relevant index functions so that
+-- Abstract these errors from the relevant index functions so that
-- the guts of the function will be small enough to inline.
{-# NOINLINE indexError #-}
indexError rng i tp
= error (showString "Ix{" . showString tp . showString "}.index: Index " .
showParen True (showsPrec 0 i) .
- showString " out of range " $
- showParen True (showsPrec 0 rng) "")
+ showString " out of range " $
+ showParen True (showsPrec 0 rng) "")
+
+hopelessIndexError :: Int -- Try to use 'indexError' instead!
+hopelessIndexError = error "Error in array index"
----------------------------------------------------------------------
instance Ix Char where
{-# INLINE unsafeIndex #-}
unsafeIndex (m,_n) i = fromEnum i - fromEnum m
+ {-# INLINE index #-} -- See Note [Out-of-bounds error messages]
+ -- and Note [Inlining index]
index b i | inRange b i = unsafeIndex b i
- | otherwise = indexError b i "Char"
+ | otherwise = indexError b i "Char"
- inRange (m,n) i = m <= i && i <= n
+ inRange (m,n) i = m <= i && i <= n
----------------------------------------------------------------------
instance Ix Int where
{-# INLINE range #-}
- -- The INLINE stops the build in the RHS from getting inlined,
- -- so that callers can fuse with the result of range
+ -- The INLINE stops the build in the RHS from getting inlined,
+ -- so that callers can fuse with the result of range
range (m,n) = [m..n]
{-# INLINE unsafeIndex #-}
unsafeIndex (m,_n) i = i - m
+ {-# INLINE index #-} -- See Note [Out-of-bounds error messages]
+ -- and Note [Inlining index]
index b i | inRange b i = unsafeIndex b i
- | otherwise = indexError b i "Int"
+ | otherwise = indexError b i "Int"
{-# INLINE inRange #-}
inRange (I# m,I# n) (I# i) = m <=# i && i <=# n
{-# INLINE unsafeIndex #-}
unsafeIndex (m,_n) i = fromInteger (i - m)
+ {-# INLINE index #-} -- See Note [Out-of-bounds error messages]
+ -- and Note [Inlining index]
index b i | inRange b i = unsafeIndex b i
- | otherwise = indexError b i "Integer"
+ | otherwise = indexError b i "Integer"
- inRange (m,n) i = m <= i && i <= n
+ inRange (m,n) i = m <= i && i <= n
----------------------------------------------------------------------
instance Ix Bool where -- as derived
{-# INLINE unsafeIndex #-}
unsafeIndex (l,_) i = fromEnum i - fromEnum l
+ {-# INLINE index #-} -- See Note [Out-of-bounds error messages]
+ -- and Note [Inlining index]
index b i | inRange b i = unsafeIndex b i
- | otherwise = indexError b i "Bool"
+ | otherwise = indexError b i "Bool"
inRange (l,u) i = fromEnum i >= fromEnum l && fromEnum i <= fromEnum u
{-# INLINE unsafeIndex #-}
unsafeIndex (l,_) i = fromEnum i - fromEnum l
+ {-# INLINE index #-} -- See Note [Out-of-bounds error messages]
+ -- and Note [Inlining index]
index b i | inRange b i = unsafeIndex b i
- | otherwise = indexError b i "Ordering"
+ | otherwise = indexError b i "Ordering"
inRange (l,u) i = fromEnum i >= fromEnum l && fromEnum i <= fromEnum u
unsafeIndex ((), ()) () = 0
{-# INLINE inRange #-}
inRange ((), ()) () = True
- {-# INLINE index #-}
+
+ {-# INLINE index #-} -- See Note [Inlining index]
index b i = unsafeIndex b i
----------------------------------------------------------------------
instance (Ix a, Ix b) => Ix (a, b) where -- as derived
{-# SPECIALISE instance Ix (Int,Int) #-}
- {- INLINE range #-}
+ {-# INLINE range #-}
range ((l1,l2),(u1,u2)) =
[ (i1,i2) | i1 <- range (l1,u1), i2 <- range (l2,u2) ]
- {- INLINE unsafeIndex #-}
+ {-# INLINE unsafeIndex #-}
unsafeIndex ((l1,l2),(u1,u2)) (i1,i2) =
unsafeIndex (l1,u1) i1 * unsafeRangeSize (l2,u2) + unsafeIndex (l2,u2) i2
- {- INLINE inRange #-}
+ {-# INLINE inRange #-}
inRange ((l1,l2),(u1,u2)) (i1,i2) =
inRange (l1,u1) i1 && inRange (l2,u2) i2
\end{code}
%*********************************************************
-%* *
+%* *
\subsection{The @Array@ types}
-%* *
+%* *
%*********************************************************
\begin{code}
-- | The type of immutable non-strict (boxed) arrays
-- with indices in @i@ and elements in @e@.
