Bike.Interpreter.Interpreter.Walk C# (CSharp) Метод

        public override object Walk(RelationalExpression node)
        {
            var lv = node.LeftExpression.Accept(this);
            switch (node.Operator)
            {
                case TokenType.LessThan:
                    return OpLessThan(lv, node.RightExpression.Accept(this));
                case TokenType.LessThanOrEqual:
                    return OpLessThanOrEqual(lv, node.RightExpression.Accept(this));
                case TokenType.GreaterThan:
                    return OpGreaterThan(lv, node.RightExpression.Accept(this));
                case TokenType.GreaterThanOrEqual:
                    return OpGreaterThanOrEqual(lv, node.RightExpression.Accept(this));
                case TokenType.Is:
                    if (lv == null)
                        return new BikeBoolean(false);
                    var targetValue = node.RightExpression.Accept(this);
                    if (targetValue is BikeObject)
                    {
                        if (!(lv is BikeObject))
                            return new BikeBoolean(false);
                        return ((BikeObject) targetValue).IsPrototypeOf((BikeObject) lv);
                    }
                    if (targetValue is Type)
                        return new BikeBoolean(Is(lv, (Type)targetValue));
                    throw ErrorFactory.CreateTypeError("The right expression must be a Bike.Object or System.Type");
                default:
                    throw ErrorFactory.CreateInvalidProgramError("Invalid relational operator");
            }
        }