Add FileSystemWatcher class to dart:io.

sdk/lib/io/file_system_entity.dart

Index: sdk/lib/io/file_system_entity.dart
diff --git a/sdk/lib/io/file_system_entity.dart b/sdk/lib/io/file_system_entity.dart
index b764f04be7ca151d28701ae498155411f4b86f5f..168a57b37b6b9deddabe5b74340b8cd0348dac9b 100644
--- a/sdk/lib/io/file_system_entity.dart
+++ b/sdk/lib/io/file_system_entity.dart
@@ -317,6 +317,12 @@ abstract class FileSystemEntity {
   FileStat statSync();
 
 
+
+  Stream<FileSystemEvent> watch({int events: FileSystemEvent.ALL_EVENTS,
+                                 bool recursive: false})
+     => new _FileSystemWatcher(path, events, recursive).stream;
+
+
   /**
    * Finds the type of file system object that a path points to. Returns
    * a [:Future<FileSystemEntityType>:] that completes with the result.
@@ -390,11 +396,204 @@ abstract class FileSystemEntity {
       (_getTypeSync(path, true) == FileSystemEntityType.DIRECTORY._type);
 
 
-  static _throwIfError(Object result, String msg) {
+  static _throwIfError(Object result, String msg, [String path]) {
     if (result is OSError) {
-      throw new FileException(msg, result);
+      throw new FileException(msg, result, path);
     } else if (result is ArgumentError) {
       throw result;
     }
   }
 }
+
+
+/**
+ * Base event class emitted by FileSystemWatcher.
+ */
+class FileSystemEvent {
+  static const int CREATE_EVENT = 1 << 0;

[Søren Gjesse, 2013/08/26 07:51:55]

How about removing the _EVENT prefix?

[Anders Johnsen, 2013/09/03 11:36:23]

Done.

+  static const int MODIFY_EVENT = 1 << 1;
+  static const int DELETE_EVENT = 1 << 2;
+  static const int MOVE_EVENT =  1 << 3;

[Søren Gjesse, 2013/08/26 07:51:55]

Two spaces after =.

[Anders Johnsen, 2013/09/03 11:36:23]

Done.

+  static const int ALL_EVENTS =
+      CREATE_EVENT | MODIFY_EVENT | DELETE_EVENT | MOVE_EVENT;
+
+  static const int _MODIFY_ATTRIBUTES_EVENT = 1 << 4;

[Søren Gjesse, 2013/08/26 07:51:55]

Add empty line.

[Anders Johnsen, 2013/09/03 11:36:23]

Done.

+  /**
+   * The type of event. See [FileSystemEvent] for a list of events.
+   */
+  final int type;
+
+  /**
+   * The path that triggered the event.

[Søren Gjesse, 2013/08/26 07:51:55]

Some doc on whether this is absolute or maybe ŕelative to the path being
listened on.

[Anders Johnsen, 2013/09/03 11:36:23]

Done.

+   */
+  final String path;
+
+  FileSystemEvent._(this.type, this.path);
+}
+
+
+/**
+ * File system event for newly created file system objects.
+ */
+class FileSystemCreateEvent extends FileSystemEvent {
+  FileSystemCreateEvent._(path)
+      : super._(FileSystemEvent.CREATE_EVENT, path);
+
+  String toString() => "FileSystemCreateEvent('$path')";
+}
+
+
+/**
+ * File system event for modifications of file system objects.
+ */
+class FileSystemModifyEvent extends FileSystemEvent {
+  /**
+   * If the content was changed and not only the attributes, [contentChanged]
+   * is `true`.
+   */
+  final bool contentChanged;
+
+  FileSystemModifyEvent._(path, this.contentChanged)
+      : super._(FileSystemEvent.MODIFY_EVENT, path);
+
+  String toString() =>
+      "FileSystemModifyEvent('$path', contentChanged=$contentChanged)";
+}
+
+
+/**
+ * File system event for deletion of file system objects.
+ */
+class FileSystemDeleteEvent extends FileSystemEvent {
+  FileSystemDeleteEvent._(path)
+      : super._(FileSystemEvent.DELETE_EVENT, path);
+
+  String toString() => "FileSystemDeleteEvent('$path')";
+}
+
+
+/**
+ * File system event for moving of file system objects.
+ */
+class FileSystemMoveEvent extends FileSystemEvent {
+  /**
+   * If the underlaying implementation is able to identify the destination of
+   * the moved file, [destination] will be set. Otherwise, it will be `null`.
+   */
+  final String destination;
+
+  FileSystemMoveEvent._(path, this.destination)
+      : super._(FileSystemEvent.MOVE_EVENT, path);
+
+  String toString() {
+    var buffer = new StringBuffer();
+    buffer.write("FileSystemMoveEvent('$path'");
+    if (destination != null) buffer.write(", '$destination'");
+    buffer.write(')');
+    return buffer.toString();
+  }
+}
+
+
+class _FileSystemWatcher {
+  final String _path;
+  final int _events;
+
+  StreamController _controller;
+  int _id;
+  _RawSocket _socket;
+
+  _FileSystemWatcher(this._path, this._events, bool recursive) {
+
+    _controller = new StreamController(
+        onListen: () {
+          print("in listen");