-data Ix i => Array i e = Array !i !i (Array# e)
+data Array i e
+ = Array !i -- the lower bound, l
+ !i -- the upper bound, u
+ !Int -- a cache of (rangeSize (l,u))
+ -- used to make sure an index is
+ -- really in range
+ (Array# e) -- The actual elements
-- | Mutable, boxed, non-strict arrays in the 'ST' monad. The type
-- arguments are as follows:
--
-- * @e@: the element type of the array.
--
-data STArray s i e = STArray !i !i (MutableArray# s e)
- -- No Ix context for STArray. They are stupid,
- -- and force an Ix context on the equality instance.
+data STArray s i e
+ = STArray !i -- the lower bound, l
+ !i -- the upper bound, u
+ !Int -- a cache of (rangeSize (l,u))
+ -- used to make sure an index is
+ -- really in range
+ (MutableArray# s e) -- The actual elements
+ -- No Ix context for STArray. They are stupid,
+ -- and force an Ix context on the equality instance.
-- Just pointer equality on mutable arrays:
instance Eq (STArray s i e) where
- STArray _ _ arr1# == STArray _ _ arr2# =
+ STArray _ _ _ arr1# == STArray _ _ _ arr2# =
sameMutableArray# arr1# arr2#
\end{code}
%*********************************************************
-%* *
+%* *
\subsection{Operations on immutable arrays}
-%* *
+%* *
%*********************************************************
\begin{code}
--
-- Because the indices must be checked for these errors, 'array' is
-- strict in the bounds argument and in the indices of the association
--- list, but nonstrict in the values. Thus, recurrences such as the
+-- list, but non-strict in the values. Thus, recurrences such as the
-- following are possible:
--
-- > a = array (1,100) ((1,1) : [(i, i * a!(i-1)) | i <- [2..100]])
-- with which the array was constructed.
{-# INLINE array #-}
array :: Ix i
- => (i,i) -- ^ a pair of /bounds/, each of the index type
- -- of the array. These bounds are the lowest and
- -- highest indices in the array, in that order.
- -- For example, a one-origin vector of length
- -- '10' has bounds '(1,10)', and a one-origin '10'
- -- by '10' matrix has bounds '((1,1),(10,10))'.
- -> [(i, e)] -- ^ a list of /associations/ of the form
- -- (/index/, /value/). Typically, this list will
- -- be expressed as a comprehension. An
- -- association '(i, x)' defines the value of
- -- the array at index 'i' to be 'x'.
- -> Array i e
-array (l,u) ies = unsafeArray (l,u) [(index (l,u) i, e) | (i, e) <- ies]
+ => (i,i) -- ^ a pair of /bounds/, each of the index type
+ -- of the array. These bounds are the lowest and
+ -- highest indices in the array, in that order.
+ -- For example, a one-origin vector of length
+ -- '10' has bounds '(1,10)', and a one-origin '10'
+ -- by '10' matrix has bounds '((1,1),(10,10))'.
+ -> [(i, e)] -- ^ a list of /associations/ of the form
+ -- (/index/, /value/). Typically, this list will
+ -- be expressed as a comprehension. An
+ -- association '(i, x)' defines the value of
+ -- the array at index 'i' to be 'x'.
