| // Copyright (c) 2012, 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. |
| |
| library event_helper; |
| |
| import 'dart:async'; |
| |
| abstract class Event { |
| void replay(EventSink sink); |
| } |
| |
| class DataEvent implements Event { |
| final data; |
| |
| DataEvent(this.data); |
| |
| void replay(EventSink sink) { |
| sink.add(data); |
| } |
| |
| int get hashCode => data.hashCode; |
| |
| bool operator ==(Object other) { |
| if (other is! DataEvent) return false; |
| DataEvent otherEvent = other; |
| return data == otherEvent.data; |
| } |
| |
| String toString() => "DataEvent: $data"; |
| } |
| |
| class ErrorEvent implements Event { |
| final error; |
| |
| ErrorEvent(this.error); |
| |
| void replay(EventSink sink) { |
| sink.addError(error); |
| } |
| |
| int get hashCode => error.error.hashCode; |
| |
| bool operator ==(Object other) { |
| if (other is! ErrorEvent) return false; |
| ErrorEvent otherEvent = other; |
| return error == otherEvent.error; |
| } |
| |
| String toString() => "ErrorEvent: ${error}"; |
| } |
| |
| class DoneEvent implements Event { |
| const DoneEvent(); |
| |
| void replay(EventSink sink) { |
| sink.close(); |
| } |
| |
| int get hashCode => 42; |
| |
| bool operator ==(Object other) => other is DoneEvent; |
| |
| String toString() => "DoneEvent"; |
| } |
| |
| /** Collector of events. */ |
| class Events implements EventSink { |
| final List<Event> events = []; |
| bool trace = false; |
| Completer onDoneSignal = new Completer(); |
| |
| Events(); |
| |
| Events.fromIterable(Iterable iterable) { |
| for (var value in iterable) add(value); |
| close(); |
| } |
| |
| /** Capture events from a stream into a new [Events] object. */ |
| factory Events.capture(Stream stream, {bool cancelOnError}) = CaptureEvents; |
| |
| // EventSink interface. |
| void add(var value) { |
| if (trace) print("Events#$hashCode: add($value)"); |
| events.add(new DataEvent(value)); |
| } |
| |
| void addError(error, [StackTrace? stackTrace]) { |
| if (trace) print("Events#$hashCode: addError($error)"); |
| events.add(new ErrorEvent(error)); |
| } |
| |
| void close() { |
| if (trace) print("Events#$hashCode: close()"); |
| events.add(const DoneEvent()); |
| onDoneSignal.complete(); |
| } |
| |
| /** |
| * Error shorthand, for writing events manually. |
| */ |
| void error(var value, [StackTrace? stackTrace]) { |
| addError(value, stackTrace); |
| } |
| |
| /** Replay the captured events on a sink. */ |
| void replay(EventSink sink) { |
| for (int i = 0; i < events.length; i++) { |
| events[i].replay(sink); |
| } |
| } |
| |
| /** |
| * Create a new [Events] with the same captured events. |
| * |
| * This does not copy a subscription. |
| */ |
| Events copy() { |
| Events result = new Events(); |
| replay(result); |
| return result; |
| } |
| |
| // Operations that only work when there is a subscription feeding the Events. |
| |
| /** |
| * Pauses the subscription that feeds this [Events]. |
| * |
| * Should only be used when there is a subscription. That is, after a |
| * call to [subscribeTo]. |
| */ |
| void pause([Future? resumeSignal]) { |
| throw new StateError("Not capturing events."); |
| } |
| |
| /** Resumes after a call to [pause]. */ |
| void resume() { |
| throw new StateError("Not capturing events."); |
| } |
| |
| /** |
| * Sets an action to be called when this [Events] receives a 'done' event. |
| * |
| * The action will also be called if capturing events from a stream with |
| * `cancelOnError` set to true and receiving an error. |
| */ |
| void onDone(void action()) { |
| onDoneSignal.future.whenComplete(action); |
| } |
| } |
| |
| class CaptureEvents extends Events { |
| late StreamSubscription subscription; |
| bool cancelOnError = false; |
| |
| CaptureEvents(Stream stream, {bool cancelOnError: false}) { |
| this.cancelOnError = cancelOnError; |
| subscription = stream.listen(add, |
| onError: addError, onDone: close, cancelOnError: cancelOnError); |
| } |
| |
| void addError(error, [StackTrace? stackTrace]) { |
| super.addError(error, stackTrace); |
| if (cancelOnError) { |
| onDoneSignal.complete(); |
| } |
| } |
| |
| void pause([Future? resumeSignal]) { |
| if (trace) print("Events#$hashCode: pause"); |
| subscription.pause(resumeSignal); |
| } |
| |
| void resume() { |
| if (trace) print("Events#$hashCode: resume"); |
| subscription.resume(); |
| } |
| |
| void onDone(void action()) { |
| if (trace) print("Events#$hashCode: onDone"); |
| super.onDone(action); |
| } |
| } |