[project @ 2006-01-06 15:51:23 by simonpj]

[haskell-directory.git] / Data / IntMap.hs

diff --git a/Data/IntMap.hs b/Data/IntMap.hs
index ff9d30b..1606413 100644 (file)
--- a/Data/IntMap.hs
+++ b/Data/IntMap.hs
@@ -136,7 +136,9 @@ import Prelude hiding (lookup,map,filter,foldr,foldl,null)
 import Data.Bits 
 import Data.Int
 import qualified Data.IntSet as IntSet
+import Data.Monoid (Monoid(..))
 import Data.Typeable
+import Data.Foldable (Foldable(foldMap))
 
 {-
 -- just for testing
@@ -147,6 +149,7 @@ import qualified List
 -}  
 
 #if __GLASGOW_HASKELL__
+import Text.Read
 import Data.Generics.Basics
 import Data.Generics.Instances
 #endif
@@ -209,6 +212,16 @@ type Prefix = Int
 type Mask   = Int
 type Key    = Int
 
+instance Monoid (IntMap a) where
+    mempty  = empty
+    mappend = union
+    mconcat = unions
+
+instance Foldable IntMap where
+    foldMap f Nil = mempty
+    foldMap f (Tip _k v) = f v
+    foldMap f (Bin _ _ l r) = foldMap f l `mappend` foldMap f r
+
 #if __GLASGOW_HASKELL__
 
 {--------------------------------------------------------------------
@@ -223,6 +236,7 @@ instance Data a => Data (IntMap a) where
   toConstr _    = error "toConstr"
   gunfold _ _   = error "gunfold"
   dataTypeOf _  = mkNorepType "Data.IntMap.IntMap"
+  dataCast1 f   = gcast1 f
 
 #endif
 
@@ -315,11 +329,19 @@ 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
@@ -797,6 +819,20 @@ 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)
@@ -813,6 +849,20 @@ 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)
@@ -848,10 +898,20 @@ 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 
 --------------------------------------------------------------------}
@@ -978,8 +1038,8 @@ instance Functor IntMap where
 --------------------------------------------------------------------}
 
 instance Show a => Show (IntMap a) where
-  showsPrec d t   = showMap (toList t)
-
+  showsPrec d m   = showParen (d > 10) $
+    showString "fromList " . shows (toList m)
 
 showMap :: (Show a) => [(Key,a)] -> ShowS
 showMap []     
@@ -991,7 +1051,25 @@ showMap (x:xs)
     showTail (x:xs) = showChar ',' . showElem x . showTail xs
     
     showElem (k,x)  = shows k . showString ":=" . shows x
-  
+
+{--------------------------------------------------------------------
+  Read
+--------------------------------------------------------------------}
+instance (Read e) => Read (IntMap e) where
+#ifdef __GLASGOW_HASKELL__
+  readPrec = parens $ prec 10 $ do
+    Ident "fromList" <- lexP
+    xs <- readPrec
+    return (fromList xs)
+
+  readListPrec = readListPrecDefault
+#else
+  readsPrec p = readParen (p > 10) $ \ r -> do
+    ("fromList",s) <- lex r
+    (xs,t) <- reads s
+    return (fromList xs,t)
+#endif
+
 {--------------------------------------------------------------------
   Typeable
 --------------------------------------------------------------------}