Copyright | Will Thompson and Iñaki García Etxebarria |
---|---|
License | LGPL-2.1 |
Maintainer | Iñaki García Etxebarria |
Safe Haskell | None |
Language | Haskell2010 |
GSeekable
is implemented by streams (implementations of
InputStream
or OutputStream
) that support seeking.
Seekable streams largely fall into two categories: resizable and fixed-size.
GSeekable
on fixed-sized streams is approximately the same as POSIX
`lseek()`) on a block device (for example: attempting to seek
past the end of the device is an error). Fixed streams typically cannot be
truncated.
GSeekable
on resizable streams is approximately the same as POSIX
`lseek()`) on a normal file. Seeking past the end and writing
data will usually cause the stream to resize by introducing zero bytes.
Synopsis
- newtype Seekable = Seekable (ManagedPtr Seekable)
- class (GObject o, IsDescendantOf Seekable o) => IsSeekable o
- toSeekable :: (MonadIO m, IsSeekable o) => o -> m Seekable
- seekableCanSeek :: (HasCallStack, MonadIO m, IsSeekable a) => a -> m Bool
- seekableCanTruncate :: (HasCallStack, MonadIO m, IsSeekable a) => a -> m Bool
- seekableSeek :: (HasCallStack, MonadIO m, IsSeekable a, IsCancellable b) => a -> Int64 -> SeekType -> Maybe b -> m ()
- seekableTell :: (HasCallStack, MonadIO m, IsSeekable a) => a -> m Int64
- seekableTruncate :: (HasCallStack, MonadIO m, IsSeekable a, IsCancellable b) => a -> Int64 -> Maybe b -> m ()
Exported types
Memory-managed wrapper type.
Instances
Eq Seekable Source # | |
GObject Seekable Source # | |
Defined in GI.Gio.Interfaces.Seekable | |
ManagedPtrNewtype Seekable Source # | |
Defined in GI.Gio.Interfaces.Seekable toManagedPtr :: Seekable -> ManagedPtr Seekable # | |
TypedObject Seekable Source # | |
Defined in GI.Gio.Interfaces.Seekable | |
HasParentTypes Seekable Source # | |
Defined in GI.Gio.Interfaces.Seekable | |
IsGValue (Maybe Seekable) Source # | Convert |
Defined in GI.Gio.Interfaces.Seekable | |
type ParentTypes Seekable Source # | |
Defined in GI.Gio.Interfaces.Seekable type ParentTypes Seekable = '[Object] |
class (GObject o, IsDescendantOf Seekable o) => IsSeekable o Source #
Type class for types which can be safely cast to Seekable
, for instance with toSeekable
.
Instances
(GObject o, IsDescendantOf Seekable o) => IsSeekable o Source # | |
Defined in GI.Gio.Interfaces.Seekable |
toSeekable :: (MonadIO m, IsSeekable o) => o -> m Seekable Source #
Methods
Click to display all available methods, including inherited ones
Methods
bindProperty, bindPropertyFull, canSeek, canTruncate, forceFloating, freezeNotify, getv, isFloating, notify, notifyByPspec, ref, refSink, runDispose, seek, stealData, stealQdata, tell, thawNotify, truncate, unref, watchClosure.
Getters
getData, getProperty, getQdata.
Setters
canSeek
:: (HasCallStack, MonadIO m, IsSeekable a) | |
=> a |
|
-> m Bool |
Tests if the stream supports the SeekableIface
.
canTruncate
:: (HasCallStack, MonadIO m, IsSeekable a) | |
=> a |
|
-> m Bool | Returns: |
Tests if the length of the stream can be adjusted with
seekableTruncate
.
seek
:: (HasCallStack, MonadIO m, IsSeekable a, IsCancellable b) | |
=> a |
|
-> Int64 |
|
-> SeekType |
|
-> Maybe b |
|
-> m () | (Can throw |
Seeks in the stream by the given offset
, modified by type
.
Attempting to seek past the end of the stream will have different results depending on if the stream is fixed-sized or resizable. If the stream is resizable then seeking past the end and then writing will result in zeros filling the empty space. Seeking past the end of a resizable stream and reading will result in EOF. Seeking past the end of a fixed-sized stream will fail.
Any operation that would result in a negative offset will fail.
If cancellable
is not Nothing
, then the operation can be cancelled by
triggering the cancellable object from another thread. If the operation
was cancelled, the error IOErrorEnumCancelled
will be returned.
tell
:: (HasCallStack, MonadIO m, IsSeekable a) | |
=> a |
|
-> m Int64 | Returns: the (positive or zero) offset from the beginning of the buffer, zero if the target is not seekable. |
Tells the current position within the stream.
truncate
:: (HasCallStack, MonadIO m, IsSeekable a, IsCancellable b) | |
=> a |
|
-> Int64 |
|
-> Maybe b |
|
-> m () | (Can throw |
Sets the length of the stream to offset
. If the stream was previously
larger than offset
, the extra data is discarded. If the stream was
previously shorter than offset
, it is extended with NUL ('\0') bytes.
If cancellable
is not Nothing
, then the operation can be cancelled by
triggering the cancellable object from another thread. If the operation
was cancelled, the error IOErrorEnumCancelled
will be returned. If an
operation was partially finished when the operation was cancelled the
partial result will be returned, without an error.