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// 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.
/// Support for asynchronous programming,
/// with classes such as Future and Stream.
/// Understanding [Future]s and [Stream]s is a prerequisite for
/// writing just about any Dart program.
/// To use this library in your code:
/// ```dart
/// import 'dart:async';
/// ```
/// ## Future
/// A Future object represents a computation whose return value
/// might not yet be available.
/// The Future returns the value of the computation
/// when it completes at some time in the future.
/// Futures are often used for potentially lengthy computations
/// such as I/O and interaction with users.
/// Many methods in the Dart libraries return Futures when
/// performing tasks. For example, when binding an HttpServer
/// to a host and port, the `bind()` method returns a Future.
/// ```dart
/// HttpServer.bind('', 4444)
/// .then((server) => print('${server.isBroadcast}'))
/// .catchError(print);
/// ```
/// [Future.then] registers a callback function that runs
/// when the Future's operation, in this case the `bind()` method,
/// completes successfully.
/// The value returned by the operation
/// is passed into the callback function.
/// In this example, the `bind()` method returns the HttpServer
/// object. The callback function prints one of its properties.
/// [Future.catchError] registers a callback function that
/// runs if an error occurs within the Future.
/// ## Stream
/// A Stream provides an asynchronous sequence of data.
/// Examples of data sequences include individual events, like mouse clicks,
/// or sequential chunks of larger data, like multiple byte lists with the
/// contents of a file
/// such as mouse clicks, and a stream of byte lists read from a file.
/// The following example opens a file for reading.
/// [Stream.listen] registers a callback function that runs
/// each time more data is available.
/// ```dart
/// Stream<List<int>> stream = File('quotes.txt').openRead();
/// stream.transform(utf8.decoder).listen(print);
/// ```
/// The stream emits a sequence of a list of bytes.
/// The program must interpret the bytes or handle the raw byte data.
/// Here, the code uses a UTF-8 decoder (provided in the `dart:convert` library)
/// to convert the sequence of bytes into a sequence
/// of Dart strings.
/// Another common use of streams is for user-generated events
/// in a web app: The following code listens for mouse clicks on a button.
/// ```dart
/// querySelector('#myButton').onClick.listen((_) => print('Click.'));
/// ```
/// ## Other resources
/// * The [dart:async section of the library tour][asynchronous-programming]:
/// A brief overview of asynchronous programming.
/// * [Use Future-Based APIs][futures-tutorial]: A closer look at Futures and
/// how to use them to write asynchronous Dart code.
/// * [Futures and Error Handling][futures-error-handling]: Everything you
/// wanted to know about handling errors and exceptions when working with
/// Futures (but were afraid to ask).
/// * [The Event Loop and Dart](
/// Learn how Dart handles the event queue and microtask queue, so you can
/// write better asynchronous code with fewer surprises.
/// * [test package: Asynchronous Tests][test-readme]: How to test asynchronous
/// code.
/// [asynchronous-programming]:
/// [futures-tutorial]:
/// [futures-error-handling]:
/// [test-readme]:
/// {@category Core}
library dart.async;
import "dart:collection" show HashMap;
import "dart:_internal"
part 'async_error.dart';
part 'broadcast_stream_controller.dart';
part 'deferred_load.dart';
part 'future.dart';
part 'future_impl.dart';
part 'schedule_microtask.dart';
part 'stream.dart';
part 'stream_controller.dart';
part 'stream_impl.dart';
part 'stream_pipe.dart';
part 'stream_transformers.dart';
part 'timer.dart';
part 'zone.dart';