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|
-- -*-haskell-*-
-- GIMP Toolkit (GTK)
--
-- Author : Axel Simon
--
-- Created: 19 March 2002
--
-- Copyright (C) 2002 Axel Simon
--
-- This library is free software; you can redistribute it and/or
-- modify it under the terms of the GNU Lesser General Public
-- License as published by the Free Software Foundation; either
-- version 2.1 of the License, or (at your option) any later version.
--
-- This library 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
-- Lesser General Public License for more details.
--
-- |
-- Maintainer : gtk2hs-users@lists.sourceforge.net
-- Stability : provisional
-- Portability : portable (depends on GHC)
--
-- Defines functions to extract data from a GList and to produce a GList from
-- a list of pointers.
--
-- * The same for GSList.
--
module System.Glib.GList (
GList,
readGList,
fromGList,
toGList,
withGList,
GSList,
readGSList,
fromGSList,
fromGSListRev,
toGSList,
withGSList,
) where
import Foreign
import Control.Exception (bracket)
import Control.Monad (foldM)
{# context lib="glib" prefix="g" #}
{#pointer * GList#}
{#pointer * GSList#}
-- methods
-- Turn a GList into a list of pointers but don't destroy the list.
--
readGList :: GList -> IO [Ptr a]
readGList glist
| glist==nullPtr = return []
| otherwise = do
x <- {#get GList->data#} glist
glist' <- {#get GList->next#} glist
xs <- readGList glist'
return (castPtr x:xs)
-- Turn a GList into a list of pointers (freeing the GList in the process).
--
fromGList :: GList -> IO [Ptr a]
fromGList glist = do
glist' <- {#call unsafe list_reverse#} glist
extractList glist' []
where
extractList gl xs
| gl==nullPtr = return xs
| otherwise = do
x <- {#get GList.data#} gl
gl' <- {#call unsafe list_delete_link#} gl gl
extractList gl' (castPtr x:xs)
-- Turn a GSList into a list of pointers but don't destroy the list.
--
readGSList :: GSList -> IO [Ptr a]
readGSList gslist
| gslist==nullPtr = return []
| otherwise = do
x <- {#get GSList->data#} gslist
gslist' <- {#get GSList->next#} gslist
xs <- readGSList gslist'
return (castPtr x:xs)
-- Turn a GSList into a list of pointers (freeing the GSList in the process).
--
fromGSList :: GSList -> IO [Ptr a]
fromGSList gslist
| gslist==nullPtr = return []
| otherwise = do
x <- {#get GSList->data#} gslist
gslist' <- {#call unsafe slist_delete_link#} gslist gslist
xs <- fromGSList gslist'
return (castPtr x:xs)
-- Turn a GSList into a list of pointers and reverse it.
--
fromGSListRev :: GSList -> IO [Ptr a]
fromGSListRev gslist =
extractList gslist []
where
extractList gslist xs
| gslist==nullPtr = return xs
| otherwise = do
x <- {#get GSList->data#} gslist
gslist' <- {#call unsafe slist_delete_link#} gslist gslist
extractList gslist' (castPtr x:xs)
-- Turn a list of something into a GList.
--
toGList :: [Ptr a] -> IO GList
toGList = foldM prepend nullPtr . reverse
where
-- prepend :: GList -> Ptr a -> IO GList
prepend l x = {#call unsafe list_prepend#} l (castPtr x)
-- Turn a list of something into a GSList.
--
toGSList :: [Ptr a] -> IO GSList
toGSList = foldM prepend nullPtr . reverse
where
-- prepend :: GSList -> Ptr a -> IO GList
prepend l x = {#call unsafe slist_prepend#} l (castPtr x)
-- Temporarily allocate a list of something
--
withGList :: [Ptr a] -> (GSList -> IO b) -> IO b
withGList xs = bracket (toGList xs) {# call unsafe g_list_free #}
-- Temporarily allocate a list of something
--
withGSList :: [Ptr a] -> (GSList -> IO b) -> IO b
withGSList xs = bracket (toGSList xs) {# call unsafe g_slist_free #}
|
