cycle_super_neg.h revision effb81e5f8246d0db0270817048dc992db66e9fb 
1// Copyright 2014 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef CYCLE_SUPER_NEG_H_
6#define CYCLE_SUPER_NEG_H_
7
8#include "heap/stubs.h"
9
10namespace WebCore {
11
12class C;
13
14// The chain:
15//   C -per-> B -sup-> A -sub-> D -ref-> C
16// is not a leaking cycle, because the super-class relationship
17// should not transitively imply sub-class relationships.
18// I.e. B -/-> D
19
20class A : public GarbageCollectedFinalized<A> {
21public:
22    virtual void trace(Visitor*) {}
23};
24
25class B : public A {
26public:
27    virtual void trace(Visitor*);
28};
29
30class C : public RefCounted<C> {
31private:
32    Persistent<B> m_b;
33};
34
35class D : public A {
36public:
37    virtual void trace(Visitor*);
38private:
39    RefPtr<C> m_c;
40};
41
42}
43
44#endif
45