Add the green node interface.

This is made invisible because only generated code should use it, so we won't pollute the autocomplete suggestions with it.

Tsu.Trees.RedGreen/src/Internal/IGreenNode.cs

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+// Copyright © 2024 GGG KILLER <[email protected]>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+// and associated documentation files (the “Software”), to deal in the Software without
+// restriction, including without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom
+// the Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
+// BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+using System.ComponentModel;
+using System.Diagnostics.CodeAnalysis;
+
+namespace Tsu.Trees.RedGreen.Internal;
+
+/// <summary>
+/// The base class for a green tree node.
+/// </summary>
+/// <remarks>
+/// This is strictly for use by the generated code and libraries, you should never access green nodes yourself.
+/// </remarks>
+[EditorBrowsable(EditorBrowsableState.Never)]
+public interface IGreenNode<TGreenRoot, TRedRoot, TKind>
+    where TGreenRoot : class, IGreenNode<TGreenRoot, TRedRoot, TKind>
+    where TRedRoot : class
+    where TKind : Enum
+{
+    /// <summary>
+    /// The kind of node this is.
+    /// </summary>
+    TKind Kind { get; }
+
+    /// <summary>
+    /// The number of slots this node contains.
+    /// </summary>
+    int SlotCount { get; }
+
+    /// <summary>
+    /// Obtains the node at the given slot.
+    /// </summary>
+    /// <param name="index"></param>
+    /// <returns></returns>
+    TGreenRoot? GetSlot(int index);
+
+    /// <summary>
+    /// Ensures the node at the provided slot will not be null and returns it.
+    /// </summary>
+    /// <param name="index"></param>
+    /// <returns></returns>
+    TGreenRoot GetRequiredSlot(int index);
+
+    /// <summary>
+    /// Enumerate all descendants of this tree in depth-first order.
+    /// </summary>
+    /// <returns></returns>
+    IEnumerable<TGreenRoot> EnumerateDescendants();
+
+    /// <summary>
+    /// Enumerates the direct children that are under this node.
+    /// </summary>
+    /// <returns></returns>
+    IEnumerable<TGreenRoot> ChildNodes();
+
+    #region Caching
+
+    /// <summary>
+    /// Whether this node can be cached.
+    /// </summary>
+    bool IsCacheable { get; }
+
+    /// <summary>
+    /// Returns the hash code to be used for caching this node.
+    /// </summary>
+    /// <returns></returns>
+    int GetCacheHash();
+
+    /// <summary>
+    /// Returns whether this node is equivalent to another cached counterpart.
+    /// </summary>
+    /// <param name="kind"></param>
+    /// <param name="child1"></param>
+    /// <returns></returns>
+    bool IsCacheEquivalent(int kind, TGreenRoot? child1);
+
+    /// <summary>
+    /// Returns whether this node is equivalent to another cached counterpart.
+    /// </summary>
+    /// <param name="kind"></param>
+    /// <param name="child1"></param>
+    /// <param name="child2"></param>
+    /// <returns></returns>
+    bool IsCacheEquivalent(int kind, TGreenRoot? child1, TGreenRoot? child2);
+
+    /// <summary>
+    /// Returns whether this node is equivalent to another cached counterpart.
+    /// </summary>
+    /// <param name="kind"></param>
+    /// <param name="child1"></param>
+    /// <param name="child2"></param>
+    /// <param name="child3"></param>
+    /// <returns></returns>
+    bool IsCacheEquivalent(int kind, TGreenRoot? child1, TGreenRoot? child2, TGreenRoot? child3);
+
+    #endregion Caching
+
+    /// <summary>
+    /// Returns whether this given node is equivalent to another.
+    /// </summary>
+    /// <param name="other"></param>
+    /// <returns></returns>
+    bool IsEquivalentTo([NotNullWhen(true)] TGreenRoot? other);
+
+    /// <summary>
+    /// Creates a red version of this node without a parent.
+    /// </summary>
+    /// <returns></returns>
+    TRedRoot CreateRed();
+
+    /// <summary>
+    /// Creates a red version of this node with the specified parent.
+    /// </summary>
+    /// <param name="parent">
+    /// The node to specify as the parent for this node.
+    /// </param>
+    /// <returns></returns>
+    TRedRoot CreateRed(TRedRoot? parent);
+}