Ryujinx/Ryujinx.Common/Collections/IntrusiveRedBlackTree.cs

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using System;
namespace Ryujinx.Common.Collections
{
/// <summary>
/// Tree that provides the ability for O(logN) lookups for keys that exist in the tree, and O(logN) lookups for keys immediately greater than or less than a specified key.
/// </summary>
/// <typeparam name="T">Derived node type</typeparam>
public class IntrusiveRedBlackTree<T> : IntrusiveRedBlackTreeImpl<T> where T : IntrusiveRedBlackTreeNode<T>, IComparable<T>
{
#region Public Methods
/// <summary>
/// Adds a new node into the tree.
/// </summary>
/// <param name="node">Node to be added</param>
/// <exception cref="ArgumentNullException"><paramref name="node"/> is null</exception>
public void Add(T node)
{
if (node == null)
{
throw new ArgumentNullException(nameof(node));
}
Insert(node);
}
/// <summary>
/// Removes a node from the tree.
/// </summary>
/// <param name="node">Note to be removed</param>
/// <exception cref="ArgumentNullException"><paramref name="node"/> is null</exception>
public void Remove(T node)
{
if (node == null)
{
throw new ArgumentNullException(nameof(node));
}
if (Delete(node) != null)
{
Count--;
}
}
/// <summary>
/// Retrieve the node that is considered equal to the specified node by the comparator.
/// </summary>
/// <param name="searchNode">Node to compare with</param>
/// <returns>Node that is equal to <paramref name="searchNode"/></returns>
/// <exception cref="ArgumentNullException"><paramref name="searchNode"/> is null</exception>
public T GetNode(T searchNode)
{
if (searchNode == null)
{
throw new ArgumentNullException(nameof(searchNode));
}
T node = Root;
while (node != null)
{
int cmp = searchNode.CompareTo(node);
if (cmp < 0)
{
node = node.Left;
}
else if (cmp > 0)
{
node = node.Right;
}
else
{
return node;
}
}
return null;
}
#endregion
#region Private Methods (BST)
/// <summary>
/// Inserts a new node into the tree.
/// </summary>
/// <param name="node">Node to be inserted</param>
private void Insert(T node)
{
T newNode = BSTInsert(node);
RestoreBalanceAfterInsertion(newNode);
}
/// <summary>
/// Insertion Mechanism for a Binary Search Tree (BST).
/// <br></br>
/// Iterates the tree starting from the root and inserts a new node
/// where all children in the left subtree are less than <paramref name="newNode"/>,
/// and all children in the right subtree are greater than <paramref name="newNode"/>.
/// </summary>
/// <param name="newNode">Node to be inserted</param>
/// <returns>The inserted Node</returns>
private T BSTInsert(T newNode)
{
T parent = null;
T node = Root;
while (node != null)
{
parent = node;
int cmp = newNode.CompareTo(node);
if (cmp < 0)
{
node = node.Left;
}
else if (cmp > 0)
{
node = node.Right;
}
else
{
return node;
}
}
newNode.Parent = parent;
if (parent == null)
{
Root = newNode;
}
else if (newNode.CompareTo(parent) < 0)
{
parent.Left = newNode;
}
else
{
parent.Right = newNode;
}
Count++;
return newNode;
}
/// <summary>
/// Removes <paramref name="nodeToDelete"/> from the tree, if it exists.
/// </summary>
/// <param name="nodeToDelete">Node to be removed</param>
/// <returns>The deleted Node</returns>
private T Delete(T nodeToDelete)
{
if (nodeToDelete == null)
{
return null;
}
T old = nodeToDelete;
T child;
T parent;
bool color;
if (LeftOf(nodeToDelete) == null)
{
child = RightOf(nodeToDelete);
}
else if (RightOf(nodeToDelete) == null)
{
child = LeftOf(nodeToDelete);
}
else
{
T element = Minimum(RightOf(nodeToDelete));
child = RightOf(element);
parent = ParentOf(element);
color = ColorOf(element);
if (child != null)
{
child.Parent = parent;
}
if (parent == null)
{
Root = child;
}
else if (element == LeftOf(parent))
{
parent.Left = child;
}
else
{
parent.Right = child;
}
if (ParentOf(element) == old)
{
parent = element;
}
element.Color = old.Color;
element.Left = old.Left;
element.Right = old.Right;
element.Parent = old.Parent;
if (ParentOf(old) == null)
{
Root = element;
}
else if (old == LeftOf(ParentOf(old)))
{
ParentOf(old).Left = element;
}
else
{
ParentOf(old).Right = element;
}
LeftOf(old).Parent = element;
if (RightOf(old) != null)
{
RightOf(old).Parent = element;
}
if (child != null && color == Black)
{
RestoreBalanceAfterRemoval(child);
}
return old;
}
parent = ParentOf(nodeToDelete);
color = ColorOf(nodeToDelete);
if (child != null)
{
child.Parent = parent;
}
if (parent == null)
{
Root = child;
}
else if (nodeToDelete == LeftOf(parent))
{
parent.Left = child;
}
else
{
parent.Right = child;
}
if (child != null && color == Black)
{
RestoreBalanceAfterRemoval(child);
}
return old;
}
#endregion
}
public static class IntrusiveRedBlackTreeExtensions
{
/// <summary>
/// Retrieve the node that is considered equal to the key by the comparator.
/// </summary>
/// <param name="tree">Tree to search at</param>
/// <param name="key">Key of the node to be found</param>
/// <returns>Node that is equal to <paramref name="key"/></returns>
public static N GetNodeByKey<N, K>(this IntrusiveRedBlackTree<N> tree, K key)
where N : IntrusiveRedBlackTreeNode<N>, IComparable<N>, IComparable<K>
where K : struct
{
N node = tree.RootNode;
while (node != null)
{
int cmp = node.CompareTo(key);
if (cmp < 0)
{
node = node.Right;
}
else if (cmp > 0)
{
node = node.Left;
}
else
{
return node;
}
}
return null;
}
}
}