+ -> Array i e
+array (l,u) ies
+ = let n = safeRangeSize (l,u)
+ in unsafeArray' (l,u) n
+ [(safeIndex (l,u) n i, e) | (i, e) <- ies]
{-# INLINE unsafeArray #-}
unsafeArray :: Ix i => (i,i) -> [(Int, e)] -> Array i e
-unsafeArray (l,u) ies = runST (ST $ \s1# ->
- case rangeSize (l,u) of { I# n# ->
- case newArray# n# arrEleBottom s1# of { (# s2#, marr# #) ->
- foldr (fill marr#) (done l u marr#) ies s2# }})
+unsafeArray b ies = unsafeArray' b (rangeSize b) ies
+
+{-# INLINE unsafeArray' #-}
+unsafeArray' :: Ix i => (i,i) -> Int -> [(Int, e)] -> Array i e
+unsafeArray' (l,u) n@(I# n#) ies = runST (ST $ \s1# ->
+ case newArray# n# arrEleBottom s1# of
+ (# s2#, marr# #) ->
+ foldr (fill marr#) (done l u n marr#) ies s2#)
{-# INLINE fill #-}
fill :: MutableArray# s e -> (Int, e) -> STRep s a -> STRep s a
-fill marr# (I# i#, e) next s1# =
- case writeArray# marr# i# e s1# of { s2# ->
- next s2# }
+-- NB: put the \s after the "=" so that 'fill'
+-- inlines when applied to three args
+fill marr# (I# i#, e) next
+ = \s1# -> case writeArray# marr# i# e s1# of
+ s2# -> next s2#
{-# INLINE done #-}
-done :: Ix i => i -> i -> MutableArray# s e -> STRep s (Array i e)
-done l u marr# s1# =
- case unsafeFreezeArray# marr# s1# of { (# s2#, arr# #) ->
- (# s2#, Array l u arr# #) }
+done :: Ix i => i -> i -> Int -> MutableArray# s e -> STRep s (Array i e)
+-- See NB on 'fill'
+done l u n marr#
+ = \s1# -> case unsafeFreezeArray# marr# s1# of
+ (# s2#, arr# #) -> (# s2#, Array l u n arr# #)
-- This is inefficient and I'm not sure why:
-- listArray (l,u) es = unsafeArray (l,u) (zip [0 .. rangeSize (l,u) - 1] es)
{-# INLINE listArray #-}
listArray :: Ix i => (i,i) -> [e] -> Array i e
listArray (l,u) es = runST (ST $ \s1# ->
- case rangeSize (l,u) of { I# n# ->
+ case safeRangeSize (l,u) of { n@(I# n#) ->
case newArray# n# arrEleBottom s1# of { (# s2#, marr# #) ->
let fillFromList i# xs s3# | i# ==# n# = s3#
| otherwise = case xs of
y:ys -> case writeArray# marr# i# y s3# of { s4# ->
fillFromList (i# +# 1#) ys s4# } in
case fillFromList 0# es s2# of { s3# ->
- done l u marr# s3# }}})
+ done l u n marr# s3# }}})
-- | The value at the given index in an array.
{-# INLINE (!) #-}
(!) :: Ix i => Array i e -> i -> e
-arr@(Array l u _) ! i = unsafeAt arr (index (l,u) i)
+arr@(Array l u n _) ! i = unsafeAt arr $ safeIndex (l,u) n i
+
+{-# INLINE safeRangeSize #-}
+safeRangeSize :: Ix i => (i, i) -> Int
+safeRangeSize (l,u) = let r = rangeSize (l, u)
+ in if r < 0 then negRange
+ else r
+
+-- Don't inline this error message everywhere!!
