{-# LANGUAGE CPP, FlexibleInstances #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
module QC.Common
(
ASCII(..)
, parseBS
, toLazyBS
, toStrictBS
, Repack
, repackBS
, repackBS_
, liftOp
) where
#if !MIN_VERSION_base(4,8,0)
import Control.Applicative
#endif
import Data.Char (isAlpha)
import Test.QuickCheck
import Test.QuickCheck.Instances ()
import qualified Data.ByteString as B
import qualified Data.ByteString.Lazy as BL
import qualified Data.Binary.Parser as P
#if !MIN_VERSION_base(4,4,0)
-- This should really be a dependency on the random package :-(
instance Random Word8 where
randomR = integralRandomR
random = randomR (minBound,maxBound)
instance Arbitrary Word8 where
arbitrary = choose (minBound, maxBound)
#endif
parseBS :: P.Get r -> BL.ByteString -> Maybe r
parseBS p lbs = case P.parseLazy p lbs of
Left _ -> Nothing
Right v -> Just v
toStrictBS :: BL.ByteString -> B.ByteString
toStrictBS = B.concat . BL.toChunks
toLazyBS :: B.ByteString -> BL.ByteString
toLazyBS = BL.fromChunks . (:[])
newtype ASCII a = ASCII { fromASCII :: a }
deriving (Eq, Ord, Show)
instance Arbitrary (ASCII B.ByteString) where
arbitrary = (ASCII . B.pack) <$> listOf (choose (0,127))
shrink = map (ASCII . B.pack) . shrink . B.unpack . fromASCII
instance Arbitrary (ASCII BL.ByteString) where
arbitrary = ASCII <$> (repackBS <$> arbitrary <*> (fromASCII <$> arbitrary))
shrink = map (ASCII . BL.pack) . shrink . BL.unpack . fromASCII
type Repack = NonEmptyList (Positive (Small Int))
repackBS :: Repack -> B.ByteString -> BL.ByteString
repackBS (NonEmpty bs) =
BL.fromChunks . repackBS_ (map (getSmall . getPositive) bs)
repackBS_ :: [Int] -> B.ByteString -> [B.ByteString]
repackBS_ = go . cycle
where go (b:bs) s
| B.null s = []
| otherwise = let (h,t) = B.splitAt b s
in h : go bs t
go _ _ = error "unpossible"
liftOp :: (Show a, Testable prop) =>
String -> (a -> a -> prop) -> a -> a -> Property
liftOp name f x y = counterexample desc (f x y)
where op = case name of
(c:_) | isAlpha c -> " `" ++ name ++ "` "
| otherwise -> " " ++ name ++ " "
_ -> " ??? "
desc = "not (" ++ show x ++ op ++ show y ++ ")"