-% -----------------------------------------------------------------------------
-% $Id: Arr.lhs,v 1.1 2001/06/28 14:15:03 simonmar Exp $
-%
-% (c) The University of Glasgow, 1994-2000
-%
-
-\section[GHC.Arr]{Module @GHC.Arr@}
-
-Array implementation, @GHC.Arr@ exports the basic array
-types and operations.
-
-For byte-arrays see @GHC.ByteArr@.
-
\begin{code}
{-# OPTIONS -fno-implicit-prelude #-}
+-----------------------------------------------------------------------------
+-- |
+-- Module : GHC.Arr
+-- Copyright : (c) The University of Glasgow, 1994-2000
+-- License : see libraries/base/LICENSE
+--
+-- Maintainer : cvs-ghc@haskell.org
+-- Stability : internal
+-- Portability : non-portable (GHC extensions)
+--
+-- GHC\'s array implementation.
+--
+-----------------------------------------------------------------------------
module GHC.Arr where
%*********************************************************
\begin{code}
-class (Ord a) => Ix a where
+class (Ord a) => Ix a where
range :: (a,a) -> [a]
index, unsafeIndex :: (a,a) -> a -> Int
inRange :: (a,a) -> a -> Bool
+ rangeSize :: (a,a) -> Int
+ 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"
unsafeIndex b i = index b i
+
+ -- As long as you don't override the default rangeSize,
+ -- you can specify unsafeRangeSize as follows, to speed up
+ -- some operations:
+ --
+ -- unsafeRangeSize b@(_l,h) = unsafeIndex b h + 1
+ --
+ rangeSize b@(_l,h) | inRange b h = unsafeIndex b h + 1
+ | otherwise = 0
+ unsafeRangeSize b = rangeSize b
\end{code}
+Note that the following is NOT right
+ 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))
+Here l<h, but the second index ranges from 2..1 and
+hence is empty
%*********************************************************
%* *
inRange (m,n) i = m <= i && i <= n
+ unsafeRangeSize b@(_l,h) = unsafeIndex b h + 1
+
----------------------------------------------------------------------
instance Ix Int where
{-# INLINE range #-}
{-# INLINE inRange #-}
inRange (I# m,I# n) (I# i) = m <=# i && i <=# n
+ unsafeRangeSize b@(_l,h) = unsafeIndex b h + 1
+
----------------------------------------------------------------------
instance Ix Integer where
{-# INLINE range #-}
inRange (m,n) i = m <= i && i <= n
+ unsafeRangeSize b@(_l,h) = unsafeIndex b h + 1
----------------------------------------------------------------------
instance Ix Bool where -- as derived
inRange (l,u) i = fromEnum i >= fromEnum l && fromEnum i <= fromEnum u
+ unsafeRangeSize b@(_l,h) = unsafeIndex b h + 1
+
----------------------------------------------------------------------
instance Ix Ordering where -- as derived
{-# INLINE range #-}
inRange (l,u) i = fromEnum i >= fromEnum l && fromEnum i <= fromEnum u
+ unsafeRangeSize b@(_l,h) = unsafeIndex b h + 1
+
----------------------------------------------------------------------
instance Ix () where
{-# INLINE range #-}
{-# INLINE index #-}
index b i = unsafeIndex b i
+ unsafeRangeSize b@(_l,h) = unsafeIndex b h + 1
----------------------------------------------------------------------
instance (Ix a, Ix b) => Ix (a, b) where -- as derived
inRange ((l1,l2),(u1,u2)) (i1,i2) =
inRange (l1,u1) i1 && inRange (l2,u2) i2
+ unsafeRangeSize b@(_l,h) = unsafeIndex b h + 1
+
-- Default method for index
----------------------------------------------------------------------
inRange (l1,u1) i1 && inRange (l2,u2) i2 &&
inRange (l3,u3) i3
+ unsafeRangeSize b@(_l,h) = unsafeIndex b h + 1
+
-- Default method for index
----------------------------------------------------------------------
inRange (l1,u1) i1 && inRange (l2,u2) i2 &&
inRange (l3,u3) i3 && inRange (l4,u4) i4
+ unsafeRangeSize b@(_l,h) = unsafeIndex b h + 1
+
-- Default method for index
instance (Ix a1, Ix a2, Ix a3, Ix a4, Ix a5) => Ix (a1,a2,a3,a4,a5) where
inRange (l3,u3) i3 && inRange (l4,u4) i4 &&
inRange (l5,u5) i5
- -- Default method for index
-\end{code}
-
+ unsafeRangeSize b@(_l,h) = unsafeIndex b h + 1
-%********************************************************
-%* *
-\subsection{Size of @Ix@ interval}
-%* *
-%********************************************************
-
-The @rangeSize@ operator returns the number of elements
-in the range for an @Ix@ pair.
-
-\begin{code}
-{-# SPECIALISE unsafeRangeSize :: (Int,Int) -> Int #-}
-{-# SPECIALISE unsafeRangeSize :: ((Int,Int),(Int,Int)) -> Int #-}
-unsafeRangeSize :: (Ix a) => (a,a) -> Int
-unsafeRangeSize b@(_l,h) = unsafeIndex b h + 1
-
-{-# SPECIALISE rangeSize :: (Int,Int) -> Int #-}
-{-# SPECIALISE rangeSize :: ((Int,Int),(Int,Int)) -> Int #-}
-rangeSize :: (Ix a) => (a,a) -> Int
-rangeSize b@(_l,h) | inRange b h = unsafeIndex b h + 1
- | otherwise = 0
-
--- Note that the following is NOT right
--- 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))
--- Here l<h, but the second index ranges from 2..1 and
--- hence is empty
+ -- Default method for index
\end{code}
%*********************************************************
type IPr = (Int, Int)
data Ix i => Array i e = Array !i !i (Array# e)
-data Ix i => STArray s i e = STArray !i !i (MutableArray# s e)
+
+-- | Mutable, boxed, non-strict arrays in the 'ST' monad. The type
+-- arguments are as follows:
+--
+-- * @s@: the state variable argument for the 'ST' type
+--
+-- * @i@: the index type of the array (should be an instance of @Ix@)
+--
+-- * @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.
-- Just pointer equality on mutable arrays:
instance Eq (STArray s i e) where
showChar ' ' .
shows (assocs a)
-{-
-instance (Ix a, Read a, Read b) => Read (Array a b) where
- readsPrec p = readParen (p > 9)
- (\r -> [(array b as, u) | ("array",s) <- lex r,
- (b,t) <- reads s,
- (as,u) <- reads t ])
--}
+-- The Read instance is in GHC.Read
\end{code}
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