public object VisitSuperExpr(Expr.Super expr)
{
int distance = locals[expr];
// Find reference to the superclass and current instance ("this").
IClass superclass = (IClass)environment.GetAt(distance, "super");
LoxInstance thisInstance = (LoxInstance)environment.GetAt(distance, "this");
// Find method from superclass.
LoxFunction method = superclass.FindMethod(thisInstance, expr.method.lexeme);
return(method);
}
public LoxFunction FindMethod(LoxInstance instance, string name)
{
if (methods.TryGetValue(name, out LoxFunction fun))
{
// Methods "this" is set to a given instance (from which instance it is accessed from).
return(fun.Bind(instance, superclass));
}
if (superclass != null)
{
return(superclass.FindMethod(instance, name));
}
return(null);
}
// Expose properties via an indexer.
public object this[Token name]
{
get
{
if (fields.TryGetValue(name.lexeme, out object val))
{
return(val);
}
var method = instanceOf.FindMethod(this, name.lexeme);
if (method != null)
{
return(method);
}
throw new RuntimeError(name, $"Undefined property '{name.lexeme}'");
}
set
{
fields.AddOrUpdate(name.lexeme, value);
}
}
