Resolving Labels

gistfile1.cs

        private static Dictionary<string, int> ResolveLabels(IList<Token> tokens)
        {
            var result = new Dictionary<string, int>(StringComparer.InvariantCultureIgnoreCase);

            var currentPosition = 0;
            foreach (var token in tokens)
            {
                var commandToken = token as CommandToken;
                if (commandToken != null)
                {
                    try
                    {
                        var opcode = Opcodes.GetByName(commandToken.Command);
                        currentPosition += opcode.Size;
                    }
                    catch (IllegalOpcodeException ex)
                    {
                        throw new CompilerException(ex.Message);
                    } 
                }
                else
                {
                    var labelToken = token as LabelDeclarationToken;
                    if (labelToken != null)
                    {
                        if (result.ContainsKey(labelToken.Label))
                        {
                            throw new CompilerException("Label redefined: " + labelToken.Label);
                        }
                        result[labelToken.Label] = currentPosition;
                    }
                }
            }

            return result;
        }