Antlr.Runtime.Lexer.GetErrorMessage C# (CSharp) Method

        public override string GetErrorMessage( RecognitionException e, string[] tokenNames )
        {
            string msg = null;
            if ( e is MismatchedTokenException )
            {
                MismatchedTokenException mte = (MismatchedTokenException)e;
                msg = "mismatched character " + GetCharErrorDisplay( e.Character ) + " expecting " + GetCharErrorDisplay( mte.Expecting );
            }
            else if ( e is NoViableAltException )
            {
                NoViableAltException nvae = (NoViableAltException)e;
                // for development, can add "decision=<<"+nvae.grammarDecisionDescription+">>"
                // and "(decision="+nvae.decisionNumber+") and
                // "state "+nvae.stateNumber
                msg = "no viable alternative at character " + GetCharErrorDisplay( e.Character );
            }
            else if ( e is EarlyExitException )
            {
                EarlyExitException eee = (EarlyExitException)e;
                // for development, can add "(decision="+eee.decisionNumber+")"
                msg = "required (...)+ loop did not match anything at character " + GetCharErrorDisplay( e.Character );
            }
            else if ( e is MismatchedNotSetException )
            {
                MismatchedNotSetException mse = (MismatchedNotSetException)e;
                msg = "mismatched character " + GetCharErrorDisplay( e.Character ) + " expecting set " + mse.Expecting;
            }
            else if ( e is MismatchedSetException )
            {
                MismatchedSetException mse = (MismatchedSetException)e;
                msg = "mismatched character " + GetCharErrorDisplay( e.Character ) + " expecting set " + mse.Expecting;
            }
            else if ( e is MismatchedRangeException )
            {
                MismatchedRangeException mre = (MismatchedRangeException)e;
                msg = "mismatched character " + GetCharErrorDisplay( e.Character ) + " expecting set " +
                      GetCharErrorDisplay( mre.A ) + ".." + GetCharErrorDisplay( mre.B );
            }
            else
            {
                msg = base.GetErrorMessage( e, tokenNames );
            }
            return msg;
        }