feat: introduce batchly visit in tas sequence

BallanceTasEditor/BallanceTasEditor/Backend/TasOperation.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
+using System.Reflection;
 using System.Text;
 using System.Threading.Tasks;
 
@@ -108,14 +109,13 @@ namespace BallanceTasEditor.Backend {
             ArgumentOutOfRangeException.ThrowIfLessThan(m_StartIndex, 0);
 
             // Do backup and set values at the same time
+            int backupIndex = 0;
             var backups = new RawTasFrame[m_EndIndex - m_StartIndex + 1];
             // Pre-build key list for fast fetching.
             var keys = Enumerable.Range(m_StartKey.ToIndex(), m_EndKey.ToIndex() - m_StartKey.ToIndex() + 1).Select((i) => TasKey.FromIndex(i)).ToArray();
-            for (int index = m_StartIndex; index <= m_EndIndex; index++) {
+            foreach (var frame in seq.BatchlyVisit(m_StartIndex, m_EndIndex)) {
-                // Fetch frame
-                var frame = seq.Visit(index);
                 // Do backup
-                frame.ToRawImplace(ref backups[index - m_StartIndex]);
+                frame.ToRawImplace(ref backups[backupIndex++]);
                 // Modify keys
                 foreach (var key in keys) {
                     switch (m_Kind) {
@@ -143,8 +143,9 @@ namespace BallanceTasEditor.Backend {
 
             // Index range is checked,
             // so we directly restore backup.
-            for (int index = m_StartIndex; index <= m_EndIndex; index++) {
+            int backupIndex = 0;
-                seq.Visit(index).FromRawImplace(m_FramesBackup[index - m_StartIndex]);
+            foreach (var frame in seq.BatchlyVisit(m_StartIndex, m_EndIndex)) {
+                frame.FromRawImplace(m_FramesBackup[backupIndex++]);
             }
 
             // Clear backups
@@ -197,12 +198,11 @@ namespace BallanceTasEditor.Backend {
             ArgumentOutOfRangeException.ThrowIfLessThan(m_StartIndex, 0);
 
             // Do backup and set values at the same time
+            int backupIndex = 0;
             var backups = new float[m_EndIndex - m_StartIndex + 1];
-            for (int index = m_StartIndex; index <= m_EndIndex; index++) {
+            foreach (var frame in seq.BatchlyVisit(m_StartIndex, m_EndIndex)) {
-                // Fetch frame
-                var frame = seq.Visit(index);
                 // Do backup
-                backups[index - m_StartIndex] = frame.GetTimeDelta();
+                backups[backupIndex++] = frame.GetTimeDelta();
                 // Modify delta time
                 frame.SetTimeDelta(m_DeltaTime);
             }
@@ -218,8 +218,9 @@ namespace BallanceTasEditor.Backend {
 
             // Index range is checked,
             // so we directly restore backup.
-            for (int index = m_StartIndex; index <= m_EndIndex; index++) {
+            int backupIndex = 0;
-                seq.Visit(index).SetTimeDelta(m_DeltaTimesBackup[index - m_StartIndex]);
+            foreach (var frame in seq.BatchlyVisit(m_StartIndex, m_EndIndex)) {
+                frame.SetTimeDelta(m_DeltaTimesBackup[backupIndex++]);
             }
 
             // Clear backups
@@ -259,9 +260,10 @@ namespace BallanceTasEditor.Backend {
             ArgumentOutOfRangeException.ThrowIfLessThan(m_StartIndex, 0);
 
             // Do backups
+            int backupIndex = 0;
             var backups = new RawTasFrame[m_EndIndex - m_StartIndex + 1];
-            for (int index = m_StartIndex; index <= m_EndIndex; index++) {
+            foreach (var frame in seq.BatchlyVisit(m_StartIndex, m_EndIndex)) {
-                seq.Visit(index).ToRawImplace(ref backups[index - m_StartIndex]);
+                frame.ToRawImplace(ref backups[backupIndex++]);
             }
             // Do remove
             seq.Remove(m_StartIndex, m_EndIndex);