+negRange :: Int -- Uninformative, but Ix does not provide Show
+negRange = error "Negative range size"
+
+{-# INLINE[1] safeIndex #-}
+-- See Note [Double bounds-checking of index values]
+-- Inline *after* (!) so the rules can fire
+safeIndex :: Ix i => (i, i) -> Int -> i -> Int
+safeIndex (l,u) n i = let i' = index (l,u) i
+ in if (0 <= i') && (i' < n)
+ then i'
+ else badSafeIndex i' n
+
+-- See Note [Double bounds-checking of index values]
+{-# RULES
+"safeIndex/I" safeIndex = lessSafeIndex :: (Int,Int) -> Int -> Int -> Int
+"safeIndex/(I,I)" safeIndex = lessSafeIndex :: ((Int,Int),(Int,Int)) -> Int -> (Int,Int) -> Int
+"safeIndex/(I,I,I)" safeIndex = lessSafeIndex :: ((Int,Int,Int),(Int,Int,Int)) -> Int -> (Int,Int,Int) -> Int
+ #-}
+
+lessSafeIndex :: Ix i => (i, i) -> Int -> i -> Int
+-- See Note [Double bounds-checking of index values]
+-- Do only (A), the semantic check
+lessSafeIndex (l,u) _ i = index (l,u) i
+
+-- Don't inline this long error message everywhere!!
+badSafeIndex :: Int -> Int -> Int
+badSafeIndex i' n = error ("Error in array index; " ++ show i' ++
+ " not in range [0.." ++ show n ++ ")")
{-# INLINE unsafeAt #-}
unsafeAt :: Ix i => Array i e -> Int -> e
-unsafeAt (Array _ _ arr#) (I# i#) =
+unsafeAt (Array _ _ _ arr#) (I# i#) =
case indexArray# arr# i# of (# e #) -> e
-- | The bounds with which an array was constructed.
{-# INLINE bounds #-}
bounds :: Ix i => Array i e -> (i,i)
-bounds (Array l u _) = (l,u)
+bounds (Array l u _ _) = (l,u)
+
+-- | The number of elements in the array.
+{-# INLINE numElements #-}
+numElements :: Ix i => Array i e -> Int
+numElements (Array _ _ n _) = n
-- | The list of indices of an array in ascending order.
{-# INLINE indices #-}
indices :: Ix i => Array i e -> [i]
-indices (Array l u _) = range (l,u)
+indices (Array l u _ _) = range (l,u)
-- | The list of elements of an array in index order.
{-# INLINE elems #-}
elems :: Ix i => Array i e -> [e]
-elems arr@(Array l u _) =
- [unsafeAt arr i | i <- [0 .. rangeSize (l,u) - 1]]
+elems arr@(Array _ _ n _) =
+ [unsafeAt arr i | i <- [0 .. n - 1]]
-- | The list of associations of an array in index order.
{-# INLINE assocs #-}
assocs :: Ix i => Array i e -> [(i, e)]
-assocs arr@(Array l u _) =
- [(i, unsafeAt arr (unsafeIndex (l,u) i)) | i <- range (l,u)]
+assocs arr@(Array l u _ _) =
+ [(i, arr ! i) | i <- range (l,u)]
--- | The 'accumArray' deals with repeated indices in the association
+-- | The 'accumArray' function deals with repeated indices in the association
-- list using an /accumulating function/ which combines the values of
-- associations with the same index.
-- For example, given a list of values of some index type, @hist@
-- not in general be recursive.
