[project @ 2005-11-13 16:52:14 by jpbernardy]

Correct handling of negative numbers in split and splitMember in IntMap and IntSet.
Better documentation for insert and insertWith in Maps.

diff --git a/Data/IntMap.hs b/Data/IntMap.hs
index 0dd6bf0..e210442 100644 (file)
--- a/Data/IntMap.hs
+++ b/Data/IntMap.hs
@@ -322,11 +322,19 @@ insert k x t
 
 -- right-biased insertion, used by 'union'
 -- | /O(min(n,W))/. Insert with a combining function.
+-- @'insertWith' f key value mp@ 
+-- will insert the pair (key, value) into @mp@ if key does
+-- not exist in the map. If the key does exist, the function will
+-- insert @f new_value old_value@.
 insertWith :: (a -> a -> a) -> Key -> a -> IntMap a -> IntMap a
 insertWith f k x t
   = insertWithKey (\k x y -> f x y) k x t
 
 -- | /O(min(n,W))/. Insert with a combining function.
+-- @'insertWithKey' f key value mp@ 
+-- will insert the pair (key, value) into @mp@ if key does
+-- not exist in the map. If the key does exist, the function will
+-- insert @f key new_value old_value@.
 insertWithKey :: (Key -> a -> a -> a) -> Key -> a -> IntMap a -> IntMap a
 insertWithKey f k x t
   = case t of
@@ -804,6 +812,20 @@ partitionWithKey pred t
 split :: Key -> IntMap a -> (IntMap a,IntMap a)
 split k t
   = case t of
+      Bin p m l r 
+          | m < 0 -> (if k >= 0 -- handle negative numbers.
+                      then let (lt,gt) = split' k l in (union r lt, gt)
+                      else let (lt,gt) = split' k r in (lt, union gt l))
+          | otherwise   -> split' k t
+      Tip ky y 
+        | k>ky      -> (t,Nil)
+        | k<ky      -> (Nil,t)
+        | otherwise -> (Nil,Nil)
+      Nil -> (Nil,Nil)
+
+split' :: Key -> IntMap a -> (IntMap a,IntMap a)
+split' k t
+  = case t of
       Bin p m l r
         | nomatch k p m -> if k>p then (t,Nil) else (Nil,t)
         | zero k m  -> let (lt,gt) = split k l in (lt,union gt r)
@@ -820,6 +842,20 @@ splitLookup :: Key -> IntMap a -> (IntMap a,Maybe a,IntMap a)
 splitLookup k t
   = case t of
       Bin p m l r
+          | m < 0 -> (if k >= 0 -- handle negative numbers.
+                      then let (lt,found,gt) = splitLookup' k l in (union r lt,found, gt)
+                      else let (lt,found,gt) = splitLookup' k r in (lt,found, union gt l))
+          | otherwise   -> splitLookup' k t
+      Tip ky y 
+        | k>ky      -> (t,Nothing,Nil)
+        | k<ky      -> (Nil,Nothing,t)
+        | otherwise -> (Nil,Just y,Nil)
+      Nil -> (Nil,Nothing,Nil)
+
+splitLookup' :: Key -> IntMap a -> (IntMap a,Maybe a,IntMap a)
+splitLookup' k t
+  = case t of
+      Bin p m l r
         | nomatch k p m -> if k>p then (t,Nothing,Nil) else (Nil,Nothing,t)
         | zero k m  -> let (lt,found,gt) = splitLookup k l in (lt,found,union gt r)
         | otherwise -> let (lt,found,gt) = splitLookup k r in (union l lt,found,gt)
@@ -855,10 +891,20 @@ foldWithKey f z t
 foldr :: (Key -> a -> b -> b) -> b -> IntMap a -> b
 foldr f z t
   = case t of
-      Bin p m l r -> foldr f (foldr f z r) l
+      Bin 0 m l r | m < 0 -> foldr' f (foldr' f z l) r  -- put negative numbers before.
+      Bin _ _ _ _ -> foldr' f z t
       Tip k x     -> f k x z
       Nil         -> z
 
+foldr' :: (Key -> a -> b -> b) -> b -> IntMap a -> b
+foldr' f z t
+  = case t of
+      Bin p m l r -> foldr' f (foldr' f z r) l
+      Tip k x     -> f k x z
+      Nil         -> z
+
+
+
 {--------------------------------------------------------------------
   List variations 
 --------------------------------------------------------------------}