BallanceTasEditor/BallanceTasEditor/Backend/TasSequence.cs

@@ -30,6 +30,21 @@ namespace BallanceTasEditor.Backend {
         /// <exception cref="IndexOutOfRangeException">给定的索引无效。</exception>
         TasFrame Visit(int index);
         /// <summary>
+        /// 按顺序访问给定索引区间内的帧的值。
+        /// </summary>
+        /// <remarks>
+        /// 实现此函数时需要格外注意以下事项：
+        /// <para/>
+        /// 该函数如果可以进行顺序访问优化，则应当优化。
+        /// 即使用此函数可以获得等于或大于单独一次使用<see cref="Visit(int)"/>函数。
+        /// <para/>
+        /// 该函数理论上的复杂度应为O(1)。
+        /// </remarks>
+        /// <param name="startIndex">要访问的帧区间的起始索引（包含）。</param>
+        /// <param name="endIndex">要访问的帧区间的终止索引（包含）</param>
+        /// <exception cref="IndexOutOfRangeException">给定的索引无效。</exception>
+        IExactSizeEnumerable<TasFrame> BatchlyVisit(int startIndex, int endIndex);
+        /// <summary>
         /// 在给定的帧索引<b>之前</b>插入给定的项目。
         /// </summary>
         /// <remarks>
@@ -93,6 +108,10 @@ namespace BallanceTasEditor.Backend {
             throw new NotImplementedException();
         }
 
+        public IExactSizeEnumerable<TasFrame> BatchlyVisit(int startIndex, int endIndex) {
+            throw new NotImplementedException();
+        }
+
         public void Insert(int index, IExactSizeEnumerable<TasFrame> items) {
             throw new NotImplementedException();
         }
@@ -120,6 +139,7 @@ namespace BallanceTasEditor.Backend {
         IEnumerator IEnumerable.GetEnumerator() {
             return GetEnumerator();
         }
+
     }
 
     /// <summary>
@@ -143,6 +163,21 @@ namespace BallanceTasEditor.Backend {
             }
         }
 
+        private IEnumerable<TasFrame> BatchlyVisitEx(int startIndex, int endIndex) {
+            if (endIndex < startIndex || startIndex < 0 || endIndex >= m_Container.Count) {
+                throw new IndexOutOfRangeException("Invalid index for frame.");
+            }
+
+            // Iterate items one by one.
+            for (int i = startIndex; i <= endIndex; ++i) {
+                yield return m_Container[i];
+            }
+        }
+
+        public IExactSizeEnumerable<TasFrame> BatchlyVisit(int startIndex, int endIndex) {
+            return new ExactSizeEnumerableAdapter<TasFrame>(BatchlyVisitEx(startIndex, endIndex), endIndex - startIndex + 1);
+        }
+
         public void Insert(int index, IExactSizeEnumerable<TasFrame> items) {
             if (index == m_Container.Count) {
                 m_Container.AddRange(items);
@@ -276,6 +311,29 @@ namespace BallanceTasEditor.Backend {
             }
         }
 
+        private IEnumerable<TasFrame> BatchlyVisitEx(int startIndex, int endIndex) {
+            if (endIndex < startIndex || startIndex < 0 || endIndex >= m_Container.Count) {
+                throw new IndexOutOfRangeException("Invalid index for frame.");
+            }
+
+            // We move to start index first.
+            MoveToIndex(startIndex);
+            // Then we copy its reference
+            LinkedListNode<TasFrame>? node = m_Cursor.Node;
+            // Then compute count
+            var count = endIndex - startIndex + 1;
+            // Now we can iterate items one by one.
+            for (int i = 0; i < count; ++i) {
+                node = node.Unwrap();
+                yield return node.Unwrap().Value;
+                node = node.Next;
+            }
+        }
+
+        public IExactSizeEnumerable<TasFrame> BatchlyVisit(int startIndex, int endIndex) {
+            return new ExactSizeEnumerableAdapter<TasFrame>(BatchlyVisitEx(startIndex, endIndex), endIndex - startIndex + 1);
+        }
+
         public void Insert(int index, IExactSizeEnumerable<TasFrame> items) {
             // YYC MARK:
             // We must test the equal first, to handle back appending properly.