/// <summary>
///
/// </summary>
/// <param name="line">The line of code to parse.</param>
/// <param name="sourceLine">The line number of the code file.</param>
void ParseLine(StringSection line, int iSourceLine, out Error error)
{
error = Error.None;
line = line.TrimLeft();
RemoveComments(ref line);
int newInstructionIndex = assembly.ParsedInstructions.Count;
bool loopLabel;
do // This loop allows us to parse alternating named and anonymous labels (* label: +++ -- anotherLabel:)
{
loopLabel = false;
loopLabel |= ParseNamedLabels(ref line, newInstructionIndex, iSourceLine);
loopLabel |= ParseAnonymousLabel(ref line, newInstructionIndex, iSourceLine);
} while (loopLabel);
if (line.IsNullOrEmpty || line[0] == ';')
{
// Nothing on this line
return;
}
// Dot-prefixed directive
if (line[0] == '.')
{
line = line.Substring(1);
var directiveName = GetSymbol(line);
line = line.Substring(directiveName.Length).TrimLeft();
if (!ParseDirective(directiveName, line, iSourceLine, out error))
{
error = new Error(ErrorCode.Directive_Not_Defined, string.Format(Error.Msg_DirectiveUndefined_name, directiveName), iSourceLine);
return;
}
return;
}
bool parsedUncolonedLabel = false; // Set to true when an uncoloned label is found so we don't look for one again.
bool loopAgain = false; // Set to true when an uncoloned label is found to loop back and try to parse the remaining text
do
{
loopAgain = false;
var symbol = GetSymbol(line);
if (symbol.Length == 0)
{
break;
}
line = line.Substring(symbol.Length).Trim();
if (ParseDirective(symbol, line, iSourceLine, out error))
{
return;
}
else if (ParseInstruction(symbol, line, iSourceLine, out error))
{
return;
}
else if ((line.Length > 0 && line[0] == '=') || (line.Length > 1 && line[0] == ':' && line[1] == '=')) // Assignments and label assignments
// := is a cross between a label and assignment: It declares a label with an explicit value.
{
bool isLabel = (line[0] == ':');
var expression = line.Substring(1).TrimLeft();
if (isLabel)
{
expression = expression.Substring(1).TrimLeft();
}
if (expression.IsNullOrEmpty)
{
error = new Error(ErrorCode.Expected_Expression, Error.Msg_ExpectedValue, iSourceLine);
}
else
{
ParseAssignment(symbol, isLabel, expression, iSourceLine);
}
}
else
{
// Todo: ensure 'symbol' is a valid label name
if (!Assembler.RequireColonOnLabels && !parsedUncolonedLabel && symbol.Length > 0)
{
if (symbol[0] == '@')
{
string labelName = mostRecentNamedLabel + "." + symbol.Substring(1).ToString();
assembly.Labels.Add(new Label(labelName, newInstructionIndex, iSourceLine, true));
}
else
{
mostRecentNamedLabel = symbol.ToString();
assembly.Labels.Add(new Label(symbol.ToString(), newInstructionIndex, iSourceLine, false));
}
parsedUncolonedLabel = true;
loopAgain = true;
}
else
{
error = new Error(ErrorCode.Unexpected_Text, Error.Msg_BadLine, iSourceLine);
}
}
} while (parsedUncolonedLabel && loopAgain);
}