Add support for copying directory structures

pkg/analyzer/lib/file_system/file_system.dart

 // Copyright (c) 2014, 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.
 
 library analyzer.file_system.file_system;
 
 import 'dart:async';
 
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/util/absolute_path.dart';
@@ skipping 14 matching lines @@
    * Throws a [FileSystemException] if the operation fails.
    */
   int get lengthSync;
 
   /**
    * Return the last-modified stamp of the file.
    * Throws a [FileSystemException] if the file does not exist.
    */
   int get modificationStamp;
 
+  @override
+  File copyTo(Folder parentFolder);
+
   /**
    * Create a new [Source] instance that serves this file.
    */
   Source createSource([Uri uri]);
 
   /**
    * Synchronously read the entire file contents as a list of bytes.
    * Throws a [FileSystemException] if the operation fails.
    */
   List<int> readAsBytesSync();
@@ skipping 62 matching lines @@
    * However, regardless of whether [path] is relative or absolute, normalize
    * it by removing path components of the form '.' or '..'.
    */
   String canonicalizePath(String path);
 
   /**
    * Return `true` if absolute [path] references a resource in this folder.
    */
   bool contains(String path);
 
+  @override
+  Folder copyTo(Folder parentFolder);
+
+  /**
+   * If this folder does not already exist, create it.
+   */
+  void create();
+
   /**
    * Return an existing child [Resource] with the given [relPath].
    * Return a not existing [File] if no such child exist.
    */
   Resource getChild(String relPath);
 
   /**
    * Return a [File] representing a child [Resource] with the given
    * [relPath].  This call does not check whether a file with the given name
    * exists on the filesystem - client must call the [File]'s `exists` getter
@@ skipping 36 matching lines @@
    */
   String get path;
 
   /**
    * Return a short version of the name that can be displayed to the user to
    * denote this resource.
    */
   String get shortName;
 
   /**
+   * Copy this resource to a child of the [parentFolder] with the same kind and
+   * [shortName] as this resource. If this resource is a folder, then all of the
+   * contents of the folder will be recursively copied.
+   *
+   * The parent folder is created if it does not already exist.
+   *
+   * Existing files and folders will be overwritten.
+   *
+   * Return the resource corresponding to this resource in the parent folder.
+   */
+  Resource copyTo(Folder parentFolder);
+
+  /**
    * Synchronously deletes this resource and its children.
    *
    * Throws an exception if the resource cannot be deleted.
    */
   void delete();
 
   /**
    * Return `true` if absolute [path] references this resource or a resource in
    * this folder.
    */
@@ skipping 93 matching lines @@
 
   @override
   Uri restoreAbsolute(Source source) =>
       _provider.pathContext.toUri(source.fullName);
 
   /**
    * Return `true` if the given [uri] is a `file` URI.
    */
   static bool isFileUri(Uri uri) => uri.scheme == FILE_SCHEME;
 }