diff --git a/Data/IntSet.hs b/Data/IntSet.hs
index a47244f..720b937 100644 (file)
--- a/Data/IntSet.hs
+++ b/Data/IntSet.hs
@@ -461,8 +461,24 @@ split :: Int -> IntSet -> (IntSet,IntSet)
 split x t
   = case t of
       Bin p m l r
-        | zero x m  -> let (lt,gt) = split x l in (lt,union gt r)
-        | otherwise -> let (lt,gt) = split x r in (union l lt,gt)
+        | m < 0       -> if x >= 0 then let (lt,gt) = split' x l in (union r lt, gt)
+                                   else let (lt,gt) = split' x r in (lt, union gt l)
+                                   -- handle negative numbers.
+        | otherwise   -> split' x t
+      Tip y 
+        | x>y         -> (t,Nil)
+        | x<y         -> (Nil,t)
+        | otherwise   -> (Nil,Nil)
+      Nil             -> (Nil, Nil)
+
+split' :: Int -> IntSet -> (IntSet,IntSet)
+split' x t
+  = case t of
+      Bin p m l r
+        | match x p m -> if zero x m then let (lt,gt) = split' x l in (lt,union gt r)
+                                     else let (lt,gt) = split' x r in (union l lt,gt)
+        | otherwise   -> if x < p then (Nil, t)
+                                  else (t, Nil)
       Tip y 
         | x>y       -> (t,Nil)
         | x<y       -> (Nil,t)
@@ -475,8 +491,24 @@ splitMember :: Int -> IntSet -> (IntSet,Bool,IntSet)
 splitMember x t
   = case t of
       Bin p m l r
-        | zero x m  -> let (lt,found,gt) = splitMember x l in (lt,found,union gt r)
-        | otherwise -> let (lt,found,gt) = splitMember x r in (union l lt,found,gt)
+        | m < 0       -> if x >= 0 then let (lt,found,gt) = splitMember' x l in (union r lt, found, gt)
+                                   else let (lt,found,gt) = splitMember' x r in (lt, found, union gt l)
+                                   -- handle negative numbers.
+        | otherwise   -> splitMember' x t
+      Tip y 
+        | x>y       -> (t,False,Nil)
+        | x<y       -> (Nil,False,t)
+        | otherwise -> (Nil,True,Nil)
+      Nil -> (Nil,False,Nil)
+
+splitMember' :: Int -> IntSet -> (IntSet,Bool,IntSet)
+splitMember' x t
+  = case t of
+      Bin p m l r
+         | match x p m ->  if zero x m then let (lt,found,gt) = splitMember x l in (lt,found,union gt r)
+                                       else let (lt,found,gt) = splitMember x r in (union l lt,found,gt)
+         | otherwise   -> if x < p then (Nil, False, t)
+                                   else (t, False, Nil)
       Tip y 
         | x>y       -> (t,False,Nil)
         | x<y       -> (Nil,False,t)
@@ -505,7 +537,12 @@ map f = fromList . List.map f . toList
 -- > elems set == fold (:) [] set
 fold :: (Int -> b -> b) -> b -> IntSet -> b
 fold f z t
-  = foldr f z t
+  = case t of
+      Bin 0 m l r | m < 0 -> foldr f (foldr f z l) r  
+      -- put negative numbers before.
+      Bin p m l r -> foldr f z t
+      Tip x       -> f x z
+      Nil         -> z
 
 foldr :: (Int -> b -> b) -> b -> IntSet -> b
 foldr f z t
@@ -532,9 +569,7 @@ toList t
 
 -- | /O(n)/. Convert the set to an ascending list of elements.
 toAscList :: IntSet -> [Int]
-toAscList t   
-  = -- NOTE: the following algorithm only works for big-endian trees
-    let (pos,neg) = span (>=0) (foldr (:) [] t) in neg ++ pos
+toAscList t = toList t
 
 -- | /O(n*min(n,W))/. Create a set from a list of integers.
 fromList :: [Int] -> IntSet

diff --git a/Data/Map.hs b/Data/Map.hs
index cafb0a1..f0b7f6f 100644 (file)
--- a/Data/Map.hs
+++ b/Data/Map.hs
@@ -301,11 +301,19 @@ insert kx x t
                EQ -> Bin sz kx x l r
 
 -- | /O(log n)/. Insert with a combining function.
+-- @'insertWith' f key value mp@ 
+-- will insert the pair (key, value) into @mp@ if key does
+-- not exist in the map. If the key does exist, the function will
+-- insert @f new_value old_value@.
 insertWith :: Ord k => (a -> a -> a) -> k -> a -> Map k a -> Map k a
 insertWith f k x m          
   = insertWithKey (\k x y -> f x y) k x m
 
 -- | /O(log n)/. Insert with a combining function.
+-- @'insertWithKey' f key value mp@ 
+-- will insert the pair (key, value) into @mp@ if key does
+-- not exist in the map. If the key does exist, the function will
+-- insert @f key new_value old_value@.
 insertWithKey :: Ord k => (k -> a -> a -> a) -> k -> a -> Map k a -> Map k a
 insertWithKey f kx x t
   = case t of