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#pragma once
#include <AK/Assertions.h>
#include <AK/StdLibExtras.h>
#include <AK/Traits.h>
namespace AK {
template<typename ListType, typename ElementType>
class DoublyLinkedListIterator {
public:
bool operator!=(const DoublyLinkedListIterator& other) const { return m_node != other.m_node; }
bool operator==(const DoublyLinkedListIterator& other) const { return m_node == other.m_node; }
DoublyLinkedListIterator& operator++()
{
m_node = m_node->next;
return *this;
}
ElementType& operator*() { return m_node->value; }
ElementType* operator->() { return &m_node->value; }
bool is_end() const { return !m_node; }
static DoublyLinkedListIterator universal_end() { return DoublyLinkedListIterator(nullptr); }
private:
friend ListType;
explicit DoublyLinkedListIterator(typename ListType::Node* node)
: m_node(node)
{
}
typename ListType::Node* m_node;
};
template<typename T>
class DoublyLinkedList {
private:
struct Node {
explicit Node(const T& v)
: value(v)
{
}
explicit Node(T&& v)
: value(move(v))
{
}
T value;
Node* next { nullptr };
Node* prev { nullptr };
};
public:
DoublyLinkedList() {}
~DoublyLinkedList() { clear(); }
bool is_empty() const { return !head(); }
void clear()
{
for (auto* node = m_head; node;) {
auto* next = node->next;
delete node;
node = next;
}
m_head = nullptr;
m_tail = nullptr;
}
T& first()
{
ASSERT(head());
return head()->value;
}
const T& first() const
{
ASSERT(head());
return head()->value;
}
T& last()
{
ASSERT(head());
return tail()->value;
}
const T& last() const
{
ASSERT(head());
return tail()->value;
}
void append(T&& value)
{
append_node(new Node(move(value)));
}
void append(const T& value)
{
append_node(new Node(value));
}
bool contains_slow(const T& value) const
{
for (auto* node = m_head; node; node = node->next) {
if (node->value == value)
return true;
}
return false;
}
using Iterator = DoublyLinkedListIterator<DoublyLinkedList, T>;
friend Iterator;
Iterator begin() { return Iterator(m_head); }
Iterator end() { return Iterator::universal_end(); }
using ConstIterator = DoublyLinkedListIterator<const DoublyLinkedList, const T>;
friend ConstIterator;
ConstIterator begin() const { return ConstIterator(m_head); }
ConstIterator end() const { return ConstIterator::universal_end(); }
ConstIterator find(const T& value) const
{
for (auto* node = m_head; node; node = node->next) {
if (Traits<T>::equals(node->value, value))
return ConstIterator(node);
}
return end();
}
Iterator find(const T& value)
{
for (auto* node = m_head; node; node = node->next) {
if (Traits<T>::equals(node->value, value))
return Iterator(node);
}
return end();
}
void remove(Iterator& it)
{
ASSERT(it.m_node);
auto* node = it.m_node;
if (node->prev) {
ASSERT(node != m_head);
node->prev->next = node->next;
} else {
ASSERT(node == m_head);
m_head = node->next;
}
if (node->next) {
ASSERT(node != m_tail);
node->next->prev = node->prev;
} else {
ASSERT(node == m_tail);
m_tail = node->prev;
}
delete node;
}
private:
void append_node(Node* node)
{
if (!m_head) {
ASSERT(!m_tail);
m_head = node;
m_tail = node;
return;
}
ASSERT(m_tail);
m_tail->next = node;
node->prev = m_tail;
m_tail = node;
}
Node* head() { return m_head; }
const Node* head() const { return m_head; }
Node* tail() { return m_tail; }
const Node* tail() const { return m_tail; }
Node* m_head { nullptr };
Node* m_tail { nullptr };
};
}
using AK::DoublyLinkedList;
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