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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/containers/linked_list.h"
#include "base/check_op.h"
namespace base::internal {
LinkNodeBase::LinkNodeBase() = default;
LinkNodeBase::LinkNodeBase(LinkNodeBase* previous, LinkNodeBase* next)
: previous_(previous), next_(next) {}
LinkNodeBase::LinkNodeBase(LinkNodeBase&& rhs) {
if (&rhs == rhs.next_) {
// rhs is the root node of an empty LinkedList. Add self-references to
// match.
CHECK_EQ(&rhs, rhs.previous_);
next_ = this;
previous_ = this;
return;
}
next_ = rhs.next_;
rhs.next_ = nullptr;
previous_ = rhs.previous_;
rhs.previous_ = nullptr;
// If the node belongs to a list, next_ and previous_ are both non-null.
// Otherwise, they are both null.
if (next_) {
next_->previous_ = this;
previous_->next_ = this;
}
}
void LinkNodeBase::RemoveFromList() {
previous_->next_ = next_;
next_->previous_ = previous_;
// next() and previous() return non-null if and only this node is not in any
// list.
next_ = nullptr;
previous_ = nullptr;
}
void LinkNodeBase::InsertBeforeBase(LinkNodeBase* e) {
CHECK_EQ(previous_, nullptr);
CHECK_EQ(next_, nullptr);
next_ = e;
previous_ = e->previous_;
e->previous_->next_ = this;
e->previous_ = this;
}
void LinkNodeBase::InsertAfterBase(LinkNodeBase* e) {
CHECK_EQ(previous_, nullptr);
CHECK_EQ(next_, nullptr);
next_ = e->next_;
previous_ = e;
e->next_->previous_ = this;
e->next_ = this;
}
void LinkNodeBase::MakeSelfReferencingBase() {
if (next_ == this) {
CHECK_EQ(previous_, this);
return;
}
CHECK_EQ(next_, nullptr);
CHECK_EQ(previous_, nullptr);
next_ = this;
previous_ = this;
}
} // namespace base::internal
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