Add exists, create and delete to directory implementation on Linux and Mac.

runtime/bin/directory_impl.dart

 // Copyright (c) 2011, 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 DirectoryException {
+  String toString() { return "DirectoryException: $message"; }
   const DirectoryException(String this.message);
   final String message;
 }
 
 
 class _DirectoryListingIsolate extends Isolate {
 
   _DirectoryListingIsolate() : super.heavy();
 
   void main() {
@@ skipping 12 matching lines @@
              bool recursive,
              SendPort dirPort,
              SendPort filePort,
              SendPort donePort,
              SendPort errorPort) native "Directory_List";
 }
 
 
 class _Directory implements Directory {
 
-  _Directory(String this._dir);
+  _Directory(String this._path);
+
+  bool exists() {
+    int exists = _exists(_path);
+    if (exists < 0) {
+      // TODO(ager): Supply a better error message.
+      throw new DirectoryException("Diretory exists test failed: $_path");
+    }
+    return (exists == 1);
+  }
+
+  void create() {
+    if (!_create(_path)) {
+      // TODO(ager): Supply a better error message.
+      throw new DirectoryException("Directory creation failed: $_path");
+    }
+  }
+
+  void delete() {
+    if (!_delete(_path)) {
+      // TODO(ager): Supply a better error message.
+      throw new DirectoryException("Directory deletion failed: $_path");
+    }
+  }
 
   void list([bool recursive = false]) {
     new _DirectoryListingIsolate().spawn().then((port) {
       // Build a map of parameters to the directory listing isolate.
       Map listingParameters = new Map();
-      listingParameters['dir'] = _dir;
+      listingParameters['dir'] = _path;
       listingParameters['recursive'] = recursive;
 
       // Setup ports to receive messages from listing.
       // TODO(ager): Do not explicitly transform to send ports when
       // implicit conversions are implemented.
       ReceivePort dirPort;
       ReceivePort filePort;
       ReceivePort donePort;
       ReceivePort errorPort;
       if (_dirHandler !== null) {
@@ skipping 55 matching lines @@
   void setErrorHandler(void errorHandler(String error)) {
     _errorHandler = errorHandler;
   }
 
   void _closePort(ReceivePort port) {
     if (port !== null) {
       port.close();
     }
   }
 
+  String get path() { return _path; }
+
+  bool _exists(String path) native "Directory_Exists";
+  bool _create(String path) native "Directory_Create";
+  bool _delete(String path) native "Directory_Delete";
+
   var _dirHandler;
   var _fileHandler;
   var _doneHandler;
   var _errorHandler;
 
-  String _dir;
+  String _path;
 }