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// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_HEAP_LIST_H_
#define V8_HEAP_LIST_H_
#include <atomic>
#include "src/base/logging.h"
namespace v8 {
namespace internal {
namespace heap {
template <class T>
class List {
public:
List() : front_(nullptr), back_(nullptr) {}
List(List&& other) V8_NOEXCEPT : front_(std::exchange(other.front_, nullptr)),
back_(std::exchange(other.back_, nullptr)) {}
List& operator=(List&& other) V8_NOEXCEPT {
front_ = std::exchange(other.front_, nullptr);
back_ = std::exchange(other.back_, nullptr);
return *this;
}
void ShallowCopyTo(List* other) const {
other->front_ = front_;
other->back_ = back_;
}
void PushBack(T* element) {
DCHECK(!element->list_node().next());
DCHECK(!element->list_node().prev());
if (back_) {
DCHECK(front_);
InsertAfter(element, back_);
} else {
AddFirstElement(element);
}
}
void PushFront(T* element) {
DCHECK(!element->list_node().next());
DCHECK(!element->list_node().prev());
if (front_) {
DCHECK(back_);
InsertBefore(element, front_);
} else {
AddFirstElement(element);
}
}
void Remove(T* element) {
DCHECK(Contains(element));
if (back_ == element) {
back_ = element->list_node().prev();
}
if (front_ == element) {
front_ = element->list_node().next();
}
T* next = element->list_node().next();
T* prev = element->list_node().prev();
if (next) next->list_node().set_prev(prev);
if (prev) prev->list_node().set_next(next);
element->list_node().set_prev(nullptr);
element->list_node().set_next(nullptr);
}
bool Contains(T* element) {
T* it = front_;
while (it) {
if (it == element) return true;
it = it->list_node().next();
}
return false;
}
bool Empty() { return !front_ && !back_; }
T* front() { return front_; }
T* back() { return back_; }
private:
void AddFirstElement(T* element) {
DCHECK(!back_);
DCHECK(!front_);
DCHECK(!element->list_node().next());
DCHECK(!element->list_node().prev());
element->list_node().set_prev(nullptr);
element->list_node().set_next(nullptr);
front_ = element;
back_ = element;
}
void InsertAfter(T* element, T* other) {
T* other_next = other->list_node().next();
element->list_node().set_next(other_next);
element->list_node().set_prev(other);
other->list_node().set_next(element);
if (other_next)
other_next->list_node().set_prev(element);
else
back_ = element;
}
void InsertBefore(T* element, T* other) {
T* other_prev = other->list_node().prev();
element->list_node().set_next(other);
element->list_node().set_prev(other_prev);
other->list_node().set_prev(element);
if (other_prev) {
other_prev->list_node().set_next(element);
} else {
front_ = element;
}
}
T* front_;
T* back_;
};
template <class T>
class ListNode {
public:
ListNode() { Initialize(); }
T* next() { return next_; }
T* prev() { return prev_; }
void Initialize() {
next_ = nullptr;
prev_ = nullptr;
}
private:
void set_next(T* next) { next_ = next; }
void set_prev(T* prev) { prev_ = prev; }
T* next_;
T* prev_;
friend class List<T>;
};
} // namespace heap
} // namespace internal
} // namespace v8
#endif // V8_HEAP_LIST_H_
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