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|
{-# LANGUAGE ForeignFunctionInterface #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
-- |
-- Module : Data.Text.ICU.Iterator
-- Copyright : (c) 2010 Bryan O'Sullivan
--
-- License : BSD-style
-- Maintainer : bos@serpentine.com
-- Stability : experimental
-- Portability : GHC
--
-- Iteration functions for Unicode, implemented as bindings to the
-- International Components for Unicode (ICU) libraries.
--
-- Unlike the C and C++ @UCharIterator@ type, the Haskell
-- 'CharIterator' type is immutable, and can safely be used in pure
-- code.
--
-- Functions using these iterators may be more efficient than their
-- counterparts. For instance, the 'CharIterator' type allows a UTF-8
-- 'ByteString' to be compared against a 'Text', without first
-- converting the 'ByteString':
--
-- > fromUtf8 bs == fromText t
module Data.Text.ICU.Iterator
(
-- * Types and constructors
CharIterator
, fromString
, fromText
, fromUtf8
) where
import Data.ByteString (ByteString)
import Data.Int (Int32)
import Data.Text (Text, pack)
import Data.Text.ICU.Internal (CharIterator(..), UCharIterator, asOrdering,
withCharIterator)
import Foreign.Ptr (Ptr)
import System.IO.Unsafe (unsafePerformIO)
instance Eq CharIterator where
a == b = compareIter a b == EQ
instance Ord CharIterator where
compare = compareIter
-- | Compare two 'CharIterator's.
compareIter :: CharIterator -> CharIterator -> Ordering
compareIter a b = unsafePerformIO . fmap asOrdering .
withCharIterator a $ withCharIterator b . u_strCompareIter
-- | Construct a 'CharIterator' from a Unicode string.
fromString :: String -> CharIterator
fromString = CIText . pack
{-# INLINE fromString #-}
-- | Construct a 'CharIterator' from a Unicode string.
fromText :: Text -> CharIterator
fromText = CIText
{-# INLINE fromText #-}
-- | Construct a 'CharIterator' from a Unicode string encoded as a
-- UTF-8 'ByteString'.
fromUtf8 :: ByteString -> CharIterator
fromUtf8 = CIUTF8
{-# INLINE fromUtf8 #-}
foreign import ccall unsafe "hs_text_icu.h __hs_u_strCompareIter" u_strCompareIter
:: Ptr UCharIterator -> Ptr UCharIterator -> IO Int32
|
