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 
10 namespace blink {
11 
12 class 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 
20 class A : public GarbageCollectedFinalized<A> {
21 public:
trace(Visitor *)22     virtual void trace(Visitor*) {}
23 };
24 
25 class B : public A {
26 public:
27     virtual void trace(Visitor*);
28 };
29 
30 class C : public RefCounted<C> {
31 private:
32     Persistent<B> m_b;
33 };
34 
35 class D : public A {
36 public:
37     virtual void trace(Visitor*);
38 private:
39     RefPtr<C> m_c;
40 };
41 
42 }
43 
44 #endif
45