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/*
* Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/RedBlackTree.h>
namespace AK {
template<Integral K>
class IntrusiveRedBlackTreeNode;
template<Integral K, typename V, IntrusiveRedBlackTreeNode<K> V::*member>
class IntrusiveRedBlackTree final : public BaseRedBlackTree<K> {
public:
IntrusiveRedBlackTree() = default;
virtual ~IntrusiveRedBlackTree() override
{
clear();
}
using BaseTree = BaseRedBlackTree<K>;
using TreeNode = IntrusiveRedBlackTreeNode<K>;
V* find(K key)
{
auto* node = static_cast<TreeNode*>(BaseTree::find(this->m_root, key));
if (!node)
return nullptr;
return node_to_value(*node);
}
V* find_largest_not_above(K key)
{
auto* node = static_cast<TreeNode*>(BaseTree::find_largest_not_above(this->m_root, key));
if (!node)
return nullptr;
return node_to_value(*node);
}
void insert(V& value)
{
auto& node = value.*member;
BaseTree::insert(&node);
node.m_in_tree = true;
}
template<typename ElementType>
class BaseIterator {
public:
BaseIterator() = default;
bool operator!=(const BaseIterator& other) const { return m_node != other.m_node; }
BaseIterator& operator++()
{
if (!m_node)
return *this;
m_prev = m_node;
// the complexity is O(logn) for each successor call, but the total complexity for all elements comes out to O(n), meaning the amortized cost for a single call is O(1)
m_node = static_cast<TreeNode*>(BaseTree::successor(m_node));
return *this;
}
BaseIterator& operator--()
{
if (!m_prev)
return *this;
m_node = m_prev;
m_prev = static_cast<TreeNode*>(BaseTree::predecessor(m_prev));
return *this;
}
ElementType& operator*()
{
VERIFY(m_node);
return *node_to_value(*m_node);
}
ElementType* operator->()
{
VERIFY(m_node);
return node_to_value(*m_node);
}
[[nodiscard]] bool is_end() const { return !m_node; }
[[nodiscard]] bool is_begin() const { return !m_prev; }
[[nodiscard]] auto key() const { return m_node->key; }
private:
friend class IntrusiveRedBlackTree;
explicit BaseIterator(TreeNode* node, TreeNode* prev = nullptr)
: m_node(node)
, m_prev(prev)
{
}
TreeNode* m_node { nullptr };
TreeNode* m_prev { nullptr };
};
using Iterator = BaseIterator<V>;
Iterator begin() { return Iterator(static_cast<TreeNode*>(this->m_minimum)); }
Iterator end() { return {}; }
Iterator begin_from(K key) { return Iterator(static_cast<TreeNode*>(BaseTree::find(this->m_root, key))); }
using ConstIterator = BaseIterator<const V>;
ConstIterator begin() const { return ConstIterator(static_cast<TreeNode*>(this->m_minimum)); }
ConstIterator end() const { return {}; }
ConstIterator begin_from(K key) const { return ConstIterator(static_cast<TreeNode*>(BaseTree::find(this->m_rootF, key))); }
bool remove(K key)
{
auto* node = static_cast<TreeNode*>(BaseTree::find(this->m_root, key));
if (!node)
return false;
BaseTree::remove(node);
node->right_child = nullptr;
node->left_child = nullptr;
node->m_in_tree = false;
return true;
}
void clear()
{
clear_nodes(static_cast<TreeNode*>(this->m_root));
this->m_root = nullptr;
this->m_minimum = nullptr;
this->m_size = 0;
}
private:
static void clear_nodes(TreeNode* node)
{
if (!node)
return;
clear_nodes(static_cast<TreeNode*>(node->right_child));
node->right_child = nullptr;
clear_nodes(static_cast<TreeNode*>(node->left_child));
node->left_child = nullptr;
node->m_in_tree = false;
}
static V* node_to_value(TreeNode& node)
{
return (V*)((u8*)&node - ((u8*)&(((V*)nullptr)->*member) - (u8*)nullptr));
}
};
template<Integral K>
class IntrusiveRedBlackTreeNode : public BaseRedBlackTree<K>::Node {
public:
IntrusiveRedBlackTreeNode(K key)
: BaseRedBlackTree<K>::Node(key)
{
}
~IntrusiveRedBlackTreeNode()
{
VERIFY(!is_in_tree());
}
[[nodiscard]] bool is_in_tree() const
{
return m_in_tree;
}
private:
template<Integral TK, typename V, IntrusiveRedBlackTreeNode<TK> V::*member>
friend class IntrusiveRedBlackTree;
bool m_in_tree { false };
};
}
using AK::IntrusiveRedBlackTree;
using AK::IntrusiveRedBlackTreeNode;
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