shrub/pkg/hs/urbit-atom/lib/Urbit/Atom.hs
2020-03-18 12:38:48 -07:00

118 lines
2.6 KiB
Haskell

{-# LANGUAGE CPP #-}
{-|
Atom implementation with fast conversions between bytestrings
and atoms.
-}
module Urbit.Atom
( Atom
, atomBytes
, bytesAtom
, atomWords
, wordsAtom
, utf8Atom
, atomUtf8
, atomUtf8Exn
, atomUtf8Lenient
)
where
import Prelude
import Data.ByteString (ByteString)
import Data.Vector.Primitive (Vector)
import GHC.Natural (Natural)
import qualified Data.Text as T
import qualified Data.Text.Encoding as T
import qualified Data.Text.Encoding.Error as T
#if defined(__GHCJS__)
import qualified Urbit.Atom.Slow as Slow
#endif
import qualified Urbit.Atom.Fast as A
--------------------------------------------------------------------------------
type Atom = Natural
-- Choose Implementation Based on Platform -------------------------------------
{- |
Convert an Atom to a bytestring. O(n), copies.
My hand-rolled implementation is faster, but doesn't work on GHCJS. So,
on GHCJS use GMP's `export` routine.
TODO GMP's `export` routine also handles big endian machines, so use
in that case too.
-}
atomBytes :: Atom -> ByteString
atomBytes =
#if defined(__GHCJS__)
A.exportBytes
#else
A.atomBytes
#endif
{- |
Convert a bytestring to an Atom. O(n), copies.
This always uses GMP's `export` routine, since it's portable and faster
than my hand-rolled implementation.
-}
bytesAtom :: ByteString -> Atom
bytesAtom = A.importBytes
{- |
Cast an atom to a vector. O(1), does not copy.
My fast implementation doesn't work on GHCJS, so fallback to the naive
implementation on that platform for now.
-}
atomWords :: Atom -> Vector Word
atomWords =
#if defined(__GHCJS__)
Slow.atomWords
#else
A.atomWords
#endif
{- |
Cast a vector to an atom. O(1), does not copy unless given a slice,
then O(n).
My fast implementation doesn't work on GHCJS, so fallback to the naive
implementation on that platform for now.
-}
wordsAtom :: Vector Word -> Atom
wordsAtom =
#if defined(__GHCJS__)
Slow.wordsAtom
#else
A.wordsAtom
#endif
-- String/Cord Conversion ------------------------------------------------------
-- | Encode a utf8-encoded atom from text.
utf8Atom :: T.Text -> Atom
utf8Atom = bytesAtom . T.encodeUtf8
-- | Interpret an atom as utf8 text.
atomUtf8 :: Atom -> Either T.UnicodeException T.Text
atomUtf8 = T.decodeUtf8' . atomBytes
-- | Interpret an atom as utf8 text, throwing an exception on bad unicode.
atomUtf8Exn :: Atom -> T.Text
atomUtf8Exn = T.decodeUtf8 . atomBytes
-- | Interpret an atom as utf8 text, replacing bad unicode characters.
atomUtf8Lenient :: Atom -> T.Text
atomUtf8Lenient = T.decodeUtf8With T.lenientDecode . atomBytes