// generates an error for an undefined `goto'; choose appropriate
// message when label name is a reserved word (which can only be `break')
private void UndefGoto( LabelDesc gt )
{
string template = Lexer.IsReservedWord( gt.Name )
? "<{0}> at line {1} not inside a loop"
: "no visible label '{0}' for <goto> at line {1}";
var msg = string.Format( template, gt.Name, gt.Line );
SemanticError( msg );
}
private LabelDesc NewLebelEntry( string name, int line, int pc )
{
var desc = new LabelDesc();
desc.Name = name;
desc.Pc = pc;
desc.Line = line;
desc.NumActVar = CurFunc.NumActVar;
return desc;
}
// check whether new label `label' matches any pending gotos in current
// block; solves forward jumps
private void FindGotos( LabelDesc label )
{
int i = CurFunc.Block.FirstGoto;
while( i < PendingGotos.Count )
{
if( PendingGotos[i].Name == label.Name )
CloseGoto( i, label );
else
++i;
}
}
private void CloseGoto( int g, LabelDesc label )
{
var gt = PendingGotos[g];
Utl.Assert( gt.Name == label.Name );
if( gt.NumActVar < label.NumActVar )
{
var v = GetLocalVar( CurFunc, gt.NumActVar );
var msg = string.Format(
"<goto {0}> at line {1} jumps into the scope of local '{2}'",
gt.Name, gt.Line, v.VarName);
SemanticError( msg );
}
Coder.PatchList( CurFunc, gt.Pc, label.Pc );
PendingGotos.RemoveAt(g);
}