LazyStream<T> class

A Stream wrapper that forwards to another Stream that's initialized lazily.

This class allows a concrete Stream to be created only once it has a listener. It's useful to wrapping APIs that do expensive computation to produce a Stream.

Inheritance
Available extensions

Constructors

LazyStream(FutureOr<Stream<T>> callback())
Creates a single-subscription Stream that calls callback when it gets a listener and forwards to the returned stream.

Properties

first → Future<T>
The first element of this stream.
no setterinherited
firstOrNull → Future<T?>

Available on Stream<T>, provided by the StreamExtensions extension

A future which completes with the first event of this stream, or with null.
no setter
hashCode → int
The hash code for this object.
no setterinherited
isBroadcast → bool
Whether this stream is a broadcast stream.
no setterinherited
isEmpty → Future<bool>
Whether this stream contains any elements.
no setterinherited
last → Future<T>
The last element of this stream.
no setterinherited
length → Future<int>
The number of elements in this stream.
no setterinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
single → Future<T>
The single element of this stream.
no setterinherited

Methods

any(bool test(T element)) → Future<bool>
Checks whether test accepts any element provided by this stream.
inherited
asBroadcastStream({void onListen(StreamSubscription<T> subscription)?, void onCancel(StreamSubscription<T> subscription)?}) → Stream<T>
Returns a multi-subscription stream that produces the same events as this.
inherited
asyncExpand<E>(Stream<E>? convert(T event)) → Stream<E>
Transforms each element into a sequence of asynchronous events.
inherited
asyncMap<E>(FutureOr<E> convert(T event)) → Stream<E>
Creates a new stream with each data event of this stream asynchronously mapped to a new event.
inherited
asyncMapBuffer<S>(Future<S> convert(List<T>)) → Stream<S>

Available on Stream<T>, provided by the AsyncMap extension

Like asyncMap but events are buffered until previous events have been processed by convert.
asyncMapSample<S>(Future<S> convert(T)) → Stream<S>

Available on Stream<T>, provided by the AsyncMap extension

Like asyncMap but events are discarded while work is happening in convert.
asyncWhere(FutureOr<bool> test(T)) → Stream<T>

Available on Stream<T>, provided by the Where extension

Discards events from this stream based on an asynchronous test callback.
audit(Duration duration) → Stream<T>

Available on Stream<T>, provided by the RateLimit extension

Audit a single event from each duration length period where there are events on this stream.
buffer(Stream<void> trigger, {bool longPoll = true}) → Stream<List<T>>

Available on Stream<T>, provided by the RateLimit extension

Buffers the values emitted on this stream and emits them when trigger emits an event.
cast<R>() → Stream<R>
Adapt this stream to be a Stream<R>.
inherited
combineLatest<T2, S>(Stream<T2> other, FutureOr<S> combine(T, T2)) → Stream<S>

Available on Stream<T>, provided by the CombineLatest extension

Combines the latest values from this stream with the latest values from other using combine.
combineLatestAll(Iterable<Stream<T>> others) → Stream<List<T>>

Available on Stream<T>, provided by the CombineLatest extension

Combine the latest value emitted from the source stream with the latest values emitted from others.
concurrentAsyncExpand<S>(Stream<S> convert(T)) → Stream<S>

Available on Stream<T>, provided by the AsyncExpand extension

Like asyncExpand but the convert callback may be called for an element before the Stream emitted by the previous element has closed.
concurrentAsyncMap<S>(FutureOr<S> convert(T)) → Stream<S>

Available on Stream<T>, provided by the AsyncMap extension

Like asyncMap but the convert callback may be called for an element before processing for the previous element is finished.
contains(Object? needle) → Future<bool>
Returns whether needle occurs in the elements provided by this stream.
inherited
debounce(Duration duration, {bool leading = false, bool trailing = true}) → Stream<T>

Available on Stream<T>, provided by the RateLimit extension

Suppresses events with less inter-event spacing than duration.
debounceBuffer(Duration duration) → Stream<List<T>>

Available on Stream<T>, provided by the RateLimit extension

Buffers values until this stream does not emit for duration then emits the collected values.
distinct([bool equals(T previous, T next)?]) → Stream<T>
Skips data events if they are equal to the previous data event.
inherited
drain<E>([E? futureValue]) → Future<E>
Discards all data on this stream, but signals when it is done or an error occurred.
inherited
elementAt(int index) → Future<T>
Returns the value of the indexth data event of this stream.
inherited
every(bool test(T element)) → Future<bool>
Checks whether test accepts all elements provided by this stream.
inherited
expand<S>(Iterable<S> convert(T element)) → Stream<S>
Transforms each element of this stream into a sequence of elements.
inherited
firstWhere(bool test(T element), {T orElse()?}) → Future<T>
Finds the first element of this stream matching test.
inherited
fold<S>(S initialValue, S combine(S previous, T element)) → Future<S>
Combines a sequence of values by repeatedly applying combine.
inherited
followedBy(Stream<T> next) → Stream<T>

Available on Stream<T>, provided by the Concatenate extension

Emits all values and errors from next following all values and errors from this stream.
forEach(void action(T element)) → Future<void>
Executes action on each element of this stream.
inherited
handleError(Function onError, {bool test(dynamic error)?}) → Stream<T>
Creates a wrapper Stream that intercepts some errors from this stream.
inherited
join([String separator = ""]) → Future<String>
Combines the string representation of elements into a single string.
inherited
lastWhere(bool test(T element), {T orElse()?}) → Future<T>
Finds the last element in this stream matching test.
inherited
listen(void onData(T)?, {Function? onError, void onDone()?, bool? cancelOnError}) → StreamSubscription<T>
Adds a subscription to this stream.
override
listenAndBuffer() → Stream<T>

Available on Stream<T>, provided by the StreamExtensions extension

Eagerly listens to this stream and buffers events until needed.
map<S>(S convert(T event)) → Stream<S>
Transforms each element of this stream into a new stream event.
inherited
merge(Stream<T> other) → Stream<T>

Available on Stream<T>, provided by the Merge extension

Merges values and errors from this stream and other in any order as they arrive.
mergeAll(Iterable<Stream<T>> others) → Stream<T>

Available on Stream<T>, provided by the Merge extension

Merges values and errors from this stream and any stream in others in any order as they arrive.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
pipe(StreamConsumer<T> streamConsumer) → Future
Pipes the events of this stream into streamConsumer.
inherited
reduce(T combine(T previous, T element)) → Future<T>
Combines a sequence of values by repeatedly applying combine.
inherited
sample(Stream<void> trigger, {bool longPoll = true}) → Stream<T>

Available on Stream<T>, provided by the RateLimit extension

Emits the most recent new value from this stream when trigger emits an event.
scan<S>(S initialValue, FutureOr<S> combine(S soFar, T element)) → Stream<S>

Available on Stream<T>, provided by the Scan extension

Emits a sequence of the accumulated values from repeatedly applying combine.
singleWhere(bool test(T element), {T orElse()?}) → Future<T>
Finds the single element in this stream matching test.
inherited
skip(int count) → Stream<T>
Skips the first count data events from this stream.
inherited
skipWhile(bool test(T element)) → Stream<T>
Skip data events from this stream while they are matched by test.
inherited
slices(int length) → Stream<List<T>>

Available on Stream<T>, provided by the StreamExtensions extension

Creates a stream whose elements are contiguous slices of this.
startWith(T initial) → Stream<T>

Available on Stream<T>, provided by the Concatenate extension

Emits initial before any values or errors from the this stream.
startWithMany(Iterable<T> initial) → Stream<T>

Available on Stream<T>, provided by the Concatenate extension

Emits all values in initial before any values or errors from this stream.
startWithStream(Stream<T> initial) → Stream<T>

Available on Stream<T>, provided by the Concatenate extension

Emits all values and errors in initial before any values or errors from this stream.
switchLatest() → Stream<T>

Available on Stream<Stream<T>>, provided by the SwitchLatest extension

Emits values from the most recently emitted Stream.
switchMap<S>(Stream<S> convert(T)) → Stream<S>

Available on Stream<T>, provided by the Switch extension

Maps events to a Stream and emits values from the most recently created Stream.
take(int count) → Stream<T>
Provides at most the first count data events of this stream.
inherited
takeUntil(Future<void> trigger) → Stream<T>

Available on Stream<T>, provided by the TakeUntil extension

Takes values from this stream which are emitted before trigger completes.
takeWhile(bool test(T element)) → Stream<T>
Forwards data events while test is successful.
inherited
tap(void onValue(T)?, {void onError(Object, StackTrace)?, void onDone()?}) → Stream<T>

Available on Stream<T>, provided by the Tap extension

Taps into this stream to allow additional handling on a single-subscriber stream without first wrapping as a broadcast stream.
throttle(Duration duration, {bool trailing = false}) → Stream<T>

Available on Stream<T>, provided by the RateLimit extension

Reduces the rate that events are emitted to at most once per duration.
timeout(Duration timeLimit, {void onTimeout(EventSink<T> sink)?}) → Stream<T>
Creates a new stream with the same events as this stream.
inherited
toList() → Future<List<T>>
Collects all elements of this stream in a List.
inherited
toSet() → Future<Set<T>>
Collects the data of this stream in a Set.
inherited
toString() → String
A string representation of this object.
inherited
transform<S>(StreamTransformer<T, S> streamTransformer) → Stream<S>
Applies streamTransformer to this stream.
inherited
where(bool test(T event)) → Stream<T>
Creates a new stream from this stream that discards some elements.
inherited
whereNotNull() → Stream<T>

Available on Stream<T?>, provided by the WhereNotNull extension

Discards null events from this stream.
whereType<S>() → Stream<S>

Available on Stream<T>, provided by the Where extension

Discards events from this stream that are not of type S.

Operators

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