    {-# LINE 2 "./System/GIO/Async/Cancellable.chs" #-}
    -- GIMP Toolkit (GTK) Binding for Haskell: binding to gio -*-haskell-*-
    --
    -- Author : Peter Gavin
    -- Created: 13-Oct-2008
    --
    -- Copyright (c) 2008 Peter Gavin
    --
    -- 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 3 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.
    --
    -- You should have received a copy of the GNU Lesser General Public
    -- License along with this program. If not, see
    -- <http:
    --
    -- GIO, the C library which this Haskell library depends on, is
    -- available under LGPL Version 2. The documentation included with
    -- this library is based on the original GIO documentation.
    --
    -- | Maintainer : gtk2hs-devel@lists.sourceforge.net
    -- Stability : alpha
    -- Portability : portable (depends on GHC)
    module System.GIO.Async.Cancellable (
    -- * Details
    -- | 'Cancellable' is a thread-safe operation cancellation stack used throughout GIO to allow for
    -- cancellation of synchronous and asynchronous operations.

    -- * Types
        Cancellable (..),
        CancellableClass,

    -- * Methods
        cancellableNew,
        cancellableIsCancelled,
        cancellableThrowErrorIfCancelled,
        cancellableGetCurrent,
        cancellablePopCurrent,
        cancellablePushCurrent,
        cancellableReset,
        cancellableCancel,

    -- * Signals
        cancellableCancelled
        ) where

    import Control.Monad
    import Data.Maybe (fromMaybe)
    import System.Glib.FFI
    import System.Glib.GError
    import System.Glib.GObject
    import System.Glib.Signals
    import System.GIO.Signals
    {-# LINE 60 "./System/GIO/Async/Cancellable.chs" #-}
    import System.GIO.Types
    {-# LINE 61 "./System/GIO/Async/Cancellable.chs" #-}

    {-# LINE 63 "./System/GIO/Async/Cancellable.chs" #-}

    -- | Creates a new 'Cancellable' object.
    --
    -- Applications that want to start one or more operations that should be cancellable should create a
    -- 'Cancellable' and pass it to the operations.
    --
    -- One 'Cancellable' can be used in multiple consecutive operations, but not in multiple concurrent
    -- operations.
    cancellableNew :: IO Cancellable
    cancellableNew =
        wrapNewGObject mkCancellable $
        g_cancellable_new
    {-# LINE 75 "./System/GIO/Async/Cancellable.chs" #-}

    -- | Checks if a cancellable job has been cancelled.
    cancellableIsCancelled :: Cancellable
     -> IO Bool -- ^ returns 'True' if cancellable is cancelled, 'False' if called with 'Nothing' or if item is not cancelled.
    cancellableIsCancelled =
        liftM toBool . (\(Cancellable arg1) -> withForeignPtr arg1 $ \argPtr1 ->g_cancellable_is_cancelled argPtr1)
    {-# LINE 81 "./System/GIO/Async/Cancellable.chs" #-}

    -- | If the cancellable is cancelled, throws a 'GError' to notify that the operation was cancelled.
    cancellableThrowErrorIfCancelled :: Cancellable -> IO ()
    cancellableThrowErrorIfCancelled cancellable =
        propagateGError $ \gErrorPtr -> do
          (\(Cancellable arg1) arg2 -> withForeignPtr arg1 $ \argPtr1 ->g_cancellable_set_error_if_cancelled argPtr1 arg2) cancellable gErrorPtr
          return ()

    -- | Gets the top cancellable from the stack.
    cancellableGetCurrent ::
      IO (Maybe Cancellable) -- ^ returns a 'Cancellable' from the top of the stack, or 'Nothing' if the stack is empty.
    cancellableGetCurrent =
        maybeNull (makeNewGObject mkCancellable) $
        g_cancellable_get_current
    {-# LINE 95 "./System/GIO/Async/Cancellable.chs" #-}

    -- | Pops cancellable off the cancellable stack (verifying that cancellable is on the top of the stack).
    cancellablePopCurrent :: Maybe Cancellable -> IO ()
    cancellablePopCurrent cancellable =
          (\(Cancellable arg1) -> withForeignPtr arg1 $ \argPtr1 ->g_cancellable_pop_current argPtr1)
    {-# LINE 100 "./System/GIO/Async/Cancellable.chs" #-}
             (fromMaybe (Cancellable nullForeignPtr) cancellable)

