53 lines
1.8 KiB
Dart
53 lines
1.8 KiB
Dart
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// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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import 'dart:async';
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import 'dart:collection';
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import 'dart:io';
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/// Returns `true` if [error] is a [FileSystemException] for a missing
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/// directory.
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bool isDirectoryNotFoundException(Object error) {
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if (error is! FileSystemException) return false;
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// See dartbug.com/12461 and tests/standalone/io/directory_error_test.dart.
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var notFoundCode = Platform.operatingSystem == 'windows' ? 3 : 2;
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return error.osError?.errorCode == notFoundCode;
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}
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/// Returns the union of all elements in each set in [sets].
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Set<T> unionAll<T>(Iterable<Set<T>> sets) =>
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sets.fold(<T>{}, (union, set) => union.union(set));
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extension BatchEvents<T> on Stream<T> {
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/// Batches all events that are sent at the same time.
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///
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/// When multiple events are synchronously added to a stream controller, the
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/// [StreamController] implementation uses [scheduleMicrotask] to schedule the
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/// asynchronous firing of each event. In order to recreate the synchronous
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/// batches, this collates all the events that are received in "nearby"
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/// microtasks.
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Stream<List<T>> batchEvents() {
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var batch = Queue<T>();
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return StreamTransformer<T, List<T>>.fromHandlers(
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handleData: (event, sink) {
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batch.add(event);
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// [Timer.run] schedules an event that runs after any microtasks that have
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// been scheduled.
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Timer.run(() {
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if (batch.isEmpty) return;
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sink.add(batch.toList());
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batch.clear();
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});
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}, handleDone: (sink) {
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if (batch.isNotEmpty) {
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sink.add(batch.toList());
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batch.clear();
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}
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sink.close();
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}).bind(this);
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}
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}
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