string DoGoto(RandomAccessIterator <SourceLine> lines)
{
var line = lines.Current;
if (line.Operands.Count == 0)
{
throw new SyntaxException(line.Instruction.Position,
"Destination not specified for \".goto\" directive.");
}
var gotoExp = line.Operands[0].Name;
if ((!char.IsLetter(gotoExp[0]) && gotoExp[0] != '_') || line.Operands.Count > 1)
{
Services.Log.LogEntry(line.Operands[0],
"\".goto\" operand must be a label.");
}
else if (line.Label != null && gotoExp.Equals(line.Label.Name, Services.StringViewComparer))
{
Services.Log.LogEntry(line.Instruction,
"Destination cannot be the same line as \".goto\" directive.");
}
else
{
var iterCopy = new RandomAccessIterator <SourceLine>(lines, true);
SourceLine currLine;
if ((currLine = iterCopy.FirstOrDefault(l =>
{
if (l.Instruction != null && _openClosures.ContainsKey(l.Instruction.Name))
{
if (l.Instruction.Name.Equals(".function", Services.StringComparison))
{
throw new SyntaxException(l.Instruction, "Function block cannot be inside another block.");
}
// leap over any blocks we find along the way we are not currently in.
if (!_blocks.Any(b => b.Index == iterCopy.Index))
{
GetProcessor(l, iterCopy.Index).SeekBlockEnd(iterCopy);
}
return(false);
}
return(l.Label != null && l.Label.Name.Equals(gotoExp, Services.StringViewComparer));
})) != null)
{
if (currLine.Instruction != null &&
(currLine.Instruction.Name.Contains('=') ||
currLine.Instruction.Name.Equals(".equ", Services.StringComparison) ||
currLine.Instruction.Name.Equals(".global", Services.StringComparison)
)
)
{
Services.Log.LogEntry(line.Instruction,
$"\"{gotoExp}\" is not a valid destination.");
}
else
{
while (_currentBlock != null)
{
// if where we landed lies outside of the current block scope
// we need to pop out of that scope.
_currentBlock.SeekBlockEnd(lines);
if (iterCopy.Index > _currentBlock.Index)
{
// did we land in a place still within the block scope?
if (iterCopy.Index > lines.Index)
{
// no, pop out
DoPop(lines);
}
else
{
// we're still within the current block, don't pop it
break;
}
}
else
{
// we went backwards, pop out of current scope
DoPop(lines);
}
}
if (iterCopy.Index >= lines.Index)
{
lines.FastForward(iterCopy.Index);
}
else if (iterCopy.Index == 0)
{
lines.Reset();
}
else
{
lines.Rewind(iterCopy.Index - 1);
}
}
}
else
{
Services.Log.LogEntry(line.Instruction,
$"Could not find destination \"{gotoExp}\".");
}
}
return(string.Empty);
}
