[project @ 2004-06-13 20:26:03 by panne]

[ghc-base.git] / Data / HashTable.hs

diff --git a/Data/HashTable.hs b/Data/HashTable.hs
index 8c88f15..37ddb5e 100644 (file)
--- a/Data/HashTable.hs
+++ b/Data/HashTable.hs
@@ -33,25 +33,42 @@ module Data.HashTable (
 -- This module is imported by Data.Dynamic, which is pretty low down in the
 -- module hierarchy, so don't import "high-level" modules
 
+#ifdef __GLASGOW_HASKELL__
 import GHC.Base
+#else
+import Prelude hiding  ( lookup )
+#endif
 import Data.Tuple      ( fst )
 import Data.Bits
 import Data.Maybe
-import Data.List       ( maximumBy, filter, length, concat )
+import Data.List       ( maximumBy, filter, length, concat, foldl )
+import Data.Int                ( Int32 )
 
+#if defined(__GLASGOW_HASKELL__)
 import GHC.Num
-import GHC.Int         ( Int32 )
 import GHC.Real                ( Integral(..), fromIntegral )
 
-import GHC.IOBase      ( IO, IOArray, newIOArray, readIOArray, writeIOArray, unsafeReadIOArray, unsafeWriteIOArray,
+import GHC.IOBase      ( IO, IOArray, newIOArray, readIOArray, writeIOArray,
+                         unsafeReadIOArray, unsafeWriteIOArray,
                          IORef, newIORef, readIORef, writeIORef )
 import GHC.Err         ( undefined )
+#else
+import Data.Char       ( ord )
+import Data.IORef      ( IORef, newIORef, readIORef, writeIORef )
+#  if defined(__HUGS__)
+import Hugs.IOArray    ( IOArray, newIOArray, readIOArray, writeIOArray,
+                         unsafeReadIOArray, unsafeWriteIOArray )
+#  elif defined(__NHC__)
+import NHC.IOExtras    ( IOArray, newIOArray, readIOArray, writeIOArray)
+#  endif
+#endif
 import Control.Monad   ( when, mapM, sequence_ )
 
+
 -----------------------------------------------------------------------
 myReadArray  :: IOArray Int32 a -> Int32 -> IO a
 myWriteArray :: IOArray Int32 a -> Int32 -> a -> IO ()
-#ifdef DEBUG
+#if defined(DEBUG) || defined(__NHC__)
 myReadArray  = readIOArray
 myWriteArray = writeIOArray
 #else
@@ -136,11 +153,12 @@ hashInt = (`rem` prime) . fromIntegral
 -- which seems to give reasonable results.
 --
 hashString :: String -> Int32
-hashString = fromIntegral . foldr f 0
-  where f c m = ord c + (m * 128) `rem` fromIntegral prime
+hashString = fromIntegral . foldl f 0
+  where f m c = ord c + (m * 128) `rem` fromIntegral prime
 
 -- | A prime larger than the maximum hash table size
-prime = 1500007 :: Int32
+prime :: Int32
+prime = 1500007
 
 -- -----------------------------------------------------------------------------
 -- Parameters
@@ -157,10 +175,14 @@ hLOAD = 4 :: Int32 -- Maximum average load of a single hash bucket
 -- -----------------------------------------------------------------------------
 -- Creating a new hash table
 
--- | Creates a new hash table
+-- | Creates a new hash table.  The following property should hold for the @eq@
+-- and @hash@ functions passed to 'new':
+--
+-- >   eq A B  =>  hash A == hash B
+--
 new
-  :: (key -> key -> Bool)    -- ^ An equality comparison on keys
-  -> (key -> Int32)         -- ^ A hash function on keys
+  :: (key -> key -> Bool)    -- ^ @eq@: An equality comparison on keys
+  -> (key -> Int32)         -- ^ @hash@: A hash function on keys
   -> IO (HashTable key val)  -- ^ Returns: an empty hash table
 
 new cmp hash_fn = do
@@ -198,7 +220,7 @@ insert (HashTable ref) key val = do
           then expandHashTable table1
           else return table1
   writeIORef ref table2
-  (segment_index,segment_offset) <- tableLocation table key
+  (segment_index,segment_offset) <- tableLocation table2 key
   segment <- myReadArray dir segment_index
   bucket <- myReadArray segment segment_offset
   myWriteArray segment segment_offset ((key,val):bucket)
@@ -232,6 +254,7 @@ expandHashTable
       table@HT{ dir=dir,
                split=split,
                max_bucket=max,
+               bcount=bcount,
                mask2=mask2 } = do
   let
       oldsegment = split `shiftR` sEGMENT_SHIFT
@@ -247,10 +270,12 @@ expandHashTable
   --
   let table' =
        if (split+1) < max
-           then table{ split = split+1 }
+           then table{ split = split+1,
+                       bcount = bcount+1 }
                -- we've expanded all the buckets in this table, so start from
                -- the beginning again.
            else table{ split = 0,
+                       bcount = bcount+1,
                        max_bucket = max * 2,
                        mask1 = mask2,
                        mask2 = mask2 `shiftL` 1 .|. 1 }