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|
{-# LANGUAGE EmptyDataDecls, BangPatterns, ForeignFunctionInterface, RecordWildCards #-}
-- |
-- Module : Data.Text.ICU.Calendar
-- Copyright : (c) 2021 Torsten Kemps-Benedix
--
-- License : BSD-style
-- Maintainer : bos@serpentine.com
-- Stability : experimental
-- Portability : GHC
--
-- Calendar functions implemented as bindings to
-- the International Components for Unicode (ICU) libraries.
module Data.Text.ICU.Enumerator
(next, toList, createEnumerator, Enumerator, UEnumerator,
) where
#include <unicode/uenum.h>
import Data.Int (Int32)
import Data.Text (Text)
import Data.Text.ICU.Error.Internal (UErrorCode, handleError)
import Data.Text.ICU.Internal (UChar, newICUPtr, fromUCharPtr)
import Foreign.ForeignPtr (withForeignPtr, ForeignPtr)
import Foreign.Marshal.Alloc (alloca)
import Foreign.Ptr (FunPtr, Ptr, nullPtr)
import Foreign.Storable (peek)
import Prelude hiding (last)
data UEnumerator
newtype Enumerator = Enumerator {enumeratorToForeignPtr :: ForeignPtr UEnumerator}
createEnumerator :: IO (Ptr UEnumerator) -> IO Enumerator
createEnumerator = newICUPtr Enumerator uenum_close
next :: Enumerator -> IO (Maybe Text)
next enum = withForeignPtr (enumeratorToForeignPtr enum) $ \enumPtr ->
alloca $ \lenPtr -> do
textPtr <- handleError $ uenum_unext enumPtr lenPtr
if textPtr == nullPtr
then pure Nothing
else do
n <- peek lenPtr
t <- fromUCharPtr textPtr (fromIntegral n)
pure $ Just t
toList :: Enumerator -> IO [Text]
toList enum = reverse <$> go []
where
go l = do
mx <- next enum
case mx of
Nothing -> pure l
Just x -> go (x:l)
foreign import ccall unsafe "hs_text_icu.h &__hs_uenum_close" uenum_close
:: FunPtr (Ptr UEnumerator -> IO ())
foreign import ccall unsafe "hs_text_icu.h __hs_uenum_unext" uenum_unext
:: Ptr UEnumerator -> Ptr Int32 -> Ptr UErrorCode
-> IO (Ptr UChar)
|
