-- GENERATED by C->Haskell Compiler, version 0.16.4 Crystal Seed, 24 Jan 2009 (Haskell)
-- Edit the ORIGNAL .chs file instead!


{-# LINE 1 "lib/CPython/Protocols/Iterator.chs" #-}{-# LANGUAGE ForeignFunctionInterface #-}

-- Copyright (C) 2009 John Millikin <jmillikin@gmail.com>
--
-- This program is free software: you can redistribute it and/or modify
-- it under the terms of the GNU General Public License as published by
-- the Free Software Foundation, either version 3 of the License, or
-- any later version.
--
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-- GNU General Public License for more details.
--
-- You should have received a copy of the GNU General Public License
-- along with this program.  If not, see <http://www.gnu.org/licenses/>.

module CPython.Protocols.Iterator
	( Iterator (..)
	, SomeIterator
	, castToIterator
	, next
	) where


import           CPython.Internal

-- | Attempt to convert an object to a generic 'Iterator'. If the object does
-- not implement the iterator protocol, returns 'Nothing'.
castToIterator :: Object a => a -> IO (Maybe SomeIterator)
castToIterator obj =
	withObject obj $ \objPtr -> do
	isIter <- fmap cToBool $ hscpythonPyIterCheck objPtr
	return $ if isIter
		then Just $ unsafeCastToIterator obj
		else Nothing

-- | Return the next value from the iteration, or 'Nothing' if there are no
-- remaining items.
next :: Iterator iter => iter -> IO (Maybe SomeObject)
next iter =
	withObject iter $ \iterPtr -> do
	raw <- pyIterNext iterPtr
	if raw == nullPtr
		then do
			err <- pyErrOccurred
{-# LINE 47 "lib/CPython/Protocols/Iterator.chs" #-}
			exceptionIf $ err /= nullPtr
			return Nothing
		else fmap Just $ stealObject raw

foreign import ccall safe "CPython/Protocols/Iterator.chs.h hscpython_PyIter_Check"
  hscpythonPyIterCheck :: ((Ptr ()) -> (IO CInt))

foreign import ccall safe "CPython/Protocols/Iterator.chs.h PyIter_Next"
  pyIterNext :: ((Ptr ()) -> (IO (Ptr ())))

foreign import ccall safe "CPython/Protocols/Iterator.chs.h PyErr_Occurred"
  pyErrOccurred :: (IO (Ptr ()))