{-
Copyright (C) 2018 Dr. Alistair Ward
This file is part of BishBosh.
BishBosh is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
BishBosh is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with BishBosh. If not, see .
-}
{- |
[@AUTHOR@] Dr. Alistair Ward
[@DESCRIPTION@] .
-}
module BishBosh.Search.KillerMoves (
-- * Types
-- ** Type-synonyms
Transformation,
-- ** Data-types
KillerMoves(),
-- * Functions
sortByHistoryHeuristic,
-- ** Mutators
insert
) where
import Control.Arrow((&&&))
import Data.Array.IArray((!), (//))
import qualified BishBosh.Attribute.LogicalColour as Attribute.LogicalColour
import qualified BishBosh.Component.Move as Component.Move
import qualified BishBosh.Property.Empty as Property.Empty
import qualified BishBosh.Search.EphemeralData as Search.EphemeralData
import qualified Data.Array.IArray
import qualified Data.Foldable
import qualified Data.IntMap
import qualified Data.List
import qualified Data.Map
import qualified Data.Map.Strict
import qualified Data.Maybe
{- |
* Used to contain the number of instances of each killer-move (a quiet move which triggered beta-cutoff),
indexed by the logical-colour of the player making the move & the number of plies into the game, at which it occurred.
* These data can be used to advance the evaluation of identical sibling moves, in the hope of achieving beta-cutoff sooner.
-}
newtype KillerMoves killerMove = MkKillerMoves {
deconstruct :: Attribute.LogicalColour.ByLogicalColour (
Data.Map.Map killerMove (
Data.IntMap.IntMap {-by NPlies-} Component.Move.NMoves
)
)
}
instance Property.Empty.Empty (KillerMoves killerMove) where
empty = MkKillerMoves . Attribute.LogicalColour.listArrayByLogicalColour $ repeat Data.Map.empty
instance Search.EphemeralData.EphemeralData (KillerMoves killerMove) where
getSize MkKillerMoves { deconstruct = nInstancesByKeyByNPliesByLogicalColour } = Data.Foldable.foldl' (
Data.Map.foldl' $ Data.IntMap.foldl' (+)
) 0 nInstancesByKeyByNPliesByLogicalColour
euthanise nPlies killerMoves@MkKillerMoves { deconstruct = nInstancesByKeyByNPliesByLogicalColour }
| nPlies <= 0 = killerMoves -- This might occur at the start of the game, because the caller subtracts a fixed value from the current number of plies.
| otherwise = MkKillerMoves $ Data.Array.IArray.amap (
Data.Map.mapMaybe $ \m -> let
m' = Data.IntMap.filterWithKey (\nPlies' _ -> nPlies' > nPlies) m
in if Data.IntMap.null m'
then Nothing
else Just m'
) nInstancesByKeyByNPliesByLogicalColour
-- | The type of a function which transforms a collection of killer-moves.
type Transformation killerMove = KillerMoves killerMove -> KillerMoves killerMove
-- | Insert a killer-move.
insert
:: Ord killerMove
=> Component.Move.NPlies -- ^ The total number of plies applied to the game.
-> killerMove
-> Transformation killerMove
insert nPlies killerMove MkKillerMoves { deconstruct = nInstancesByKeyByNPliesByLogicalColour } = MkKillerMoves $ nInstancesByKeyByNPliesByLogicalColour // [
id &&& Data.Map.Strict.insertWith (
Data.IntMap.unionWith (+)
) killerMove (
Data.IntMap.singleton nPlies 1
) . (nInstancesByKeyByNPliesByLogicalColour !) $ if even nPlies
then Attribute.LogicalColour.Black
else Attribute.LogicalColour.White -- White makes the first move.
] -- Singleton.
-- | Sorts an arbitrary list using the History-heuristic; .
sortByHistoryHeuristic
:: Ord killerMove
=> Attribute.LogicalColour.LogicalColour
-> (a -> killerMove) -- ^ Constructor.
-> KillerMoves killerMove
-> [a]
-> [a]
sortByHistoryHeuristic logicalColour killerMoveConstructor MkKillerMoves { deconstruct = nInstancesByNPliesByKeyByLogicalColour } = Data.List.sortOn $ Data.Maybe.maybe 0 (
negate {-largest first-} . Data.IntMap.foldl' (+) 0
) . (
`Data.Map.lookup` (nInstancesByNPliesByKeyByLogicalColour ! logicalColour)
) . killerMoveConstructor