refactor(xanthous): Generators -> Generators.Level

I'm going to start adding generators for things like text soon, so it
makes sense to specifically sequester level generators as their own
thing

Change-Id: I175025375204fab7d75eba67dd06dab9bd2939d3
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3201
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI

users/grfn/xanthous/src/Xanthous/Generators/Level/Util.hs

@@ -0,0 +1,220 @@
+{-# LANGUAGE QuantifiedConstraints #-}
+{-# LANGUAGE AllowAmbiguousTypes #-}
+--------------------------------------------------------------------------------
+module Xanthous.Generators.Level.Util
+  ( MCells
+  , Cells
+  , CellM
+  , randInitialize
+  , initializeEmpty
+  , numAliveNeighborsM
+  , numAliveNeighbors
+  , fillOuterEdgesM
+  , cloneMArray
+  , floodFill
+  , regions
+  , fillAll
+  , fillAllM
+  , fromPoints
+  , fromPointsM
+  ) where
+--------------------------------------------------------------------------------
+import           Xanthous.Prelude hiding (Foldable, toList, for_)
+--------------------------------------------------------------------------------
+import           Data.Array.ST
+import           Data.Array.Unboxed
+import           Control.Monad.ST
+import           Control.Monad.Random
+import           Data.Monoid
+import           Data.Foldable (Foldable, toList, for_)
+import qualified Data.Set as Set
+import           Data.Semigroup.Foldable
+import           Linear.V2
+--------------------------------------------------------------------------------
+import           Xanthous.Util (foldlMapM', maximum1, minimum1)
+import           Xanthous.Data (Dimensions, width, height)
+--------------------------------------------------------------------------------
+
+type MCells s = STUArray s (V2 Word) Bool
+type Cells = UArray (V2 Word) Bool
+type CellM g s a = RandT g (ST s) a
+
+randInitialize :: RandomGen g => Dimensions -> Double -> CellM g s (MCells s)
+randInitialize dims aliveChance = do
+  res <- initializeEmpty dims
+  for_ [0..dims ^. width] $ \i ->
+    for_ [0..dims ^. height] $ \j -> do
+      val <- (>= aliveChance) <$> getRandomR (0, 1)
+      lift $ writeArray res (V2 i j) val
+  pure res
+
+initializeEmpty :: RandomGen g => Dimensions -> CellM g s (MCells s)
+initializeEmpty dims =
+  lift $ newArray (0, V2 (dims ^. width) (dims ^. height)) False
+
+numAliveNeighborsM
+  :: forall a i m
+  . (MArray a Bool m, Ix i, Integral i)
+  => a (V2 i) Bool
+  -> V2 i
+  -> m Word
+numAliveNeighborsM cells (V2 x y) = do
+  cellBounds <- getBounds cells
+  getSum <$> foldlMapM'
+    (fmap (Sum . fromIntegral . fromEnum) . boundedGet cellBounds)
+    neighborPositions
+
+  where
+    boundedGet :: (V2 i, V2 i) -> (Int, Int) -> m Bool
+    boundedGet (V2 minX minY, V2 maxX maxY) (i, j)
+      | x <= minX
+        || y <= minY
+        || x >= maxX
+        || y >= maxY
+      = pure True
+      | otherwise =
+        let nx = fromIntegral $ fromIntegral x + i
+            ny = fromIntegral $ fromIntegral y + j
+        in readArray cells $ V2 nx ny
+
+numAliveNeighbors
+  :: forall a i
+  . (IArray a Bool, Ix i, Integral i)
+  => a (V2 i) Bool
+  -> V2 i
+  -> Word
+numAliveNeighbors cells (V2 x y) =
+  let cellBounds = bounds cells
+  in getSum $ foldMap
+      (Sum . fromIntegral . fromEnum . boundedGet cellBounds)
+      neighborPositions
+
+  where
+    boundedGet :: (V2 i, V2 i) -> (Int, Int) -> Bool
+    boundedGet (V2 minX minY, V2 maxX maxY) (i, j)
+      | x <= minX
+        || y <= minY
+        || x >= maxX
+        || y >= maxY
+      = True
+      | otherwise =
+        let nx = fromIntegral $ fromIntegral x + i
+            ny = fromIntegral $ fromIntegral y + j
+        in cells ! V2 nx ny
+
+neighborPositions :: [(Int, Int)]
