Make file system watcher compile on Mac OS 106, and add a runtime-call to test if the system suppor…

runtime/bin/file_patch.dart

 // 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.
 
 patch class _FileUtils {
   /* patch */ static SendPort _newServicePort() native "File_NewServicePort";
 }
 
 patch class _File {
   /* patch */ static _exists(String path) native "File_Exists";
@@ skipping 28 matching lines @@
       native "File_SetPosition";
   /* patch */ static _truncate(int id, int length) native "File_Truncate";
   /* patch */ static _length(int id) native "File_Length";
   /* patch */ static _flush(int id) native "File_Flush";
 }
 
 patch class _FileSystemWatcher {
   /* patch */ factory _FileSystemWatcher(
       String path, int events, bool recursive)
     => new _FileSystemWatcherImpl(path, events, recursive);
+
+  /* patch */ static bool get isSupported => _FileSystemWatcherImpl.isSupported;

[kustermann, 2013/09/03 15:18:58]

Wouldn't it make sense to cache the 'isSupported' value.
Otherwise we always call into c++ and do a syscall.

[Anders Johnsen, 2013/09/03 15:32:56]

As this is not performance critical, I'll not cache it, but you are right, it
could be done here.

 }
 
 class _FileSystemWatcherImpl
     extends NativeFieldWrapperClass1
     implements _FileSystemWatcher {
   final String _path;
   final int _events;
   final bool _recursive;
 
   StreamController _controller;
   StreamSubscription _subscription;
 
   _FileSystemWatcherImpl(this._path, this._events, this._recursive) {
+    if (!isSupported) {
+      throw new FileException(
+          "File system watching is not supported on this system",
+          _path);
+    }
     _controller = new StreamController(onListen: _listen, onCancel: _cancel);
   }
 
   void _listen() {
     int socketId;
     try {
       socketId = _watchPath(_path, _events, identical(true, _recursive));
     } catch (e) {
       throw new FileException(
           "Failed to watch path",
@@ skipping 61 matching lines @@
 
   void _cancel() {
     _unwatchPath();
     if (_subscription != null) {
       _subscription.cancel();
     }
   }
 
   Stream<FileSystemEvent> get stream => _controller.stream;
 
+  static bool get isSupported native "FileSystemWatcher_IsSupported";
+
   int _watchPath(String path, int events, bool recursive)
       native "FileSystemWatcher_WatchPath";
   void _unwatchPath() native "FileSystemWatcher_UnwatchPath";
   List _readEvents() native "FileSystemWatcher_ReadEvents";
 }
 
 Uint8List _makeUint8ListView(Uint8List source, int offsetInBytes, int length) {
   return new Uint8List.view(source.buffer, offsetInBytes, length);
 }