added RcRentedArray (#41)

src/DotRecast.Core/Buffers/RcRentedArray.cs

@@ -0,0 +1,60 @@
+using System;
+using System.Buffers;
+using System.Runtime.CompilerServices;
+
+namespace DotRecast.Core.Buffers
+{
+    public static class RcRentedArray
+    {
+        public static RcRentedArray<T> RentDisposableArray<T>(int minimumLength)
+        {
+            var array = ArrayPool<T>.Shared.Rent(minimumLength);
+            return new RcRentedArray<T>(ArrayPool<T>.Shared, array, minimumLength);
+        }
+    }
+
+    public class RcRentedArray<T> : IDisposable
+    {
+        private ArrayPool<T> _owner;
+        private T[] _array;
+        private readonly RcAtomicInteger _disposed;
+
+        public int Length { get; }
+
+        internal RcRentedArray(ArrayPool<T> owner, T[] array, int length)
+        {
+            _owner = owner;
+            _array = array;
+            Length = length;
+            _disposed = new RcAtomicInteger(0);
+        }
+
+        public T this[int index]
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get
+            {
+                ThrowHelper.ThrowExceptionIfIndexOutOfRange(index, Length);
+                return _array[index];
+            }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            set
+            {
+                ThrowHelper.ThrowExceptionIfIndexOutOfRange(index, Length);
+                _array[index] = value;
+            }
+        }
+
+
+        public void Dispose()
+        {
+            if (1 != _disposed.IncrementAndGet())
+                return;
+
+            _owner?.Return(_array, true);
+            _array = null;
+            _owner = null;
+        }
+    }
+}

src/DotRecast.Core/Collections/RcStackArray128.cs

@@ -139,21 +139,12 @@ namespace DotRecast.Core.Collections
         public T V126;
         public T V127;
 
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void ThrowExceptionIfIndexOutOfRange(int index)
-        {
-            if (0 > index || index >= Size)
-            {
-                throw new IndexOutOfRangeException($"{index}");
-            }
-        }
-
         public T this[int index]
         {
             [MethodImpl(MethodImplOptions.AggressiveInlining)]
             get
             {
-                ThrowExceptionIfIndexOutOfRange(index);
+                ThrowHelper.ThrowExceptionIfIndexOutOfRange(index, Length);
 
                 return index switch
                 {
@@ -291,7 +282,7 @@ namespace DotRecast.Core.Collections
 
             set
             {
-                ThrowExceptionIfIndexOutOfRange(index);
+                ThrowHelper.ThrowExceptionIfIndexOutOfRange(index, Length);
 
                 switch (index)
                 {

src/DotRecast.Core/Collections/RcStackArray16.cs

@@ -27,22 +27,12 @@ namespace DotRecast.Core.Collections
         public T V14;
         public T V15;
         
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void ThrowExceptionIfIndexOutOfRange(int index)
-        {
-            if (0 > index || index >= Size)
-            {
-                throw new IndexOutOfRangeException($"{index}");
-            }
-        }
-
         public T this[int index]
         {
             [MethodImpl(MethodImplOptions.AggressiveInlining)]
             get
             {
-                ThrowExceptionIfIndexOutOfRange(index);
+                ThrowHelper.ThrowExceptionIfIndexOutOfRange(index, Length);
 
                 return index switch
                 {
@@ -68,7 +58,7 @@ namespace DotRecast.Core.Collections
 
             set
             {
-                ThrowExceptionIfIndexOutOfRange(index);
+                ThrowHelper.ThrowExceptionIfIndexOutOfRange(index, Length);
 
                 switch (index)
                 {

src/DotRecast.Core/Collections/RcStackArray256.cs

@@ -267,21 +267,12 @@ namespace DotRecast.Core.Collections
         public T V254;
         public T V255;
 
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void ThrowExceptionIfIndexOutOfRange(int index)
-        {
-            if (0 > index || index >= Size)
-            {
-                throw new IndexOutOfRangeException($"{index}");
-            }
-        }
-
         public T this[int index]
         {
             [MethodImpl(MethodImplOptions.AggressiveInlining)]
             get
             {
-                ThrowExceptionIfIndexOutOfRange(index);
+                ThrowHelper.ThrowExceptionIfIndexOutOfRange(index, Length);
 
                 return index switch
                 {
@@ -547,7 +538,7 @@ namespace DotRecast.Core.Collections
 
             set
             {
-                ThrowExceptionIfIndexOutOfRange(index);
+                ThrowHelper.ThrowExceptionIfIndexOutOfRange(index, Length);
 
                 switch (index)
                 {

src/DotRecast.Core/Collections/RcStackArray32.cs

@@ -43,21 +43,12 @@ namespace DotRecast.Core.Collections
         public T V30;
         public T V31;
 
