From ba07e5bf41b97ad061f75008c6e8fd31e9a4991e Mon Sep 17 00:00:00 2001
From: disarray2077 <86157825+disarray2077@users.noreply.github.com>
Date: Mon, 21 Feb 2022 01:52:19 -0300
Subject: [PATCH] Add `LinkedList<T>` to corlib

---
 BeefLibs/corlib/src/Collections/LinkedList.bf | 490 ++++++++++++++++++
 1 file changed, 490 insertions(+)
 create mode 100644 BeefLibs/corlib/src/Collections/LinkedList.bf

diff --git a/BeefLibs/corlib/src/Collections/LinkedList.bf b/BeefLibs/corlib/src/Collections/LinkedList.bf
new file mode 100644
index 00000000..43fda23c
--- /dev/null
+++ b/BeefLibs/corlib/src/Collections/LinkedList.bf
@@ -0,0 +1,490 @@
+// This file contains portions of code released by Microsoft under the MIT license as part
+// of an open-sourcing initiative in 2014 of the C# core libraries.
+// The original source was submitted to https://github.com/Microsoft/referencesource
+
+#if PARANOID
+#define VERSION_LINKEDLIST
+#endif
+
+using System;
+using System.Diagnostics;
+
+using internal System.Collections; // to allow the deletion of LinkedListNode.
+
+namespace System.Collections
+{
+	public class LinkedList<T> : ICollection<T>, IEnumerable<T>
+	{
+		// This LinkedList is a doubly-Linked circular list.
+		private LinkedListNode<T> mHead;
+		private int_cosize mCount;
+#if VERSION_LINKEDLIST
+		private int32 mVersion;
+#endif
+
+		public this()
+		{
+		}
+
+		public this(IEnumerator<T> collection)
+		{
+			for (T item in collection)
+				AddLast(item);
+		}
+
+		public ~this()
+		{
+			Clear();
+		}
+
+		public int Count
+		{
+			get
+			{
+				return mCount;
+			}
+		}
+
+		public LinkedListNode<T> First
+		{
+			get
+			{
+				return mHead;
+			}
+		}
+
+		public LinkedListNode<T> Last
+		{
+			get
+			{
+				return mHead == null ? null : mHead.mPrev;
+			}
+		}
+
+		void ICollection<T>.Add(T value)
+		{
+			AddLast(value);
+		}
+
+		public LinkedListNode<T> AddAfter(LinkedListNode<T> node, T value)
+		{
+			Debug.Assert(node != null);
+			Debug.Assert(node.mList == this, "The LinkedList node already belongs to a LinkedList");
+			LinkedListNode<T> result = new LinkedListNode<T>(node.mList, value);
+			publicInsertNodeBefore(node.mNext, result);
+			return result;
+		}
+
+		public void AddAfter(LinkedListNode<T> node, LinkedListNode<T> newNode)
+		{
+			Debug.Assert(node != null && newNode != null);
+			Debug.Assert(node.mList == this, "The LinkedList node does not belong to current LinkedList");
+			Debug.Assert(newNode.mList == null, "The LinkedList node already belongs to a LinkedList");
+			publicInsertNodeBefore(node.mNext, newNode);
+			newNode.mList = this;
+		}
+
+		public LinkedListNode<T> AddBefore(LinkedListNode<T> node, T value)
+		{
+			Debug.Assert(node != null);
+			Debug.Assert(node.mList == this, "The LinkedList node does not belong to current LinkedList");
+			LinkedListNode<T> result = new LinkedListNode<T>(node.mList, value);
+			publicInsertNodeBefore(node, result);
+			if (node == mHead)
+				mHead = result;
+			return result;
+		}
+
+		public void AddBefore(LinkedListNode<T> node, LinkedListNode<T> newNode)
+		{
+			Debug.Assert(node != null && newNode != null);
+			Debug.Assert(node.mList == this, "The LinkedList node does not belong to current LinkedList");
+			Debug.Assert(newNode.mList == null, "The LinkedList node already belongs to a LinkedList");
+			publicInsertNodeBefore(node, newNode);
+			newNode.mList = this;
+			if (node == mHead)
+				mHead = newNode;
+		}
+
+		public LinkedListNode<T> AddFirst(T value)
+		{
+			LinkedListNode<T> result = new LinkedListNode<T>(this, value);
+			if (mHead == null)
