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    1 {-# LANGUAGE DeriveDataTypeable #-}
    2 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
    3 module GHC.Types.CostCentre.State
    4    ( CostCentreState
    5    , newCostCentreState
    6    , CostCentreIndex
    7    , unCostCentreIndex
    8    , getCCIndex
    9    )
   10 where
   11 
   12 import GHC.Prelude
   13 import GHC.Data.FastString
   14 import GHC.Data.FastString.Env
   15 
   16 import Data.Data
   17 import GHC.Utils.Binary
   18 
   19 -- | Per-module state for tracking cost centre indices.
   20 --
   21 -- See documentation of 'GHC.Types.CostCentre.cc_flavour' for more details.
   22 newtype CostCentreState = CostCentreState (FastStringEnv Int)
   23 
   24 -- | Initialize cost centre state.
   25 newCostCentreState :: CostCentreState
   26 newCostCentreState = CostCentreState emptyFsEnv
   27 
   28 -- | An index into a given cost centre module,name,flavour set
   29 newtype CostCentreIndex = CostCentreIndex { unCostCentreIndex :: Int }
   30   deriving (Eq, Ord, Data, Binary)
   31 
   32 -- | Get a new index for a given cost centre name.
   33 getCCIndex :: FastString
   34            -> CostCentreState
   35            -> (CostCentreIndex, CostCentreState)
   36 getCCIndex nm (CostCentreState m) =
   37     (CostCentreIndex idx, CostCentreState m')
   38   where
   39     m_idx = lookupFsEnv m nm
   40     idx = maybe 0 id m_idx
   41     m' = extendFsEnv m nm (idx + 1)