From 9d26b4953211a560e7847c8a3bd0e2678e6c9be9 Mon Sep 17 00:00:00 2001
From: Eoin Mcloughlin <helloworld@eoinrul.es>
Date: Tue, 3 Sep 2024 21:13:55 +0100
Subject: [PATCH 1/2] Add algorithm from ss14#30292 to ItemList, for use in
 other UIs

---
 .../UserInterface/Controls/ItemList.cs        | 55 ++++++++++++++++++-
 1 file changed, 54 insertions(+), 1 deletion(-)

diff --git a/Robust.Client/UserInterface/Controls/ItemList.cs b/Robust.Client/UserInterface/Controls/ItemList.cs
index 053d05c61de..b885cbee529 100644
--- a/Robust.Client/UserInterface/Controls/ItemList.cs
+++ b/Robust.Client/UserInterface/Controls/ItemList.cs
@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Diagnostics.Contracts;
@@ -176,6 +176,59 @@ public void Insert(int index, Item item)
                 _scrollBar.MoveToEnd();
         }
 
+        /// <summary>
+        /// Replace the current list of items with the items in newItems.
+        /// newItems should be in the order which they should appear in the list.
+        /// Provided the existing items have not been re-ordered relative to each
+        /// other, Any items which already exist in the list are not destroyed,
+        /// which maintains consistency of scrollbars, selected items, etc.
+        /// </summary>
+        /// <param name="newItems">The list of items to update this list to</param>
+        /// <param name="itemCmp">Comparison function to compare existing to new items.</param>
+        public void SetItems(List<Item> newItems, Comparison<Item> itemCmp)
+        {
+            // Walk through the existing items in this list and in newItems
+            // in parallel to synchronize our items with those in newItems.
+            int i = this.Count - 1;
+            int j = newItems.Count - 1;
+            while(i >= 0 && j >= 0)
+            {
+                var cmpResult = itemCmp(this[i], newItems[j]);
+                if (cmpResult == 0)
+                {
+                    // This item exists in both our list and `newItems`. Nothing to do.
+                    i--;
+                    j--;
+                }
+                else if (cmpResult > 0)
+                {
+                    // Item exists in our list, but not in `newItems`. Remove it.
+                    RemoveAt(i);
+                    i--;
+                }
+                else if (cmpResult < 0)
+                {
+                    // A new entry which doesn't exist in our list. Insert it.
+                    Insert(i + 1, newItems[j]);
+                    j--;
+                }
+            }
+
+            // Any remaining items in our list don't exist in `newItems`, so remove them
+            while (i >= 0)
+            {
+                RemoveAt(i);
+                i--;
+            }
+
+            // And finally, any remaining items in `newItems`, don't exist in our list. Create them.
+            while (j >= 0)
+            {
+                Insert(0, newItems[j]);
+                j--;
+            }
+        }
+
         // Without this attribute, this would compile into a property called "Item", causing problems with the Item class.
         [System.Runtime.CompilerServices.IndexerName("IndexItem")]
         public Item this[int index]

From c5cb32474bc238c4e56ad449df565cba747926ff Mon Sep 17 00:00:00 2001
From: Eoin Mcloughlin <helloworld@eoinrul.es>
Date: Mon, 4 Nov 2024 20:15:40 +0000
Subject: [PATCH 2/2] Add overload for common case of comparing items by their
 text label

---
 .../UserInterface/Controls/ItemList.cs        | 20 +++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/Robust.Client/UserInterface/Controls/ItemList.cs b/Robust.Client/UserInterface/Controls/ItemList.cs
index b885cbee529..985b6e031d1 100644
--- a/Robust.Client/UserInterface/Controls/ItemList.cs
+++ b/Robust.Client/UserInterface/Controls/ItemList.cs
@@ -178,12 +178,24 @@ public void Insert(int index, Item item)
 
         /// <summary>
         /// Replace the current list of items with the items in newItems.
-        /// newItems should be in the order which they should appear in the list.
+        /// newItems should be in the order which they should appear in the list,
+        /// and items are considered equal if the Item text is equal in each item.
+        ///
         /// Provided the existing items have not been re-ordered relative to each
-        /// other, Any items which already exist in the list are not destroyed,
+        /// other, any items which already exist in the list are not destroyed,
         /// which maintains consistency of scrollbars, selected items, etc.
         /// </summary>
         /// <param name="newItems">The list of items to update this list to</param>
+        public void SetItems(List<Item> newItems)
+        {
+            SetItems(newItems, (a,b) => string.Compare(a.Text, b.Text));
+        }
+
+        /// <inheritdoc />
+        /// <summary>
+        /// This variant allows for a custom equality operator to compare items, when
+        /// comparing the Item text is not desired.
+        /// </summary>
         /// <param name="itemCmp">Comparison function to compare existing to new items.</param>
         public void SetItems(List<Item> newItems, Comparison<Item> itemCmp)
         {
@@ -214,14 +226,14 @@ public void SetItems(List<Item> newItems, Comparison<Item> itemCmp)
                 }
             }
 
-            // Any remaining items in our list don't exist in `newItems`, so remove them
+            // Any remaining items in our list don't exist in `newItems` so remove them
             while (i >= 0)
             {
                 RemoveAt(i);
                 i--;
             }
 
-            // And finally, any remaining items in `newItems`, don't exist in our list. Create them.
+            // And finally, any remaining items in `newItems` don't exist in our list. Create them.
             while (j >= 0)
             {
                 Insert(0, newItems[j]);