public class RegTest{
  
  //Regular Expression: a*
  public static RegExp testCase1(){
    return new Star(new Letter('a'));
  }

  //Regular Expression: ((a|b)c)*
  public static RegExp testCase2(){
    return new Star(new Concat(new Alt(new Letter('a'), new Letter('b')), new Letter('c')));
  }
  
  //Regular Expression: (((ac)|(bc)*)c)
  public static RegExp testCase3(){
    return new Concat(new Alt(new Concat(new Letter('a'), new Letter('c')), new Star(new Concat(new Letter('b'),new Letter('c')))), new Letter('c'));
  }
  
  //Regular Expression: ((a*|b*)|c)
  public static RegExp testCase4(){
    return new Alt(new Alt(new Star(new Letter('a')), new Star(new Letter('b'))), new Letter('c'));
  }
  
  //Regular Expression: (((ab)|(cd))*e) 
  public static RegExp testCase5(){
    return new Concat(new Star(new Alt(new Concat(new Letter('a'), new Letter('b')), new Concat(new Letter('c'), new Letter('d')))), new Letter('e'));
  }

  //Regular Expression: ((((a|b)|c)|d)e)*
  public static RegExp testCase6(){
    return new Star(new Concat(new Alt(new Alt(new Alt(new Letter('a'), new Letter('b')), new Letter('c')), new Letter('d')), new Letter('e')));
  }
}