Method undo

packages/core/src/command_manager/undo_manager.ts:43–53

()

  }

  undo(): ICollaCommandExecuteResult | null {
    const { _undoStack: undoStack, _commandManager: commandManager } = this;
    if (!undoStack.length) {
      return null;
    }
    const undoAction = undoStack.pop();
    if (undoAction && commandManager && commandManager.hasCommand(undoAction.cmd)) {
      return commandManager._executeActions(undoAction.cmd, undoAction.result, ExecuteType.Undo);
    }
    return null;
  }

  redo(): ICollaCommandExecuteResult<{}> | null {
    const { _redoStack: redoStack, _commandManager: commandManager } = this;