private Expr Assignment()
{
Expr expr = Or();
if (Match(TokenType.EQUAL))
{
Token equals = Previous();
Expr value = Assignment();
if (expr is Expr.Variable)
{
Token name = ((Expr.Variable)expr).name;
return(new Expr.Assign(name, value));
}
else if (expr is Expr.Get)
{
Expr.Get get = (Expr.Get)expr;
return(new Expr.Set(get.obj, get.name, value));
}
Error(equals, "Invalid assignment target.");
}
return(expr);
}
public object VisitGetExpr(Expr.Get expr)
{
var obj = Evaluate(expr.obj);
if (obj is LoxInstance)
{
return(((LoxInstance)obj).Get(expr.name));
}
throw new RuntimeError(expr.name, "Only instances have properties.");
}
private Expr Call()
{
Expr expr = Primary();
while (true)
{
if (Match(LEFT_PAREN))
{
expr = FinishCall(expr);
}
else if (Match(DOT))
{
var name = Consume(IDENTIFIER, "Expect property name after '.'.");
expr = new Expr.Get(expr, name);
}
else
{
break;
}
}
return(expr);
}
public object VisitGetExpr(Expr.Get expr)
{
Resolve(expr.obj);
return(null);
}
public string VisitGetExpr(Expr.Get expr)
{
throw new NotImplementedException();
}
public Void Visit(Expr.Get expr)
{
Resolve(expr.Obj);
return(Void.Instance);
}
object Expr.IVisitor <object> .VisitGetExpr(Expr.Get expr)
{
Resolve(expr.obj);
return(null);
}