weak_ptr.cc revision ddb351dbec246cf1fab5ec20d2d5520909041de1 
1// Copyright (c) 2011 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#include "base/memory/weak_ptr.h"
6
7namespace base {
8namespace internal {
9
10WeakReference::Flag::Flag(Flag** handle) : handle_(handle) {
11}
12
13void WeakReference::Flag::Invalidate() {
14  DCHECK(thread_checker_.CalledOnValidThread());
15  handle_ = NULL;
16}
17
18bool WeakReference::Flag::IsValid() const {
19  DCHECK(thread_checker_.CalledOnValidThread());
20  return handle_ != NULL;
21}
22
23WeakReference::Flag::~Flag() {
24  if (handle_)
25    *handle_ = NULL;
26}
27
28WeakReference::WeakReference() {
29}
30
31WeakReference::WeakReference(Flag* flag) : flag_(flag) {
32}
33
34WeakReference::~WeakReference() {
35}
36
37bool WeakReference::is_valid() const {
38  return flag_ && flag_->IsValid();
39}
40
41WeakReferenceOwner::WeakReferenceOwner() : flag_(NULL) {
42}
43
44WeakReferenceOwner::~WeakReferenceOwner() {
45  Invalidate();
46}
47
48WeakReference WeakReferenceOwner::GetRef() const {
49  if (!flag_)
50    flag_ = new WeakReference::Flag(&flag_);
51  return WeakReference(flag_);
52}
53
54void WeakReferenceOwner::Invalidate() {
55  if (flag_) {
56    flag_->Invalidate();
57    flag_ = NULL;
58  }
59}
60
61WeakPtrBase::WeakPtrBase() {
62}
63
64WeakPtrBase::~WeakPtrBase() {
65}
66
67WeakPtrBase::WeakPtrBase(const WeakReference& ref) : ref_(ref) {
68}
69
70}  // namespace internal
71}  // namespace base
72