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| 1 // Copyright (c) 2015, the Dart project authors. Please see the AUTHORS file |
| 2 // for details. All rights reserved. Use of this source code is governed by a |
| 3 // BSD-style license that can be found in the LICENSE file. |
| 4 |
| 5 library watcher.file_watcher; |
| 6 |
| 7 import 'dart:io'; |
| 8 |
| 9 import 'watch_event.dart'; |
| 10 import '../watcher.dart'; |
| 11 import 'file_watcher/native.dart'; |
| 12 import 'file_watcher/polling.dart'; |
| 13 |
| 14 /// Watches a file and emits [WatchEvent]s when the file has changed. |
| 15 /// |
| 16 /// Note that since each watcher only watches a single file, it will only emit |
| 17 /// [ChangeType.MODIFY] events, except when the file is deleted at which point |
| 18 /// it will emit a single [ChangeType.REMOVE] event and then close the stream. |
| 19 /// |
| 20 /// If the file is deleted and quickly replaced (when a new file is moved in its |
| 21 /// place, for example) this will emit a [ChangeTime.MODIFY] event. |
| 22 abstract class FileWatcher implements Watcher { |
| 23 /// Creates a new [FileWatcher] monitoring [file]. |
| 24 /// |
| 25 /// If a native file watcher is available for this platform, this will use it. |
| 26 /// Otherwise, it will fall back to a [PollingFileWatcher]. Notably, native |
| 27 /// file watching is *not* supported on Windows. |
| 28 /// |
| 29 /// If [pollingDelay] is passed, it specifies the amount of time the watcher |
| 30 /// will pause between successive polls of the directory contents. Making this |
| 31 /// shorter will give more immediate feedback at the expense of doing more IO |
| 32 /// and higher CPU usage. Defaults to one second. Ignored for non-polling |
| 33 /// watchers. |
| 34 factory FileWatcher(String file, {Duration pollingDelay}) { |
| 35 // [File.watch] doesn't work on Windows, but |
| 36 // [FileSystemEntity.isWatchSupported] is still true because directory |
| 37 // watching does work. |
| 38 if (FileSystemEntity.isWatchSupported && !Platform.isWindows) { |
| 39 return new NativeFileWatcher(file); |
| 40 } |
| 41 return new PollingFileWatcher(file, pollingDelay: pollingDelay); |
| 42 } |
| 43 } |
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