ladybird/AK/InlineLinkedList.h
Nicholas Baron aa4d41fe2c
AK+Kernel+LibELF: Remove the need for IteratorDecision::Continue
By constraining two implementations, the compiler will select the best
fitting one. All this will require is duplicating the implementation and
simplifying for the `void` case.

This constraining also informs both the caller and compiler by passing
the callback parameter types as part of the constraint
(e.g.: `IterationFunction<int>`).

Some `for_each` functions in LibELF only take functions which return
`void`. This is a minimal correctness check, as it removes one way for a
function to incompletely do something.

There seems to be a possible idiom where inside a lambda, a `return;` is
the same as `continue;` in a for-loop.
2021-05-16 10:36:52 +01:00

318 lines
6.9 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Assertions.h>
#include <AK/Concepts.h>
#include <AK/Types.h>
namespace AK {
template<typename T>
class InlineLinkedList;
template<typename T>
class InlineLinkedListIterator {
public:
bool operator!=(const InlineLinkedListIterator& other) const { return m_node != other.m_node; }
bool operator==(const InlineLinkedListIterator& other) const { return m_node == other.m_node; }
InlineLinkedListIterator& operator++()
{
m_node = m_node->next();
return *this;
}
T& operator*() { return *m_node; }
T* operator->() { return m_node; }
bool is_end() const { return !m_node; }
static InlineLinkedListIterator universal_end() { return InlineLinkedListIterator(nullptr); }
private:
friend InlineLinkedList<T>;
explicit InlineLinkedListIterator(T* node)
: m_node(node)
{
}
T* m_node;
};
template<typename T>
class InlineLinkedListNode {
public:
InlineLinkedListNode();
void set_prev(T*);
void set_next(T*);
T* prev() const;
T* next() const;
};
template<typename T>
inline InlineLinkedListNode<T>::InlineLinkedListNode()
{
set_prev(0);
set_next(0);
}
template<typename T>
inline void InlineLinkedListNode<T>::set_prev(T* prev)
{
static_cast<T*>(this)->m_prev = prev;
}
template<typename T>
inline void InlineLinkedListNode<T>::set_next(T* next)
{
static_cast<T*>(this)->m_next = next;
}
template<typename T>
inline T* InlineLinkedListNode<T>::prev() const
{
return static_cast<const T*>(this)->m_prev;
}
template<typename T>
inline T* InlineLinkedListNode<T>::next() const
{
return static_cast<const T*>(this)->m_next;
}
template<typename T>
class InlineLinkedList {
public:
InlineLinkedList() = default;
bool is_empty() const { return !m_head; }
size_t size_slow() const;
void clear();
T* head() const { return m_head; }
T* remove_head();
T* remove_tail();
T* tail() const { return m_tail; }
void prepend(T*);
void append(T*);
void remove(T*);
void append(InlineLinkedList<T>&);
void insert_before(T*, T*);
void insert_after(T*, T*);
bool contains_slow(T* value) const
{
for (T* node = m_head; node; node = node->next()) {
if (node == value)
return true;
}
return false;
}
template<IteratorFunction<T&> F>
IterationDecision for_each(F func) const
{
for (T* node = m_head; node; node = node->next()) {
IterationDecision decision = func(*node);
if (decision != IterationDecision::Continue)
return decision;
}
return IterationDecision::Continue;
}
template<VoidFunction<T&> F>
void for_each(F func) const
{
for (T* node = m_head; node; node = node->next())
func(*node);
}
using Iterator = InlineLinkedListIterator<T>;
friend Iterator;
Iterator begin() { return Iterator(m_head); }
Iterator end() { return Iterator::universal_end(); }
using ConstIterator = InlineLinkedListIterator<const T>;
friend ConstIterator;
ConstIterator begin() const { return ConstIterator(m_head); }
ConstIterator end() const { return ConstIterator::universal_end(); }
private:
T* m_head { nullptr };
T* m_tail { nullptr };
};
template<typename T>
inline size_t InlineLinkedList<T>::size_slow() const
{
size_t size = 0;
for (T* node = m_head; node; node = node->next())
++size;
return size;
}
template<typename T>
inline void InlineLinkedList<T>::clear()
{
m_head = 0;
m_tail = 0;
}
template<typename T>
inline void InlineLinkedList<T>::prepend(T* node)
{
if (!m_head) {
VERIFY(!m_tail);
m_head = node;
m_tail = node;
node->set_prev(0);
node->set_next(0);
return;
}
VERIFY(m_tail);
m_head->set_prev(node);
node->set_next(m_head);
node->set_prev(0);
m_head = node;
}
template<typename T>
inline void InlineLinkedList<T>::append(T* node)
{
if (!m_tail) {
VERIFY(!m_head);
m_head = node;
m_tail = node;
node->set_prev(0);
node->set_next(0);
return;
}
VERIFY(m_head);
m_tail->set_next(node);
node->set_prev(m_tail);
node->set_next(0);
m_tail = node;
}
template<typename T>
inline void InlineLinkedList<T>::insert_before(T* before_node, T* node)
{
VERIFY(before_node);
VERIFY(node);
VERIFY(before_node != node);
VERIFY(!is_empty());
if (m_head == before_node) {
VERIFY(!before_node->prev());
m_head = node;
node->set_prev(0);
node->set_next(before_node);
before_node->set_prev(node);
} else {
VERIFY(before_node->prev());
node->set_prev(before_node->prev());
before_node->prev()->set_next(node);
node->set_next(before_node);
before_node->set_prev(node);
}
}
template<typename T>
inline void InlineLinkedList<T>::insert_after(T* after_node, T* node)
{
VERIFY(after_node);
VERIFY(node);
VERIFY(after_node != node);
VERIFY(!is_empty());
if (m_tail == after_node) {
VERIFY(!after_node->next());
m_tail = node;
node->set_prev(after_node);
node->set_next(0);
after_node->set_next(node);
} else {
VERIFY(after_node->next());
node->set_prev(after_node);
node->set_next(after_node->next());
after_node->next()->set_prev(node);
after_node->set_next(node);
}
}
template<typename T>
inline void InlineLinkedList<T>::remove(T* node)
{
if (node->prev()) {
VERIFY(node != m_head);
node->prev()->set_next(node->next());
} else {
VERIFY(node == m_head);
m_head = node->next();
}
if (node->next()) {
VERIFY(node != m_tail);
node->next()->set_prev(node->prev());
} else {
VERIFY(node == m_tail);
m_tail = node->prev();
}
node->set_next(0);
node->set_prev(0);
}
template<typename T>
inline T* InlineLinkedList<T>::remove_head()
{
T* node = head();
if (node)
remove(node);
return node;
}
template<typename T>
inline T* InlineLinkedList<T>::remove_tail()
{
T* node = tail();
if (node)
remove(node);
return node;
}
template<typename T>
inline void InlineLinkedList<T>::append(InlineLinkedList<T>& other)
{
if (!other.head())
return;
if (!head()) {
m_head = other.head();
m_tail = other.tail();
other.clear();
return;
}
VERIFY(tail());
VERIFY(other.head());
T* other_head = other.head();
T* other_tail = other.tail();
other.clear();
VERIFY(!m_tail->next());
m_tail->set_next(other_head);
VERIFY(!other_head->prev());
other_head->set_prev(m_tail);
m_tail = other_tail;
}
}
using AK::InlineLinkedList;
using AK::InlineLinkedListNode;