{-# INLINE accumArray #-}
accumArray :: Ix i
- => (e -> a -> e) -- ^ accumulating function
- -> e -- ^ initial value
- -> (i,i) -- ^ bounds of the array
- -> [(i, a)] -- ^ association list
- -> Array i e
-accumArray f init (l,u) ies =
- unsafeAccumArray f init (l,u) [(index (l,u) i, e) | (i, e) <- ies]
+ => (e -> a -> e) -- ^ accumulating function
+ -> e -- ^ initial value
+ -> (i,i) -- ^ bounds of the array
+ -> [(i, a)] -- ^ association list
+ -> Array i e
+accumArray f initial (l,u) ies =
+ let n = safeRangeSize (l,u)
+ in unsafeAccumArray' f initial (l,u) n
+ [(safeIndex (l,u) n i, e) | (i, e) <- ies]
{-# INLINE unsafeAccumArray #-}
unsafeAccumArray :: Ix i => (e -> a -> e) -> e -> (i,i) -> [(Int, a)] -> Array i e
-unsafeAccumArray f init (l,u) ies = runST (ST $ \s1# ->
- case rangeSize (l,u) of { I# n# ->
- case newArray# n# init s1# of { (# s2#, marr# #) ->
- foldr (adjust f marr#) (done l u marr#) ies s2# }})
+unsafeAccumArray f initial b ies = unsafeAccumArray' f initial b (rangeSize b) ies
+
+{-# INLINE unsafeAccumArray' #-}
+unsafeAccumArray' :: Ix i => (e -> a -> e) -> e -> (i,i) -> Int -> [(Int, a)] -> Array i e
+unsafeAccumArray' f initial (l,u) n@(I# n#) ies = runST (ST $ \s1# ->
+ case newArray# n# initial s1# of { (# s2#, marr# #) ->
+ foldr (adjust f marr#) (done l u n marr#) ies s2# })
{-# INLINE adjust #-}
adjust :: (e -> a -> e) -> MutableArray# s e -> (Int, a) -> STRep s b -> STRep s b
-adjust f marr# (I# i#, new) next s1# =
- case readArray# marr# i# s1# of { (# s2#, old #) ->
- case writeArray# marr# i# (f old new) s2# of { s3# ->
- next s3# }}
+-- See NB on 'fill'
+adjust f marr# (I# i#, new) next
+ = \s1# -> case readArray# marr# i# s1# of
+ (# s2#, old #) ->
+ case writeArray# marr# i# (f old new) s2# of
+ s3# -> next s3#
-- | Constructs an array identical to the first argument except that it has
-- been updated by the associations in the right argument.
-- but GHC's implementation uses the last association for each index.
{-# INLINE (//) #-}
(//) :: Ix i => Array i e -> [(i, e)] -> Array i e
-arr@(Array l u _) // ies =
- unsafeReplace arr [(index (l,u) i, e) | (i, e) <- ies]
+arr@(Array l u n _) // ies =
+ unsafeReplace arr [(safeIndex (l,u) n i, e) | (i, e) <- ies]
{-# INLINE unsafeReplace #-}
unsafeReplace :: Ix i => Array i e -> [(Int, e)] -> Array i e
-unsafeReplace arr@(Array l u _) ies = runST (do
- STArray _ _ marr# <- thawSTArray arr
- ST (foldr (fill marr#) (done l u marr#) ies))
+unsafeReplace arr ies = runST (do
+ STArray l u n marr# <- thawSTArray arr
+ ST (foldr (fill marr#) (done l u n marr#) ies))
-- | @'accum' f@ takes an array and an association list and accumulates
-- pairs from the list into the array with the accumulating function @f@.
--
{-# INLINE accum #-}
accum :: Ix i => (e -> a -> e) -> Array i e -> [(i, a)] -> Array i e
-accum f arr@(Array l u _) ies =
- unsafeAccum f arr [(index (l,u) i, e) | (i, e) <- ies]
+accum f arr@(Array l u n _) ies =
+ unsafeAccum f arr [(safeIndex (l,u) n i, e) | (i, e) <- ies]
{-# INLINE unsafeAccum #-}
unsafeAccum :: Ix i => (e -> a -> e) -> Array i e -> [(Int, a)] -> Array i e
-unsafeAccum f arr@(Array l u _) ies = runST (do
- STArray _ _ marr# <- thawSTArray arr
- ST (foldr (adjust f marr#) (done l u marr#) ies))
+unsafeAccum f arr ies = runST (do
+ STArray l u n marr# <- thawSTArray arr
+ ST (foldr (adjust f marr#) (done l u n marr#) ies))
{-# INLINE amap #-}
amap :: Ix i => (a -> b) -> Array i a -> Array i b
-amap f arr@(Array l u _) =
- unsafeArray (l,u) [(i, f (unsafeAt arr i)) | i <- [0 .. rangeSize (l,u) - 1]]
+amap f arr@(Array l u n _) =
+ unsafeArray' (l,u) n [(i, f (unsafeAt arr i)) | i <- [0 .. n - 1]]
-- | 'ixmap' allows for transformations on array indices.
