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