package com.jsql.view.swing.text.action;
   
   import javax.swing.text.BadLocationException;
   import javax.swing.text.DefaultEditorKit;
   import javax.swing.text.Document;
   
   /**
    * Action to cancel Beep sound when deleting last character.
    * Used on TextPane and TextArea.
   */
  public class DeletePrevCharAction extends AbstractCharAction {
      
      /**
       * Creates this object with the appropriate identifier.
       */
      public DeletePrevCharAction() {
          super(DefaultEditorKit.deletePrevCharAction);
      }
  
      @Override
      protected void delete(Document doc, int dot) throws BadLocationException {
          if (dot > 0) {
              
              var delChars = 1;
  
              if (dot > 1) {
                  
                  String dotChars = doc.getText(dot - 2, 2);
                  var c0 = dotChars.charAt(0);
                  var c1 = dotChars.charAt(1);
  
                  if (c0 >= '\uD800' && c0 <= '\uDBFF' && c1 >= '\uDC00' && c1 <= '\uDFFF') {
                      delChars = 2;
                  }
              }
  
              doc.remove(dot - delChars, delChars);
          }
      }
  }