public object VisitClassStmt(Stmt.Class stmt)
{
environment.Define(stmt.Name.lexeme, null);
object superclass = null;
if (stmt.Superclass != null)
{
superclass = Evaluate(stmt.Superclass);
if (!(superclass is BasilClass))
{
throw new RuntimeError(stmt.Name, "Superclass must be a class.");
}
environment = new Environment(environment);
environment.Define("super", superclass);
}
Dictionary <string, BasilFunction> methods = new Dictionary <string, BasilFunction>();
foreach (var method in stmt.Methods)
{
BasilFunction function = new BasilFunction(method, environment, method.name.lexeme.Equals("init"));
methods.Add(method.name.lexeme, function);
}
BasilClass klass = new BasilClass(stmt.Name.lexeme, (BasilClass)superclass, methods);
if (superclass != null)
{
environment = environment.Enclosing;
}
environment.Assign(stmt.Name, klass);
return(null);
}
public object VisitSuperExpr(Expr.Super expr)
{
int distance = locals[expr];
BasilClass superclass = (BasilClass)environment.GetAt(distance, "super");
// "this" is always one level nearer than "super"'s environment.
BasilInstance objekt = (BasilInstance)environment.GetAt(distance - 1, "this");
BasilFunction method = superclass.FindMethod(objekt, expr.Method.lexeme);
if (method == null)
{
throw new RuntimeError(expr.Method, $"Undefined property '{expr.Method.lexeme}'.");
}
return(method);
}
public BasilInstance(BasilClass klass)
{
this.klass = klass;
}
public BasilClass(string name, BasilClass superclass, Dictionary <string, BasilFunction> methods)
{
Name = name;
this.superclass = superclass;
this.methods = methods;
}