    -- | Pushes cancellable onto the cancellable stack. The current cancllable can then be recieved using
    -- 'cancellableGetCurrent' .
    --
    -- This is useful when implementing cancellable operations in code that does not allow you to pass down
    -- the cancellable object.
    --
    -- This is typically called automatically by e.g. 'File' operations, so you rarely have to call this
    -- yourself.
    cancellablePushCurrent :: Maybe Cancellable -> IO ()
    cancellablePushCurrent cancellable =
          (\(Cancellable arg1) -> withForeignPtr arg1 $ \argPtr1 ->g_cancellable_push_current argPtr1)
    {-# LINE 113 "./System/GIO/Async/Cancellable.chs" #-}
             (fromMaybe (Cancellable nullForeignPtr) cancellable)

    -- | Resets cancellable to its uncancelled state.
    cancellableReset :: Cancellable -> IO ()
    cancellableReset = (\(Cancellable arg1) -> withForeignPtr arg1 $ \argPtr1 ->g_cancellable_reset argPtr1)
    {-# LINE 118 "./System/GIO/Async/Cancellable.chs" #-}

    -- | Will set cancellable to cancelled, and will emit the "cancelled" signal. (However, see the warning
    -- about race conditions in the documentation for that signal if you are planning to connect to it.)
    --
    -- This function is thread-safe. In other words, you can safely call it from a thread other than the
    -- one running the operation that was passed the cancellable.
    --
    -- The convention within gio is that cancelling an asynchronous operation causes it to complete
    -- asynchronously. That is, if you cancel the operation from the same thread in which it is running,
    -- then the operation's 'AsyncReadyCallback' will not be invoked until the application returns to the
    -- main loop.
    cancellableCancel :: Cancellable -> IO ()
    cancellableCancel = (\(Cancellable arg1) -> withForeignPtr arg1 $ \argPtr1 ->g_cancellable_cancel argPtr1)
    {-# LINE 131 "./System/GIO/Async/Cancellable.chs" #-}

    -- | Emitted when the operation has been cancelled.
    --
    -- Can be used by implementations of cancellable operations. If the operation is cancelled from another
    -- thread, the signal will be emitted in the thread that cancelled the operation, not the thread that
    -- is running the operation.
    --
    -- Note that disconnecting from this signal (or any signal) in a multi-threaded program is prone to
    -- race conditions. For instance it is possible that a signal handler may be invoked even after a call
    -- to 'signalHandlerDisconnect' for that handler has already returned.
    --
    -- There is also a problem when cancellation happen right before connecting to the signal. If this
    -- happens the signal will unexpectedly not be emitted, and checking before connecting to the signal
    -- leaves a race condition where this is still happening.
    cancellableCancelled :: Signal Cancellable (IO ())
    cancellableCancelled =
        Signal $ connect_NONE__NONE "cancelled"

    foreign import ccall safe "g_cancellable_new"
      g_cancellable_new :: (IO (Ptr Cancellable))

    foreign import ccall safe "g_cancellable_is_cancelled"
      g_cancellable_is_cancelled :: ((Ptr Cancellable) -> (IO CInt))

    foreign import ccall safe "g_cancellable_set_error_if_cancelled"
      g_cancellable_set_error_if_cancelled :: ((Ptr Cancellable) -> ((Ptr (Ptr ())) -> (IO CInt)))

    foreign import ccall safe "g_cancellable_get_current"
      g_cancellable_get_current :: (IO (Ptr Cancellable))

    foreign import ccall safe "g_cancellable_pop_current"
      g_cancellable_pop_current :: ((Ptr Cancellable) -> (IO ()))

    foreign import ccall safe "g_cancellable_push_current"
      g_cancellable_push_current :: ((Ptr Cancellable) -> (IO ()))

    foreign import ccall safe "g_cancellable_reset"
      g_cancellable_reset :: ((Ptr Cancellable) -> (IO ()))

    foreign import ccall safe "g_cancellable_cancel"
      g_cancellable_cancel :: ((Ptr Cancellable) -> (IO ()))