AK: Implement IntrusiveRedBlackTree container

This container is similar to the RedBlackTree container, but instead of
transparently allocating tree nodes on insertion and freeing on removal
this container piggybacks on intrusive node fields in the stored class

AK/IntrusiveRedBlackTree.h

@@ -0,0 +1,195 @@
+/*
+ * Copyright (c) 2021, Idan Horowitz <idan.horowitz@gmail.com>
+ * 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/RedBlackTree.h>
+
+namespace AK {
+
+template<Integral K>
+class IntrusiveRedBlackTreeNode;
+
+template<Integral K, typename V, IntrusiveRedBlackTreeNode<K> V::*member>
+class IntrusiveRedBlackTree : 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; }
+
+    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());
+    }
+
+    bool is_in_tree()
+    {
+        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;

AK/Tests/CMakeLists.txt

@@ -28,6 +28,7 @@ set(AK_TEST_SOURCES
     TestHashTable.cpp
     TestIPv4Address.cpp
     TestIndexSequence.cpp
+    TestIntrusiveRedBlackTree.cpp
     TestJSON.cpp
     TestLexicalPath.cpp
     TestMACAddress.cpp

AK/Tests/TestIntrusiveRedBlackTree.cpp

@@ -0,0 +1,138 @@
+/*
+ * Copyright (c) 2021, Idan Horowitz <idan.horowitz@gmail.com>
+ * 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.
+ */
+
+#include <AK/TestSuite.h>
+
+#include <AK/IntrusiveRedBlackTree.h>
+#include <AK/NonnullOwnPtrVector.h>
+#include <AK/Random.h>
+
+class IntrusiveTest {
+public:
+    IntrusiveTest(int key, int value)
+        : m_tree_node(key)
+        , m_some_value(value)
+    {
+    }
+
+    IntrusiveRedBlackTreeNode<int> m_tree_node;
+    int m_some_value;
+};
+
+TEST_CASE(construct)
+{
+    IntrusiveRedBlackTree<int, IntrusiveTest, &IntrusiveTest::m_tree_node> empty;
+    EXPECT(empty.is_empty());
+    EXPECT(empty.size() == 0);
+}
+
+TEST_CASE(ints)
+{
+    IntrusiveRedBlackTree<int, IntrusiveTest, &IntrusiveTest::m_tree_node> test;
+    IntrusiveTest first { 1, 10 };
+    test.insert(first);
+    IntrusiveTest second { 3, 20 };
+    test.insert(second);
+    IntrusiveTest third { 2, 30 };
+    test.insert(third);
+    EXPECT_EQ(test.size(), 3u);
+    EXPECT_EQ(test.find(3)->m_some_value, 20);
+    EXPECT_EQ(test.find(2)->m_some_value, 30);
+    EXPECT_EQ(test.find(1)->m_some_value, 10);
+    EXPECT(!test.remove(4));
+    EXPECT(test.remove(2));
+    EXPECT(test.remove(1));
+    EXPECT(test.remove(3));
+    EXPECT_EQ(test.size(), 0u);
+}
+
+TEST_CASE(largest_smaller_than)
+{
+    IntrusiveRedBlackTree<int, IntrusiveTest, &IntrusiveTest::m_tree_node> test;
+    IntrusiveTest first { 1, 10 };
+    test.insert(first);
+    IntrusiveTest second { 11, 20 };
+    test.insert(second);
+    IntrusiveTest third { 21, 30 };
+    test.insert(third);
+    EXPECT_EQ(test.size(), 3u);
+    EXPECT_EQ(test.find_largest_not_above(3)->m_some_value, 10);
+    EXPECT_EQ(test.find_largest_not_above(17)->m_some_value, 20);
+    EXPECT_EQ(test.find_largest_not_above(22)->m_some_value, 30);
+    EXPECT_EQ(test.find_largest_not_above(-5), nullptr);
+    VERIFY(test.remove(1));
+    VERIFY(test.remove(11));
+    VERIFY(test.remove(21));
+}
+
+TEST_CASE(key_ordered_iteration)
+{
+    constexpr auto amount = 10000;
+    IntrusiveRedBlackTree<int, IntrusiveTest, &IntrusiveTest::m_tree_node> test;
+    NonnullOwnPtrVector<IntrusiveTest> m_entries;
+    Array<int, amount> keys {};
+
+    // generate random key order
+    for (int i = 0; i < amount; i++) {
+        keys[i] = i;
+    }
+    for (size_t i = 0; i < amount; i++) {
+        swap(keys[i], keys[get_random<size_t>() % amount]);
+    }
+
+    // insert random keys
+    for (size_t i = 0; i < amount; i++) {
+        auto entry = make<IntrusiveTest>(keys[i], keys[i]);
+        test.insert(*entry);
+        m_entries.append(move(entry));
+    }
+
+    // check key-ordered iteration
+    int index = 0;
+    for (auto& value : test) {
+        EXPECT(value.m_some_value == index++);
+    }
+
+    // ensure we can remove all of them (aka, tree structure is not destroyed somehow)
+    for (size_t i = 0; i < amount; i++) {
+        EXPECT(test.remove(i));
+    }
+}
+
+TEST_CASE(clear)
+{
+    IntrusiveRedBlackTree<int, IntrusiveTest, &IntrusiveTest::m_tree_node> test;
+    NonnullOwnPtrVector<IntrusiveTest> m_entries;
+    for (size_t i = 0; i < 1000; i++) {
+        auto entry = make<IntrusiveTest>(i, i);
+        test.insert(*entry);
+        m_entries.append(move(entry));
+    }
+    test.clear();
+    EXPECT_EQ(test.size(), 0u);
+}
+
+TEST_MAIN(RedBlackTree)