[project @ 2005-10-22 00:28:21 by ross]

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

diff --git a/Data/IntSet.hs b/Data/IntSet.hs
index 1d46218..6220827 100644 (file)
--- a/Data/IntSet.hs
+++ b/Data/IntSet.hs
@@ -94,7 +94,6 @@ import Data.Bits
 import Data.Int
 
 import qualified Data.List as List
-import Data.Monoid
 import Data.Typeable
 
 {-
@@ -104,6 +103,12 @@ 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# )
@@ -154,6 +159,23 @@ data IntSet = Nil
 type Prefix = Int
 type Mask   = Int
 
+#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
 --------------------------------------------------------------------}
@@ -383,7 +405,7 @@ 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)
@@ -424,7 +446,7 @@ 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@.
 --
@@ -443,24 +465,24 @@ 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)
+        | 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)
       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@
@@ -558,19 +580,11 @@ 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 []     
@@ -582,6 +596,24 @@ 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
 --------------------------------------------------------------------}
 
@@ -598,10 +630,10 @@ 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