+			{
+				publicInsertNodeToEmptyList(result);
+			}
+			else
+			{
+				publicInsertNodeBefore(mHead, result);
+				mHead = result;
+			}
+			return result;
+		}
+
+		public void AddFirst(LinkedListNode<T> node)
+		{
+			Debug.Assert(node != null);
+			Debug.Assert(node.mList == null, "The LinkedList node already belongs to a LinkedList");
+
+			if (mHead == null)
+			{
+				publicInsertNodeToEmptyList(node);
+			}
+			else
+			{
+				publicInsertNodeBefore(mHead, node);
+				mHead = node;
+			}
+			node.mList = this;
+		}
+
+		public LinkedListNode<T> AddLast(T value)
+		{
+			LinkedListNode<T> result = new LinkedListNode<T>(this, value);
+			if (mHead == null)
+			{
+				publicInsertNodeToEmptyList(result);
+			}
+			else
+			{
+				publicInsertNodeBefore(mHead, result);
+			}
+			return result;
+		}
+
+		public void AddLast(LinkedListNode<T> node)
+		{
+			Debug.Assert(node != null);
+			Debug.Assert(node.mList == null, "The LinkedList node already belongs to a LinkedList");
+
+			if (mHead == null)
+			{
+				publicInsertNodeToEmptyList(node);
+			}
+			else
+			{
+				publicInsertNodeBefore(mHead, node);
+			}
+			node.mList = this;
+		}
+
+		public void Clear()
+		{
+			LinkedListNode<T> current = mHead;
+			while (current != null)
+			{
+				LinkedListNode<T> temp = current;
+				current = current.Next; // use Next the instead of "next", otherwise it will loop forever
+				delete temp;
+			}
+
+			mHead = null;
+			mCount = 0;
+#if VERSION_LINKEDLIST
+			mVersion++;
+#endif
+		}
+
+		public bool Contains(T value)
+		{
+			return Find(value) != null;
+		}
+
+		public void CopyTo(Span<T> array)
+		{
+			Debug.Assert(array.Length < Count);
+
+			LinkedListNode<T> node = mHead;
+			if (node != null)
+			{
+				int index = 0;
+				repeat
+				{
+					array[index++] = node.mItem;
+					node = node.mNext;
+				} while (node != mHead);
+			}
+		}
+
+		public LinkedListNode<T> Find(T value)
+		{
+			LinkedListNode<T> node = mHead;
+			if (node != null)
+			{
+				if (value != null)
+				{
+					repeat
+					{
+						if (node.mItem == value)
+						{
+							return node;
+						}
+						node = node.mNext;
+					} while (node != mHead);
+				}
+				else
+				{
+					repeat
+					{
+						if (node.mItem == null)
+						{
+							return node;
+						}
+						node = node.mNext;
+					} while (node != mHead);
+				}
+			}
+			return null;
+		}
+
+		public LinkedListNode<T> FindLast(T value)
+		{
+			if (mHead == null) return null;
+
+			LinkedListNode<T> last = mHead.mPrev;
+			LinkedListNode<T> node = last;
+			if (node != null)
+			{
+				if (value != null)
+				{
+					repeat
+					{
+						if (node.mItem == value)
+						{
+							return node;
+						}
+
+						node = node.mPrev;
+					} while (node != last);
+				}
+				else
+				{
+					repeat
+					{
+						if (node.mItem == null)
+						{
+							return node;
+						}
+						node = node.mPrev;
+					} while (node != last);
+				}
+			}
+			return null;
+		}
+
+		public Enumerator GetEnumerator()
+		{
+			return Enumerator(this);
+		}
+
+		public bool Remove(T value)
+		{
+			LinkedListNode<T> node = Find(value);
+			if (node != null)
+			{
+				publicRemoveNode(node);
+				return true;
+			}
+			return false;
+		}
+
+		public void Remove(LinkedListNode<T> node)
+		{
+			Debug.Assert(node != null);
+			Debug.Assert(node.mList == this, "The LinkedList node does not belong to current LinkedList");
+			publicRemoveNode(node);
+		}
+
+		public void RemoveFirst()
+		{
+			Debug.Assert(mHead != null, "RemoveFirst called on a LinkedList with no nodes");
+			publicRemoveNode(mHead);
+		}
+