-- It may be thought of as providing function composition on the right
{-# INLINE ixmap #-}
ixmap :: (Ix i, Ix j) => (i,i) -> (i -> j) -> Array j e -> Array i e
ixmap (l,u) f arr =
- unsafeArray (l,u) [(unsafeIndex (l,u) i, arr ! f i) | i <- range (l,u)]
+ array (l,u) [(i, arr ! f i) | i <- range (l,u)]
{-# INLINE eqArray #-}
eqArray :: (Ix i, Eq e) => Array i e -> Array i e -> Bool
-eqArray arr1@(Array l1 u1 _) arr2@(Array l2 u2 _) =
- if rangeSize (l1,u1) == 0 then rangeSize (l2,u2) == 0 else
+eqArray arr1@(Array l1 u1 n1 _) arr2@(Array l2 u2 n2 _) =
+ if n1 == 0 then n2 == 0 else
l1 == l2 && u1 == u2 &&
- and [unsafeAt arr1 i == unsafeAt arr2 i | i <- [0 .. rangeSize (l1,u1) - 1]]
+ and [unsafeAt arr1 i == unsafeAt arr2 i | i <- [0 .. n1 - 1]]
{-# INLINE cmpArray #-}
cmpArray :: (Ix i, Ord e) => Array i e -> Array i e -> Ordering
{-# INLINE cmpIntArray #-}
cmpIntArray :: Ord e => Array Int e -> Array Int e -> Ordering
-cmpIntArray arr1@(Array l1 u1 _) arr2@(Array l2 u2 _) =
- if rangeSize (l1,u1) == 0 then if rangeSize (l2,u2) == 0 then EQ else LT else
- if rangeSize (l2,u2) == 0 then GT else
- case compare l1 l2 of
- EQ -> foldr cmp (compare u1 u2) [0 .. rangeSize (l1, min u1 u2) - 1]
- other -> other
- where
+cmpIntArray arr1@(Array l1 u1 n1 _) arr2@(Array l2 u2 n2 _) =
+ if n1 == 0 then
+ if n2 == 0 then EQ else LT
+ else if n2 == 0 then GT
+ else case compare l1 l2 of
+ EQ -> foldr cmp (compare u1 u2) [0 .. (n1 `min` n2) - 1]
+ other -> other
+ where
cmp i rest = case compare (unsafeAt arr1 i) (unsafeAt arr2 i) of
EQ -> rest
other -> other
%*********************************************************
-%* *
+%* *
\subsection{Array instances}
-%* *
+%* *
%*********************************************************
\begin{code}
showsPrec appPrec1 (bounds a) .
showChar ' ' .
showsPrec appPrec1 (assocs a)
- -- Precedence of 'array' is the precedence of application
+ -- Precedence of 'array' is the precedence of application
-- The Read instance is in GHC.Read
\end{code}
%*********************************************************
-%* *
+%* *
\subsection{Operations on mutable arrays}
-%* *
+%* *
%*********************************************************
Idle ADR question: What's the tradeoff here between flattening these
\begin{code}
{-# INLINE newSTArray #-}
newSTArray :: Ix i => (i,i) -> e -> ST s (STArray s i e)
-newSTArray (l,u) init = ST $ \s1# ->
- case rangeSize (l,u) of { I# n# ->
- case newArray# n# init s1# of { (# s2#, marr# #) ->
- (# s2#, STArray l u marr# #) }}
+newSTArray (l,u) initial = ST $ \s1# ->
+ case safeRangeSize (l,u) of { n@(I# n#) ->
+ case newArray# n# initial s1# of { (# s2#, marr# #) ->
+ (# s2#, STArray l u n marr# #) }}
{-# INLINE boundsSTArray #-}
boundsSTArray :: STArray s i e -> (i,i)
-boundsSTArray (STArray l u _) = (l,u)
+boundsSTArray (STArray l u _ _) = (l,u)
+
+{-# INLINE numElementsSTArray #-}
+numElementsSTArray :: STArray s i e -> Int
+numElementsSTArray (STArray _ _ n _) = n
{-# INLINE readSTArray #-}
