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|
{-# LANGUAGE CPP, MagicHash, Rank2Types, TypeFamilies, BangPatterns, TypeOperators #-}
-- |
-- Module : Data.Double.Conversion.Text
-- Copyright : (c) 2011 MailRank, Inc.
--
-- License : BSD-style
-- Maintainer : bos@serpentine.com
-- Stability : experimental
-- Portability : GHC
--
-- Fast, efficient support for converting between double precision
-- floating point values and text.
--
-- These functions are about 30 times faster than the default 'show'
-- implementation for the 'Double' type.
module Data.Double.Conversion.Internal.Text
(
convert
) where
import Control.Monad (when)
#if MIN_VERSION_base(4,4,0)
import Control.Monad.ST.Unsafe (unsafeIOToST)
#else
import Control.Monad.ST (unsafeIOToST)
#endif
import Control.Monad.ST (ST, runST)
import Data.Double.Conversion.Internal.FFI (ForeignFloating)
import qualified Data.Text.Array as A
import Data.Text.Internal (Text(Text))
import Foreign.C.Types (CDouble, CFloat, CInt)
import GHC.Prim (MutableByteArray#)
convert :: (RealFloat a, RealFloat b, b ~ ForeignFloating a) => String -> CInt
-> (forall s. b -> MutableByteArray# s -> IO CInt)
-> a -> Text
{-# SPECIALIZE convert :: String -> CInt -> (forall s. CDouble -> MutableByteArray# s -> IO CInt) -> Double -> Text #-}
{-# SPECIALIZE convert :: String -> CInt -> (forall s. CFloat -> MutableByteArray# s -> IO CInt) -> Float -> Text #-}
{-# INLINABLE convert #-}
convert func len act val = runST go
where
go :: (forall s. ST s Text)
go = do
buf <- A.new (fromIntegral len)
#if MIN_VERSION_text(2,0,0)
let !(A.MutableByteArray ma) = buf
#else
let ma = A.maBA buf
#endif
size <- unsafeIOToST $ act (realToFrac val) ma
when (size == -1) .
error $ "Data.Double.Conversion.Text." ++ func ++
": conversion failed (invalid precision requested)"
frozen <- A.unsafeFreeze buf
return $ Text frozen 0 (fromIntegral size)
|