+neighborPositions = [(i, j) | i <- [-1..1], j <- [-1..1], (i, j) /= (0, 0)]
+
+fillOuterEdgesM :: (MArray a Bool m, Ix i) => a (V2 i) Bool -> m ()
+fillOuterEdgesM arr = do
+  (V2 minX minY, V2 maxX maxY) <- getBounds arr
+  for_ (range (minX, maxX)) $ \x -> do
+    writeArray arr (V2 x minY) True
+    writeArray arr (V2 x maxY) True
+  for_ (range (minY, maxY)) $ \y -> do
+    writeArray arr (V2 minX y) True
+    writeArray arr (V2 maxX y) True
+
+cloneMArray
+  :: forall a a' i e m.
+  ( Ix i
+  , MArray a e m
+  , MArray a' e m
+  , IArray UArray e
+  )
+  => a i e
+  -> m (a' i e)
+cloneMArray = thaw @_ @UArray <=< freeze
+
+--------------------------------------------------------------------------------
+
+-- | Flood fill a cell array starting at a point, returning a list of all the
+-- (true) cell locations reachable from that point
+floodFill :: forall a i.
+            ( IArray a Bool
+            , Ix i
+            , Enum i
+            , Bounded i
+            , Eq i
+            )
+          => a (V2 i) Bool -- ^ array
+          -> (V2 i)        -- ^ position
+          -> Set (V2 i)
+floodFill = go mempty
+  where
+    go :: Set (V2 i) -> a (V2 i) Bool -> (V2 i) -> Set (V2 i)
+    go res arr@(bounds -> arrBounds) idx@(V2 x y)
+      | not (inRange arrBounds idx) =  res
+      | not (arr ! idx) =  res
+      | otherwise =
+        let neighbors
+              = filter (inRange arrBounds)
+              . filter (/= idx)
+              . filter (`notMember` res)
+              $ V2
+              <$> [(if x == minBound then x else pred x)
+                   ..
+                   (if x == maxBound then x else succ x)]
+              <*> [(if y == minBound then y else pred y)
+                   ..
+                   (if y == maxBound then y else succ y)]
+        in foldl' (\r idx' ->
+                     if arr ! idx'
+                     then r <> (let r' = r & contains idx' .~ True
+                               in r' `seq` go r' arr idx')
+                     else r)
+           (res & contains idx .~ True) neighbors
+{-# SPECIALIZE floodFill :: UArray (V2 Word) Bool -> (V2 Word) -> Set (V2 Word) #-}
+
+-- | Gives a list of all the disconnected regions in a cell array, represented
+-- each as lists of points
+regions :: forall a i.
+          ( IArray a Bool
+          , Ix i
+          , Enum i
+          , Bounded i
+          , Eq i
+          )
+        => a (V2 i) Bool
+        -> [Set (V2 i)]
+regions arr
+  | Just firstPoint <- findFirstPoint arr =
+      let region = floodFill arr firstPoint
+          arr' = fillAll region arr
+      in region : regions arr'
+  | otherwise = []
+  where
+    findFirstPoint :: a (V2 i) Bool -> Maybe (V2 i)
+    findFirstPoint = fmap fst . headMay . filter snd . assocs
+{-# SPECIALIZE regions :: UArray (V2 Word) Bool -> [Set (V2 Word)] #-}
+
+fillAll :: (IArray a Bool, Ix i, Foldable f) => f i -> a i Bool -> a i Bool
+fillAll ixes a = accum (const fst) a $ (, (False, ())) <$> toList ixes
+
+fillAllM :: (MArray a Bool m, Ix i, Foldable f) => f i -> a i Bool -> m ()
+fillAllM ixes a = for_ ixes $ \i -> writeArray a i False
+
+fromPoints
+  :: forall a f i.
+    ( IArray a Bool
+    , Ix i
+    , Functor f
+    , Foldable1 f
+    )
+  => f (i, i)
+  -> a (i, i) Bool
+fromPoints points =
+  let pts = Set.fromList $ toList points
+      dims = ( (minimum1 $ fst <$> points, minimum1 $ snd <$> points)
+             , (maximum1 $ fst <$> points, maximum1 $ snd <$> points)
+             )
+  in array dims $ range dims <&> \i -> (i, i `member` pts)
+
+fromPointsM
+  :: (MArray a Bool m, Ix i, Element f ~ i, MonoFoldable f)
+  => NonNull f
+  -> m (a i Bool)
+fromPointsM points = do
+  arr <- newArray (minimum points, maximum points) False
+  fillAllM (otoList points) arr
+  pure arr