Make IOSink implement StringSink

sdk/lib/io/file_impl.dart

 // Copyright (c) 2013, 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.
 
 part of dart.io;
 
 
 class _FileStream extends Stream<List<int>> {
   // Stream controller.
   StreamController<List<int>> _controller;
@@ skipping 450 matching lines @@
   String fullPathSync() {
     var result = _fullPath(_path);
     throwIfError(result, "Cannot retrieve full path for file '$_path'");
     return result;
   }
 
   Stream<List<int>> openRead() {
     return new _FileStream(_path);
   }
 
-  IOSink<File> openWrite([FileMode mode = FileMode.WRITE]) {
+  IOSink<File> openWrite({FileMode mode: FileMode.WRITE,
+                          Encoding encoding: Encoding.UTF_8}) {
     if (mode != FileMode.WRITE &&
         mode != FileMode.APPEND) {
       throw new FileIOException(
           "Wrong FileMode. Use FileMode.WRITE or FileMode.APPEND");
     }
     var consumer = new _FileStreamConsumer(this, mode);
-    return new IOSink<File>(consumer);
+    return new IOSink<File>(consumer, encoding: encoding);
   }
 
   Future<List<int>> readAsBytes() {
     _ensureFileService();
     Completer<List<int>> completer = new Completer<List<int>>();
     var chunks = new _BufferList();
     openRead().listen(
       (d) => chunks.add(d),
       onDone: () {
         var result = chunks.readBytes(chunks.length);
@@ skipping 51 matching lines @@
       return _decodeLines(bytes, encoding);
     });
   }
 
   List<String> readAsLinesSync([Encoding encoding = Encoding.UTF_8]) {
     return _decodeLines(readAsBytesSync(), encoding);
   }
 
   Future<File> writeAsBytes(List<int> bytes,
                             [FileMode mode = FileMode.WRITE]) {
-    Completer<File> completer = new Completer<File>();
     try {
-      var stream = openWrite(mode);
-      stream.add(bytes);
-      stream.close();
-      stream.done
-        .then((_) {
-          completer.complete(this);
-        })
-        .catchError((e) {
-          completer.completeError(e);
-        });
+      IOSink<File> sink = openWrite(mode: mode);
+      sink.writeBytes(bytes);
+      sink.close();
+      return sink.done.then((_) => this);;
     } catch (e) {
-      Timer.run(() => completer.completeError(e));
-      return completer.future;
+      return new Future.immediateError(e);
     }
-    return completer.future;
   }
 
   void writeAsBytesSync(List<int> bytes, [FileMode mode = FileMode.WRITE]) {
     RandomAccessFile opened = openSync(mode);
     opened.writeListSync(bytes, 0, bytes.length);
     opened.closeSync();
   }
 
   Future<File> writeAsString(String contents,
                              {FileMode mode: FileMode.WRITE,
@@ skipping 472 matching lines @@
           new FileIOException("File closed '$_path'"));
     });
     return completer.future;
   }
 
   final String _path;
   int _id;
 
   SendPort _fileService;
 }