public object Call(Interpreter interpreter, IList <object> arguments)
{
LoxInstance instance = new LoxInstance(this);
// Constructor
LoxFunction initializer = _methods.Get("init");
if (initializer != null)
{
initializer.Bind(instance).Call(interpreter, arguments);
}
return(instance);
}
/// <summary>
/// Get a property
/// </summary>
/// <param name="name">The name</param>
/// <returns>The property</returns>
public object Get(Token name)
{
// Field?
if (_fields.TryGetValue(name.Lexeme, out object val))
{
return(val);
}
// Method?
LoxFunction method = _class.FindMethod(this, name.Lexeme);
if (method != null)
{
return(method);
}
throw new RuntimeErrorException(name, $"Undefined property '{name.Lexeme}'.");
}
public object Visit(Expr.Super expr)
{
// Look up the superclass
int? distance = _locals.Get(expr);
LoxClass superclass = (LoxClass)_environment.GetAt(distance.Value, "super");
// "this" is always one level nearer than "super"
LoxInstance obj = (LoxInstance)_environment.GetAt(distance.Value - 1, "this");
// Lookup the method
LoxFunction method = superclass.FindMethod(obj, expr.Method.Lexeme);
if (method == null)
{
throw new RuntimeErrorException(expr.Method, $"Undefined property '{expr.Method.Lexeme}'.");
}
return(method);
}
public object Visit(Stmt.Class stmt)
{
_environment.Define(stmt.Name.Lexeme, null);
// Superclass
object superclass = null;
if (stmt.Superclass != null)
{
superclass = Evaluate(stmt.Superclass);
if (!(superclass is LoxClass))
{
throw new RuntimeErrorException(stmt.Superclass.Name, "Superclass must be a class.");
}
_environment = new LoxEnvironment(_environment);
_environment.Define("super", superclass);
}
// Methods
HashMap <string, LoxFunction> methods = new HashMap <string, LoxFunction>();
foreach (Stmt.Function method in stmt.Methods)
{
LoxFunction function = new LoxFunction(method, _environment, method.Name.Lexeme.Equals("init"));
methods.Put(method.Name.Lexeme, function);
}
LoxClass @class = new LoxClass(stmt.Name.Lexeme, (LoxClass)superclass, methods);
if (superclass != null)
{
_environment = _environment.Enclosing;
}
_environment.Assign(stmt.Name, @class);
return(null);
}