+		public void RemoveLast()
+		{
+			Debug.Assert(mHead != null, "RemoveLast called on a LinkedList with no nodes");
+			publicRemoveNode(mHead.mPrev);
+		}
+
+		private void publicInsertNodeBefore(LinkedListNode<T> node, LinkedListNode<T> newNode)
+		{
+			newNode.mNext = node;
+			newNode.mPrev = node.mPrev;
+			node.mPrev.mNext = newNode;
+			node.mPrev = newNode;
+#if VERSION_LINKEDLIST
+			mVersion++;
+#endif
+			mCount++;
+		}
+
+		private void publicInsertNodeToEmptyList(LinkedListNode<T> newNode)
+		{
+			Debug.Assert(mHead == null && mCount == 0, "LinkedList must be empty when this method is called!");
+			newNode.mNext = newNode;
+			newNode.mPrev = newNode;
+			mHead = newNode;
+#if VERSION_LINKEDLIST
+			mVersion++;
+#endif
+			mCount++;
+		}
+
+		private void publicRemoveNode(LinkedListNode<T> node)
+		{
+			Debug.Assert(node.mList == this, "Deleting the node from another list!");
+			Debug.Assert(mHead != null, "This method shouldn't be called on empty list!");
+			if (node.mNext == node)
+			{
+				Debug.Assert(mCount == 1 && mHead == node, "this should only be true for a list with only one node");
+				DeleteAndNullify!(mHead);
+			}
+			else
+			{
+				node.mNext.mPrev = node.mPrev;
+				node.mPrev.mNext = node.mNext;
+				if (mHead == node)
+				{
+					mHead = node.mNext;
+				}
+				delete node;
+			}
+			mCount--;
+#if VERSION_LINKEDLIST
+			mVersion++;
+#endif
+		}
+
+		public struct Enumerator : IEnumerator<T>, IResettable
+		{
+			private LinkedList<T> mList;
+			private LinkedListNode<T> mNode;
+#if VERSION_LINKEDLIST
+			private int32 mVersion;
+#endif
+			private T mCurrent;
+			private int mIndex;
+
+			public this(LinkedList<T> list)
+			{
+				mList = list;
+#if VERSION_LINKEDLIST
+				mVersion = list.mVersion;
+#endif
+				mNode = list.mHead;
+				mCurrent = default(T);
+				mIndex = 0;
+			}
+
+			public T Current
+			{
+				get
+				{
+					return mCurrent;
+				}
+			}
+
+			public bool MoveNext() mut
+			{
+#if VERSION_LINKEDLIST
+				if (mVersion != mList.mVersion)
+					Runtime.FatalError("LinkedList changed during enumeration");
+#endif
+
+				if (mNode == null)
+				{
+					mIndex = mList.Count + 1;
+					return false;
+				}
+
+				++mIndex;
+				mCurrent = mNode.mItem;
+				mNode = mNode.mNext;
+				if (mNode == mList.mHead)
+					mNode = null;
+				return true;
+			}
+
+			public Result<T> GetNext() mut
+			{
+				if (MoveNext())
+					return .Ok(Current);
+				return .Err;
+			}
+
+			void IResettable.Reset() mut
+			{
+#if VERSION_LINKEDLIST
+				if (mVersion != mList.mVersion)
+					Runtime.FatalError("LinkedList changed during enumeration");
+#endif
+
+				mCurrent = default(T);
+				mNode = mList.mHead;
+				mIndex = 0;
+			}
+		}
+	}
+
+	public sealed class LinkedListNode<T>
+	{
+		public LinkedList<T> mList;
+		public LinkedListNode<T> mNext;
+		public LinkedListNode<T> mPrev;
+		public T mItem;
+
+		public this(T value)
+		{
+			mItem = value;
+		}
+
+		public this(LinkedList<T> list, T value)
+		{
+			mList = list;
+			mItem = value;
+		}
+
+		// This class can only be deleted by the LinkedList.
+		internal ~this()
+		{
+		}
+
+		public LinkedList<T> List
+		{
+			get
+			{
+				return mList;
+			}
+		}
+
+		public LinkedListNode<T> Next
+		{
+			get
+			{
+				return mNext == null || mNext == mList.[Friend]mHead ? null : mNext;
+			}
+		}
+
+		public LinkedListNode<T> Previous
+		{
+			get
+			{
+				return mPrev == null || this == mList.[Friend]mHead ? null : mPrev;
+			}
+		}
+
+		public T Value
+		{
+			get
+			{
+				return mItem;
+			}
+
+			set
+			{
+				mItem = value;
+			}
+		}
+	}
+}