text: /*
   * Copyright (c) 2017 Samsung Electronics Co., Ltd. All rights reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  using ElmSharp;
  
  namespace BasicCalculator.ViewModels
  {
      /// <summary>
      /// Delegate to register key-pressed events.
      /// </summary>
      /// <param name="keyName">Pressed key name.</param>
      public delegate void KeyPressedDelegate(string keyName);
  
      /// <summary>
      /// Class to handle key-pressed events.
      /// </summary>
      public class KeyboardHandler
      {
          private readonly CalculatorViewModel _viewModel;
  
          /// <summary>
          /// Method called when a key is pressed.
          /// </summary>
          /// <param name="keyName">Pressed key name.</param>
          public void KeyPressed(string keyName)
          {
              _viewModel.AppendToExpression(keyName);
          }
  
          /// <summary>
          /// Constructor to ViewModel object reference.
          /// </summary>
          /// <param name="viewModel">CalculatorViewModel object reference.</param>
          public KeyboardHandler(CalculatorViewModel viewModel) => _viewModel = viewModel;
      }
  }