#if __GLASGOW_HASKELL__ >= 703
#elif __GLASGOW_HASKELL__ >= 701
#endif
module Data.Vector.Fusion.Stream.Size (
Size(..), smaller, larger, toMax, upperBound
) where
import Data.Vector.Fusion.Util ( delay_inline )
data Size = Exact Int
| Max Int
| Unknown
deriving( Eq, Show )
instance Num Size where
Exact m + Exact n = Exact (m+n)
Exact m + Max n = Max (m+n)
Max m + Exact n = Max (m+n)
Max m + Max n = Max (m+n)
_ + _ = Unknown
Exact m Exact n = Exact (mn)
Exact m Max n = Max m
Max m Exact n = Max (mn)
Max m Max n = Max m
Max m Unknown = Max m
_ _ = Unknown
fromInteger n = Exact (fromInteger n)
smaller :: Size -> Size -> Size
smaller (Exact m) (Exact n) = Exact (delay_inline min m n)
smaller (Exact m) (Max n) = Max (delay_inline min m n)
smaller (Exact m) Unknown = Max m
smaller (Max m) (Exact n) = Max (delay_inline min m n)
smaller (Max m) (Max n) = Max (delay_inline min m n)
smaller (Max m) Unknown = Max m
smaller Unknown (Exact n) = Max n
smaller Unknown (Max n) = Max n
smaller Unknown Unknown = Unknown
larger :: Size -> Size -> Size
larger (Exact m) (Exact n) = Exact (delay_inline max m n)
larger (Exact m) (Max n) | m >= n = Exact m
| otherwise = Max n
larger (Max m) (Exact n) | n >= m = Exact n
| otherwise = Max m
larger (Max m) (Max n) = Max (delay_inline max m n)
larger _ _ = Unknown
toMax :: Size -> Size
toMax (Exact n) = Max n
toMax (Max n) = Max n
toMax Unknown = Unknown
lowerBound :: Size -> Int
lowerBound (Exact n) = n
lowerBound _ = 0
upperBound :: Size -> Maybe Int
upperBound (Exact n) = Just n
upperBound (Max n) = Just n
upperBound Unknown = Nothing