ladybird/AK/SinglyLinkedList.h
Lenny Maiorani e6f907a155 AK: Simplify constructors and conversions from nullptr_t
Problem:
- Many constructors are defined as `{}` rather than using the ` =
  default` compiler-provided constructor.
- Some types provide an implicit conversion operator from `nullptr_t`
  instead of requiring the caller to default construct. This violates
  the C++ Core Guidelines suggestion to declare single-argument
  constructors explicit
  (https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#c46-by-default-declare-single-argument-constructors-explicit).

Solution:
- Change default constructors to use the compiler-provided default
  constructor.
- Remove implicit conversion operators from `nullptr_t` and change
  usage to enforce type consistency without conversion.
2021-01-12 09:11:45 +01:00

254 lines
6.6 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#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++()
{
m_prev = m_node;
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; }
bool is_begin() const { return !m_prev; }
private:
friend ListType;
explicit SinglyLinkedListIterator(typename ListType::Node* node, typename ListType::Node* prev = nullptr)
: m_node(node)
, m_prev(prev)
{
}
typename ListType::Node* m_node { nullptr };
typename ListType::Node* m_prev { nullptr };
};
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(); }
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()
{
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;
}
T take_first()
{
ASSERT(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;
}
void append(const T& value)
{
append(T(value));
}
void append(T&& value)
{
auto* node = new Node(move(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); });
}
void remove(Iterator iterator)
{
ASSERT(!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;
}
void insert_before(Iterator iterator, const T& value)
{
insert_before(iterator, T(value));
}
void insert_before(Iterator iterator, T&& value)
{
auto* node = new Node(move(value));
node->next = iterator.m_node;
if (m_head == iterator.m_node)
m_head = node;
if (iterator.m_prev)
iterator.m_prev->next = node;
}
void insert_after(Iterator iterator, const T& value)
{
insert_after(iterator, T(value));
}
void insert_after(Iterator iterator, T&& value)
{
if (iterator.is_end()) {
append(value);
return;
}
auto* node = new Node(move(value));
node->next = iterator.m_node->next;
iterator.m_node->next = node;
if (m_tail == iterator.m_node)
m_tail = node;
}
private:
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;