Implement File.directory() and File.directorySync() to get

runtime/bin/file_impl.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.
 
 class _FileInputStream extends _BaseDataInputStream implements InputStream {
   _FileInputStream(RandomAccessFile this._file, int this._length) {
     _streamMarkedClosed = true;
     _checkScheduleCallbacks();
   }
 
@@ skipping 386 matching lines @@
   _DeleteOperation(String this._name);
 
   void execute(ReceivePort port) {
     _replyPort.send(_FileUtils.checkedDelete(_name), port.toSendPort());
   }
 
   String _name;
 }
 
 
+class _DirectoryOperation extends _FileOperation {
+  _DirectoryOperation(String this._name);
+
+  void execute(ReceivePort port) {
+    if (_name is String) {
+      if (_FileUtils.exists(_name)) {
+        _replyPort.send(_FileUtils.directory(_name), port.toSendPort());
+        return;
+      }
+    }
+    // Either _name is not a string or the file does not exist.
+    _replyPort.send(null, port.toSendPort());
+  }
+
+  String _name;
+}
+
+
 class _ExitOperation extends _FileOperation {
   void execute(ReceivePort port) {
     port.close();
   }
 }
 
 
 class _FileOperationIsolate extends Isolate {
   _FileOperationIsolate() : super.heavy();
 
@@ skipping 55 matching lines @@
   _FileOperationIsolate _isolate;
 }
 
 
 // Helper class containing static file helper methods.
 class _FileUtils {
   static bool exists(String name) native "File_Exists";
   static int open(String name, int mode) native "File_Open";
   static bool create(String name) native "File_Create";
   static bool delete(String name) native "File_Delete";
+  static String directory(String name) native "File_Directory";
   static String fullPath(String name) native "File_FullPath";
   static int close(int id) native "File_Close";
   static int readByte(int id) native "File_ReadByte";
   static int readList(int id, List<int> buffer, int offset, int bytes)
       native "File_ReadList";
   static int writeByte(int id, int value) native "File_WriteByte";
   static int writeList(int id, List<int> buffer, int offset, int bytes) {
     // When using the Dart C API to access raw data, using a ByteArray is
     // currently much faster. This function will make a copy of the
     // supplied List to a ByteArray if it isn't already.
@@ skipping 138 matching lines @@
     if (_asyncUsed) {
       throw new FileIOException(
           "Mixed use of synchronous and asynchronous API");
     }
     bool deleted = _FileUtils.checkedDelete(_name);
     if (!deleted) {
       throw new FileIOException("Cannot delete file: $_name");
     }
   }
 
+  void directory() {
+    _asyncUsed = true;
+    var handleDirectoryResult = (path, ignored) {
+      var handler =
+          (_directoryHandler != null) ? _directoryHandler : (s) => null;
+      if (path != null) {
+        handler(new Directory(path));
+      } else if (_errorHandler != null) {
+        _errorHandler("Cannot get containing directory for: ${_name}");
+      }
+    };
+    var operation = new _DirectoryOperation(_name);
+    _scheduler.enqueue(operation, handleDirectoryResult);
+  }
+
+  void directorySync() {
+    if (_asyncUsed) {
+      throw new FileIOException(
+          "Mixed use of synchronous and asynchronous API");
+    }
+    if (!existsSync()) {
+      throw new FileIOException("Cannot get directory for: $_name");
+    }
+    return new Directory(_FileUtils.directory(_name));
+  }
+
   void open([FileMode mode = FileMode.READ]) {
     _asyncUsed = true;
     if (mode != FileMode.READ &&
         mode != FileMode.WRITE &&
         mode != FileMode.APPEND) {
       if (_errorHandler != null) {
         _errorHandler("Unknown file mode. Use FileMode.READ, FileMode.WRITE " +
                       "or FileMode.APPEND.");
         return;
       }
@@ skipping 139 matching lines @@
   }
 
   void set createHandler(void handler()) {
     _createHandler = handler;
   }
 
   void set deleteHandler(void handler()) {
     _deleteHandler = handler;
   }
 
+  void set directoryHandler(void handler(Directory directory)) {
+    _directoryHandler = handler;
+  }
+
   void set openHandler(void handler(RandomAccessFile file)) {
     _openHandler = handler;
   }
 
   void set inputStreamHandler(void handler(InputStream stream)) {
     _inputStreamHandler = handler;
   }
 
   void set outputStreamHandler(void handler(OutputStream stream)) {
     _outputStreamHandler = handler;
   }
 
   void set fullPathHandler(void handler(String)) {
     _fullPathHandler = handler;
   }
 
   void set errorHandler(void handler(String error)) {
     _errorHandler = handler;
   }
 
   String _name;
   bool _asyncUsed;
 
   _FileOperationScheduler _scheduler;
 
   Function _existsHandler;
   Function _createHandler;
   Function _deleteHandler;
+  Function _directoryHandler;
   Function _openHandler;
   Function _inputStreamHandler;
   Function _outputStreamHandler;
   Function _fullPathHandler;
   Function _errorHandler;
 }
 
 
 class _RandomAccessFile implements RandomAccessFile {
   _RandomAccessFile(int this._id, String this._name)
@@ skipping 396 matching lines @@
   Function _readByteHandler;
   Function _readListHandler;
   Function _noPendingWriteHandler;
   Function _positionHandler;
   Function _setPositionHandler;
   Function _truncateHandler;
   Function _lengthHandler;
   Function _flushHandler;
   Function _errorHandler;
 }