更新Demo

更新Demo

UnityProject/Packages/UniTask/Runtime/Internal/ArrayUtil.cs

@@ -0,0 +1,73 @@
+#pragma warning disable CS1591 // Missing XML comment for publicly visible type or member
+
+using System;
+using System.Collections.Generic;
+using System.Runtime.CompilerServices;
+
+namespace Cysharp.Threading.Tasks.Internal
+{
+    internal static class ArrayUtil
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static void EnsureCapacity<T>(ref T[] array, int index)
+        {
+            if (array.Length <= index)
+            {
+                EnsureCore(ref array, index);
+            }
+        }
+
+        // rare case, no inlining.
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static void EnsureCore<T>(ref T[] array, int index)
+        {
+            var newSize = array.Length * 2;
+            var newArray = new T[(index < newSize) ? newSize : (index * 2)];
+            Array.Copy(array, 0, newArray, 0, array.Length);
+
+            array = newArray;
+        }
+
+        /// <summary>
+        /// Optimizing utility to avoid .ToArray() that creates buffer copy(cut to just size).
+        /// </summary>
+        public static (T[] array, int length) Materialize<T>(IEnumerable<T> source)
+        {
+            if (source is T[] array)
+            {
+                return (array, array.Length);
+            }
+
+            var defaultCount = 4;
+            if (source is ICollection<T> coll)
+            {
+                defaultCount = coll.Count;
+                var buffer = new T[defaultCount];
+                coll.CopyTo(buffer, 0);
+                return (buffer, defaultCount);
+            }
+            else if (source is IReadOnlyCollection<T> rcoll)
+            {
+                defaultCount = rcoll.Count;
+            }
+
+            if (defaultCount == 0)
+            {
+                return (Array.Empty<T>(), 0);
+            }
+
+            {
+                var index = 0;
+                var buffer = new T[defaultCount];
+                foreach (var item in source)
+                {
+                    EnsureCapacity(ref buffer, index);
+                    buffer[index++] = item;
+                }
+
+                return (buffer, index);
+            }
+        }
+    }
+}
+