+
+
+data CharAccumState
+ = CharAccumState {
+ casChunks ∷ !(S.Seq BS.ByteString)
+ , casLastChunk ∷ !(S.Seq Char)
+ }
+
+instance Monoid CharAccumState where
+ mempty
+ = CharAccumState {
+ casChunks = (∅)
+ , casLastChunk = (∅)
+ }
+ mappend a b
+ = b {
+ casChunks = (casChunks a ⊳ lastChunk a) ⋈ casChunks b
+ }
+
+lastChunk ∷ CharAccumState → BS.ByteString
+{-# INLINE lastChunk #-}
+lastChunk = BS.pack ∘ F.toList ∘ casLastChunk
+
+snoc ∷ CharAccumState → Char → CharAccumState
+{-# INLINEABLE snoc #-}
+snoc cas c
+ | S.length (casLastChunk cas) ≥ LS.defaultChunkSize
+ = cas {
+ casChunks = casChunks cas ⊳ lastChunk cas
+ , casLastChunk = S.singleton c
+ }
+ | otherwise
+ = cas {
+ casLastChunk = casLastChunk cas ⊳ c
+ }
+
+finish ∷ CharAccumState → LS.ByteString
+{-# INLINEABLE finish #-}
+finish cas
+ = let chunks = F.toList $ casChunks cas ⊳ lastChunk cas
+ str = LS.fromChunks chunks
+ in
+ str
+
+manyCharsTill ∷ ∀m b. (Monad m, Alternative m)
+ ⇒ m Char
+ → m b
+ → m LS.ByteString
+{-# INLINEABLE manyCharsTill #-}
+manyCharsTill p end = scan (∅)
+ where
+ scan ∷ CharAccumState → m LS.ByteString
+ {-# INLINE scan #-}
+ scan s
+ = (end *> pure (finish s))
+ <|>
+ (scan =≪ (snoc s <$> p))