From: Simon Marlow <simonmar@microsoft.com>
Date: Wed, 1 Feb 2006 13:04:27 +0000 (+0000)
Subject: When splitting a bucket, keep the contents in the same order
X-Git-Tag: 2007-09-13~423
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=a01ece51085a2a8571c9bda7803b8ea5021c2a85;p=ghc-base.git

When splitting a bucket, keep the contents in the same order
To retain the property that multiple inserts shadow each other
(see ticket #661, test hash001)
---

diff --git a/Data/HashTable.hs b/Data/HashTable.hs
index 0f31af5..1463a0d 100644
--- a/Data/HashTable.hs
+++ b/Data/HashTable.hs
@@ -41,7 +41,7 @@ import Prelude	hiding	( lookup )
 import Data.Tuple	( fst )
 import Data.Bits
 import Data.Maybe
-import Data.List	( maximumBy, filter, length, concat, foldl )
+import Data.List	( maximumBy, filter, length, concat, foldl, reverse )
 import Data.Int		( Int32 )
 
 #if defined(__GLASGOW_HASKELL__)
@@ -295,9 +295,9 @@ expandHashTable
    let
     split_bucket old new [] = do
 	segment <- myReadArray dir oldsegment
-	myWriteArray segment oldindex old
+	myWriteArray segment oldindex (reverse old)
 	segment <- myReadArray dir newsegment
-	myWriteArray segment newindex new
+	myWriteArray segment newindex (reverse new)
     split_bucket old new ((k,v):xs) = do
 	h <- bucketIndex table' k
 	if h == newbucket