blob: 81fe6d87a02f58b1fe2d294b2703f2fefd0fb283 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
|
-----------------------------------------------------------------------------
-- |
-- Module : Data.Unique
-- Copyright : (c) The University of Glasgow 2001
-- License : BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer : libraries@haskell.org
-- Stability : experimental
-- Portability : non-portable
--
-- An infinite supply of unique objects, supporting ordering and equality.
--
-----------------------------------------------------------------------------
module Data.Unique (
Unique, -- instance (Eq, Ord)
newUnique, -- :: IO Unique
hashUnique -- :: Unique -> Int
) where
import Prelude
import Control.Concurrent
import System.IO.Unsafe (unsafePerformIO)
#ifdef __GLASGOW_HASKELL__
import GHC.Base
import GHC.Num ( Integer(..) )
#endif
newtype Unique = Unique Integer deriving (Eq,Ord)
uniqSource :: MVar Integer
uniqSource = unsafePerformIO (newMVar 0)
{-# NOINLINE uniqSource #-}
newUnique :: IO Unique
newUnique = do
val <- takeMVar uniqSource
let next = val+1
putMVar uniqSource next
return (Unique next)
hashUnique :: Unique -> Int
#ifdef __GLASGOW_HASKELL__
hashUnique (Unique (S# i)) = I# i
hashUnique (Unique (J# s d)) | s ==# 0# = 0
| otherwise = I# (indexIntArray# d 0#)
#else
hashUnique (Unique u) = u `mod` (fromIntegral (maxBound :: Int) + 1)
#endif
|
