Delete proxy and total samples, which have bit-rotted.

samples/total/client/UndoStack.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.
-
-/**
- * A stack of [Command]s with a current position that supports [execute], [undo], and [redo]
- * methods.  Calling [execute] destroys any previously "undone" commands beyond the current
- * position.  Attempting to undo beyond the first command or redo beyond the last command are
- * treated as no-ops.
- */
-class UndoStack {
-
-  int _undoPosition;
-  List<Command> _undoStack;
-
-  UndoStack() {
-    this._undoStack = new List<Command>();
-    this._undoPosition = -1;
-  }
-
-  /**
-   * Return [:true:] if there is a command on the stack that can be "redone."
-   */
-  bool canRedo() => _undoPosition < _undoStack.length - 1;
-
-  /**
-   * Return [:true:] if there is a command on the stack that can be "undone."
-   */
-  bool canUndo() => _undoPosition >= 0;
-
-  /**
-   * Execute a command and make it the next "undoable" command.
-   * Any commands that have previously been "undone" will be removed from the stack.
-   */
-  void execute(Command command) {
-    int pos = ++_undoPosition;
-    if (pos == _undoStack.length) {
-      _undoStack.add(command);
-    } else {
-      _undoStack[pos] = command;
-      // Remove susequent commands on the stack
-      _undoStack.length = pos + 1;
-    }
-    command.execute();
-  }
-
-  /**
-   * Redo the most recently "undone" command, or do nothing if there is none.
-   */
-  void redo() {
-    if (_undoPosition < _undoStack.length - 1) {
-      ++_undoPosition;
-      Command command = _undoStack[_undoPosition];
-      print("Redo ${command.description}");
-      command.execute();
-    }
-  }
-
-  /**
-   * Undo the most recent command, or do nothing if there is none.
-   */
-  void undo() {
-    if (_undoPosition >= 0) {
-      Command command = _undoStack[_undoPosition];
-      _undoPosition--;
-      print("Undo ${command.description}");
-      command.unexecute();
-    }
-  }
-}