| // Copyright (c) 2015, 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. |
| |
| import 'dart:io'; |
| |
| import '../watcher.dart'; |
| import 'file_watcher/native.dart'; |
| import 'file_watcher/polling.dart'; |
| |
| /// Watches a file and emits [WatchEvent]s when the file has changed. |
| /// |
| /// Note that since each watcher only watches a single file, it will only emit |
| /// [ChangeType.MODIFY] events, except when the file is deleted at which point |
| /// it will emit a single [ChangeType.REMOVE] event and then close the stream. |
| /// |
| /// If the file is deleted and quickly replaced (when a new file is moved in its |
| /// place, for example) this will emit a [ChangeTime.MODIFY] event. |
| abstract class FileWatcher implements Watcher { |
| /// Creates a new [FileWatcher] monitoring [file]. |
| /// |
| /// If a native file watcher is available for this platform, this will use it. |
| /// Otherwise, it will fall back to a [PollingFileWatcher]. Notably, native |
| /// file watching is *not* supported on Windows. |
| /// |
| /// If [pollingDelay] is passed, it specifies the amount of time the watcher |
| /// will pause between successive polls of the directory contents. Making this |
| /// shorter will give more immediate feedback at the expense of doing more IO |
| /// and higher CPU usage. Defaults to one second. Ignored for non-polling |
| /// watchers. |
| factory FileWatcher(String file, {Duration pollingDelay}) { |
| // [File.watch] doesn't work on Windows, but |
| // [FileSystemEntity.isWatchSupported] is still true because directory |
| // watching does work. |
| if (FileSystemEntity.isWatchSupported && !Platform.isWindows) { |
| return new NativeFileWatcher(file); |
| } |
| return new PollingFileWatcher(file, pollingDelay: pollingDelay); |
| } |
| } |