VCR.hs

-- Communicating Haskell Processes.
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-- | A module for recording View Centric Reasoning (VCR) traces.  A view centric
-- reasnoning trace is a list of sets of events.  Each set contains independent
-- events that have no causal relationship between them.  Hopefully we will
-- publish a paper explaining all this in detail soon.
module Control.Concurrent.CHP.Traces.VCR (VCRTrace(..), runCHP_VCRTrace, runCHP_VCRTraceAndPrint) where

import Control.Concurrent.STM
import Control.Monad.State
import qualified Data.Map as Map
import qualified Data.Set as Set
import Text.PrettyPrint.HughesPJ

import Control.Concurrent.CHP.Base
import Control.Concurrent.CHP.Traces.Base

-- | A VCR (View-Centric Reasoning) trace.  It is the channel labels,
-- accompanied by a sequential list of sets of recorded events.  Each of
-- the sets is a set of independent events.  The set at the head of the
-- list is the first-recorded (oldest).
newtype VCRTrace = VCRTrace (ChannelLabels, [Set.Set RecordedEvent])

instance Show VCRTrace where
  show = renderStyle (Style OneLineMode 1 1) . prettyPrint

instance Trace VCRTrace where
  emptyTrace = VCRTrace (Map.empty, [])
  runCHPAndTrace p = do tv <- atomically $ newTVar []
                        runCHPProgramWith' (VCRTraceRev tv) toPublic p

  prettyPrint (VCRTrace (labels, eventSets))
    = char '<' <+> (sep $ punctuate (char ',') $ map (braces . sep . punctuate (char ',')) ropes) <+> char '>'
    where
      labels' = ensureAllNamed labels (concatMap Set.toList eventSets)
      es = map (nameVCR labels') eventSets

      ropes :: [[Doc]]
      ropes = map (map text . Set.toList) es


toPublic :: ChannelLabels -> SubTraceStore -> IO VCRTrace
toPublic l (VCRTraceRev tv)
  = do setList <- atomically $ readTVar tv
       return $ VCRTrace (l, map (Set.map snd) $ reverse setList)
toPublic _ _ = error "Error in VCR trace -- tracing type got switched"

nameVCR :: ChannelLabels -> Set.Set RecordedEvent -> Set.Set String
nameVCR m x = Set.fromList $ evalState (mapM nameEvent $ Set.toList x) m


runCHP_VCRTrace :: CHP a -> IO (Maybe a, VCRTrace)
runCHP_VCRTrace = runCHPAndTrace

runCHP_VCRTraceAndPrint :: CHP a -> IO ()
runCHP_VCRTraceAndPrint p = do (_, tr) <- runCHP_VCRTrace p
                               putStrLn $ show tr