ReplayBloc<Event extends ReplayEvent, State> class abstract

A specialized Bloc which supports undo and redo operations.

ReplayBloc accepts an optional limit which determines the max size of the history.

A custom ReplayBloc can be created by extending ReplayBloc.

abstract class CounterEvent {}
class CounterIncrementPressed extends CounterEvent {}

class CounterBloc extends ReplayBloc<CounterEvent, int> {
  CounterBloc() : super(0) {
    on<CounterIncrementPressed>((event, emit) => emit(state + 1));
  }
}

Then the built-in undo and redo operations can be used.

final bloc = CounterBloc();

bloc.add(CounterIncrementPressed());

bloc.undo();

bloc.redo();

The undo/redo history can be destroyed at any time by calling clear.

See also:

Inheritance
Mixed in types

Constructors

ReplayBloc(State state, {int? limit})
A specialized Bloc which supports undo and redo operations.

Properties

canRedo → bool
Checks wether the undo/redo stack is at the current change.
no setterinherited
canUndo → bool
Checks whether the undo/redo stack is empty.
no setterinherited
hashCode → int
The hash code for this object.
no setterinherited
isClosed → bool
Whether the bloc is closed.
no setterinherited
limit ← int
Sets the internal undo/redo size limit. By default there is no limit.
no getterinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
state → State
The current state.
no setterinherited
stream → Stream<State>
The current stream of states.
no setterinherited

Methods

add(Event event) → void
Notifies the Bloc of a new event which triggers all corresponding EventHandler instances.
inherited
addError(Object error, [StackTrace? stackTrace]) → void
Reports an error which triggers onError with an optional StackTrace.
inherited
clearHistory() → void
Clear undo/redo history.
inherited
close() → Future<void>
Closes the event and state Streams. This method should be called when a Bloc is no longer needed. Once close is called, events that are added will not be processed. In addition, if close is called while events are still being processed, the Bloc will finish processing the pending events.
inherited
emit(State state) → void
emit is only for internal use and should never be called directly outside of tests. The Emitter instance provided to each EventHandler should be used instead.
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
on<E extends Event>(EventHandler<E, State> handler, {EventTransformer<E>? transformer}) → void
Register event handler for an event of type E. There should only ever be one event handler per event type E.
inherited
onChange(Change<State> change) → void
Called whenever a change occurs with the given change. A change occurs when a new state is emitted. onChange is called before the state of the cubit is updated. onChange is a great spot to add logging/analytics for a specific cubit.
inherited
onError(Object error, StackTrace stackTrace) → void
Called whenever an error occurs and notifies BlocObserver.onError.
inherited
onEvent(covariant ReplayEvent event) → void
Called whenever an event is added to the Bloc. A great spot to add logging/analytics at the individual Bloc level.
inherited
onTransition(covariant Transition<ReplayEvent, State> transition) → void
Called whenever a transition occurs with the given transition. A transition occurs when a new event is added and a new state is emitted from a corresponding EventHandler.
inherited
redo() → void
Redo the previous change.
inherited
shouldReplay(State state) → bool
Checks whether the given state should be replayed from the undo/redo stack.
inherited
toString() → String
A string representation of this object.
inherited
undo() → void
Undo the last change.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited