Index: pkg/dev_compiler/tool/input_sdk/lib/async/stream.dart |
diff --git a/pkg/dev_compiler/tool/input_sdk/lib/async/stream.dart b/pkg/dev_compiler/tool/input_sdk/lib/async/stream.dart |
deleted file mode 100644 |
index d0b0d0bfcad0ca3de7bda06c3b961c2cc5f694c9..0000000000000000000000000000000000000000 |
--- a/pkg/dev_compiler/tool/input_sdk/lib/async/stream.dart |
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@@ -1,1820 +0,0 @@ |
-// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file |
-// for details. All rights reserved. Use of this source code is governed by a |
-// BSD-style license that can be found in the LICENSE file. |
- |
-part of dart.async; |
- |
-// ------------------------------------------------------------------- |
-// Core Stream types |
-// ------------------------------------------------------------------- |
- |
-typedef void _TimerCallback(); |
- |
-/** |
- * A source of asynchronous data events. |
- * |
- * A Stream provides a way to receive a sequence of events. |
- * Each event is either a data event or an error event, |
- * representing the result of a single computation. |
- * When the events provided by a Stream have all been sent, |
- * a single "done" event will mark the end. |
- * |
- * You can [listen] on a stream to make it start generating events, |
- * and to set up listeners that receive the events. |
- * When you listen, you receive a [StreamSubscription] object |
- * which is the active object providing the events, |
- * and which can be used to stop listening again, |
- * or to temporarily pause events from the subscription. |
- * |
- * There are two kinds of streams: "Single-subscription" streams and |
- * "broadcast" streams. |
- * |
- * *A single-subscription stream* allows only a single listener during the whole |
- * lifetime of the stream. |
- * It doesn't start generating events until it has a listener, |
- * and it stops sending events when the listener is unsubscribed, |
- * even if the source of events could still provide more. |
- * |
- * Listening twice on a single-subscription stream is not allowed, even after |
- * the first subscription has been canceled. |
- * |
- * Single-subscription streams are generally used for streaming chunks of |
- * larger contiguous data like file I/O. |
- * |
- * *A broadcast stream* allows any number of listeners, and it fires |
- * its events when they are ready, whether there are listeners or not. |
- * |
- * Broadcast streams are used for independent events/observers. |
- * |
- * If several listeners want to listen to a single subscription stream, |
- * use [asBroadcastStream] to create a broadcast stream on top of the |
- * non-broadcast stream. |
- * |
- * On either kind of stream, stream transformations, such as [where] and |
- * [skip], return the same type of stream as the one the method was called on, |
- * unless otherwise noted. |
- * |
- * When an event is fired, the listener(s) at that time will receive the event. |
- * If a listener is added to a broadcast stream while an event is being fired, |
- * that listener will not receive the event currently being fired. |
- * If a listener is canceled, it immediately stops receiving events. |
- * |
- * When the "done" event is fired, subscribers are unsubscribed before |
- * receiving the event. After the event has been sent, the stream has no |
- * subscribers. Adding new subscribers to a broadcast stream after this point |
- * is allowed, but they will just receive a new "done" event as soon |
- * as possible. |
- * |
- * Stream subscriptions always respect "pause" requests. If necessary they need |
- * to buffer their input, but often, and preferably, they can simply request |
- * their input to pause too. |
- * |
- * The default implementation of [isBroadcast] returns false. |
- * A broadcast stream inheriting from [Stream] must override [isBroadcast] |
- * to return `true`. |
- */ |
-abstract class Stream<T> { |
- Stream(); |
- |
- /** |
- * Internal use only. We do not want to promise that Stream stays const. |
- * |
- * If mixins become compatible with const constructors, we may use a |
- * stream mixin instead of extending Stream from a const class. |
- */ |
- const Stream._internal(); |
- |
- /** |
- * Creates an empty broadcast stream. |
- * |
- * This is a stream which does nothing except sending a done event |
- * when it's listened to. |
- */ |
- const factory Stream.empty() = _EmptyStream<T>; |
- |
- /** |
- * Creates a new single-subscription stream from the future. |
- * |
- * When the future completes, the stream will fire one event, either |
- * data or error, and then close with a done-event. |
- */ |
- factory Stream.fromFuture(Future<T> future) { |
- // Use the controller's buffering to fill in the value even before |
- // the stream has a listener. For a single value, it's not worth it |
- // to wait for a listener before doing the `then` on the future. |
- _StreamController<T> controller = new StreamController<T>(sync: true); |
- future.then((value) { |
- controller._add(value); |
- controller._closeUnchecked(); |
- }, |
- onError: (error, stackTrace) { |
- controller._addError(error, stackTrace); |
- controller._closeUnchecked(); |
- }); |
- return controller.stream; |
- } |
- |
- /** |
- * Create a stream from a group of futures. |
- * |
- * The stream reports the results of the futures on the stream in the order |
- * in which the futures complete. |
- * |
- * If some futures have completed before calling `Stream.fromFutures`, |
- * their result will be output on the created stream in some unspecified |
- * order. |
- * |
- * When all futures have completed, the stream is closed. |
- * |
- * If no future is passed, the stream closes as soon as possible. |
- */ |
- factory Stream.fromFutures(Iterable<Future<T>> futures) { |
- _StreamController<T> controller = new StreamController<T>(sync: true); |
- int count = 0; |
- var onValue = (T value) { |
- if (!controller.isClosed) { |
- controller._add(value); |
- if (--count == 0) controller._closeUnchecked(); |
- } |
- }; |
- var onError = (error, stack) { |
- if (!controller.isClosed) { |
- controller._addError(error, stack); |
- if (--count == 0) controller._closeUnchecked(); |
- } |
- }; |
- // The futures are already running, so start listening to them immediately |
- // (instead of waiting for the stream to be listened on). |
- // If we wait, we might not catch errors in the futures in time. |
- for (var future in futures) { |
- count++; |
- future.then(onValue, onError: onError); |
- } |
- // Use schedule microtask since controller is sync. |
- if (count == 0) scheduleMicrotask(controller.close); |
- return controller.stream; |
- } |
- |
- /** |
- * Creates a single-subscription stream that gets its data from [data]. |
- * |
- * The iterable is iterated when the stream receives a listener, and stops |
- * iterating if the listener cancels the subscription. |
- * |
- * If iterating [data] throws an error, the stream ends immediately with |
- * that error. No done event will be sent (iteration is not complete), but no |
- * further data events will be generated either, since iteration cannot |
- * continue. |
- */ |
- factory Stream.fromIterable(Iterable<T> data) { |
- return new _GeneratedStreamImpl<T>( |
- () => new _IterablePendingEvents<T>(data)); |
- } |
- |
- /** |
- * Creates a stream that repeatedly emits events at [period] intervals. |
- * |
- * The event values are computed by invoking [computation]. The argument to |
- * this callback is an integer that starts with 0 and is incremented for |
- * every event. |
- * |
- * If [computation] is omitted the event values will all be `null`. |
- */ |
- factory Stream.periodic(Duration period, |
- [T computation(int computationCount)]) { |
- Timer timer; |
- int computationCount = 0; |
- StreamController<T> controller; |
- // Counts the time that the Stream was running (and not paused). |
- Stopwatch watch = new Stopwatch(); |
- |
- void sendEvent() { |
- watch.reset(); |
- T data; |
- if (computation != null) { |
- try { |
- data = computation(computationCount++); |
- } catch (e, s) { |
- controller.addError(e, s); |
- return; |
- } |
- } |
- controller.add(data); |
- } |
- |
- void startPeriodicTimer() { |
- assert(timer == null); |
- timer = new Timer.periodic(period, (Timer timer) { |
- sendEvent(); |
- }); |
- } |
- |
- controller = new StreamController<T>(sync: true, |
- onListen: () { |
- watch.start(); |
- startPeriodicTimer(); |
- }, |
- onPause: () { |
- timer.cancel(); |
- timer = null; |
- watch.stop(); |
- }, |
- onResume: () { |
- assert(timer == null); |
- Duration elapsed = watch.elapsed; |
- watch.start(); |
- timer = new Timer(period - elapsed, () { |
- timer = null; |
- startPeriodicTimer(); |
- sendEvent(); |
- }); |
- }, |
- onCancel: () { |
- if (timer != null) timer.cancel(); |
- timer = null; |
- }); |
- return controller.stream; |
- } |
- |
- /** |
- * Creates a stream where all events of an existing stream are piped through |
- * a sink-transformation. |
- * |
- * The given [mapSink] closure is invoked when the returned stream is |
- * listened to. All events from the [source] are added into the event sink |
- * that is returned from the invocation. The transformation puts all |
- * transformed events into the sink the [mapSink] closure received during |
- * its invocation. Conceptually the [mapSink] creates a transformation pipe |
- * with the input sink being the returned [EventSink] and the output sink |
- * being the sink it received. |
- * |
- * This constructor is frequently used to build transformers. |
- * |
- * Example use for a duplicating transformer: |
- * |
- * class DuplicationSink implements EventSink<String> { |
- * final EventSink<String> _outputSink; |
- * DuplicationSink(this._outputSink); |
- * |
- * void add(String data) { |
- * _outputSink.add(data); |
- * _outputSink.add(data); |
- * } |
- * |
- * void addError(e, [st]) { _outputSink.addError(e, st); } |
- * void close() { _outputSink.close(); } |
- * } |
- * |
- * class DuplicationTransformer implements StreamTransformer<String, String> { |
- * // Some generic types ommitted for brevety. |
- * Stream bind(Stream stream) => new Stream<String>.eventTransformed( |
- * stream, |
- * (EventSink sink) => new DuplicationSink(sink)); |
- * } |
- * |
- * stringStream.transform(new DuplicationTransformer()); |
- * |
- * The resulting stream is a broadcast stream if [source] is. |
- */ |
- factory Stream.eventTransformed(Stream source, |
- EventSink mapSink(EventSink<T> sink)) { |
- return new _BoundSinkStream(source, mapSink); |
- } |
- |
- /** |
- * Reports whether this stream is a broadcast stream. |
- */ |
- bool get isBroadcast => false; |
- |
- /** |
- * Returns a multi-subscription stream that produces the same events as this. |
- * |
- * The returned stream will subscribe to this stream when its first |
- * subscriber is added, and will stay subscribed until this stream ends, |
- * or a callback cancels the subscription. |
- * |
- * If [onListen] is provided, it is called with a subscription-like object |
- * that represents the underlying subscription to this stream. It is |
- * possible to pause, resume or cancel the subscription during the call |
- * to [onListen]. It is not possible to change the event handlers, including |
- * using [StreamSubscription.asFuture]. |
- * |
- * If [onCancel] is provided, it is called in a similar way to [onListen] |
- * when the returned stream stops having listener. If it later gets |
- * a new listener, the [onListen] function is called again. |
- * |
- * Use the callbacks, for example, for pausing the underlying subscription |
- * while having no subscribers to prevent losing events, or canceling the |
- * subscription when there are no listeners. |
- */ |
- Stream<T> asBroadcastStream({ |
- void onListen(StreamSubscription<T> subscription), |
- void onCancel(StreamSubscription<T> subscription) }) { |
- return new _AsBroadcastStream<T>(this, onListen, onCancel); |
- } |
- |
- /** |
- * Adds a subscription to this stream. |
- * |
- * On each data event from this stream, the subscriber's [onData] handler |
- * is called. If [onData] is null, nothing happens. |
- * |
- * On errors from this stream, the [onError] handler is given a |
- * object describing the error. |
- * |
- * The [onError] callback must be of type `void onError(error)` or |
- * `void onError(error, StackTrace stackTrace)`. If [onError] accepts |
- * two arguments it is called with the stack trace (which could be `null` if |
- * the stream itself received an error without stack trace). |
- * Otherwise it is called with just the error object. |
- * If [onError] is omitted, any errors on the stream are considered unhandled, |
- * and will be passed to the current [Zone]'s error handler. |
- * By default unhandled async errors are treated |
- * as if they were uncaught top-level errors. |
- * |
- * If this stream closes, the [onDone] handler is called. |
- * |
- * If [cancelOnError] is true, the subscription is ended when |
- * the first error is reported. The default is false. |
- */ |
- StreamSubscription<T> listen(void onData(T event), |
- { Function onError, |
- void onDone(), |
- bool cancelOnError}); |
- |
- /** |
- * Creates a new stream from this stream that discards some data events. |
- * |
- * The new stream sends the same error and done events as this stream, |
- * but it only sends the data events that satisfy the [test]. |
- * |
- * The returned stream is a broadcast stream if this stream is. |
- * If a broadcast stream is listened to more than once, each subscription |
- * will individually perform the `test`. |
- */ |
- Stream<T> where(bool test(T event)) { |
- return new _WhereStream<T>(this, test); |
- } |
- |
- /** |
- * Creates a new stream that converts each element of this stream |
- * to a new value using the [convert] function. |
- * |
- * For each data event, `o`, in this stream, the returned stream |
- * provides a data event with the value `convert(o)`. |
- * If [convert] throws, the returned stream reports the exception as an error |
- * event instead. |
- * |
- * Error and done events are passed through unchanged to the returned stream. |
- * |
- * The returned stream is a broadcast stream if this stream is. |
- * The [convert] function is called once per data event per listener. |
- * If a broadcast stream is listened to more than once, each subscription |
- * will individually call [convert] on each data event. |
- */ |
- Stream/*<S>*/ map/*<S>*/(/*=S*/ convert(T event)) { |
- return new _MapStream<T, dynamic/*=S*/>(this, convert); |
- } |
- |
- /** |
- * Creates a new stream with each data event of this stream asynchronously |
- * mapped to a new event. |
- * |
- * This acts like [map], except that [convert] may return a [Future], |
- * and in that case, the stream waits for that future to complete before |
- * continuing with its result. |
- * |
- * The returned stream is a broadcast stream if this stream is. |
- */ |
- Stream/*<E>*/ asyncMap/*<E>*/(convert(T event)) { |
- StreamController/*<E>*/ controller; |
- StreamSubscription/*<T>*/ subscription; |
- |
- void onListen() { |
- final add = controller.add; |
- assert(controller is _StreamController || |
- controller is _BroadcastStreamController); |
- final _EventSink/*<E>*/ eventSink = |
- controller as Object /*=_EventSink<E>*/; |
- final addError = eventSink._addError; |
- subscription = this.listen( |
- (T event) { |
- dynamic newValue; |
- try { |
- newValue = convert(event); |
- } catch (e, s) { |
- controller.addError(e, s); |
- return; |
- } |
- if (newValue is Future) { |
- subscription.pause(); |
- newValue.then(add, onError: addError) |
- .whenComplete(subscription.resume); |
- } else { |
- controller.add(newValue as Object/*=E*/); |
- } |
- }, |
- onError: addError, |
- onDone: controller.close |
- ); |
- } |
- |
- if (this.isBroadcast) { |
- controller = new StreamController/*<E>*/.broadcast( |
- onListen: onListen, |
- onCancel: () { subscription.cancel(); }, |
- sync: true |
- ); |
- } else { |
- controller = new StreamController/*<E>*/( |
- onListen: onListen, |
- onPause: () { subscription.pause(); }, |
- onResume: () { subscription.resume(); }, |
- onCancel: () { subscription.cancel(); }, |
- sync: true |
- ); |
- } |
- return controller.stream; |
- } |
- |
- /** |
- * Creates a new stream with the events of a stream per original event. |
- * |
- * This acts like [expand], except that [convert] returns a [Stream] |
- * instead of an [Iterable]. |
- * The events of the returned stream becomes the events of the returned |
- * stream, in the order they are produced. |
- * |
- * If [convert] returns `null`, no value is put on the output stream, |
- * just as if it returned an empty stream. |
- * |
- * The returned stream is a broadcast stream if this stream is. |
- */ |
- Stream/*<E>*/ asyncExpand/*<E>*/(Stream/*<E>*/ convert(T event)) { |
- StreamController/*<E>*/ controller; |
- StreamSubscription<T> subscription; |
- void onListen() { |
- assert(controller is _StreamController || |
- controller is _BroadcastStreamController); |
- final _EventSink/*<E>*/ eventSink = |
- controller as Object /*=_EventSink<E>*/; |
- subscription = this.listen( |
- (T event) { |
- Stream/*<E>*/ newStream; |
- try { |
- newStream = convert(event); |
- } catch (e, s) { |
- controller.addError(e, s); |
- return; |
- } |
- if (newStream != null) { |
- subscription.pause(); |
- controller.addStream(newStream) |
- .whenComplete(subscription.resume); |
- } |
- }, |
- onError: eventSink._addError, // Avoid Zone error replacement. |
- onDone: controller.close |
- ); |
- } |
- if (this.isBroadcast) { |
- controller = new StreamController/*<E>*/.broadcast( |
- onListen: onListen, |
- onCancel: () { subscription.cancel(); }, |
- sync: true |
- ); |
- } else { |
- controller = new StreamController/*<E>*/( |
- onListen: onListen, |
- onPause: () { subscription.pause(); }, |
- onResume: () { subscription.resume(); }, |
- onCancel: () { subscription.cancel(); }, |
- sync: true |
- ); |
- } |
- return controller.stream; |
- } |
- |
- /** |
- * Creates a wrapper Stream that intercepts some errors from this stream. |
- * |
- * If this stream sends an error that matches [test], then it is intercepted |
- * by the [handle] function. |
- * |
- * The [onError] callback must be of type `void onError(error)` or |
- * `void onError(error, StackTrace stackTrace)`. Depending on the function |
- * type the stream either invokes [onError] with or without a stack |
- * trace. The stack trace argument might be `null` if the stream itself |
- * received an error without stack trace. |
- * |
- * An asynchronous error [:e:] is matched by a test function if [:test(e):] |
- * returns true. If [test] is omitted, every error is considered matching. |
- * |
- * If the error is intercepted, the [handle] function can decide what to do |
- * with it. It can throw if it wants to raise a new (or the same) error, |
- * or simply return to make the stream forget the error. |
- * |
- * If you need to transform an error into a data event, use the more generic |
- * [Stream.transform] to handle the event by writing a data event to |
- * the output sink. |
- * |
- * The returned stream is a broadcast stream if this stream is. |
- * If a broadcast stream is listened to more than once, each subscription |
- * will individually perform the `test` and handle the error. |
- */ |
- Stream<T> handleError(Function onError, { bool test(error) }) { |
- return new _HandleErrorStream<T>(this, onError, test); |
- } |
- |
- /** |
- * Creates a new stream from this stream that converts each element |
- * into zero or more events. |
- * |
- * Each incoming event is converted to an [Iterable] of new events, |
- * and each of these new events are then sent by the returned stream |
- * in order. |
- * |
- * The returned stream is a broadcast stream if this stream is. |
- * If a broadcast stream is listened to more than once, each subscription |
- * will individually call `convert` and expand the events. |
- */ |
- Stream/*<S>*/ expand/*<S>*/(Iterable/*<S>*/ convert(T value)) { |
- return new _ExpandStream<T, dynamic/*=S*/>(this, convert); |
- } |
- |
- /** |
- * Pipe the events of this stream into [streamConsumer]. |
- * |
- * The events of this stream are added to `streamConsumer` using |
- * [StreamConsumer.addStream]. |
- * The `streamConsumer` is closed when this stream has been successfully added |
- * to it - when the future returned by `addStream` completes without an error. |
- * |
- * Returns a future which completes when the stream has been consumed |
- * and the consumer has been closed. |
- * |
- * The returned future completes with the same result as the future returned |
- * by [StreamConsumer.close]. |
- * If the adding of the stream itself fails in some way, |
- * then the consumer is expected to be closed, and won't be closed again. |
- * In that case the returned future completes with the error from calling |
- * `addStream`. |
- */ |
- Future pipe(StreamConsumer<T> streamConsumer) { |
- return streamConsumer.addStream(this).then((_) => streamConsumer.close()); |
- } |
- |
- /** |
- * Chains this stream as the input of the provided [StreamTransformer]. |
- * |
- * Returns the result of [:streamTransformer.bind:] itself. |
- * |
- * The `streamTransformer` can decide whether it wants to return a |
- * broadcast stream or not. |
- */ |
- Stream/*<S>*/ transform/*<S>*/( |
- StreamTransformer<T, dynamic/*=S*/ > streamTransformer) { |
- return streamTransformer.bind(this); |
- } |
- |
- /** |
- * Reduces a sequence of values by repeatedly applying [combine]. |
- */ |
- Future<T> reduce(T combine(T previous, T element)) { |
- _Future<T> result = new _Future<T>(); |
- bool seenFirst = false; |
- T value; |
- StreamSubscription subscription; |
- subscription = this.listen( |
- (T element) { |
- if (seenFirst) { |
- _runUserCode(() => combine(value, element), |
- (T newValue) { value = newValue; }, |
- _cancelAndErrorClosure(subscription, result)); |
- } else { |
- value = element; |
- seenFirst = true; |
- } |
- }, |
- onError: result._completeError, |
- onDone: () { |
- if (!seenFirst) { |
- try { |
- throw IterableElementError.noElement(); |
- } catch (e, s) { |
- _completeWithErrorCallback(result, e, s); |
- } |
- } else { |
- result._complete(value); |
- } |
- }, |
- cancelOnError: true |
- ); |
- return result; |
- } |
- |
- /** Reduces a sequence of values by repeatedly applying [combine]. */ |
- Future/*<S>*/ fold/*<S>*/(var/*=S*/ initialValue, |
- /*=S*/ combine(var/*=S*/ previous, T element)) { |
- |
- _Future/*<S>*/ result = new _Future/*<S>*/(); |
- var/*=S*/ value = initialValue; |
- StreamSubscription subscription; |
- subscription = this.listen( |
- (T element) { |
- _runUserCode( |
- () => combine(value, element), |
- (/*=S*/ newValue) { value = newValue; }, |
- _cancelAndErrorClosure(subscription, result) |
- ); |
- }, |
- onError: (e, st) { |
- result._completeError(e, st); |
- }, |
- onDone: () { |
- result._complete(value); |
- }, |
- cancelOnError: true); |
- return result; |
- } |
- |
- /** |
- * Collects string of data events' string representations. |
- * |
- * If [separator] is provided, it is inserted between any two |
- * elements. |
- * |
- * Any error in the stream causes the future to complete with that |
- * error. Otherwise it completes with the collected string when |
- * the "done" event arrives. |
- */ |
- Future<String> join([String separator = ""]) { |
- _Future<String> result = new _Future<String>(); |
- StringBuffer buffer = new StringBuffer(); |
- StreamSubscription subscription; |
- bool first = true; |
- subscription = this.listen( |
- (T element) { |
- if (!first) { |
- buffer.write(separator); |
- } |
- first = false; |
- try { |
- buffer.write(element); |
- } catch (e, s) { |
- _cancelAndErrorWithReplacement(subscription, result, e, s); |
- } |
- }, |
- onError: (e) { |
- result._completeError(e); |
- }, |
- onDone: () { |
- result._complete(buffer.toString()); |
- }, |
- cancelOnError: true); |
- return result; |
- } |
- |
- /** |
- * Checks whether [needle] occurs in the elements provided by this stream. |
- * |
- * Completes the [Future] when the answer is known. |
- * If this stream reports an error, the [Future] will report that error. |
- */ |
- Future<bool> contains(Object needle) { |
- _Future<bool> future = new _Future<bool>(); |
- StreamSubscription subscription; |
- subscription = this.listen( |
- (T element) { |
- _runUserCode( |
- () => (element == needle), |
- (bool isMatch) { |
- if (isMatch) { |
- _cancelAndValue(subscription, future, true); |
- } |
- }, |
- _cancelAndErrorClosure(subscription, future) |
- ); |
- }, |
- onError: future._completeError, |
- onDone: () { |
- future._complete(false); |
- }, |
- cancelOnError: true); |
- return future; |
- } |
- |
- /** |
- * Executes [action] on each data event of the stream. |
- * |
- * Completes the returned [Future] when all events of the stream |
- * have been processed. Completes the future with an error if the |
- * stream has an error event, or if [action] throws. |
- */ |
- Future forEach(void action(T element)) { |
- _Future future = new _Future(); |
- StreamSubscription subscription; |
- subscription = this.listen( |
- (T element) { |
- _runUserCode( |
- () => action(element), |
- (_) {}, |
- _cancelAndErrorClosure(subscription, future) |
- ); |
- }, |
- onError: future._completeError, |
- onDone: () { |
- future._complete(null); |
- }, |
- cancelOnError: true); |
- return future; |
- } |
- |
- /** |
- * Checks whether [test] accepts all elements provided by this stream. |
- * |
- * Completes the [Future] when the answer is known. |
- * If this stream reports an error, the [Future] will report that error. |
- */ |
- Future<bool> every(bool test(T element)) { |
- _Future<bool> future = new _Future<bool>(); |
- StreamSubscription subscription; |
- subscription = this.listen( |
- (T element) { |
- _runUserCode( |
- () => test(element), |
- (bool isMatch) { |
- if (!isMatch) { |
- _cancelAndValue(subscription, future, false); |
- } |
- }, |
- _cancelAndErrorClosure(subscription, future) |
- ); |
- }, |
- onError: future._completeError, |
- onDone: () { |
- future._complete(true); |
- }, |
- cancelOnError: true); |
- return future; |
- } |
- |
- /** |
- * Checks whether [test] accepts any element provided by this stream. |
- * |
- * Completes the [Future] when the answer is known. |
- * |
- * If this stream reports an error, the [Future] reports that error. |
- * |
- * Stops listening to the stream after the first matching element has been |
- * found. |
- * |
- * Internally the method cancels its subscription after this element. This |
- * means that single-subscription (non-broadcast) streams are closed and |
- * cannot be reused after a call to this method. |
- */ |
- Future<bool> any(bool test(T element)) { |
- _Future<bool> future = new _Future<bool>(); |
- StreamSubscription subscription; |
- subscription = this.listen( |
- (T element) { |
- _runUserCode( |
- () => test(element), |
- (bool isMatch) { |
- if (isMatch) { |
- _cancelAndValue(subscription, future, true); |
- } |
- }, |
- _cancelAndErrorClosure(subscription, future) |
- ); |
- }, |
- onError: future._completeError, |
- onDone: () { |
- future._complete(false); |
- }, |
- cancelOnError: true); |
- return future; |
- } |
- |
- |
- /** Counts the elements in the stream. */ |
- Future<int> get length { |
- _Future<int> future = new _Future<int>(); |
- int count = 0; |
- this.listen( |
- (_) { count++; }, |
- onError: future._completeError, |
- onDone: () { |
- future._complete(count); |
- }, |
- cancelOnError: true); |
- return future; |
- } |
- |
- /** |
- * Reports whether this stream contains any elements. |
- * |
- * Stops listening to the stream after the first element has been received. |
- * |
- * Internally the method cancels its subscription after the first element. |
- * This means that single-subscription (non-broadcast) streams are closed and |
- * cannot be reused after a call to this getter. |
- */ |
- Future<bool> get isEmpty { |
- _Future<bool> future = new _Future<bool>(); |
- StreamSubscription subscription; |
- subscription = this.listen( |
- (_) { |
- _cancelAndValue(subscription, future, false); |
- }, |
- onError: future._completeError, |
- onDone: () { |
- future._complete(true); |
- }, |
- cancelOnError: true); |
- return future; |
- } |
- |
- /** Collects the data of this stream in a [List]. */ |
- Future<List<T>> toList() { |
- List<T> result = <T>[]; |
- _Future<List<T>> future = new _Future<List<T>>(); |
- this.listen( |
- (T data) { |
- result.add(data); |
- }, |
- onError: future._completeError, |
- onDone: () { |
- future._complete(result); |
- }, |
- cancelOnError: true); |
- return future; |
- } |
- |
- /** |
- * Collects the data of this stream in a [Set]. |
- * |
- * The returned set is the same type as returned by `new Set<T>()`. |
- * If another type of set is needed, either use [forEach] to add each |
- * element to the set, or use |
- * `toList().then((list) => new SomeOtherSet.from(list))` |
- * to create the set. |
- */ |
- Future<Set<T>> toSet() { |
- Set<T> result = new Set<T>(); |
- _Future<Set<T>> future = new _Future<Set<T>>(); |
- this.listen( |
- (T data) { |
- result.add(data); |
- }, |
- onError: future._completeError, |
- onDone: () { |
- future._complete(result); |
- }, |
- cancelOnError: true); |
- return future; |
- } |
- |
- /** |
- * Discards all data on the stream, but signals when it's done or an error |
- * occured. |
- * |
- * When subscribing using [drain], cancelOnError will be true. This means |
- * that the future will complete with the first error on the stream and then |
- * cancel the subscription. |
- * |
- * In case of a `done` event the future completes with the given |
- * [futureValue]. |
- */ |
- Future/*<E>*/ drain/*<E>*/([/*=E*/ futureValue]) |
- => listen(null, cancelOnError: true).asFuture/*<E>*/(futureValue); |
- |
- /** |
- * Provides at most the first [n] values of this stream. |
- * |
- * Forwards the first [n] data events of this stream, and all error |
- * events, to the returned stream, and ends with a done event. |
- * |
- * If this stream produces fewer than [count] values before it's done, |
- * so will the returned stream. |
- * |
- * Stops listening to the stream after the first [n] elements have been |
- * received. |
- * |
- * Internally the method cancels its subscription after these elements. This |
- * means that single-subscription (non-broadcast) streams are closed and |
- * cannot be reused after a call to this method. |
- * |
- * The returned stream is a broadcast stream if this stream is. |
- * For a broadcast stream, the events are only counted from the time |
- * the returned stream is listened to. |
- */ |
- Stream<T> take(int count) { |
- return new _TakeStream<T>(this, count); |
- } |
- |
- /** |
- * Forwards data events while [test] is successful. |
- * |
- * The returned stream provides the same events as this stream as long |
- * as [test] returns [:true:] for the event data. The stream is done |
- * when either this stream is done, or when this stream first provides |
- * a value that [test] doesn't accept. |
- * |
- * Stops listening to the stream after the accepted elements. |
- * |
- * Internally the method cancels its subscription after these elements. This |
- * means that single-subscription (non-broadcast) streams are closed and |
- * cannot be reused after a call to this method. |
- * |
- * The returned stream is a broadcast stream if this stream is. |
- * For a broadcast stream, the events are only tested from the time |
- * the returned stream is listened to. |
- */ |
- Stream<T> takeWhile(bool test(T element)) { |
- return new _TakeWhileStream<T>(this, test); |
- } |
- |
- /** |
- * Skips the first [count] data events from this stream. |
- * |
- * The returned stream is a broadcast stream if this stream is. |
- * For a broadcast stream, the events are only counted from the time |
- * the returned stream is listened to. |
- */ |
- Stream<T> skip(int count) { |
- return new _SkipStream<T>(this, count); |
- } |
- |
- /** |
- * Skip data events from this stream while they are matched by [test]. |
- * |
- * Error and done events are provided by the returned stream unmodified. |
- * |
- * Starting with the first data event where [test] returns false for the |
- * event data, the returned stream will have the same events as this stream. |
- * |
- * The returned stream is a broadcast stream if this stream is. |
- * For a broadcast stream, the events are only tested from the time |
- * the returned stream is listened to. |
- */ |
- Stream<T> skipWhile(bool test(T element)) { |
- return new _SkipWhileStream<T>(this, test); |
- } |
- |
- /** |
- * Skips data events if they are equal to the previous data event. |
- * |
- * The returned stream provides the same events as this stream, except |
- * that it never provides two consecutive data events that are equal. |
- * |
- * Equality is determined by the provided [equals] method. If that is |
- * omitted, the '==' operator on the last provided data element is used. |
- * |
- * The returned stream is a broadcast stream if this stream is. |
- * If a broadcast stream is listened to more than once, each subscription |
- * will individually perform the `equals` test. |
- */ |
- Stream<T> distinct([bool equals(T previous, T next)]) { |
- return new _DistinctStream<T>(this, equals); |
- } |
- |
- /** |
- * Returns the first element of the stream. |
- * |
- * Stops listening to the stream after the first element has been received. |
- * |
- * Internally the method cancels its subscription after the first element. |
- * This means that single-subscription (non-broadcast) streams are closed |
- * and cannot be reused after a call to this getter. |
- * |
- * If an error event occurs before the first data event, the resulting future |
- * is completed with that error. |
- * |
- * If this stream is empty (a done event occurs before the first data event), |
- * the resulting future completes with a [StateError]. |
- * |
- * Except for the type of the error, this method is equivalent to |
- * [:this.elementAt(0):]. |
- */ |
- Future<T> get first { |
- _Future<T> future = new _Future<T>(); |
- StreamSubscription subscription; |
- subscription = this.listen( |
- (T value) { |
- _cancelAndValue(subscription, future, value); |
- }, |
- onError: future._completeError, |
- onDone: () { |
- try { |
- throw IterableElementError.noElement(); |
- } catch (e, s) { |
- _completeWithErrorCallback(future, e, s); |
- } |
- }, |
- cancelOnError: true); |
- return future; |
- } |
- |
- /** |
- * Returns the last element of the stream. |
- * |
- * If an error event occurs before the first data event, the resulting future |
- * is completed with that error. |
- * |
- * If this stream is empty (a done event occurs before the first data event), |
- * the resulting future completes with a [StateError]. |
- */ |
- Future<T> get last { |
- _Future<T> future = new _Future<T>(); |
- T result = null; |
- bool foundResult = false; |
- listen( |
- (T value) { |
- foundResult = true; |
- result = value; |
- }, |
- onError: future._completeError, |
- onDone: () { |
- if (foundResult) { |
- future._complete(result); |
- return; |
- } |
- try { |
- throw IterableElementError.noElement(); |
- } catch (e, s) { |
- _completeWithErrorCallback(future, e, s); |
- } |
- }, |
- cancelOnError: true); |
- return future; |
- } |
- |
- /** |
- * Returns the single element. |
- * |
- * If an error event occurs before or after the first data event, the |
- * resulting future is completed with that error. |
- * |
- * If [this] is empty or has more than one element throws a [StateError]. |
- */ |
- Future<T> get single { |
- _Future<T> future = new _Future<T>(); |
- T result = null; |
- bool foundResult = false; |
- StreamSubscription subscription; |
- subscription = this.listen( |
- (T value) { |
- if (foundResult) { |
- // This is the second element we get. |
- try { |
- throw IterableElementError.tooMany(); |
- } catch (e, s) { |
- _cancelAndErrorWithReplacement(subscription, future, e, s); |
- } |
- return; |
- } |
- foundResult = true; |
- result = value; |
- }, |
- onError: future._completeError, |
- onDone: () { |
- if (foundResult) { |
- future._complete(result); |
- return; |
- } |
- try { |
- throw IterableElementError.noElement(); |
- } catch (e, s) { |
- _completeWithErrorCallback(future, e, s); |
- } |
- }, |
- cancelOnError: true); |
- return future; |
- } |
- |
- /** |
- * Finds the first element of this stream matching [test]. |
- * |
- * Returns a future that is filled with the first element of this stream |
- * that [test] returns true for. |
- * |
- * If no such element is found before this stream is done, and a |
- * [defaultValue] function is provided, the result of calling [defaultValue] |
- * becomes the value of the future. |
- * |
- * Stops listening to the stream after the first matching element has been |
- * received. |
- * |
- * Internally the method cancels its subscription after the first element that |
- * matches the predicate. This means that single-subscription (non-broadcast) |
- * streams are closed and cannot be reused after a call to this method. |
- * |
- * If an error occurs, or if this stream ends without finding a match and |
- * with no [defaultValue] function provided, the future will receive an |
- * error. |
- */ |
- Future<dynamic> firstWhere(bool test(T element), {Object defaultValue()}) { |
- _Future<dynamic> future = new _Future(); |
- StreamSubscription subscription; |
- subscription = this.listen( |
- (T value) { |
- _runUserCode( |
- () => test(value), |
- (bool isMatch) { |
- if (isMatch) { |
- _cancelAndValue(subscription, future, value); |
- } |
- }, |
- _cancelAndErrorClosure(subscription, future) |
- ); |
- }, |
- onError: future._completeError, |
- onDone: () { |
- if (defaultValue != null) { |
- _runUserCode(defaultValue, future._complete, future._completeError); |
- return; |
- } |
- try { |
- throw IterableElementError.noElement(); |
- } catch (e, s) { |
- _completeWithErrorCallback(future, e, s); |
- } |
- }, |
- cancelOnError: true); |
- return future; |
- } |
- |
- /** |
- * Finds the last element in this stream matching [test]. |
- * |
- * As [firstWhere], except that the last matching element is found. |
- * That means that the result cannot be provided before this stream |
- * is done. |
- */ |
- Future<dynamic> lastWhere(bool test(T element), {Object defaultValue()}) { |
- _Future<dynamic> future = new _Future(); |
- T result = null; |
- bool foundResult = false; |
- StreamSubscription subscription; |
- subscription = this.listen( |
- (T value) { |
- _runUserCode( |
- () => true == test(value), |
- (bool isMatch) { |
- if (isMatch) { |
- foundResult = true; |
- result = value; |
- } |
- }, |
- _cancelAndErrorClosure(subscription, future) |
- ); |
- }, |
- onError: future._completeError, |
- onDone: () { |
- if (foundResult) { |
- future._complete(result); |
- return; |
- } |
- if (defaultValue != null) { |
- _runUserCode(defaultValue, future._complete, future._completeError); |
- return; |
- } |
- try { |
- throw IterableElementError.noElement(); |
- } catch (e, s) { |
- _completeWithErrorCallback(future, e, s); |
- } |
- }, |
- cancelOnError: true); |
- return future; |
- } |
- |
- /** |
- * Finds the single element in this stream matching [test]. |
- * |
- * Like [lastMatch], except that it is an error if more than one |
- * matching element occurs in the stream. |
- */ |
- Future<T> singleWhere(bool test(T element)) { |
- _Future<T> future = new _Future<T>(); |
- T result = null; |
- bool foundResult = false; |
- StreamSubscription subscription; |
- subscription = this.listen( |
- (T value) { |
- _runUserCode( |
- () => true == test(value), |
- (bool isMatch) { |
- if (isMatch) { |
- if (foundResult) { |
- try { |
- throw IterableElementError.tooMany(); |
- } catch (e, s) { |
- _cancelAndErrorWithReplacement(subscription, future, e, s); |
- } |
- return; |
- } |
- foundResult = true; |
- result = value; |
- } |
- }, |
- _cancelAndErrorClosure(subscription, future) |
- ); |
- }, |
- onError: future._completeError, |
- onDone: () { |
- if (foundResult) { |
- future._complete(result); |
- return; |
- } |
- try { |
- throw IterableElementError.noElement(); |
- } catch (e, s) { |
- _completeWithErrorCallback(future, e, s); |
- } |
- }, |
- cancelOnError: true); |
- return future; |
- } |
- |
- /** |
- * Returns the value of the [index]th data event of this stream. |
- * |
- * Stops listening to the stream after the [index]th data event has been |
- * received. |
- * |
- * Internally the method cancels its subscription after these elements. This |
- * means that single-subscription (non-broadcast) streams are closed and |
- * cannot be reused after a call to this method. |
- * |
- * If an error event occurs before the value is found, the future completes |
- * with this error. |
- * |
- * If a done event occurs before the value is found, the future completes |
- * with a [RangeError]. |
- */ |
- Future<T> elementAt(int index) { |
- if (index is! int || index < 0) throw new ArgumentError(index); |
- _Future<T> future = new _Future<T>(); |
- StreamSubscription subscription; |
- int elementIndex = 0; |
- subscription = this.listen( |
- (T value) { |
- if (index == elementIndex) { |
- _cancelAndValue(subscription, future, value); |
- return; |
- } |
- elementIndex += 1; |
- }, |
- onError: future._completeError, |
- onDone: () { |
- future._completeError( |
- new RangeError.index(index, this, "index", null, elementIndex)); |
- }, |
- cancelOnError: true); |
- return future; |
- } |
- |
- /** |
- * Creates a new stream with the same events as this stream. |
- * |
- * Whenever more than [timeLimit] passes between two events from this stream, |
- * the [onTimeout] function is called. |
- * |
- * The countdown doesn't start until the returned stream is listened to. |
- * The countdown is reset every time an event is forwarded from this stream, |
- * or when the stream is paused and resumed. |
- * |
- * The [onTimeout] function is called with one argument: an |
- * [EventSink] that allows putting events into the returned stream. |
- * This `EventSink` is only valid during the call to `onTimeout`. |
- * |
- * If `onTimeout` is omitted, a timeout will just put a [TimeoutException] |
- * into the error channel of the returned stream. |
- * |
- * The returned stream is a broadcast stream if this stream is. |
- * If a broadcast stream is listened to more than once, each subscription |
- * will have its individually timer that starts counting on listen, |
- * and the subscriptions' timers can be paused individually. |
- */ |
- Stream<T> timeout(Duration timeLimit, {void onTimeout(EventSink<T> sink)}) { |
- StreamController<T> controller; |
- // The following variables are set on listen. |
- StreamSubscription<T> subscription; |
- Timer timer; |
- Zone zone; |
- _TimerCallback timeout; |
- |
- void onData(T event) { |
- timer.cancel(); |
- controller.add(event); |
- timer = zone.createTimer(timeLimit, timeout); |
- } |
- void onError(error, StackTrace stackTrace) { |
- timer.cancel(); |
- assert(controller is _StreamController || |
- controller is _BroadcastStreamController); |
- dynamic eventSink = controller; |
- eventSink._addError(error, stackTrace); // Avoid Zone error replacement. |
- timer = zone.createTimer(timeLimit, timeout); |
- } |
- void onDone() { |
- timer.cancel(); |
- controller.close(); |
- } |
- void onListen() { |
- // This is the onListen callback for of controller. |
- // It runs in the same zone that the subscription was created in. |
- // Use that zone for creating timers and running the onTimeout |
- // callback. |
- zone = Zone.current; |
- if (onTimeout == null) { |
- timeout = () { |
- controller.addError(new TimeoutException("No stream event", |
- timeLimit), null); |
- }; |
- } else { |
- // TODO(floitsch): the return type should be 'void', and the type |
- // should be inferred. |
- var registeredOnTimeout = |
- zone.registerUnaryCallback/*<dynamic, EventSink<T>>*/(onTimeout); |
- _ControllerEventSinkWrapper wrapper = |
- new _ControllerEventSinkWrapper(null); |
- timeout = () { |
- wrapper._sink = controller; // Only valid during call. |
- zone.runUnaryGuarded(registeredOnTimeout, wrapper); |
- wrapper._sink = null; |
- }; |
- } |
- |
- subscription = this.listen(onData, onError: onError, onDone: onDone); |
- timer = zone.createTimer(timeLimit, timeout); |
- } |
- Future onCancel() { |
- timer.cancel(); |
- Future result = subscription.cancel(); |
- subscription = null; |
- return result; |
- } |
- controller = isBroadcast |
- ? new _SyncBroadcastStreamController<T>(onListen, onCancel) |
- : new _SyncStreamController<T>( |
- onListen, |
- () { |
- // Don't null the timer, onCancel may call cancel again. |
- timer.cancel(); |
- subscription.pause(); |
- }, |
- () { |
- subscription.resume(); |
- timer = zone.createTimer(timeLimit, timeout); |
- }, |
- onCancel); |
- return controller.stream; |
- } |
-} |
- |
-/** |
- * A subscription on events from a [Stream]. |
- * |
- * When you listen on a [Stream] using [Stream.listen], |
- * a [StreamSubscription] object is returned. |
- * |
- * The subscription provides events to the listener, |
- * and holds the callbacks used to handle the events. |
- * The subscription can also be used to unsubscribe from the events, |
- * or to temporarily pause the events from the stream. |
- */ |
-abstract class StreamSubscription<T> { |
- /** |
- * Cancels this subscription. |
- * |
- * After this call, the subscription no longer receives events. |
- * |
- * The stream may need to shut down the source of events and clean up after |
- * the subscription is canceled. |
- * |
- * Returns a future that is completed once the stream has finished |
- * its cleanup. May also return `null` if no cleanup was necessary. |
- * |
- * Typically, futures are returned when the stream needs to release resources. |
- * For example, a stream might need to close an open file (as an asynchronous |
- * operation). If the listener wants to delete the file after having |
- * canceled the subscription, it must wait for the cleanup future to complete. |
- * |
- * A returned future completes with a `null` value. |
- * If the cleanup throws, which it really shouldn't, the returned future |
- * completes with that error. |
- */ |
- Future cancel(); |
- |
- /** |
- * Set or override the data event handler of this subscription. |
- * |
- * This method overrides the handler that has been set at the invocation of |
- * [Stream.listen]. |
- */ |
- void onData(void handleData(T data)); |
- |
- /** |
- * Set or override the error event handler of this subscription. |
- * |
- * This method overrides the handler that has been set at the invocation of |
- * [Stream.listen] or by calling [asFuture]. |
- */ |
- void onError(Function handleError); |
- |
- /** |
- * Set or override the done event handler of this subscription. |
- * |
- * This method overrides the handler that has been set at the invocation of |
- * [Stream.listen] or by calling [asFuture]. |
- */ |
- void onDone(void handleDone()); |
- |
- /** |
- * Request that the stream pauses events until further notice. |
- * |
- * While paused, the subscription will not fire any events. |
- * If it receives events from its source, they will be buffered until |
- * the subscription is resumed. |
- * The underlying source is usually informed about the pause, |
- * so it can stop generating events until the subscription is resumed. |
- * |
- * To avoid buffering events on a broadcast stream, it is better to |
- * cancel this subscription, and start to listen again when events |
- * are needed. |
- * |
- * If [resumeSignal] is provided, the stream will undo the pause |
- * when the future completes. If the future completes with an error, |
- * the stream will resume, but the error will not be handled! |
- * |
- * A call to [resume] will also undo a pause. |
- * |
- * If the subscription is paused more than once, an equal number |
- * of resumes must be performed to resume the stream. |
- * |
- * Currently DOM streams silently drop events when the stream is paused. This |
- * is a bug and will be fixed. |
- */ |
- void pause([Future resumeSignal]); |
- |
- /** |
- * Resume after a pause. |
- */ |
- void resume(); |
- |
- /** |
- * Returns true if the [StreamSubscription] is paused. |
- */ |
- bool get isPaused; |
- |
- /** |
- * Returns a future that handles the [onDone] and [onError] callbacks. |
- * |
- * This method *overwrites* the existing [onDone] and [onError] callbacks |
- * with new ones that complete the returned future. |
- * |
- * In case of an error the subscription will automatically cancel (even |
- * when it was listening with `cancelOnError` set to `false`). |
- * |
- * In case of a `done` event the future completes with the given |
- * [futureValue]. |
- */ |
- Future/*<E>*/ asFuture/*<E>*/([var/*=E*/ futureValue]); |
-} |
- |
- |
-/** |
- * An interface that abstracts creation or handling of [Stream] events. |
- */ |
-abstract class EventSink<T> implements Sink<T> { |
- /** Send a data event to a stream. */ |
- void add(T event); |
- |
- /** Send an async error to a stream. */ |
- void addError(errorEvent, [StackTrace stackTrace]); |
- |
- /** Close the sink. No further events can be added after closing. */ |
- void close(); |
-} |
- |
- |
-/** [Stream] wrapper that only exposes the [Stream] interface. */ |
-class StreamView<T> extends Stream<T> { |
- final Stream<T> _stream; |
- |
- const StreamView(Stream<T> stream) : _stream = stream, super._internal(); |
- |
- bool get isBroadcast => _stream.isBroadcast; |
- |
- Stream<T> asBroadcastStream( |
- {void onListen(StreamSubscription<T> subscription), |
- void onCancel(StreamSubscription<T> subscription)}) |
- => _stream.asBroadcastStream(onListen: onListen, onCancel: onCancel); |
- |
- StreamSubscription<T> listen(void onData(T value), |
- { Function onError, |
- void onDone(), |
- bool cancelOnError }) { |
- return _stream.listen(onData, onError: onError, onDone: onDone, |
- cancelOnError: cancelOnError); |
- } |
-} |
- |
- |
-/** |
- * Abstract interface for a "sink" accepting multiple entire streams. |
- * |
- * A consumer can accept a number of consecutive streams using [addStream], |
- * and when no further data need to be added, the [close] method tells the |
- * consumer to complete its work and shut down. |
- * |
- * This class is not just a [Sink<Stream>] because it is also combined with |
- * other [Sink] classes, like it's combined with [EventSink] in the |
- * [StreamSink] class. |
- * |
- * The [Stream.pipe] accepts a `StreamConsumer` and will pass the stream |
- * to the consumer's [addStream] method. When that completes, it will |
- * call [close] and then complete its own returned future. |
- */ |
-abstract class StreamConsumer<S> { |
- /** |
- * Consumes the elements of [stream]. |
- * |
- * Listens on [stream] and does something for each event. |
- * |
- * Returns a future which is completed when the stream is done being added, |
- * and the consumer is ready to accept a new stream. |
- * No further calls to [addStream] or [close] should happen before the |
- * returned future has completed. |
- * |
- * The consumer may stop listening to the stream after an error, |
- * it may consume all the errors and only stop at a done event, |
- * or it may be canceled early if the receiver don't want any further events. |
- * |
- * If the consumer stops listening because of some error preventing it |
- * from continuing, it may report this error in the returned future, |
- * otherwise it will just complete the future with `null`. |
- */ |
- Future addStream(Stream<S> stream); |
- |
- /** |
- * Tells the consumer that no further streams will be added. |
- * |
- * This allows the consumer to complete any remaining work and release |
- * resources that are no longer needed |
- * |
- * Returns a future which is completed when the consumer has shut down. |
- * If cleaning up can fail, the error may be reported in the returned future, |
- * otherwise it completes with `null`. |
- */ |
- Future close(); |
-} |
- |
- |
-/** |
- * A object that accepts stream events both synchronously and asynchronously. |
- * |
- * A [StreamSink] unifies the asynchronous methods from [StreamConsumer] and |
- * the synchronous methods from [EventSink]. |
- * |
- * The [EventSink] methods can't be used while the [addStream] is called. |
- * As soon as the [addStream]'s [Future] completes with a value, the |
- * [EventSink] methods can be used again. |
- * |
- * If [addStream] is called after any of the [EventSink] methods, it'll |
- * be delayed until the underlying system has consumed the data added by the |
- * [EventSink] methods. |
- * |
- * When [EventSink] methods are used, the [done] [Future] can be used to |
- * catch any errors. |
- * |
- * When [close] is called, it will return the [done] [Future]. |
- */ |
-abstract class StreamSink<S> implements EventSink<S>, StreamConsumer<S> { |
- /** |
- * Tells the stream sink that no further streams will be added. |
- * |
- * This allows the stream sink to complete any remaining work and release |
- * resources that are no longer needed |
- * |
- * Returns a future which is completed when the stream sink has shut down. |
- * If cleaning up can fail, the error may be reported in the returned future, |
- * otherwise it completes with `null`. |
- * |
- * Returns the same future as [done]. |
- * |
- * The stream sink may close before the [close] method is called, either due |
- * to an error or because it is itself providing events to someone who has |
- * stopped listening. In that case, the [done] future is completed first, |
- * and the `close` method will return the `done` future when called. |
- * |
- * Unifies [StreamConsumer.close] and [EventSink.close] which both mark their |
- * object as not expecting any further events. |
- */ |
- Future close(); |
- |
- /** |
- * Return a future which is completed when the [StreamSink] is finished. |
- * |
- * If the `StreamSink` fails with an error, |
- * perhaps in response to adding events using [add], [addError] or [close], |
- * the [done] future will complete with that error. |
- * |
- * Otherwise, the returned future will complete when either: |
- * |
- * * all events have been processed and the sink has been closed, or |
- * * the sink has otherwise been stopped from handling more events |
- * (for example by cancelling a stream subscription). |
- */ |
- Future get done; |
-} |
- |
- |
-/** |
- * The target of a [Stream.transform] call. |
- * |
- * The [Stream.transform] call will pass itself to this object and then return |
- * the resulting stream. |
- * |
- * It is good practice to write transformers that can be used multiple times. |
- */ |
-abstract class StreamTransformer<S, T> { |
- /** |
- * Creates a [StreamTransformer]. |
- * |
- * The returned instance takes responsibility of implementing ([bind]). |
- * When the user invokes `bind` it returns a new "bound" stream. Only when |
- * the user starts listening to the bound stream, the `listen` method |
- * invokes the given closure [transformer]. |
- * |
- * The [transformer] closure receives the stream, that was bound, as argument |
- * and returns a [StreamSubscription]. In almost all cases the closure |
- * listens itself to the stream that is given as argument. |
- * |
- * The result of invoking the [transformer] closure is a [StreamSubscription]. |
- * The bound stream-transformer (created by the `bind` method above) then sets |
- * the handlers it received as part of the `listen` call. |
- * |
- * Conceptually this can be summarized as follows: |
- * |
- * 1. `var transformer = new StreamTransformer(transformerClosure);` |
- * creates a `StreamTransformer` that supports the `bind` method. |
- * 2. `var boundStream = stream.transform(transformer);` binds the `stream` |
- * and returns a bound stream that has a pointer to `stream`. |
- * 3. `boundStream.listen(f1, onError: f2, onDone: f3, cancelOnError: b)` |
- * starts the listening and transformation. This is accomplished |
- * in 2 steps: first the `boundStream` invokes the `transformerClosure` with |
- * the `stream` it captured: `transformerClosure(stream, b)`. |
- * The result `subscription`, a [StreamSubscription], is then |
- * updated to receive its handlers: `subscription.onData(f1)`, |
- * `subscription.onError(f2)`, `subscription(f3)`. Finally the subscription |
- * is returned as result of the `listen` call. |
- * |
- * There are two common ways to create a StreamSubscription: |
- * |
- * 1. by creating a new class that implements [StreamSubscription]. |
- * Note that the subscription should run callbacks in the [Zone] the |
- * stream was listened to. |
- * 2. by allocating a [StreamController] and to return the result of |
- * listening to its stream. |
- * |
- * Example use of a duplicating transformer: |
- * |
- * stringStream.transform(new StreamTransformer<String, String>( |
- * (Stream<String> input, bool cancelOnError) { |
- * StreamController<String> controller; |
- * StreamSubscription<String> subscription; |
- * controller = new StreamController<String>( |
- * onListen: () { |
- * subscription = input.listen((data) { |
- * // Duplicate the data. |
- * controller.add(data); |
- * controller.add(data); |
- * }, |
- * onError: controller.addError, |
- * onDone: controller.close, |
- * cancelOnError: cancelOnError); |
- * }, |
- * onPause: () { subscription.pause(); }, |
- * onResume: () { subscription.resume(); }, |
- * onCancel: () { subscription.cancel(); }, |
- * sync: true); |
- * return controller.stream.listen(null); |
- * }); |
- */ |
- const factory StreamTransformer( |
- StreamSubscription<T> transformer(Stream<S> stream, bool cancelOnError)) |
- = _StreamSubscriptionTransformer<S, T>; |
- |
- /** |
- * Creates a [StreamTransformer] that delegates events to the given functions. |
- * |
- * Example use of a duplicating transformer: |
- * |
- * stringStream.transform(new StreamTransformer<String, String>.fromHandlers( |
- * handleData: (String value, EventSink<String> sink) { |
- * sink.add(value); |
- * sink.add(value); // Duplicate the incoming events. |
- * })); |
- */ |
- factory StreamTransformer.fromHandlers({ |
- void handleData(S data, EventSink<T> sink), |
- void handleError(Object error, StackTrace stackTrace, EventSink<T> sink), |
- void handleDone(EventSink<T> sink)}) |
- = _StreamHandlerTransformer<S, T>; |
- |
- /** |
- * Transform the incoming [stream]'s events. |
- * |
- * Creates a new stream. |
- * When this stream is listened to, it will start listening on [stream], |
- * and generate events on the new stream based on the events from [stream]. |
- * |
- * Subscriptions on the returned stream should propagate pause state |
- * to the subscription on [stream]. |
- */ |
- Stream<T> bind(Stream<S> stream); |
-} |
- |
-/** |
- * An [Iterator] like interface for the values of a [Stream]. |
- * |
- * This wraps a [Stream] and a subscription on the stream. It listens |
- * on the stream, and completes the future returned by [moveNext] when the |
- * next value becomes available. |
- */ |
-abstract class StreamIterator<T> { |
- |
- /** Create a [StreamIterator] on [stream]. */ |
- factory StreamIterator(Stream<T> stream) |
- // TODO(lrn): use redirecting factory constructor when type |
- // arguments are supported. |
- => new _StreamIteratorImpl<T>(stream); |
- |
- /** |
- * Wait for the next stream value to be available. |
- * |
- * Returns a future which will complete with either `true` or `false`. |
- * Completing with `true` means that another event has been received and |
- * can be read as [current]. |
- * Completing with `false` means that the stream itearation is done and |
- * no further events will ever be available. |
- * The future may complete with an error, if the stream produces an error, |
- * which also ends iteration. |
- * |
- * The function must not be called again until the future returned by a |
- * previous call is completed. |
- */ |
- Future<bool> moveNext(); |
- |
- /** |
- * The current value of the stream. |
- * |
- * Is `null` before the first call to [moveNext] and after a call to |
- * `moveNext` completes with a `false` result or an error. |
- * |
- * When a `moveNext` call completes with `true`, the `current` field holds |
- * the most recent event of the stream, and it stays like that until the next |
- * call to `moveNext`. |
- * Between a call to `moveNext` and when its returned future completes, |
- * the value is unspecified. |
- */ |
- T get current; |
- |
- /** |
- * Cancels the stream iterator (and the underlying stream subscription) early. |
- * |
- * The stream iterator is automatically canceled if the [moveNext] future |
- * completes with either `false` or an error. |
- * |
- * If you need to stop listening for values before the stream iterator is |
- * automatically closed, you must call [cancel] to ensure that the stream |
- * is properly closed. |
- * |
- * If [moveNext] has been called when the iterator is cancelled, |
- * its returned future will complete with `false` as value, |
- * as will all further calls to [moveNext]. |
- * |
- * Returns a future if the cancel-operation is not completed synchronously. |
- * Otherwise returns `null`. |
- */ |
- Future cancel(); |
-} |
- |
- |
-/** |
- * Wraps an [_EventSink] so it exposes only the [EventSink] interface. |
- */ |
-class _ControllerEventSinkWrapper<T> implements EventSink<T> { |
- EventSink _sink; |
- _ControllerEventSinkWrapper(this._sink); |
- |
- void add(T data) { _sink.add(data); } |
- void addError(error, [StackTrace stackTrace]) { |
- _sink.addError(error, stackTrace); |
- } |
- void close() { _sink.close(); } |
-} |