From 14c734c24407d7e8250ccf8dcba113065c37d623 Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Tue, 6 Oct 2020 21:21:09 +0900
Subject: [PATCH] Add a very simple method of applying batch changes to
 EditorBeatmap

---
 osu.Game/Screens/Edit/EditorBeatmap.cs        | 69 ++++++++++++++++---
 .../Edit/LegacyEditorBeatmapPatcher.cs        | 21 +++---
 2 files changed, 73 insertions(+), 17 deletions(-)

diff --git a/osu.Game/Screens/Edit/EditorBeatmap.cs b/osu.Game/Screens/Edit/EditorBeatmap.cs
index 3248c5b8be..549423dfb8 100644
--- a/osu.Game/Screens/Edit/EditorBeatmap.cs
+++ b/osu.Game/Screens/Edit/EditorBeatmap.cs
@@ -91,6 +91,8 @@ namespace osu.Game.Screens.Edit
 
         private readonly HashSet<HitObject> pendingUpdates = new HashSet<HitObject>();
 
+        private bool isBatchApplying;
+
         /// <summary>
         /// Adds a collection of <see cref="HitObject"/>s to this <see cref="EditorBeatmap"/>.
         /// </summary>
@@ -126,12 +128,17 @@ namespace osu.Game.Screens.Edit
 
             mutableHitObjects.Insert(index, hitObject);
 
-            // must be run after any change to hitobject ordering
-            beatmapProcessor?.PreProcess();
-            processHitObject(hitObject);
-            beatmapProcessor?.PostProcess();
+            if (isBatchApplying)
+                batchPendingInserts.Add(hitObject);
+            else
+            {
+                // must be run after any change to hitobject ordering
+                beatmapProcessor?.PreProcess();
+                processHitObject(hitObject);
+                beatmapProcessor?.PostProcess();
 
-            HitObjectAdded?.Invoke(hitObject);
+                HitObjectAdded?.Invoke(hitObject);
+            }
         }
 
         /// <summary>
@@ -180,12 +187,58 @@ namespace osu.Game.Screens.Edit
             bindable.UnbindAll();
             startTimeBindables.Remove(hitObject);
 
-            // must be run after any change to hitobject ordering
+            if (isBatchApplying)
+                batchPendingDeletes.Add(hitObject);
+            else
+            {
+                // must be run after any change to hitobject ordering
+                beatmapProcessor?.PreProcess();
+                processHitObject(hitObject);
+                beatmapProcessor?.PostProcess();
+
+                HitObjectRemoved?.Invoke(hitObject);
+            }
+        }
+
+        private readonly List<HitObject> batchPendingInserts = new List<HitObject>();
+
+        private readonly List<HitObject> batchPendingDeletes = new List<HitObject>();
+
+        /// <summary>
+        /// Apply a batch of operations in one go, without performing Pre/Postprocessing each time.
+        /// </summary>
+        /// <param name="applyFunction">The function which will apply the batch changes.</param>
+        public void ApplyBatchChanges(Action<EditorBeatmap> applyFunction)
+        {
+            if (isBatchApplying)
+                throw new InvalidOperationException("Attempting to perform a batch application from within an existing batch");
+
+            isBatchApplying = true;
+
+            applyFunction(this);
+
             beatmapProcessor?.PreProcess();
-            processHitObject(hitObject);
             beatmapProcessor?.PostProcess();
 
-            HitObjectRemoved?.Invoke(hitObject);
+            isBatchApplying = false;
+
+            foreach (var h in batchPendingDeletes)
+            {
+                processHitObject(h);
+                HitObjectRemoved?.Invoke(h);
+            }
+
+            batchPendingDeletes.Clear();
+
+            foreach (var h in batchPendingInserts)
+            {
+                processHitObject(h);
+                HitObjectAdded?.Invoke(h);
+            }
+
+            batchPendingInserts.Clear();
+
+            isBatchApplying = false;
         }
 
         /// <summary>
diff --git a/osu.Game/Screens/Edit/LegacyEditorBeatmapPatcher.cs b/osu.Game/Screens/Edit/LegacyEditorBeatmapPatcher.cs
index 57b7ce6940..fb7d0dd826 100644
--- a/osu.Game/Screens/Edit/LegacyEditorBeatmapPatcher.cs
+++ b/osu.Game/Screens/Edit/LegacyEditorBeatmapPatcher.cs
@@ -68,16 +68,19 @@ namespace osu.Game.Screens.Edit
             toRemove.Sort();
             toAdd.Sort();
 
-            // Apply the changes.
-            for (int i = toRemove.Count - 1; i >= 0; i--)
-                editorBeatmap.RemoveAt(toRemove[i]);
-
-            if (toAdd.Count > 0)
+            editorBeatmap.ApplyBatchChanges(eb =>
             {
-                IBeatmap newBeatmap = readBeatmap(newState);
-                foreach (var i in toAdd)
-                    editorBeatmap.Insert(i, newBeatmap.HitObjects[i]);
-            }
+                // Apply the changes.
+                for (int i = toRemove.Count - 1; i >= 0; i--)
+                    eb.RemoveAt(toRemove[i]);
+
+                if (toAdd.Count > 0)
+                {
+                    IBeatmap newBeatmap = readBeatmap(newState);
+                    foreach (var i in toAdd)
+                        eb.Insert(i, newBeatmap.HitObjects[i]);
+                }
+            });
         }
 
         private string readString(byte[] state) => Encoding.UTF8.GetString(state);