Assembler.Assembler.Parse C# (CSharp) Method

        private void Parse()
        {
            var t = tokens[pos];

            while (t.Type != TokenType.EndOfFile)
            {
                if (t.Type == TokenType.Label)
                {
                    if (labels.ContainsKey(t.Value))
                        throw new AssemblerException(string.Format("Duplicate label '{0}' on line {1}.", t.Value, t.Line));

                    labels.Add(t.Value, new Label(t.Value, instructions.Count));
                    pos++;
                }
                else if (t.Type == TokenType.Keyword)
                {
                    instructions.Add(ParseInstruction());
                }
                else if (t.Type == TokenType.Word && new List<string> { "db", "dw", "rb" }.Contains(t.Value.ToLower()))
                {
                    string type = t.Value.ToLower();
                    var dataLine = t.Line;
                    t = tokens[++pos];

                    var data = new DataInstruction();
                    while (t.Type == TokenType.String || t.Type == TokenType.Number)
                    {
                        if (t.Type == TokenType.String)
                        {
                            data.Add(t.Value);
                        }
                        else
                        {
                            switch (type)
                            {
                                case "db":
                                {
                                    byte value;
                                    if (!byte.TryParse(t.Value, out value))
                                        throw new AssemblerException(string.Format("Value out of range on line {0}.", t.Line));

                                    data.Add(value);
                                    break;
                                }

                                case "dw":
                                {
                                    short value;
                                    if (!short.TryParse(t.Value, out value))
                                        throw new AssemblerException(string.Format("Value out of range on line {0}.", t.Line));

                                    data.Add(value);
                                    break;
                                }

                                case "rb":
                                {
                                    short value;
                                    if (!short.TryParse(t.Value, out value) || value < 0)
                                        throw new AssemblerException(String.Format("Value out of range on line {0}.", t.Line));

                                    while (value-- > 0)
                                        data.Add(0);
                                    break;
                                }
                            }
                        }

                        pos++;

                        if (tokens[pos].Type == TokenType.Comma)
                        {
                            t = tokens[++pos];
                            continue;
                        }

                        break;
                    }

                    if (!data.HasData)
                        throw new AssemblerException(string.Format("Empty data directive on line {0}.", dataLine));

                    instructions.Add(data);
                }
                else
                {
                    throw new AssemblerException(string.Format("Unexpected {0} on line {1}.", t.Value, t.Line));
                }

                t = tokens[pos];
            }
        }