protected override string OnAssemble(RandomAccessIterator <SourceLine> lines)
{
var line = lines.Current;
if (Reserved.IsOneOf("Goto", line.Instruction.Name))
{
return(DoGoto(lines));
}
if (Reserved.IsOneOf("Functional", line.Instruction.Name))
{
if (line.Instruction.Name.Equals(".function", Services.StringComparison))
{
DefineFunction(lines);
}
else if (_currentBlock != null)
{
throw new SyntaxException(line.Instruction.Position,
"Directive \".endfunction\" can only be made inside function block.");
}
return(string.Empty);
}
if (_openClosures.ContainsKey(line.Instruction.Name))
{
var block = GetProcessor(line, lines.Index);
if (_blocks.Count == 0)
{
ScanBlock(lines);
}
_blocks.Push(block);
_currentBlock = block;
}
if (line.Instruction.Name.Equals(".block", Services.StringComparison) && line.Label != null)
{
DefineLabel(line.Label, PCOnAssemble, false);
}
var isBreakCont = Reserved.IsOneOf("BreakContinue", line.Instruction.Name);
if (_currentBlock == null || (!isBreakCont && !_currentBlock.IsReserved(line.Instruction.Name)))
{
throw new SyntaxException(line.Instruction.Position,
$"\"{line.Instruction.Name}\" directive must come inside a block.");
}
if (isBreakCont)
{
if (line.Operands.Count > 0)
{
throw new SyntaxException(line.Operands[0], "Unexpected expression.");
}
var isBreak = line.Instruction.Name.Equals(".break", Services.StringComparison);
if ((!_currentBlock.AllowContinue && line.Instruction.Name.Equals(".continue", Services.StringComparison)) ||
(!_currentBlock.AllowBreak && isBreak))
{
while (_currentBlock != null)
{
var allowBreak = false;
_currentBlock.SeekBlockEnd(lines);
if (isBreak)
{
allowBreak = _currentBlock.AllowBreak;
}
else if (!isBreak && _currentBlock.AllowContinue)
{
break;
}
DoPop(lines);
if (isBreak && allowBreak)
{
return(string.Empty);
}
}
if (_currentBlock == null)
{
var err = isBreak ? "break" : "continue";
throw new SyntaxException(line.Instruction.Position,
$"No enclosing loop out of which to {err}.");
}
}
else if (isBreak)
{
DoPop(lines);
return(string.Empty);
}
else
{
_currentBlock.SeekBlockEnd(lines);
}
}
_currentBlock.ExecuteDirective(lines);
if (lines.Current.Instruction != null && lines.Current.Instruction.Name.Equals(_currentBlock.BlockClosure, Services.StringComparison))
{
DoPop(lines);
}
if (line.Label != null)
{
return($".{Services.Output.LogicalPC,-42:x4}{line.Source.Substring(line.Label.Position - 1, line.Label.Name.Length)}");
}
return(string.Empty);
}
