async

Add support for Dart 2.0 library changes to Stream and StreamTransformer. Changed classes that implement StreamTransformer to extend StreamTransformerBase, and changed signatures of firstWhere, lastWhere, and singleWhere on classes extending Stream. See also issue 31847.

Remove deprecated public result.dart and stream_zip.dart libraries and deprecated classes ReleaseStreamTransformer and CaptureStreamTransformer.

Add captureAll and flattenList static methods to Result.

Change ErrorResult to not be generic and always be a Result<Null>. That makes an error independent of the type of result it occurs instead of.

Add collectBytes and collectBytesCancelable functions which collects list-of-byte events into a single byte list.

Fix a bug where rejecting a StreamQueueTransaction would throw a StateError if StreamQueue.rest had been called on one of its child queues.

StreamQueue.withTransaction() now properly returns whether or not the transaction was committed.

Add an AsyncCache class that caches asynchronous operations for a period of time.

Add StreamQueue.peek and StreamQueue.lookAheead. These allow users to look at events without consuming them.

Add StreamQueue.startTransaction() and StreamQueue.withTransaction(). These allow users to conditionally consume events based on their values.

Add StreamQueue.cancelable(), which allows users to easily make a CancelableOperation that can be canceled without affecting the queue.

Add StreamQueue.eventsDispatched which counts the number of events that have been dispatched by a given queue.

Add a subscriptionTransformer() function to create StreamTransformers that modify the behavior of subscriptions to a stream.

Add a typedStreamTransformer() function. This wraps an untyped StreamTransformer with the correct type parameters, and asserts the types of events as they're emitted from the transformed stream.

Add a StreamSinkTransformer.typed() static method. This wraps an untyped StreamSinkTransformer with the correct type parameters, and asserts the types of arguments passed in to the resulting sink.

Add DelegatingFuture.typed(), DelegatingStreamSubscription.typed(), DelegatingStreamConsumer.typed(), DelegatingSink.typed(), DelegatingEventSink.typed(), and DelegatingStreamSink.typed() static methods. These wrap untyped instances of these classes with the correct type parameter, and assert the types of values as they're accessed.

Add a DelegatingStream class. This is behaviorally identical to StreamView from dart:async, but it follows this package's naming conventions and provides a DelegatingStream.typed() static method.

Fix all strong mode warnings and add generic method annotations.

new StreamQueue(), new SubscriptionStream(), new DelegatingStreamSubscription(), new DelegatingStreamConsumer(), new DelegatingSink(), new DelegatingEventSink(), and new DelegatingStreamSink() now take arguments with generic type arguments (for example Stream<T>) rather than without (for example Stream<dynamic>). Passing a type that wasn't is-compatible with the fully-specified generic would already throw an error under some circumstances, so this is not considered a breaking change.

ErrorResult now takes a type parameter.

Result.asError now returns a Result<T>.

Deprecate top-level libraries other than package:async/async.dart, which exports these libraries' interfaces.

Add Result.captureStreamTransformer, Result.releaseStreamTransformer, Result.captureSinkTransformer, and Result.releaseSinkTransformer.

Deprecate CaptureStreamTransformer, ReleaseStreamTransformer, CaptureSink, and ReleaseSink. Result.captureStreamTransformer, Result.releaseStreamTransformer, Result.captureSinkTransformer, and Result.releaseSinkTransformer should be used instead.

Added StreamSinkCompleter, for creating a StreamSink now and providing its destination later as another sink.

Added StreamCompleter.setError, a shortcut for emitting a single error event on the resulting stream.

Added NullStreamSink, an implementation of StreamSink that discards all events.

Added CancelableOperation.valueOrCancellation(), which allows users to be notified when an operation is canceled elsewhere.

Added StreamSinkTransformer which transforms events before they're passed to a StreamSink, similarly to how StreamTransformer transforms events after they're emitted by a stream.

Added AsyncMemoizer.future, which allows the result to be accessed before runOnce() is called.

Added CancelableOperation, an asynchronous operation that can be canceled. It can be created using a CancelableCompleter.

Added RestartableTimer, a non-periodic timer that can be reset over and over.

Added StreamCompleter class for creating a stream now and providing its events later as another stream.

Added StreamQueue class which allows requesting events from a stream before they are avilable. It is like a StreamIterator that can queue requests.

Added SubscriptionStream which creates a single-subscription stream from an existing stream subscription.

Added a ResultFuture class for synchronously accessing the result of a wrapped future.

Added FutureGroup.onIdle and FutureGroup.isIdle, which provide visibility into whether a group is actively waiting on any futures.

Add an AsyncMemoizer class for running an asynchronous block of code exactly once.

Added delegating wrapper classes for a number of core async types: DelegatingFuture, DelegatingStreamConsumer, DelegatingStreamController, DelegatingSink, DelegatingEventSink, DelegatingStreamSink, and DelegatingStreamSubscription. These are all simple wrappers that forward all calls to the wrapped objects. They can be used to expose only the desired interface for subclasses, or extended to add extra functionality.

Added a FutureGroup class for waiting for a group of futures, potentially of unknown size, to complete.

Added a StreamGroup class for merging the events of a group of streams, potentially of unknown size.

Added a StreamSplitter class for splitting a stream into multiple new streams.