public Void VisitFunctionStmt(Stmt.Function stmt)
{
ElizFunction function = new ElizFunction(stmt, environment, false);
environment.Define(stmt.name.Lexeme, function);
return(null);
}
public object VisitBaseExpr(Expr.Base expr)
{
int distance = locals[expr];
ElizClass superclass = (ElizClass)environment.GetAt(distance, "base");
// "this" is always one level nearer than "super"'s environment.
ElizInstance @object = (ElizInstance)environment.GetAt(distance - 1, "this");
ElizFunction method = superclass.FindMethod(expr.method.Lexeme);
if (method == null)
{
throw new RuntimeError(expr.method, $"Undefined property '{expr.method.Lexeme}'.");
}
return(method.Bind(@object));
}
public Void VisitClassStmt(Stmt.Class stmt)
{
object baseclass = null;
if (stmt.baseclass != null)
{
baseclass = Evaluate(stmt.baseclass);
if (!(baseclass is ElizClass))
{
throw new RuntimeError(stmt.baseclass.name, "Baseclass must be a class.");
}
}
environment.Define(stmt.name.Lexeme, null);
if (stmt.baseclass != null)
{
environment = new Environment(environment);
environment.Define("base", baseclass);
}
Dictionary <string, ElizFunction> methods = new Dictionary <string, ElizFunction>();
foreach (Stmt.Function method in stmt.methods)
{
ElizFunction function = new ElizFunction(method, environment, method.name.Lexeme.Equals("init"));
methods[method.name.Lexeme] = function;
}
ElizClass klass = new ElizClass(stmt.name.Lexeme, (ElizClass)baseclass, methods);
if (baseclass != null)
{
environment = environment.enclosing;
}
environment.Assign(stmt.name, klass);
return(null);
}