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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/memory/weak_ptr.h"
namespace base {
namespace internal {
WeakReference::Flag::Flag() : is_valid_(true) {
// Flags only become bound when checked for validity, or invalidated,
// so that we can check that later validity/invalidation operations on
// the same Flag take place on the same sequenced thread.
sequence_checker_.DetachFromSequence();
}
void WeakReference::Flag::Invalidate() {
// The flag being invalidated with a single ref implies that there are no
// weak pointers in existence. Allow deletion on other thread in this case.
DCHECK(sequence_checker_.CalledOnValidSequencedThread() || HasOneRef())
<< "WeakPtrs must be invalidated on the same sequenced thread.";
is_valid_ = false;
}
bool WeakReference::Flag::IsValid() const {
DCHECK(sequence_checker_.CalledOnValidSequencedThread())
<< "WeakPtrs must be checked on the same sequenced thread.";
return is_valid_;
}
WeakReference::Flag::~Flag() {
}
WeakReference::WeakReference() {
}
WeakReference::WeakReference(const Flag* flag) : flag_(flag) {
}
WeakReference::~WeakReference() {
}
bool WeakReference::is_valid() const { return flag_.get() && flag_->IsValid(); }
WeakReferenceOwner::WeakReferenceOwner() {
}
WeakReferenceOwner::~WeakReferenceOwner() {
Invalidate();
}
WeakReference WeakReferenceOwner::GetRef() const {
// If we hold the last reference to the Flag then create a new one.
if (!HasRefs())
flag_ = new WeakReference::Flag();
return WeakReference(flag_.get());
}
void WeakReferenceOwner::Invalidate() {
if (flag_.get()) {
flag_->Invalidate();
flag_ = NULL;
}
}
WeakPtrBase::WeakPtrBase() {
}
WeakPtrBase::~WeakPtrBase() {
}
WeakPtrBase::WeakPtrBase(const WeakReference& ref) : ref_(ref) {
}
} // namespace internal
} // namespace base
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