X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Data%2FIntSet.hs;h=36cac361a07f717f03a9aeba141b5494253c573b;hb=53004f977617674ddec5d7315f0be92e0358ae7d;hp=510498ca7579013a147901c2e815cd7362187ebf;hpb=fa680a0011bc07ef4643ea9f9b32439eda293650;p=haskell-directory.git

diff --git a/Data/IntSet.hs b/Data/IntSet.hs
index 510498c..36cac36 100644
--- a/Data/IntSet.hs
+++ b/Data/IntSet.hs
@@ -10,10 +10,11 @@
 --
 -- An efficient implementation of integer sets.
 --
--- This module is intended to be imported @qualified@, to avoid name
--- clashes with "Prelude" functions.  eg.
+-- Since many function names (but not the type name) clash with
+-- "Prelude" names, this module is usually imported @qualified@, e.g.
 --
--- >  import Data.IntSet as Set
+-- >  import Data.IntSet (IntSet)
+-- >  import qualified Data.IntSet as IntSet
 --
 -- The implementation is based on /big-endian patricia trees/.  This data
 -- structure performs especially well on binary operations like 'union'
@@ -46,6 +47,7 @@ module Data.IntSet  (
             , null
             , size
             , member
+            , notMember
             , isSubsetOf
             , isProperSubsetOf
             
@@ -94,7 +96,8 @@ import Data.Bits
 import Data.Int
 
 import qualified Data.List as List
-import Data.Monoid
+import Data.Monoid (Monoid(..))
+import Data.Typeable
 
 {-
 -- just for testing
@@ -103,6 +106,12 @@ import List (nub,sort)
 import qualified List
 -}
 
+#if __GLASGOW_HASKELL__
+import Text.Read
+import Data.Generics.Basics
+import Data.Generics.Instances
+#endif
+
 #if __GLASGOW_HASKELL__ >= 503
 import GHC.Word
 import GHC.Exts ( Word(..), Int(..), shiftRL# )
@@ -153,6 +162,28 @@ data IntSet = Nil
 type Prefix = Int
 type Mask   = Int
 
+instance Monoid IntSet where
+    mempty  = empty
+    mappend = union
+    mconcat = unions
+
+#if __GLASGOW_HASKELL__
+
+{--------------------------------------------------------------------
+  A Data instance  
+--------------------------------------------------------------------}
+
+-- This instance preserves data abstraction at the cost of inefficiency.
+-- We omit reflection services for the sake of data abstraction.
+
+instance Data IntSet where
+  gfoldl f z is = z fromList `f` (toList is)
+  toConstr _    = error "toConstr"
+  gunfold _ _   = error "gunfold"
+  dataTypeOf _  = mkNorepType "Data.IntSet.IntSet"
+
+#endif
+
 {--------------------------------------------------------------------
   Query
 --------------------------------------------------------------------}
@@ -180,6 +211,10 @@ member x t
       Tip y -> (x==y)
       Nil   -> False
     
+-- | /O(log n)/. Is the element not in the set?
+notMember :: Int -> IntSet -> Bool
+notMember k = not . member k
+
 -- 'lookup' is used by 'intersection' for left-biasing
 lookup :: Int -> IntSet -> Maybe Int
 lookup k t
@@ -382,7 +417,7 @@ subsetCmp Nil Nil = EQ
 subsetCmp Nil t   = LT
 
 -- | /O(n+m)/. Is this a subset?
--- @(s1 `isSubsetOf` s2)@ tells whether s1 is a subset of s2.
+-- @(s1 `isSubsetOf` s2)@ tells whether @s1@ is a subset of @s2@.
 
 isSubsetOf :: IntSet -> IntSet -> Bool
 isSubsetOf t1@(Bin p1 m1 l1 r1) t2@(Bin p2 m2 l2 r2)
@@ -423,7 +458,7 @@ partition pred t
       Nil -> (Nil,Nil)
 
 
--- | /O(log n)/. The expression (@split x set@) is a pair @(set1,set2)@
+-- | /O(log n)/. The expression (@'split' x set@) is a pair @(set1,set2)@
 -- where all elements in @set1@ are lower than @x@ and all elements in
 -- @set2@ larger than @x@.
 --
@@ -432,8 +467,24 @@ 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)
@@ -442,24 +493,40 @@ split x t
 
 -- | /O(log n)/. Performs a 'split' but also returns whether the pivot
 -- element was found in the original set.
-splitMember :: Int -> IntSet -> (Bool,IntSet,IntSet)
+splitMember :: Int -> IntSet -> (IntSet,Bool,IntSet)
 splitMember x t
   = case t of
       Bin p m l r
-        | zero x m  -> let (found,lt,gt) = splitMember x l in (found,lt,union gt r)
-        | otherwise -> let (found,lt,gt) = splitMember x r in (found,union l lt,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       -> (False,t,Nil)
-        | x<y       -> (False,Nil,t)
-        | otherwise -> (True,Nil,Nil)
-      Nil -> (False,Nil,Nil)
+        | x>y       -> (t,False,Nil)
+        | x<y       -> (Nil,False,t)
+        | otherwise -> (Nil,True,Nil)
+      Nil -> (Nil,False,Nil)
 
 {----------------------------------------------------------------------
   Map
 ----------------------------------------------------------------------}
 
 -- | /O(n*min(n,W))/. 
--- @map f s@ is the set obtained by applying @f@ to each element of @s@.
+-- @'map' f s@ is the set obtained by applying @f@ to each element of @s@.
 -- 
 -- It's worth noting that the size of the result may be smaller if,
 -- for some @(x,y)@, @x \/= y && f x == f y@
@@ -476,7 +543,12 @@ 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
@@ -503,9 +575,7 @@ 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
@@ -557,19 +627,11 @@ instance Ord IntSet where
     -- tentative implementation. See if more efficient exists.
 
 {--------------------------------------------------------------------
-  Monoid 
---------------------------------------------------------------------}
-
-instance Monoid IntSet where
-    mempty = empty
-    mappend = union
-    mconcat = unions
-
-{--------------------------------------------------------------------
   Show
 --------------------------------------------------------------------}
 instance Show IntSet where
-  showsPrec d s  = showSet (toList s)
+  showsPrec p xs = showParen (p > 10) $
+    showString "fromList " . shows (toList xs)
 
 showSet :: [Int] -> ShowS
 showSet []     
@@ -581,6 +643,31 @@ showSet (x:xs)
     showTail (x:xs) = showChar ',' . shows x . showTail xs
 
 {--------------------------------------------------------------------
+  Read
+--------------------------------------------------------------------}
+instance Read IntSet 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
+--------------------------------------------------------------------}
+
+#include "Typeable.h"
+INSTANCE_TYPEABLE0(IntSet,intSetTc,"IntSet")
+
+{--------------------------------------------------------------------
   Debugging
 --------------------------------------------------------------------}
 -- | /O(n)/. Show the tree that implements the set. The tree is shown
@@ -590,10 +677,10 @@ showTree s
   = showTreeWith True False s
 
 
-{- | /O(n)/. The expression (@showTreeWith hang wide map@) shows
+{- | /O(n)/. The expression (@'showTreeWith' hang wide map@) shows
  the tree that implements the set. If @hang@ is
- @True@, a /hanging/ tree is shown otherwise a rotated tree is shown. If
- @wide@ is true, an extra wide version is shown.
+ 'True', a /hanging/ tree is shown otherwise a rotated tree is shown. If
+ @wide@ is 'True', an extra wide version is shown.
 -}
 showTreeWith :: Bool -> Bool -> IntSet -> String
 showTreeWith hang wide t