ladybird/AK/SinglyLinkedList.h

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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Assertions.h>
#include <AK/Find.h>
#include <AK/StdLibExtras.h>
#include <AK/Traits.h>
#include <AK/Types.h>
namespace AK {
template<typename ListType, typename ElementType>
class SinglyLinkedListIterator {
public:
SinglyLinkedListIterator() = default;
bool operator!=(const SinglyLinkedListIterator& other) const { return m_node != other.m_node; }
SinglyLinkedListIterator& operator++()
{
if (m_removed)
m_removed = false;
else
m_prev = m_node;
m_node = m_next;
if (m_next)
m_next = m_next->next;
return *this;
}
ElementType& operator*()
{
VERIFY(!m_removed);
return m_node->value;
}
ElementType* operator->()
{
VERIFY(!m_removed);
return &m_node->value;
}
bool is_end() const { return !m_node; }
bool is_begin() const { return !m_prev; }
void remove(ListType& list)
{
m_removed = true;
list.remove(*this);
};
private:
friend ListType;
explicit SinglyLinkedListIterator(typename ListType::Node* node, typename ListType::Node* prev = nullptr)
: m_node(node)
, m_prev(prev)
, m_next(node ? node->next : nullptr)
{
}
typename ListType::Node* m_node { nullptr };
typename ListType::Node* m_prev { nullptr };
typename ListType::Node* m_next { nullptr };
bool m_removed { false };
};
template<typename T>
class SinglyLinkedList {
private:
struct Node {
explicit Node(T&& v)
: value(move(v))
{
}
explicit Node(const T& v)
: value(v)
{
}
T value;
Node* next { nullptr };
};
public:
SinglyLinkedList() = default;
~SinglyLinkedList() { clear(); }
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bool is_empty() const { return !head(); }
inline size_t size_slow() const
{
size_t size = 0;
for (auto* node = m_head; node; node = node->next)
++size;
return size;
}
void clear()
{
for (auto* node = m_head; node;) {
auto* next = node->next;
delete node;
node = next;
}
m_head = nullptr;
m_tail = nullptr;
}
T& first()
{
VERIFY(head());
return head()->value;
}
const T& first() const
{
VERIFY(head());
return head()->value;
}
T& last()
{
VERIFY(head());
return tail()->value;
}
const T& last() const
{
VERIFY(head());
return tail()->value;
}
T take_first()
{
VERIFY(m_head);
auto* prev_head = m_head;
T value = move(first());
if (m_tail == m_head)
m_tail = nullptr;
m_head = m_head->next;
delete prev_head;
return value;
}
template<typename U = T>
void append(U&& value)
{
auto* node = new Node(forward<U>(value));
if (!m_head) {
m_head = node;
m_tail = node;
return;
}
m_tail->next = node;
m_tail = node;
}
bool contains_slow(const T& value) const
{
return find(value) != end();
}
using Iterator = SinglyLinkedListIterator<SinglyLinkedList, T>;
friend Iterator;
Iterator begin() { return Iterator(m_head); }
Iterator end() { return {}; }
using ConstIterator = SinglyLinkedListIterator<const SinglyLinkedList, const T>;
friend ConstIterator;
ConstIterator begin() const { return ConstIterator(m_head); }
ConstIterator end() const { return {}; }
template<typename TUnaryPredicate>
ConstIterator find_if(TUnaryPredicate&& pred) const
{
return AK::find_if(begin(), end(), forward<TUnaryPredicate>(pred));
}
template<typename TUnaryPredicate>
Iterator find_if(TUnaryPredicate&& pred)
{
return AK::find_if(begin(), end(), forward<TUnaryPredicate>(pred));
}
ConstIterator find(const T& value) const
{
return find_if([&](auto& other) { return Traits<T>::equals(value, other); });
}
Iterator find(const T& value)
{
return find_if([&](auto& other) { return Traits<T>::equals(value, other); });
}
template<typename U = T>
void insert_before(Iterator iterator, U&& value)
{
auto* node = new Node(forward<U>(value));
node->next = iterator.m_node;
if (m_head == iterator.m_node)
m_head = node;
if (iterator.m_prev)
iterator.m_prev->next = node;
}
template<typename U = T>
void insert_after(Iterator iterator, U&& value)
{
if (iterator.is_end()) {
append(value);
return;
}
auto* node = new Node(forward<U>(value));
node->next = iterator.m_node->next;
iterator.m_node->next = node;
if (m_tail == iterator.m_node)
m_tail = node;
}
private:
void remove(Iterator& iterator)
{
VERIFY(!iterator.is_end());
if (m_head == iterator.m_node)
m_head = iterator.m_node->next;
if (m_tail == iterator.m_node)
m_tail = iterator.m_prev;
if (iterator.m_prev)
iterator.m_prev->next = iterator.m_node->next;
delete iterator.m_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::SinglyLinkedList;