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void ThrowExceptionIfIndexOutOfRange(int index)
-        {
-            if (0 > index || index >= Size)
-            {
-                throw new IndexOutOfRangeException($"{index}");
-            }
-        }
-
         public T this[int index]
         {
             [MethodImpl(MethodImplOptions.AggressiveInlining)]
             get
             {
-                ThrowExceptionIfIndexOutOfRange(index);
+                ThrowHelper.ThrowExceptionIfIndexOutOfRange(index, Length);
 
                 return index switch
                 {
@@ -99,7 +90,7 @@ namespace DotRecast.Core.Collections
 
             set
             {
-                ThrowExceptionIfIndexOutOfRange(index);
+                ThrowHelper.ThrowExceptionIfIndexOutOfRange(index, Length);
 
                 switch (index)
                 {

src/DotRecast.Core/Collections/RcStackArray512.cs

@@ -523,21 +523,12 @@ namespace DotRecast.Core.Collections
         public T V510;
         public T V511;
 
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void ThrowExceptionIfIndexOutOfRange(int index)
-        {
-            if (0 > index || index >= Size)
-            {
-                throw new IndexOutOfRangeException($"{index}");
-            }
-        }
-
         public T this[int index]
         {
             [MethodImpl(MethodImplOptions.AggressiveInlining)]
             get
             {
-                ThrowExceptionIfIndexOutOfRange(index);
+                ThrowHelper.ThrowExceptionIfIndexOutOfRange(index, Length);
 
                 return index switch
                 {
@@ -1060,7 +1051,7 @@ namespace DotRecast.Core.Collections
 
             set
             {
-                ThrowExceptionIfIndexOutOfRange(index);
+                ThrowHelper.ThrowExceptionIfIndexOutOfRange(index, Length);
 
                 switch (index)
                 {
@@ -1576,7 +1567,6 @@ namespace DotRecast.Core.Collections
                     case 509: V509 = value; break;
                     case 510: V510 = value; break;
                     case 511: V511 = value; break;
-                    
                 }
             }
         }

src/DotRecast.Core/Collections/RcStackArray64.cs

@@ -75,21 +75,12 @@ namespace DotRecast.Core.Collections
         public T V62;
         public T V63;
 
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void ThrowExceptionIfIndexOutOfRange(int index)
-        {
-            if (0 > index || index >= Size)
-            {
-                throw new IndexOutOfRangeException($"{index}");
-            }
-        }
-
         public T this[int index]
         {
             [MethodImpl(MethodImplOptions.AggressiveInlining)]
             get
             {
-                ThrowExceptionIfIndexOutOfRange(index);
+                ThrowHelper.ThrowExceptionIfIndexOutOfRange(index, Length);
 
                 return index switch
                 {
@@ -163,7 +154,7 @@ namespace DotRecast.Core.Collections
 
             set
             {
-                ThrowExceptionIfIndexOutOfRange(index);
+                ThrowHelper.ThrowExceptionIfIndexOutOfRange(index, Length);
 
                 switch (index)
                 {

test/DotRecast.Core.Test/RcRentedArrayTest.cs

@@ -0,0 +1,52 @@
+using System;
+using System.Collections.Generic;
+using DotRecast.Core.Buffers;
+using NUnit.Framework;
+
+namespace DotRecast.Core.Test;
+
+public class RcRentedArrayTest
+{
+    public List<int> RandomValues(int length)
+    {
+        var rand = new RcRand();
+
+        // excepted values
+        var list = new List<int>();
+        for (int i = 0; i < length; ++i)
+        {
+            list.Add(rand.NextInt32());
+        }
+
+        return list;
+    }
+
+    [Test]
+    public void Test()
+    {
+        var rand = new RcRand();
+        for (int loop = 0; loop < 1024; ++loop)
+        {
+            int length = (int)(rand.Next() * 2048);
+            var values = RandomValues(length);
+            using var array = RcRentedArray.RentDisposableArray<float>(length);
+
+            for (int i = 0; i < array.Length; ++i)
+            {
+                array[i] = values[i];
+            }
+
+            for (int i = 0; i < array.Length; ++i)
+            {
+                Assert.That(array[i], Is.EqualTo(values[i]));
+            }
+            
+            Assert.That(array[^1], Is.EqualTo(values[^1]));
+            
+            Assert.Throws<IndexOutOfRangeException>(() => array[-1] = 0);
+            Assert.Throws<IndexOutOfRangeException>(() => array[array.Length + 1] = 0);
+            Assert.Throws<IndexOutOfRangeException>(() => _ = array[-1]);
+            Assert.Throws<IndexOutOfRangeException>(() => _ = array[array.Length + 1]);
+        }
+    }
+}