Optics.hs

{-# LANGUAGE ViewPatterns #-}
{-# LANGUAGE PatternSynonyms #-}
-- | Lazy 'ByteString' lenses.
module Data.ByteString.Lazy.Optics
  ( packedBytes, unpackedBytes, bytes
  , packedChars, unpackedChars, chars
  , pattern Bytes
  , pattern Chars
  ) where

import Data.ByteString.Lazy (ByteString)
import qualified Data.ByteString.Lazy       as Words
import qualified Data.ByteString.Lazy.Char8 as Char8
import Data.Int (Int64)
import Data.Word (Word8)

import Optics.Core
import Optics.Extra.Internal.ByteString

-- | 'Data.ByteString.Lazy.pack' (or 'Data.ByteString.Lazy.unpack') a list of
-- bytes into a 'ByteString'.
--
-- @
-- 'packedBytes' ≡ 're' 'unpackedBytes'
-- 'Data.ByteString.pack' x ≡  x '^.' 'packedBytes'
-- 'Data.ByteString.unpack' x ≡ x '^.' 're' 'packedBytes'
-- @
--
-- >>> [104,101,108,108,111] ^. packedBytes == Char8.pack "hello"
-- True
packedBytes :: Iso' [Word8] ByteString
packedBytes = iso Words.pack Words.unpack
{-# INLINE packedBytes #-}

-- | 'Data.ByteString.Lazy.unpack' (or 'Data.ByteString.Lazy.pack') a
-- 'ByteString' into a list of bytes.
--
-- @
-- 'unpackedBytes' ≡ 're' 'packedBytes'
-- 'Data.ByteString.unpack' x ≡ x '^.' 'unpackedBytes'
-- 'Data.ByteString.pack' x ≡  x '^.' 're' 'unpackedBytes'
-- @
--
-- >>> "hello" ^. packedChars % unpackedBytes
-- [104,101,108,108,111]
unpackedBytes :: Iso' ByteString [Word8]
unpackedBytes = re packedBytes
{-# INLINE unpackedBytes #-}

-- | Traverse the individual bytes in a 'ByteString'.
--
-- This 'Traversal' walks each strict 'ByteString' chunk in a tree-like fashion
-- enable zippers to seek to locations more quickly and accelerate many monoidal
-- queries, but up to associativity (and constant factors) it is equivalent to
-- the much slower:
--
-- @
-- 'bytes' ≡ 'unpackedBytes' '%' 'traversed'
-- @
--
-- >>> anyOf bytes (== 0x80) (Char8.pack "hello")
-- False
--
-- Note that when just using this as a 'Setter', @'sets'
-- 'Data.ByteString.Lazy.map'@ can be more efficient.
bytes :: IxTraversal' Int64 ByteString Word8
bytes = traversedLazy
{-# INLINE bytes #-}

-- | 'Data.ByteString.Lazy.Char8.pack' (or 'Data.ByteString.Lazy.Char8.unpack')
-- a list of characters into a 'ByteString'.
--
-- When writing back to the 'ByteString' it is assumed that every 'Char' lies
-- between @'\x00'@ and @'\xff'@.
--
-- @
-- 'packedChars' ≡ 're' 'unpackedChars'
-- 'Data.ByteString.Char8.pack' x ≡ x '^.' 'packedChars'
-- 'Data.ByteString.Char8.unpack' x ≡ x '^.' 're' 'packedChars'
-- @
--
-- >>> foldOf (packedChars % each % to (\w -> let x = showHex w "" in if Prelude.length x == 1 then '0':x else x)) "hello"
-- "68656c6c6f"
packedChars :: Iso' String ByteString
packedChars = iso Char8.pack Char8.unpack
{-# INLINE packedChars #-}

-- | 'Data.ByteString.Lazy.Char8.unpack' (or 'Data.ByteString.Lazy.Char8.pack')
-- a list of characters into a 'ByteString'
--
-- When writing back to the 'ByteString' it is assumed that every 'Char' lies
-- between @'\x00'@ and @'\xff'@.
--
-- @
-- 'unpackedChars' ≡ 're' 'packedChars'
-- 'Data.ByteString.Char8.unpack' x ≡ x '^.' 'unpackedChars'
-- 'Data.ByteString.Char8.pack' x ≡ x '^.' 're' 'unpackedChars'
-- @
--
-- >>> [104,101,108,108,111] ^. packedBytes % unpackedChars
-- "hello"
unpackedChars :: Iso' ByteString String
unpackedChars = re packedChars
{-# INLINE unpackedChars #-}

-- | Traverse the individual bytes in a 'ByteString' as characters.
--
-- When writing back to the 'ByteString' it is assumed that every 'Char' lies
-- between @'\x00'@ and @'\xff'@.
--
-- This 'Traversal' walks each strict 'ByteString' chunk in a tree-like fashion
-- enable zippers to seek to locations more quickly and accelerate many monoidal
-- queries, but up to associativity (and constant factors) it is equivalent to:
--
-- @
-- 'chars' = 'unpackedChars' '%' 'traversed'
-- @
--
-- >>> anyOf chars (== 'h') $ Char8.pack "hello"
-- True
chars :: IxTraversal' Int64 ByteString Char
chars = traversedLazy8
{-# INLINE chars #-}

pattern Bytes :: [Word8] -> ByteString
pattern Bytes b <- (view unpackedBytes -> b) where
  Bytes b = review unpackedBytes b

pattern Chars :: [Char] -> ByteString
pattern Chars b <- (view unpackedChars -> b) where
  Chars b = review unpackedChars b

-- $setup
-- >>> import Numeric
-- >>> import Optics.Each