readSTArray :: Ix i => STArray s i e -> i -> ST s e
-readSTArray marr@(STArray l u _) i =
- unsafeReadSTArray marr (index (l,u) i)
+readSTArray marr@(STArray l u n _) i =
+ unsafeReadSTArray marr (safeIndex (l,u) n i)
{-# INLINE unsafeReadSTArray #-}
unsafeReadSTArray :: Ix i => STArray s i e -> Int -> ST s e
-unsafeReadSTArray (STArray _ _ marr#) (I# i#) = ST $ \s1# ->
- readArray# marr# i# s1#
+unsafeReadSTArray (STArray _ _ _ marr#) (I# i#)
+ = ST $ \s1# -> readArray# marr# i# s1#
{-# INLINE writeSTArray #-}
writeSTArray :: Ix i => STArray s i e -> i -> e -> ST s ()
-writeSTArray marr@(STArray l u _) i e =
- unsafeWriteSTArray marr (index (l,u) i) e
+writeSTArray marr@(STArray l u n _) i e =
+ unsafeWriteSTArray marr (safeIndex (l,u) n i) e
{-# INLINE unsafeWriteSTArray #-}
unsafeWriteSTArray :: Ix i => STArray s i e -> Int -> e -> ST s ()
-unsafeWriteSTArray (STArray _ _ marr#) (I# i#) e = ST $ \s1# ->
- case writeArray# marr# i# e s1# of { s2# ->
- (# s2#, () #) }
+unsafeWriteSTArray (STArray _ _ _ marr#) (I# i#) e = ST $ \s1# ->
+ case writeArray# marr# i# e s1# of
+ s2# -> (# s2#, () #)
\end{code}
%*********************************************************
-%* *
+%* *
\subsection{Moving between mutable and immutable}
-%* *
+%* *
%*********************************************************
\begin{code}
freezeSTArray :: Ix i => STArray s i e -> ST s (Array i e)
-freezeSTArray (STArray l u marr#) = ST $ \s1# ->
- case rangeSize (l,u) of { I# n# ->
+freezeSTArray (STArray l u n@(I# n#) marr#) = ST $ \s1# ->
case newArray# n# arrEleBottom s1# of { (# s2#, marr'# #) ->
let copy i# s3# | i# ==# n# = s3#
| otherwise =
copy (i# +# 1#) s5# }} in
case copy 0# s2# of { s3# ->
case unsafeFreezeArray# marr'# s3# of { (# s4#, arr# #) ->
- (# s4#, Array l u arr# #) }}}}
+ (# s4#, Array l u n arr# #) }}}
{-# INLINE unsafeFreezeSTArray #-}
unsafeFreezeSTArray :: Ix i => STArray s i e -> ST s (Array i e)
-unsafeFreezeSTArray (STArray l u marr#) = ST $ \s1# ->
+unsafeFreezeSTArray (STArray l u n marr#) = ST $ \s1# ->
case unsafeFreezeArray# marr# s1# of { (# s2#, arr# #) ->
- (# s2#, Array l u arr# #) }
+ (# s2#, Array l u n arr# #) }
thawSTArray :: Ix i => Array i e -> ST s (STArray s i e)
-thawSTArray (Array l u arr#) = ST $ \s1# ->
- case rangeSize (l,u) of { I# n# ->
+thawSTArray (Array l u n@(I# n#) arr#) = ST $ \s1# ->
case newArray# n# arrEleBottom s1# of { (# s2#, marr# #) ->
let copy i# s3# | i# ==# n# = s3#
| otherwise =
case writeArray# marr# i# e s3# of { s4# ->
copy (i# +# 1#) s4# }} in
case copy 0# s2# of { s3# ->
- (# s3#, STArray l u marr# #) }}}
+ (# s3#, STArray l u n marr# #) }}
{-# INLINE unsafeThawSTArray #-}
unsafeThawSTArray :: Ix i => Array i e -> ST s (STArray s i e)
-unsafeThawSTArray (Array l u arr#) = ST $ \s1# ->
+unsafeThawSTArray (Array l u n arr#) = ST $ \s1# ->
case unsafeThawArray# arr# s1# of { (# s2#, marr# #) ->
- (# s2#, STArray l u marr# #) }
+ (# s2#, STArray l u n marr# #) }
\end{code}
projects / ghc-base.git / blobdiff