/// <summary>
 /// Creates an instance of <see cref="KeyValueSyntax"/>
 /// </summary>
 /// <param name="key">The key</param>
 /// <param name="value">The value</param>
 public KeyValueSyntax(KeySyntax key, ValueSyntax value) : this()
 {
     Key        = key ?? throw new ArgumentNullException(nameof(key));
     Value      = value ?? throw new ArgumentNullException(nameof(value));
     EqualToken = SyntaxFactory.Token(TokenKind.Equal);
     EqualToken.AddLeadingWhitespace();
     EqualToken.AddTrailingWhitespace();
     EndOfLineToken = SyntaxFactory.NewLine();
 }
        public Token GetToken()
        {
            State = LexicAnalyserState.Initial;
            Value = HasNext ? Character.ToString() : "";
            Token token = null;

            while (HasNext && token == null)
            {
                switch (State)
                {
                case LexicAnalyserState.Initial:
                    HandleInitial();
                    break;

                case LexicAnalyserState.NonTerminal:
                    token = new NonTerminalToken(Value);
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Space:
                    token = new SpaceToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Terminal:
                    token = new TerminalToken(Value);
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Empty:
                    token = new EmptyToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.NewLine:
                    token = new NewLineToken(Value);
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Identifier:
                    token = new IdentifierToken(Value);
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Number:
                    token = new NumberToken(Value);
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Var:
                    token = new VarToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Write:
                    token = new WriteToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Read:
                    token = new ReadToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.If:
                    token = new IfToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.End:
                    token = new EndToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Then:
                    token = new ThenToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Begin:
                    token = new BeginToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.While:
                    token = new WhileToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Do:
                    token = new DoToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.SemiColon:
                    token = new SemiColonToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.OpenParentheses:
                    token = new OpenParenthesesToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.CloseParentheses:
                    token = new CloseParenthesesToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Plus:
                    token = new PlusToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Sub:
                    token = new SubToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Great:
                    token = new GreatToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Less:
                    token = new LessToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Equal:
                    token = new EqualToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Repeat:
                    token = new RepeatToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Until:
                    token = new UntilToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.Attribution:
                    token = new AttributionToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.NotEqual:
                    token = new NotEqualToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.GreatOrEqual:
                    token = new GreatOrEqualToken();
                    CurrentIndex++;
                    break;

                case LexicAnalyserState.LessOrEqual:
                    token = new LessOrEqualToken();
                    CurrentIndex++;
                    break;

                default:
                    throw new ArgumentOutOfRangeException();
                }
            }

            return(token);
        }