[Søren Gjesse, 2013/08/26 07:51:55]

Debug print.

[Anders Johnsen, 2013/09/03 11:36:23]

Done.

+          _id = _watchPath(_path, _events, recursive);
+          FileSystemEntity._throwIfError(_id, "Failed to watch path", _path);
+          _listen();
+        },
+        onCancel: () {
+          if (_socket != null) {
+            _socket.close();
+          }
+        });
+  }
+
+  void _stop() {
+    _controller.close();
+    _unwatchPath(_id);
+  }
+
+  void _listen() {

[Søren Gjesse, 2013/08/26 07:51:55]

I think we should do _NativeSocket setup the same way as in socket_patch.dart. I
suggest creating the _NativeSocket on the call to  watchPath (new constructor
_NativeSocket.watcher()), and then passing this object to the native call making
the native call set to socket is field (like e.g. Socket_CreateConnect). Then I
don't think we need _getSocketId and setSocketId on _NativeSocket.

[Anders Johnsen, 2013/09/03 11:36:23]

I've tried to simplify as much as possible.

+    int socketId = _getSocketId(_id);
+    var native = new _NativeSocket.normal();
+    native.isClosedWrite = true;
+    native.setSocketId(socketId);
+    _socket = new _RawSocket(native);
+    print(socketId);

[Søren Gjesse, 2013/08/26 07:51:55]

Debug print.

[Anders Johnsen, 2013/09/03 11:36:23]

Done.

+    _socket.expand((event) {
+      print(event);
+      var events = [];
+      var pair = {};
+      if (event == RawSocketEvent.READ) {
+        String getPath(event) {
+          var path = _path;
+          if (event[2] != null) {
+            path += Platform.pathSeparator;
+            path += event[2];
+          }
+          return path;
+        }
+        while (_socket.available() > 0) {
+          for (var event in _readEvents(_id)) {
+              print(event);

[Søren Gjesse, 2013/08/26 07:51:55]

Debug print.

[Anders Johnsen, 2013/09/03 11:36:23]

Done.

+            var path = getPath(event);
+            if ((event[0] & FileSystemEvent.CREATE_EVENT) != 0) {
+              events.add(new FileSystemCreateEvent._(path));
+            }
+            if ((event[0] & FileSystemEvent.MODIFY_EVENT) != 0) {
+              events.add(new FileSystemModifyEvent._(path, true));
+            }
+            if ((event[0] & FileSystemEvent._MODIFY_ATTRIBUTES_EVENT) != 0) {
+              events.add(new FileSystemModifyEvent._(path, false));
+            }
+            if ((event[0] & FileSystemEvent.MOVE_EVENT) != 0) {
+              int link = event[3];
+              if (link > 0) {
+                if (pair.containsKey(link)) {
+                  events.add(
+                      new FileSystemMoveEvent._(getPath(pair[link]), path));
+                  pair.remove(link);
+                } else {
+                  pair[link] = event;
+                }
+              } else {
+                events.add(new FileSystemMoveEvent._(path, null));
+              }
+            }
+            if ((event[0] & FileSystemEvent.DELETE_EVENT) != 0) {
+              events.add(new FileSystemDeleteEvent._(path));
+            }
+          }
+        }
+        for (var event in pair.values) {
+          events.add(new FileSystemMoveEvent._(getPath(event), null));
+        }
+      } else if (event == RawSocketEvent.CLOSED) {
+        _stop();
+      } else if (event == RawSocketEvent.READ_CLOSED) {
+      } else {
+        assert(false);
+      }
+      print(events);
+      return events;
+    }).where((event) => (event.type & _events) != 0).listen(_controller.add);
+  }
+
+  Stream<FileSystemEvent> get stream => _controller.stream;
+
+  external _watchPath(String path, int events, bool recursive);
+  external void _unwatchPath(int id);
+  external int _getSocketId(int id);
+  external List _readEvents(int id);
+}