A controller with the stream it controls.
This controller allows sending data, error and done events on its stream. This class can be used to create a simple stream that others can listen on, and to push events to that stream.
It's possible to check whether the stream is paused or not, and whether it has subscribers or not, as well as getting a callback when either of these change.
If the stream starts or stops having listeners (first listener subscribing,
last listener unsubscribing), the onSubscriptionStateChange callback
is notified as soon as possible. If the subscription stat changes during
an event firing or a callback being executed, the change will not be reported
until the current event or callback has finished.
If the pause state has also changed during an event or callback, only the
subscription state callback is notified.
If the subscriber state has not changed, but the pause state has, the
onPauseStateChange callback is notified as soon as possible, after firing
a current event or completing another callback. This happens if the stream
is not paused, and a listener pauses it, or if the stream has been resumed
from pause and has no pending events. If the listeners resume a paused stream
while it still has queued events, the controller will still consider the
stream paused until all queued events have been dispatched.
Whether to invoke a callback depends only on the state before and after a stream action, for example firing an event. If the state changes multiple times during the action, and then ends up in the same state as before, no callback is performed.
If listeners are added after the stream has completed (sent a "done" event), the listeners will be sent a "done" event eventually, but they won't affect the stream at all, and won't trigger callbacks. From the controller's point of view, the stream is completely inert when has completed.
- Implements
-
- StreamSink<T>
- Implemented by
Constructors
- StreamController({void onListen(), void onPause(), void onResume(), dynamic onCancel(), bool sync: false })
-
A controller with a stream that supports only one single subscriber.
factory - StreamController.broadcast({void onListen(), void onCancel(), bool sync: false })
-
A controller where stream can be listened to more than once.
factory
Properties
- hasListener → bool
-
Whether there is a subscriber on the
Stream.read-only - isClosed → bool
-
Whether the stream controller is closed for adding more events.
read-only - isPaused → bool
-
Whether the subscription would need to buffer events.
read-only - onCancel → ControllerCancelCallback
-
The callback which is called when the stream is canceled.
read / write - onListen → ControllerCallback
-
The callback which is called when the stream is listened to.
read / write - onPause → ControllerCallback
-
The callback which is called when the stream is paused.
read / write - onResume → ControllerCallback
-
The callback which is called when the stream is resumed.
read / write - sink → StreamSink<T>
-
Returns a view of this object that only exposes the
StreamSinkinterface.read-only - stream → Stream<T>
-
The stream that this controller is controlling.
read-only - done → Future
-
Return a future which is completed when the
StreamSinkis finished.read-only, inherited - hashCode → int
-
The hash code for this object.
read-only, inherited - runtimeType → Type
-
A representation of the runtime type of the object.
read-only, inherited
Operators
-
operator ==(
other) → bool -
The equality operator.
inherited
Methods
-
add(
T event) → void -
Sends a data
event. -
addError(
Object error, [ StackTrace stackTrace ]) → void -
Sends or enqueues an error event.
-
addStream(
Stream<T> source, { bool cancelOnError: true }) → Future -
Receives events from
sourceand puts them into this controller's stream. -
close(
) → Future -
Closes the stream.
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a non-existent method or property is accessed.
inherited -
toString(
) → String -
Returns a string representation of this object.
inherited